Home Welcome Getting Started Conferences Authors

2002 Part 2     Front Cover (2002 - Part 2)    No author information available Summary: Not available         Table of Contents (2002 - Part 2)    No author information available Summary: Not available         Superconducting RF cavities: past, present and future    E. Chiaveri Summary: In the last two decades many laboratories around the world, notably Argonne (ANL), TJNAF (formerly CEBAF), CERN, DESY and KEK, undertook the development of the technology of superconducting (SC) accelerating cavities. The aim was either to increase the accelerator energy or to save electrical consumption or both. This technology has been used extensively in the operating machines showing good performances and strong reliability. At present, the technology using bulk niobium (Nb) or Nb coated on copper (Cu) is mature enough to be applied for many different applications, such as synchrotron light sources and spallation neutron drivers. Results, R&D work and future projects will be presented with emphasis on application to linear accelerators.         Superconducting RF cavities and a 1.9 K cooling system for a femtosecond light source    M.A. Green, J.N. Corlett and P. Ferracin Summary: The proposed femto-second light source consists of a re-circulating linac that delivers an electron beam to an arc of superconducting undulator magnets that deliver very short pulses of X-rays to materials science experiments. Superconducting RF cavities accelerate the electrons through the re-circulating linac. The design acceleration gradient for the 1300 MHz RF cavity system is 25 MV per meter. TESLA cavities operating in CW mode can provide this level of acceleration. This report presents the parameters of the proposed femto-second light source superconducting linac. Each nine-cell cavity will generate 44 W of AC loss at 1.9 K. The AC loss is added to the other losses in the accelerator cavity system. The superconducting RF cavity losses and linac refrigeration requirements are summarized in this report.         Design of a superconducting multipole wiggler for synchrotron radiation    C.S. Hwang, B. Wang, J.Y. Chen, R. Wahrer, C.H. Chang, T.C. Fan, F.Y. Lin, H.H. Chen, M.H. Huang and C.T. Chen Summary: A 32-pole superconducting magnet with a 12 /spl times/ 80 mm/sup 2/ cold bore aperture was designed to serve as a multipole wiggler in the Taiwan synchrotron light source. The magnet consists of 32 pairs of racetrack NbTi superconducting coils with a periodic length of 60 mm, and can produce a maximum magnetic field of 3.2 Tesla at a pole gap of 18 mm. The superconducting coils, the aluminum-supporting block, and the return iron yokes are cooled to 4.4 K in LHe bath. The temperature of cold bore beam duct will be at 70 K using liquid nitrogen. Technical issues concerning the design of the magnet and its construction are discussed. A prototype magnet with five poles was also constructed to characterize the magnet design by means of various methods of magnetic field measurement.         New concepts in transverse field magnet design    A.V. Gavrilin, M.D. Bird, V.E. Keilin and A.V. Dudarev Summary: The National High Magnetic Field Laboratory (NHMFL) in Tallahassee, Florida, USA, continues research and development of transverse field magnets (with the field perpendicular to the access tube). Presently, the emphasis is on a novel approach with concentric nested coils tilted at an angle to the central axis; current flows in opposite directions within the coils at opposite tilt angle, generating a transverse dipole field. Superconducting tilted coils using wire-wound technology and resistive tilted coils using advanced technology are being examined. Some very preliminary, conceptual designs and magnetic field calculations are presented. Related problems, including behavior under the Lorentz forces are discussed briefly.         First field measurements and performance tests of a superconductive undulator for light sources with a period length of 14 mm    A. Geisler, A. Hobl, D. Krischel, R. Rossmanith and M. Schillo Summary: Undulators in electron/positron accelerators are powerful sources of UV radiation and X-rays. The field-generating elements in classical undulators are either permanent magnets or electromagnets. For undulators with short periods, permanent magnets are used and the field strength (for a given period length and gap) is limited by the material properties. In this paper a novel concept is described which allows these limitations to be overcome by using an in-vacuo undulator with superconductive wires.         The LHC main dipoles and quadrupoles toward series production    L. Rossi Summary: The Large Hadron Collider (LHC) is under construction at CERN. Most of its 27 km underground tunnel will be filled with superconducting magnets, mainly 15 m long dipoles and 3.3 m long quadrupoles. In total 1248 dipole and 400 quadrupole magnets will be built (including spares), all wound with copper stabilized NbTi Rutherford cables and designed to operate in superfluid helium at 1.9 K. The dipoles operative field is 8.3 T, the system being designed for possible operation up to 9 T (ultimate field). The pre-series dipole production has started in 2000 in three companies while the series dipole construction will start at the beginning of 2003. As far as quadrupoles are concerned, the prototypal phase (carried out at CEA-Saclay, F) is followed directly by the series construction, started in March 2002. In the paper the magnet main characteristics are reviewed and the special tooling, put in place to fulfill the mass production with suitable accuracy and safety margin, is described. The results obtained on the first fifteen pre-series magnets as well as the effect of the corrective actions taken to meet the necessary field quality are discussed. Finally a realistic plan of the project, foreseeing that last dipoles are delivered in summer 2006, is presented.         Production status of the LHC inner triplet magnet system    J.S. Kerby Summary: The inner triplet magnet systems for the LHC provide the final focus of the two proton beams immediately before collision at the four interaction points in the machine. At both the high and low luminosity interaction regions, the quadrupole magnets composing the Q1 through Q3 optical elements are capable of operation at 215 T/m when cooled to 1.9 K, and subjected at the high luminosity interaction points to significant beam heating. The design and production of the system is the result of several years of international collaboration between laboratories and industries on three continents.         Performance of the first LHC pre-series superconducting dipoles    L. Bottura, D. Leroy, M. Modena, M. Pojer, P. Pugnat, L. Rossi, S. Sanfilippo, A. Siemko, J. Vlogaert, L. Walckiers and C. Wyss Summary: Within the LHC magnet program, a preseries production of final design, full-scale superconducting dipoles has presently started in industry and magnets are being tested at CERN. The main features of these magnets are: two-in-one structure, 56 mm aperture, six-block two layer coils wound from 15.1 mm wide graded NbTi cables, and all-polyimide insulation. This paper reviews the main test results of magnets tested to date in both supercritical and superfluid helium. The results of the quench training, conductor performance, magnet protection, sensitivity to ramp rate, and magnetic field quality are presented and discussed in terms of the design parameters and the aims of the LHC magnet program.         Persistent and coupling current effects in the LHC superconducting dipoles    S. Amet, L. Bottura, V. Granata, S. Le Naour, R.K. Mishra, L. Oberli, D. Richter, S. Sanfilippo, A. Verweij, L. Walckiers and R. Wolf Summary: One of the main issues for the operation of the LHC accelerator at CERN is the field errors generated by persistent and coupling currents in the main dipoles at injection conditions, i.e., 0.54 T dipole field. For this reason we are conducting systematic magnetic field measurements to quantify the above effects and compare them to the expected values from measurement on strands and cables. We discuss the results in terms of DC effects from persistent current magnetization, AC effects with short time constant from strand and cable coupling currents, and long-term decay during constant current excitation. Average and spread of the measured field errors over the population of magnets tested are as expected or smaller. Field decay at injection, and subsequent snap-back, show for the moment the largest variation from magnet to magnet, with weak correlation to parameters that can be controlled during production. For this reason these effects are likely to result in the largest spread of field errors over the whole dipole production.         Field measurement of Fermilab-built quadrupole magnets for the LHC interaction regions    R. Bossert, R. Carcagno, J. DiMarco, S. Feher, H. Glass, V.V. Kashikhin, J. Kerby, M.J. Lamm, A. Nobrega, D. Orris, R. Rabehl, G. Sabbi, P. Schlabach, J. Strait, C. Sylvester, M. Tartaglia, J.C. Tompkins, G. Velev and A.V. Zlobin Summary: Superconducting low-beta quadrupole magnets for the interaction regions of the Large Hadron Collider have been developed by the US-LHC Accelerator Project. These 70 mm bore 5.5 m quadrupole magnets are intended to operate in superfluid helium at 1.9 K with a nominal field gradient of 215 T/m. Fabrication and testing of these magnets has begun at Fermilab. Magnetic field measurements of the first magnets produced are described and compared with results from prototype magnets as well as with requirements set by machine performance studies.         Mechanical characteristics of the ATLAS B0 model coil    A. Foussat, N. Dolgetta, A. Dudarev, C. Mayri, P. Miele, Z. Sun, H.H.J. Ten Kate and G. Volpini Summary: The ATLAS B0 model coil has been tested at CERN to verify the design parameters of the Barrel Toroid coils (BT). The mechanical behavior of the B0 superconducting coil and its support structure is reported and compared with coil design calculations. The mechanical stresses and structural force levels during cooling down and excitation phases were monitored using strain gauges, position sensors and capacitive force transducers instrumentation. In the ATLAS magnet test facility, a magnetic mirror is used to reproduce the electromagnetic forces present in the BT coils, once these are assembled in toroid in the underground cavern in 2004.         Bucket testing of a compact sweeper magnet for nuclear physics    M.D. Bird, I.R. Dixon, A.V. Gavrilin, J. Toth and A. Zeller Summary: A superconducting dipole, designed for use as a sweeper magnet for nuclear physics experiments, is being constructed by the National High Magnetic Field Laboratory for operation at the National Superconducting Cyclotron Laboratory (NSCL). The magnet consists of two D-shaped NbTi coils and will operate at at a peak mid-plane field of 3.95 T in a gap of 140 mm. Peak field on the conductor will be 6.25 T. The winding pack current density is 143 A/mm2. A multi-particle beam will enter the magnet from the upstream side. The neutrons continue straight through to a neutron detector. The charged particles will be swept 43 degrees on a one meter radius into a mass spectrometer. Status of manufacturing and results of single-coil tests are presented.         Performance comparison of Nb/sub 3/Sn magnets at LBNL    L. Chiesa, S. Caspi, M. Coccoli, D.R. Dietderich, P. Ferracin, S.A. Gourlay, R.R. Hafalia, A.F. Lietzke, A.D. McInturff, G. Sabbi and R.M. Scanlan Summary: The Superconducting Magnet group at Lawrence Berkeley National Laboratory has been successfully developing Nb/sub 3/Sn high-field dipole magnet technology for the last ten years. Noteworthy magnet tests include D20 (50 mm bore, 4-layer cos /spl theta/, 12.8 T, accelerator quality dipole), and recent racetrack dipoles: 1) RT1 (2-layer, 12 T, no bore, no training), 2) RD3b (3-layer, 14.7 T, 10 mm bore), 3) RD3c (3-layer, 10 T, low-harmonics 35 mm bore), and 4) some small Nb/sub 3/Sn magnets that utilized new technology. The performance of these magnets is summarized, comparing 1) cable and magnet geometry parameters, 2) training behavior, 3) ramp rate sensitivity, 4) RRR measurements, 5) peak temperatures and voltages, and 6) fast flux adjustments that occur during ramping.         An approach for faster high field magnet technology development    R.R. Hafalia, S. Caspi, L. Chiesa, M. Coccoli, D.R. Dietderich, S.A. Gourlay, A.F. Lietzke, J.W. O'Neill, G. Sabbi and R.M. Scanlan Summary: The Superconducting Magnet Program at LBNL has developed a magnet design supporting our new Subscale Magnet Program, that facilitates rapid testing of small superconducting racetrack coils in the field range of 10-12 Tesla. Several coils have been made from a variety of Nb/sub 3/Sn/Cu cables, insulated, wound, reacted, potted and assembled into a small reusable yoke and shell loading structure. Bladder and key technology have provided a rapid and efficient means for adjusting coil pre-stress during both initial assembly, and between thermal cycles. This affords the opportunity to test moderately long rectangular cable samples under "magnet conditions" on a time scale considerably closer to that for traditional short-sample cable tests. We have built and tested four coils with the initial aim of determining the feasibility of reducing overall conductor costs with "mixed-strand" cables. Details of cost reduction improvements, coil construction, magnet structure, and assembly procedures are reported, along with the relative performance of the mixed-strand coil.         Nb/sub 3/Sn quadrupole magnets for the LHC IR    G. Sabbi, S. Caspi, L. Chiesa, M. Coccoli, D.R. Dietderich, P. Ferracin, S.A. Gourlay, R.R. Hafalia, A.F. Lietzke, A.D. McInturff and R.M. Scanlan Summary: The development of insertion quadrupoles with 205 T/m gradient and 90 mm bore represents a promising strategy to achieve the ultimate luminosity goal of 2.5 /spl times/ 10/sup 34/ cm/sup -2/s/sup -1/ at the Large Hadron Collider (LHC). At present, Nb/sub 3/Sn is the only practical conductor which can meet these requirements. Since Nb/sub 3/Sn is brittle, and considerably more strain sensitive than NbTi, the design concepts and fabrication techniques developed for NbTi magnets need to be modified appropriately. In addition, IR magnets must provide high field quality and operate reliably under severe radiation loads. The results of conceptual design studies addressing these issues are presented.         Conceptual design study of Nb/sub 3/Sn low-beta quadrupoles for 2nd generation LHC IRs    A.V. Zlobin, G. Ambrosio, N. Andreev, E. Barzi, P. Bauer, D. Chichili, Y. Huang, L. Imbasciati, V.V. Kashikhin, M. Lamm, P. Limon, I. Novitski, T. Peterson, J.B. Strait, S. Yadav and R. Yamada Summary: Conceptual designs of 90-mm aperture high-gradient quadrupoles based on the Nb/sub 3/Sn superconductor, are being developed at Fermilab for possible 2nd generation IRs with the similar optics as in the current low-beta insertions. Magnet designs and results of magnetic, mechanical, thermal and quench protection analysis for these magnets are presented and discussed.         Passive correction of the persistent current effect in Nb/sub 3/Sn accelerator magnets    V.V. Kashikhin, E. Barzi, D. Chichili, J. DiMarco, M. Lamm, P. Schlabach and A.V. Zlobin Summary: Superconducting accelerator magnets must provide a uniform field during operation. However, the field quality significantly deteriorates due to persistent currents induced in superconducting filaments. This effect is especially large for the Nb/sub 3/Sn conductor being implemented in the next generation of accelerator magnets. A simple and inexpensive method of passive correction of the persistent current effect was developed and experimentally verified. This paper describes numerical simulations of the passive correctors and reports the test results.         Superconducting current transformer for testing Nb/sub 3/Sn cable splicing technique    N. Andreev, E. Barzi, S. Bhashyam, C. Boffo, D.R. Chichili, S. Yadav, I. Terechkine and A.V. Zlobin Summary: To provide a quick feedback on different approaches to superconducting cable splicing design and assembly techniques, a superconducting current transformer that can deliver more than 20 kA for testing splice samples was designed and fabricated. The existing infrastructure of the Short Sample Test Facility at Fermilab, including its cryostat, power supply, and data acquisition system, was used for housing and operating the transformer. This report presents the design features of the transformer and the main results of cable splice tests.         Nb/sub 3/Sn accelerator magnet development around the world    M.J. Lamm Summary: During the past 30 years superconducting magnet systems have enabled accelerators to achieve energies and luminosities that would have been impractical if not impossible with resistive magnets. By far, NbTi has been the preferred conductor for this application because of its ductility and insensitivity of Jc to mechanical strain. This is despite the fact that Nb/sub 3/Sn has a more favorable Jc vs. B dependence and can operate at much higher temperatures. Unfortunately, NbTi conductor is reaching the limit of it usefulness for high field applications. Despite incremental increases in Jc and operation at superfluid temperatures, magnets are limited to approximately a 10 T field. Improvements in conductor performance combined with future requirements for accelerator magnets to have bore fields greater than 10 T or operate in areas of large beam-induced heat loads now make Nb/sub 3/Sn look attractive. Thus, laboratories in several countries are actively engaged in programs to develop Nb/sub 3/Sn accelerator magnets for future accelerator applications. A summary of this important research activity is presented along with a brief history of Nb/sub 3/Sn accelerator magnet development and a discussion of requirements for future accelerator magnets.         Fabrication and test of a racetrack magnet using pre-reacted Nb/sub 3/Sn cable    G. Ambrosio, N. Andreev, E. Barzi, P. Bauer, S. Bhashyam, R. Carcagno, D. Chichili, K. Ewald, S. Feher, L. Imbasciati, P. Limon, M. Lamm, I. Novitski, D. Orris, Y. Pischalnikov, C. Sylvester, M. Tartaglia, J. Tompkins and A.V. Zlobin Summary: A racetrack magnet, using Nb/sub 3/Sn superconducting cable reacted before winding, has been fabricated and tested at Fermilab. It consists of two flat racetrack coils, connected in a common-coil configuration, separated by a 5 mm thick fiberglass plate. Synthetic oil was used to prevent sintering of the strands during the heat treatment. The coils were wound and vacuum impregnated in the mechanical structure. The turn-to-turn insulation, consisting of Kapton/spl reg/ and pre-impregnated fiberglass tapes as wide as the cable, was wound together with the bare cable in order to form a continuous inter-turn spacer. The coils were instrumented with voltage taps, temperature sensors, spot heaters and quench heaters. The maximum current achieved was 12675A which is 78% of the short sample limit at 5.1 K (minimum temperature in the coil during 75 A/s ramp). Measurement of the temperature margin revealed a low degradation in the innermost turns. Quench performances at different temperatures and ramp rate effects have been measured and are presented and discussed.         Conductor related design considerations for a 1 meter 10 T Nb/sub 3/Sn dipole magnet    A. den Ouden, W.A.J. Wessel, H.J.G. Krooshoop, H. van Weeren, H.H.J. Ten Kate, G.A. Kirby, R. Ostojic, T. Taylor and N. Siegel Summary: A single-bore 1 meter long 10 T Nb/sub 3/Sn dipole magnet with a 88 mm bore is being developed. Based on powder-in-tube (PIT) Nb/sub 3/Sn strands exhibiting 22 /spl mu/m thick filaments, a Rutherford-type cable with a stainless steel core of 25 micron is employed. All properties relevant for magnet design and operation like critical current, filament magnetization and coupling current control have been investigated experimentally. Their impact on magnet operation is discussed. The effectiveness and reliability of a quench protection system for Nb/sub 3/Sn accelerator magnets relies mainly on the normal zone propagation properties and properly designed and positioned protection heaters. We present measurements and calculations of propagation properties and discuss the consequences for protection heater design.         Test results of RD3c, a Nb/sub 3/Sn common-coil racetrack dipole magnet    A.F. Lietzke, S. Caspi, L. Chiesa, M. Coccoli, D.R. Dietderich, P. Ferracin, S.A. Gourlay, R.R. Hafalia, A.D. McInturff, G. Sabbi and R.M. Scanlan Summary: The superconducting magnet group at Lawrence Berkeley National Laboratory has been developing racetrack coil technology for economical, high-field accelerator magnets from brittle superconductor. Recent tests have demonstrated 1) robust, reusable, double-layer, flat racetrack, wind and react Nb/sub 3/Sn coils, 2) a reusable, easily assembled coil-support structure that can minimize conductor movement and 3) nearly 15 T dipole fields, without conductor degradation. RD3c was our first attempt to compare measured and calculated field harmonics. A single-layer, Nb/sub 3/Sn, flat racetrack inner-coil was wound on both sides of a bore-plate and reacted and encapsulated (as before in RD3b). Hard coil-spacers were wound into the inner coils to adjust the geometric field harmonics and identify any problems from hard-spacers. The resulting insert coil-module was sandwiched between existing outer-coil modules, and pre-stressed within the previous yoke and shell structure. The bore-plate was thick enough to protect the rotating coil and its anti-cryostat from this pre-stress. Magnet training started at 77% of the un-degraded short-sample current, and progressed in 15 quenches to 92%, high enough to make realistic, saturated iron magnetic measurements. Although there was considerable training, the multipole dependencies correlated well with calculations. A sub-set of the tests are reported and discussed.         Construction experience with MQXB quadrupole magnets built at Fermilab for the LHC interaction regions    R. Bossert, J. Kerby, F. Nobrega, M.J. Lamm, J. Rife, S. Feher, W. Robotham, P. Schlabach, S. Yadav and A.B. Zlobin Summary: Fermilab is building eighteen full length cold masses for the LHC Interaction Region inner triplets. One prototype and several production assemblies have been completed. This paper summarizes the construction details. Topics include coil fabrication, ground insulation, collaring, instrumentation, electrical testing, and final assembly. In-process measurements are presented and explained. Problems encountered during construction and their solutions are discussed.         Splice testing for LHC quadrupole magnets    E. Barzi, R. Bossert, S. Feher, J. Kerby, V.V. Kashikhin, M.J. Lamm, D. Orris, G. Ray, M. Tartaglia and A.V. Zlobin Summary: Electrical splices between NbTi Rutherford type cables need to be made for the LHC IR inner triplet quadrupoles. Splices between magnets as well as internal to the magnets are necessary. Various splice configurations, solders, and fluxes have been considered. Testing of these splices at cryogenic temperatures and at various currents has been completed. The results were satisfactory; Fermilab is capable of making excellent low resistance (<1n/spl Omega/) solder joints for the LHC project.         A method to determine the flexural rigidity of the main dipole for the Large Hadron Collider    M. La China, G. Cavallari, P. Ferracin, J.G. Perez, E. Todesco and W. Scandale Summary: The Large Hadron Collider (LHC) superconducting dipole cold mass is a cylindrical structure 15 m long, made of a shrinking cylinder which contains iron laminations and collared coils. This structure, weighing about 28 tons, is horizontally bent by 5 mrad. Its shape should be preserved from the assembly phase to the operational condition at cryogenic temperature. Hence, an accurate comprehension of the mechanical behavior of the cold mass is required. In particular, the flexural rigidity in both horizontal and vertical directions represents one of the foremost properties. To determine the flexural rigidity, deformations of the cold mass induced by the self weight have been measured and compared with the predictions of an analytical structural model. Particular care has been taken in reducing the experimental error by an appropriate fitting procedure.         Performance of the final prototype of the 6-kA matching quadrupoles for the LHC insertions and status of the industrialization program    J. Lucas, R. Ostojic, D. Tommasini, W.V. Delsolaro and D. Landgrebe Summary: The LHC insertions will be equipped with individually powered superconducting quadrupoles, which have a coil aperture of 56 mm, and operate at a nominal gradient of 200 T/m at 1.9 K and a current of 6 kA. Three versions of the magnet are required for the LHC, with magnetic lengths of 2.4 m, 3.4 m and 4.8 m, but otherwise identical. After a prototype program which validated the design options, the contract for the fabrication of one hundred magnets was adjudicated to European industry. In this report we describe the main construction features of the magnets, present the performance of the final prototype, and give the status of the industrial fabrication program.         Test results of a variant-design LHC twin-aperture dipole magnet    C. Giloux, R. Mompo, A. Siemko, T.M. Taylor, W.V. Delsolaro, L. Walckiers, A. Yamamoto, T. Shintomi, T. Nakamoto, N. Ohuchi, T. Ogitsu and K. Tsuchiya Summary: Since 1989, KEK and CERN carried out jointly an experimental program in the frame of the R&D work for the LHC main dipole. The mechanical structure of this design is based on a separate coil/collar and "horizontally split iron" concept. A total of four single aperture and two twin-aperture 1 m long dipole magnets were built. The last twin-aperture magnet was tested at CERN, reaching a maximum field of 9.55 T at 1.9 K. This paper reports the magnet training performance and quench localization at 1.9 K and 4.5 K. The performance as a function of current ramp rate and measurements of the field quality are also reported.         Time dependence of magnetic periodic patterns measured on the MQXA magnets for the LHC-IR    K. Sugita, T. Ogitsu, T. Nakamoto, N. Ohuchi, T. Shintomi, K. Tsuchiya and A. Yamamoto Summary: Superconducting quadrupole magnets for the LHC-IR have been developed and tested by KEK in collaboration with CERN. Magnetic field measurements of the magnets were performed. The magnets satisfy the requirements for the accelerator operation. In addition to the field quality measurements, fine structures of the magnetic field along the magnet axis were measured at the beam injection current using a 25 mm long rotating harmonic coil. Periodic patterns of the magnetic field were observed in higher order multipole coefficients. The pitch of the periodic patterns is equal to the cable twist pitch. The time dependent change of the amplitude of the periodic pattern was also observed. In this paper, the measurement and results are reported.         Production and performance of the LHC interaction region quadrupoles at KEK    T. Nakamoto, Y. Ajima, T. Fujii, E. Hashiguchi, N. Higashi, H. Hirano, M. Iida, T. Kanahara, N. Kimura, S. Murai, W. Odajima, T. Ogitsu, H. Ohhata, N. Ohuchi, T. Orikasa, T. Shintomi, S. Sugawara, K. Sugita, K. Tanaka, A. Terashima, K. Tsuchiya and A. Yamamoto Summary: The MQXA superconducting low-beta quadrupole magnets for the LHC interaction regions are required to generate a field gradient of up to 215 T/m at 1.9 K along an effective magnetic length of 6.37 m. After completion of an R&D program on short models and full length prototypes, the series production of magnets has started, with to date five series magnets subsequently tested at KEK. Basic characteristics such as normal training, subsequent full energy dump, thermal cycle, ramp rate dependence and temperature dependence have been studied and results indicate that magnets have satisfactory quench performance. Magnetic field measurements performed at 1.9 K show the field quality to be uniform and to satisfy the stringent beam optics requirements.         Alignment of production quadrupole magnets for the LHC interaction regions    J. DiMarco, H. Glass, J. Kerby, M.J. Lamm, T. Nicol, T. Page, P. Schlabach, C. Sylvester, J.C. Tompkins and G. Velev Summary: Production has started for the high-gradient superconducting quadrupole magnets developed by the US LHC Accelerator Project for the Interaction Regions of the Large Hadron Collider. The first full-scale Q2 assembly has recently been measured during fabrication at Fermilab. This paper reports on the mechanical alignment processes used during production of the combined cold-mass assembly and during its installation in the cryostat, and the validation of these processes in meeting accelerator requirements. Also presented are the results of measurements of the field axis and roll angle of the completed magnet assembly. Results are compared to machine performance requirements.         Superconducting magnets for the "International Accelerator Facility for Beams of Ions and Antiprotons" at GSI    G. Moritz Summary: The concept for GSI's planned future facility is based on two superconducting synchrotrons, SIS 100 and SIS 200. The two accelerators are in the same tunnel and have the same radius R, for operation at BR=100 Tm and 200 Tm respectively. Superconducting magnets are necessary to reach the appropriate magnetic field and may considerably reduce the investment and operating costs, in comparison with conventional magnets. An R&D program was initiated to develop dipole magnets with maximum fields of 2 and 4 Tesla and dipole ramp rates of 4 T/s and 1 T/s, respectively. These requirements were chosen to achieve high average beam intensities. The SIS 100 dipole is a window-frame Nuclotron-type dipole and is being developed in collaboration with JINR (Dubna, Russia). This magnet has been operated at 4 T/s up to a field of 2 Tesla. Reduced losses and improved magnetic field quality are required for the SIS 100 accelerator. In a separate collaboration with BNL (Upton, USA), the one coil layer cos/spl theta/-type RHIC arc dipole, originally designed for operation at 3.5 Tesla with a rather slow ramp rate of 0.042 T/s, will be upgraded for the SIS 200 accelerator to operate at a ramp rate of 1T/s, up to a field of 4 T. R&D for a 6 Tesla dipole was started in collaboration with IHEP (Protvino, Russia), to further increase the rigidity of the SIS 200 ring to 300 Tm. Alternative schemes have been investigated. Besides the synchrotrons, the planned facility will consist of several storage rings and the Super Fragment Separator (SFRS), which have mainly DC magnets with large apertures. NSCL (East Lansing, USA) prepared a feasibility study for these superconducting magnets. The main results of the R&D are presented.         Superferric model dipole magnet with the yoke at 80 K for the GSI future fast cycling synchrotron    A. Kovalenko, N. Agapov, S. Averichev, A. Donyagin, H. Khodzhibagiyan, G. Kuznetsov, A. Starikov, E. Fischer, G. Hess, G. Moritz and C. Muehle Summary: Experimental data of a fast cycling (f=1 Hz) 2T dipole magnet based on a superconducting NbTi multi filament hollow cable cooled with forced two phase helium flow at T=4.5K and iron yoke at T=80 K are presented. A new magnet design is proposed. The magnet yoke made of laminated steel consists of two parts: the internal smaller part has close mechanical and thermal contact with the coil while the outer part is separated from the cold mass with a gap of 1 mm and cooled with liquid nitrogen.         Superferric magnets for the proposed international accelerator facility at GSI    A.F. Zeller, J.C. DeKamp, G. Moritz, C. Muhle, M. Winkler and B. Langenbeck Summary: The proposed International Accelerator Facility at Gesellschaft fur Schwerionenforschung (GSI) has several new experimental devices that may require superconducting magnets to provide the required magnetic fields. Superferric magnets have been designed that allow the production of the required high gradients in the large aperture quadrupoles and also allow the insertion of sextupole and octupole inserts. Dipoles have been designed that fulfill the field uniformity and radiation resistance requirements. Most of the magnets are static field, but the New Experimental Storage Ring (NESR) needs magnets that ramp at 1 T/s. Solutions are presented that use warm iron to reduce losses.         The Advanced Hydrotest Facility (AHF) large bore quadrupole focusing magnet system    J.H. Schultz, T. Antaya, J.V. Minervini, A.L. Radovinsky, B.A. Smith, R.J. Camille Jr., R.L. Myatt, A. Jason, P. Walstrom and J.A. Waynert Summary: The Advanced Hydrotest Facility (AHF) at Los Alamos will provide proton radiography of large-scale, dynamic events. The large bore (Case II) quadrupole focusing magnets are a subsystem in this facility, consisting of four complete imaging lines with a total of eight imaging plates and 52 quadrupole magnets. Each large bore quadrupole has an inner winding diameter of 660 mm and provides a gradient of 10.4 T/m with a 300 mm field of view. Each magnet is a two-layer saddle, contained by a three cm steel shell. The conductor is a Rutherford cable, soldered into a C-shaped copper channel. The magnets are cooled by the forced-flow of two-phase helium through coolant pipes. Since the winding was calculated to absorb bursts of 0.35 J/kg irradiation, both NbTi and Nb/sub 3/Sn designs are being considered.         Magnet engineering and test results of the high field magnet R&D program at BNL    J. Cozzolino, M. Anerella, J. Escallier, G. Ganetis, A. Ghosh, R. Gupta, M. Harrison, A. Jain, A. Marone, J. Muratore, B. Parker, W. Sampson, R. Soika and P. Wanderer Summary: The Superconducting Magnet Division at Brookhaven National Laboratory (BNL) has been carrying out design, engineering, and technology development of high performance magnets for future accelerators. High Temperature Superconductors (HTS) play a major role in the BNL vision of a few high performance interaction region (IR) magnets that would be placed in a machine about ten years from now. This paper presents the engineering design of a "react and wind" Nb/sub 3/Sn magnet that will provide a 12 Tesla background field on HTS coils. In addition, the coil production tooling as well as the most recent 10-turn R&D coil test results will be discussed.         Next generation IR magnets for hadron colliders    R. Gupta, M. Anerella, J. Cozzolino, J. Escallier, G. Ganetis, M. Harrison and P. Wanderer Summary: Brookhaven National Laboratory (BNL) is developing "React & Wind" designs and technology for building long high field accelerator magnets. This paper presents the R&D program for interaction region (IR) magnets made with "Rutherford" cable for the luminosity upgrade of the Large Hadron Collider (LHC). This paper will introduce a few new end design concepts that make the bend radius of the cable in the end independent of the coil aperture. These designs are suitable for building magnets with "React & Wind" technology.         Construction of block-coil high-field model dipoles for future hadron colliders    R. Blackburn, T. Elliott, W. Henchel, A. McInturff, P. McIntyre and A. Sattarov Summary: A family of high-field dipoles is being developed at Texas A&M University, as part of the program to improve the cost-effectiveness of superconducting magnet technology for future hadron colliders. The TAMU technology employs stress management, flux-plate control of persistent-current multipoles, conductor optimization using mixed-strand cable, and metal-filled bladders to provide pre-load and surface compliance. Construction details and status of the latest model dipole will be presented.         Superconducting sector magnets for a flux-coupled isochronous cyclotron stack    P. McIntyre and A. Sattarov Summary: A flux-coupled stack of 800 MeV isochronous cyclotrons is being designed as a basis for accelerator-driven thorium-cycle fission power. The sector magnet consists of a stack of independently suspended cold-iron cores (each with its superconducting coil closely coupled), and a warm-iron flux return that contains and supports the stack of cores. This design makes it feasible to provide multiple independent cyclotrons within a common, compact structure.         Magnetic design of large-bore superconducting quadrupoles for the AHF    N. Andreev, A. Jason, V.S. Kashikhin, V.V. Kashikhin, P.J. Limon, J. Tompkins and P. Walstrom Summary: The Advanced Hydrotest Facility (AHF), under study by LANL, utilizes large-bore superconducting quadrupole magnets to image protons for radiography of fast events. The lens system uses two types of quadrupoles: a large bore (48-cm beam aperture) for wide field of view imaging and a smaller bore (23 cm aperture) for higher resolution images. The gradients of the magnets are 10.14 T/m and 18.58 T/m with magnetic lengths of 4.3 m and 3.0 m, respectively. The magnets are sufficiently novel to present a design challenge. Evaluation and comparisons were made for various types of magnet design: shell and racetrack coils, cold and warm iron, as well as an active superconducting shield. Nb/sub 3/Sn cable was considered as an alternative to NbTi to avoid quenching under high beam-scattering conditions. Several options are discussed and compared.         The double-helix dipole - a novel approach to accelerator magnet design    C.L. Goodzeit, M.J. Ball and R.B. Meinke Summary: We describe a new technology for superconducting dipoles that has significant advantages for use in particle accelerators. The dipole field is obtained by using concentric pairs of helically-wound coils that are tilted at opposite angles; this effectively cancels the solenoid component of the field and adds the dipole content of each layer. This coil configuration produces a dipole field with systematic errors <10/sup -8/ of the main field in 85% of the coil aperture. We show, using a design example, how many of the inherent problems with the traditional cosine theta type of coil are eliminated and the cost of development and manufacturing the magnets is substantially reduced.         Modulated double-helix quadrupole magnets    R.B. Meinke, C.L. Goodzeit and M.J. Ball Summary: We describe a new technology for superconducting quadrupole magnets especially for use in particle accelerators. The principle is based on the application of a sinusoidal modulation to the axial positions of the conductor windings in solenoids. The method can also be employed to produce higher-order multipole fields. Due to their solenoid-like geometry, these coils are significantly simpler to manufacture than standard (racetrack) cosine-2-theta coils and have significantly smaller systematic field errors without using any field-shaping spacers. When two complementary coil layers (with opposite current flow) are combined, the solenoid components of the fields are cancelled and the quadrupole or higher-order fields add. An example of such a design is described which generates a gradient of 130 T/m with systematic errors less than 10/sup -8/ at 67% of the aperture.         Superconducting solenoids for an international muon cooling experiment    M.A. Green and J.M. Rey Summary: The international muon ionization cooling experiment MICE will consist of two focusing cooling cells and a pair of uniform field solenoids used for particle identification and emittance measurements. The 2.75-meter long cooling cells have a pair of field flip coils and a coupling coil. The 0.52-meter diameter field flip coils surround an absorber that removes transverse and longitudinal momentum from the muons to be cooled. The beam in the absorber is at a minimum beta point so that scattering of the muons is minimized. The 1.7-meter diameter coupling coils are outside of conventional 201.25 MHz RF cavities that accelerate the muons putting longitudinal momentum into the muons without putting back the transverse momentum into the beam. A third set of flip coils helps the muon beam transition from and to the experimental solenoids. The 0.6-meter diameter experimental solenoids have a uniform field region (good to about 1 part in 1000) that is 1.3-meters long. The MICE experiment magnets must operate as a single unit so that the field profile will produce the maximum muon cooling.         Superconducting magnet systems for the muon-electron conversion experiment    B.A. Smith, A. Radovinsky, P.H. Titus, J.L. Smith, J.G. Brisson, J.V. Minervini, J.H. Schultz, R.J. Camille Jr., W.R. Molzon, M. Hebert, T.J. Liu and W.V. Hassenzahl Summary: The Muon-to-Electron Conversion Experiment (MECO) seeks to detect muon to electron conversion, providing evidence that the conservation of muon and electron type lepton number can be violated. Observation of this violation would suggest physics beyond the Standard Model. The experiment is to be installed at Brookhaven National Laboratory (BNL). A high energy proton beam produces pions upon hitting a heavy target inside the 1.5 m diameter by 5 m long Production Solenoid (PS). A fraction of the muons from pion decay are captured in the 0.5 m diameter bore by the 13 m long, S-shaped Transport Solenoid (TS), which contains collimators, providing sign and momentum selection. The muons are stopped in a target inside a 1.9 m bore by 10 m long Detector Solenoid (DS) that houses detectors to measure the energy of the conversion electrons. Magnetic field is controlled to 5 T /spl plusmn/5% at the high-field end of the PS and to 1 T /spl plusmn/0.2% in the detector region of the DS. The conceptual design for the magnets is summarized, including conductor, coil, structure and cryogenic design.         Cryogenic system for a large superconducting magnet in space    S.M. Harrison, E. Ettlinger, G. Kaiser, B. Blau, H. Hofer, I.L. Horvath, S.C.C. Ting, J. Ulbricht and G. Viertel Summary: The Alpha Magnetic Spectrometer (AMS) is a particle physics experiment for use on the International Space Station (ISS). At the heart of the detector will be a large superconducting magnet cooled to a temperature of 1.8 K by 2500 liters of superfluid helium. The magnet and cryogenic system are currently under construction by Space Cryomagnetics Ltd of Culham, England. This paper describes the cryogenic system for the magnet, designed for the unusual challenges of operating a superconducting system in space. Results from experiments demonstrating some of the new techniques and devices developed for the magnet cryogenics are also presented.         The NHMFL 45-T hybrid magnet system: past, present, and future    J.R. Miller Summary: A hybrid magnet system, combining superconducting and resistive magnet technologies for the production of 45-T steady field in a 32-mm room-temperature bore, has been operated successfully as a user facility for the past two years at the National High Magnetic Field Laboratory in Tallahassee, Florida. The superconducting outsert is a 710-mm bore magnet with demonstrated capability for 100-MJ stored energy, over 14-T field on axis, and nearly 16-T maximum field at the windings. This system continues to provide to researchers the highest steady field available anywhere in the world, even after degradation of the superconducting outsert, which resulted from an "unprotected" quench in July 2000. This paper reviews the important specifications and design features for the superconducting outsert, its nearly 3-year history of operation, as well as plans for its repair and future upgrades.         Operation of a 920-MHz high-resolution NMR magnet at TML    T. Kiyoshi, M. Yoshikawa, A. Sato, K. Itoh, S. Matsumoto, H. Wada, S. Ito, T. Miki, T. Miyazaki, T. Kamikado, O. Ozaki, T. Hase, M. Hamada, S. Hayashi, Y. Kawate and R. Hirose Summary: As a milestone in the 1-GHz NMR magnet project that is being carried out at the Tsukuba Magnet Laboratory (TML), a 920-MHz high-resolution NMR magnet was successfully manufactured. It is made of 15%Sn-bronze-processed (Nb, Ti)/sub 3/Sn, Ta-reinforced (Nb, Ti)/sub 3/Sn, and NbTi conductors. The room-temperature bore of the cryostat is 54 mm in diameter. All the coils are cooled with pressurized superfluid helium at 1.55 K. The magnet was moved to a new building of the TML in December 2001. A persistent operation at 920 MHz started in April 2002. The field homogeneity after correcting with superconducting shim coils was less than 0.1 ppm in a sample volume. Field decay decreased to below 1.3 Hz/h at the beginning of July. NMR measurements using this magnet started in July.         Development of a 5 T HTS insert magnet as part of 25 T class magnets    H.W. Weijers, Y.S. Hascicek, K. Marken, A. Mbaruku, M. Meinesz, H. Miao, S.H. Thompson, F. Trillaud, U.P. Trociewitz and J. Schwartz Summary: The development of a 25 T superconducting magnet is usually envisioned with the use of an HTS insert coil. Previously, we reported the successful development of a 3 T coil in a 19 T background field based on BSCCO 2212 conductor. Here we report on the progress toward a larger 5 T insert with 38 mm free bore. The design is introduced, which calls for 2 stacks of double pancakes and an outer layer wound section, all electrically in series. Reacted conductor is used with insulated steel tapes as reinforcement. Results in terms of field dependence of the critical currents and stress tolerance are presented for both bare conductors and double pancakes. The latter are tested in a 19 T, 0.17 m cold bore, magnet assembly.         Convergence studies of D-shaped coil/bobbin interactions in a sweeper magnet system    J. Toth and M.D. Bird Summary: For high field solenoids and beamline dipole magnets, structural reinforcement, while complicated, is relatively straight-forward due the high degree of symmetry. In high field, large gap dipoles there frequently is a lower order symmetry. Consequently, the stress state is likely to be more complicated and to require higher precision analysis than is frequently available. Results of a systematic parameter study of a large gap superconducting dipole being constructed by the NHMFL are presented. The magnet consists of two D-shaped NbTi coils and will provide a peak mid-plane field of 3.95 T in a 140 mm gap resulting in a 6.25 T peak field in the conductor and net forces on the coils legs of up to 1.45 MN each. Extensive model-based computer analyses have been applied for optimizing the shape of the coils and the stainless steel bobbin to reduce the strain to an acceptable level while maintaining overall field quality and a reasonable fraction of critical current. Results obtained by applying common engineering practices are compared with those obtained by introducing additional modeling details. Thus, the data presented provide a justified basis for evaluating the adequacy of the alternative modeling approaches for the sweeper magnet and similar magnet systems.         Evaluation method of critical current and current sharing temperature for large-current cable-in-conduit conductors    Y. Nunoya, T. Isono, M. Sugimoto, Y. Takahashi, G. Nishijima, K. Matsui, N. Koizumi, T. Ando and K. Okuno Summary: An evaluation method of critical current (I/sub c/) and current sharing temperature (T/sub cs/) is proposed and applied to the experiment of ITER Center Solenoid (ITER-CS) Model Coil Insert, which is a Nb/sub 3/Sn superconducting coil. Voltage behavior related to normal state transition of conductors during I/sub c/ or T/sub cs/ measurement is not yet well understood especially in the case of such a large cable with more than one thousand strands as the ITER-CS Insert, because the magnetic field, which has a large effect on its superconducting property, is not constant inside the cable. From the detailed analysis of the voltage behavior of coils, it is found that the integral of electric field averaged over conductor cross section along strand-longitudinal direction is equal to the voltage which is measured by voltage taps during a coil test. This is because the twist pitch of a cable is less than the range of longitudinal field variation in the case of a large-cable-conductor coil. This evaluation method can estimate voltage behavior and predict I/sub c/ and T/sub cs/ values, which are important parameters for the design of a large-cable-conductor coil, based on the property of the strands composing the conductor.         Diagnosis of ITER's large scale superconducting coils using acoustic emission techniques    A. Ninomiya, K. Arai, K. Takano, T. Ishigohka, K. Kaiho, H. Nakajima, H. Tsuji, K. Okuno, N. Martovetsky and I. Rodin Summary: In 2000, Japan Atomic Energy Research Institute (JAERI) and its collaboration team accomplished many kinds of experiments under the magnetic field of 13 T for the ITER Project. The target coils are the central solenoid (CS) model coil and the CS insert coil. In 2001, the test using both the CS model coil and the toroidal field (TF) insert coil was carried out and successfully finished. During the experiment, we have measured the change in the amount of mechanical disturbances inside the coil using acoustic emission (AE) technology. In this paper, we report the general trend of AE characteristics obtained in the experiments for two years. That is to say, as for the CS model coil, we investigated the training characteristics of the CS model coil that experienced one cooling cycle from 4.2 K to room temperature. As a result, we confirmed the training effect of the CS model coil wound by forced flow CIC conductors. On the other hand, as for the insert coil, some peculiar AE signals were observed during the CS insert coil cyclic test. On this matter, a re-examination was carried out.         Tests and analysis of quench propagation in the ITER toroidal field conductor insert    L. Savoldi Richard, A. Portone and R. Zanino Summary: The International Thermonuclear Experimental Reactor (ITER) Toroidal Field Conductor Insert (TFCI) has been tested at JAERI Naka, Japan, in 2001, in the background field of the Central Solenoid Model Coil. The TFCI, a well-instrumented /spl sim/43 m long Nb/sub 3/Sn solenoid with a thin Ti jacket, wound inside a SS mandrel and cooled by supercritical helium (SHe) at 4.5 K and 0.6 MPa, was successfully operated up to 46 kA and 13 T. Among others, tests of quench propagation, with delay time of the current dump up to 7 s, were performed driven by an inductive heater. The experimental results of these tests are presented. The hot spot temperature reached in the TFCI during the quench is qualitatively assessed. A more quantitative quench analysis is then performed using the Mithrandir code, confirming the qualitative estimation of the hot spot temperature and showing the importance of heat loss to the mandrel in the slowing down of quench propagation. The computed results reproduce well the main experimental features of the quench transient up to the current dump.         Electromagnetic analysis of the ITER Toroidal Field Coil Insert properties    L. Zani and S. Egorov Summary: In the framework of design and development of the International Thermonuclear Experimental Reactor (ITER) Toroidal Field (TF) Coils, a 45 m conductor winding has been manufactured by the Russian Home Team: the Toroidal Field Coil Insert (TFCI). It was tested in the JAERI facility (Naka, Japan) under various field and temperature conditions. The work presented here concerns the analysis of the electromagnetic behavior of the TFCI using a model developed at CEA. Our work focuses in particular on all observations related to voltage variation with temperature: current sharing temperature (T/sub CS/), n-value, and modeled strand behavior inside conductor.         Current distribution measurement in the busbars of the ITER TF Model Coil    D. Ciazynski, H. Cloez, P. Decool, F. Wuechner and L. Zani Summary: The ITER Toroidal Field Model Coil (TFMC) was tested in 2001 at FZK (Karlsruhe, Germany). The BB1 busbars were instrumented with Hall probes to measure the current distribution across their cable sections. The BB1 busbars are pieces of conductor, about 7 m long, connecting the coil terminals to the BB2 busbars (going to the current leads). The cable is composed of 1152 twisted NbTi strands grouped into six main subcables (petals), each wrapped with a steel foil. The experimental setup is described as well as the method used for calculating the current distribution which leads to estimate the current unbalance among the petals. We observed a slight but monotonous evolution of the steady current distribution as current increases. We also analyzed the transient evolution between inductively and resistively driven current distributions, during a current plateau following a ramp. Assuming the inductive distribution to be uniform, leads finally to a low absolute nonuniformity (within /spl plusmn/6%) of the steady current distribution among the petals. The transient behavior is also discussed through a simple theoretical model.         Modeling of thermal-hydraulic effects of AC losses in the ITER Central Solenoid Insert Coil using the M&M code    R. Zanino, L. Savoldi Richard and E. Zapretilina Summary: During 2000, AC losses and the effects of possible ramp-rate limitation (RRL) were investigated on the International Thermonuclear Experimental Reactor (ITER) Central Solenoid Insert Coil (CSIC), at JAERI Naka, Japan. The CSIC was mounted inside the bore of the ITER Central Solenoid Model Coil (CSMC), at the maximum field of about 13 T and experiencing the largest magnetic field variations. The thermal-hydraulic response of the coil to different transport current scenarios was assessed by measuring the temperature increase and pressurization of the supercritical helium (SHe) coolant, together with the evolution of the mass-flow rate. Here we implement in the M&M code a detailed general model of AC losses, which is being validated for the first time. The resulting tool is then applied to the analysis of two CSIC tests, with different ramp-up of the transport current followed by the same dump, and used to qualitatively assess the major thermal-hydraulic effects of AC losses in the coil.         Electrical characterization of the NbTi strand for the ENEA stability SEx-up experiment    P. Gislon, L. Muzzi, S. Chiarelli, A. Di Zenobio, M.V. Ricci and M. Spadoni Summary: A NbTi 36 strands cable-in-conduit conductor will be wound in a coil (SEx-Up Experiment) in the framework of a study of the performance of a subsize cable for the Poloidal Field Coils of ITER. The basic multifilamentary NbTi strand has been extensively characterized. The electrical characterization enabled us to get a database, essential for the future analysis of the experimental data, and to find the strand characteristic parameters for the I/sub c/(H, T) fit. We measured critical temperature vs. applied magnetic field, transport critical current vs. applied magnetic field, and magnetization vs. applied magnetic field and temperature. The last measurement gives the hysteresis losses, and implicitly the critical current values; magnetization data have been therefore correlated with direct J/sub c/ transport measurements, taking into account the self-field effect. A good match has been found, so magnetization data allowed us to enlarge the range of field and temperature toward regions in which the transport measurements are more difficult, namely low fields or high temperatures.         Sensitivity of Nb/sub 3/Sn ITER conductor design to selected parameters    D. Bessette Summary: The toroidal field coils and the central solenoid of ITER are to be wound from Nb/sub 3/Sn CICC (cable-in-conduit conductors) which can be operated up to 68 kA, 11.8 T and 41.4 kA, 13.5 T respectively. The design approach of these conductors is based on the optimization of both the cable current density and the quantity of sc (superconducting) strand in the cable for the most severe conditions expected during operation. The amount of sc strands and the total amount of copper in cables are set by design rules such as "temperature margin" to operate below the critical current, "Stekly parameter" to ensure stability in operation and "hot spot temperature" in case of quench. The design approach is reviewed on the basis of the test results of the ITER Model Coils conductors. A sensitivity study is then carried out to assess the impact on the conductor design of parameters such as the strand critical current density (J/sub c/), the residual resistivity ratio of copper (RRR), the copper to noncopper ratio of the sc strands as well as some of the operating conditions.         Test of the NbAl insert and ITER central solenoid model coil    K. Okuno, N. Martovetsky, N. Koizumi, M. Sugimoto, T. Isono, K. Hamada, Y. Nunoya, K. Matsui, K. Kawano, T. Kato, H. Nakajima, M. Oshikiri, K. Takano, Z. Hara, R. Takahashi, T. Kubo, Y. Takahashi, N. Mitchell, M. Takayasu, J. Minervini, K. Arai, K. Tsugawa, A. Ninomiya, M. Ricci, L. Savoldi and R. Zanino Summary: The Central Solenoid Model Coil (CSMC) was designed and built by an ITER collaboration in 1993-2001. Three heavily instrumented Inserts have been also built for testing in the background field of the CSMC. The Nb/sub 3/Al Insert was designed and built by Japan to explore the feasibility of an alternative to Nb/sub 3/Sn superconductor for fusion magnets. The Nb/sub 3/Al Insert coil was tested in the CSMC Test Facility at the Japan Atomic Energy Research Institute, Naka, Japan in March-May 2002. It was the third Insert tested in this facility under this program. The Nb/sub 3/Al Insert coil was charged successfully without training in the background field of the CSMC to the design current of 46 kA at 13 T peak field and later was successfully charged up to 60 kA in 12.5 T field. This paper presents the test results overview.         Test of the ITER TF insert and Central Solenoid Model Coil    N. Martovetsky, M. Takayasu, J. Minervini, T. Isono, M. Sugimoto, T. Kato, K. Kawano, N. Koizumi, H. Nakajima, Y. Nunoya, K. Okuno, H. Tsuji, M. Oshikiri, N. Mitchell, Y. Takahashi, S. Egorov, I. Rodin, E. Zapretilina, R. Zanino, L. Savoldi, K. Arai, A. Ninomiya, A. Taran, A. Vorobieva and K. Mareev Summary: The Central Solenoid Model Coil (CSMC) was designed and built by ITER collaboration between the European Union, Japan, Russian Federation and the United States in 1993-2001. Three heavily instrumented insert coils have been also built for testing in the background field of the CSMC to cover a wide operational space. The TF Insert was designed and built by the Russian Federation to simulate the conductor performance under the ITER TF coil conditions. The TF Insert Coil was tested in the CSMC Test Facility at the Japan Atomic Energy Research Institute, Naka, Japan in September-October 2001. Some measurements were performed also on the CSMC to study effects of electromagnetic and cooldown cycles. The TF Insert coil was charged successfully, without training, in the background field of the CSMC to the design current of 46 kA at 13 T peak field. The TF Insert met or exceeded all design objectives, however some interesting results require thorough analyses. This paper presents the overview of main results of the testing - magnet critical parameters, joint performance, effect of cycles on performance, quench and some results of the post-test analysis.         Evaluation of the current sharing temperature of the ITER Toroidal Field Model Coil    R. Heller, D. Ciazynski, J.L. Duchateau, V. Marchese, L. Savoldi-Richard and R. Zanino Summary: The construction and testing of the Toroidal Field Model Coil (TFMC) is part of one of the ITER large R&D projects. The main goal was to demonstrate the feasibility and the mechanical integrity of the design. One of the highlights of the first test phase was to measure the current sharing temperature, T/sub CS/, of the conductor by heating the helium entering from the inlet. Because neither temperature sensors nor voltage taps are positioned inside the coil, only the helium inlet temperature and the voltage along the whole conductor length can be used for the evaluation of T/sub CS/. In addition, an inner pancake joint is located at the inlet in a rather high magnetic field and the peak field region is only about 1.5 m apart from the joint. The determination of the T/sub CS/ relies on the exact knowledge of the thermohydraulics of both the joint and the conductor region. The paper describes and compares the different numerical models used for the evaluation of the T/sub CS/. Nine T/sub CS/ tests at different coil currents were performed, all ending in a quench. The measured T/sub CS/ is in good agreement with the expectations.         The voltage/current characteristic (n index) of the cable-in-conduit conductors for fusion    P. Bruzzone, R. Wesche and B. Stepanov Summary: The index n of the voltage-current characteristic of large superconductors is a crucial parameter to assess the allowed range for coil operation. In the tests of the Insert coils at the CSMC as well as in the short sample test in the SULTAN facility, it is observed that the index n dramatically decreases from the Nb/sub 3/Sn strands extracted from cable-in-conduit provide the evidence of a permanent performance drop in the strands, likely due to the transverse load accumulation at the strand crossovers in the cable. This effect is not observed in NbTi conductors. The immediate implications for the Nb/sub 3/Sn conductor design are discussed and layout modifications to mitigate the effect are proposed.         Parametric studies of subsize NbTi cable-in-conduit superconductors for ITER-FEAT    P. Bruzzone, B. Stepanov, M. Vogel, T. Gloor and R. Wesche Summary: A parametric study of the ac loss behavior and the stability of 3 NbTi subsize cable-in-conduit conductors has been performed in the SULTAN test facility. Two of the conductors are distinguished only by the SnAg and the Ni coating of the strands. The effective transverse resistance in the SnAg conductor is considerably lower than that found for the conductor with Ni coated strands. Hence, the coupling loss in the SnAg coated conductor is considerably higher than that in the Ni coated conductor. Cyclic loading of the conductor reduces the coupling loss in the SnAg coated conductor, whereas the ac loss of the Ni coated conductor is unchanged. The stability of the conductors has been found to be closely related to the ac loss. Due to the smaller ac loss in the Ni coated conductor the minimum field integral of (dB/dt)/sup 2/dt required to initiate a quench is considerably larger than that for the SnAg coated conductor.         Manufacture and test of NbTi subsize joint samples for the ITER poloidal field coils    L. Zani, P. Decool, H. Cloez, J.P. Serries and Z. Bej Summary: In the framework of the design and the development of the ITER PF coils, two subsize joint samples (scale /spl sim/1/6) made of two different NbTi strands were manufactured at CEA/Cadarache (France) and were tested in the JOSEFA test facility at CEA. The characterization of joints was achieved in the areas of resistance T/sub CS/, pulsed field losses, and thermodynamic stability. The experimental results were interpreted with regard to the ITER specifications.         Operational status of the superconducting system for LHD    T. Mito, A. Nishimura, S. Yamada, S. Imagawa, K. Takahata, N. Yanagi, H. Chikaraishi, H. Tamura, R. Maekawa and O. Motojima Summary: Large Helical Device (LHD) is a heliotron-type experimental fusion device which has the capability of confining current-less and steady-state plasma. The primary feature on the engineering aspect of LHD is using superconducting (SC) coils for magnetic confinement: two pool boiling helical coils (H1, H2) and three pairs of forced-flow poloidal coils (IV, IS, OV). These coils are connected to the power supplies by SC bus-lines. Five plasma experimental campaigns have been performed successfully in four years from 1998. The fifth operation cycle started in August 2001 and finished in March 2002. We have succeeded to obtain high plasma parameters such as 10 keV of electron temperature, 5 keV of ion temperature and beta value of 3.2%. The operational histories of the SC coils, the SC bus-lines and the cryogenic system have been demonstrating high reliability of the large scale SC system. The operational status and the results of device engineering experiments are summarized.         W7-X DEMO coil cryogenic tests in the CEA/Saclay test facility    T. Schild, L. Genini, M. Jacquemet, A.U. Holting, T. Rummel and L. Wegener Summary: In the frame of the W7-X stellarator project, CEA cooperates with Max-Planck-Institut fur Plasmaphysik to perform the acceptance tests of all 70 superconducting coils of the W7-X magnet system. The test facility is now complete and its performance is being checked using the W7-X prototype coil. The main objective of the tests of the series coils is to demonstrate their proper function and to determine their margin of operation. Since many coils will be tested and compared to each other, it is important to measure the margin of operation in a reproducible way with sufficient accuracy. Either increasing the current, increasing the temperature or mixed operation can induce quenches. The test results on the prototype coil are analyzed with respect to the temperature and current margin and compared to the expected values calculated from superconducting strand data. The paper summarizes the results of these tests and the methods of evaluation.         Innovative high-pressure laminate insulation for fusion magnets    P.E. Fabian, N.A. Munshi and S.W. Feucht Summary: High-pressure laminate (HPL) composite materials, such as G-10, have been used for many years in both the electrical and magnet industry as insulation for demanding applications. Because of their relative ease of fabrication and ability to be inspected prior to magnet installation, these materials have remained an attractive insulation option for current magnet designers. However, composite insulation for use in many new Next Step Option (NSO) fusion devices must meet an increasingly demanding set of requirements, including cryogenic and elevated temperature performance while withstanding higher radiation levels. The lack of performance in high radiation environments by materials such as G-10 has led Composite Technology Development, Inc. (CTD) to develop a series of new, innovative HPL insulation systems that can meet the new fusion magnet challenges. Material development has focused on highly radiation-resistant resin systems, as well as lower radiation resistant, low cost alternatives. Prototype laminates have been fabricated and evaluated by a leading industrial partner to ensure their suitability for large-scale production. This paper will present several new insulation systems capable of being fabricated in the HPL process, provide processing characteristics, along with mechanical and electrical property data.         Enhanced adhesive shear strength of cyanate ester electrical insulation for fusion magnets    J.A. Rice, K.R. Gall and G. Voss Summary: In many Next-Step Option (NSO) fusion magnet designs the shear strength of the electrical insulation and its adhesion to the conductor is a performance limiting factor, especially during high temperature excursions. Significant design compromises, such as the need for large compressive loads or increased part cross-sections, must be made in order to accommodate the low shear strength of the insulation. Improving the shear strength of the insulation/conductor system will reduce the negative impact on system design and allow for higher temperature operation. Typical adhesive shear strength of conventional epoxy-based insulation systems on clean copper ranges from 76 MPa in liquid nitrogen to only 17 MPa at 100 /spl deg/C. These values are insufficient for the planned applications. On the other hand, cyanate ester based insulation has been shown to exhibit enhanced properties that will allow for magnet operation at 100 /spl deg/C and possibly even higher. A new cyanate ester resin has been developed by Composite Technology Development exhibiting improved adhesive strength to copper, especially at elevated temperatures. It is expected that the high temperature value can be further increased with optimization. In addition, the enhanced radiation resistance of cyanate ester resins implies that the new insulation systems will out-perform traditional epoxy-based insulations and lead to reduced costs for future fusion energy devices.         Design of toroidal field coil for the JT-60 superconducting tokamak    K. Tsuchiya, K. Kizu, Y.M. Miura, T. Ando, T. Isono, K. Matsui, N. Koizumi, M. Matsukawa, A. Sakasai and S. Ishida Summary: The modification of JT-60 is programmed to be a superconducting tokamak (JT-60SC) that has superconducting toroidal field (TF) and poloidal field coils. The TF coil system, which consists of 18 D-shaped coils, makes the field of 3.8 T at plasma center (R = 2.8 m). The stored magnetic energy in total is 1.7 GJ. A squared Nb/sub 3/Al cable-in-conduit (CIC) conductor using SS316LN jacket allows us to fabricate the TFC by a react-and-wind (R&W) technique because of low strain sensitivity of Nb/sub 3/Al J/sub c/ characteristic. In order to support TF coils against the centering force, the inboard side of the TF coil case is wedged. Shear panels and keys between the TF coils are placed against the overturning force induced by poloidal fields. Stress analysis of the TF coil support structure was carried out. In the case of the maximum displacement caused by overturning force, the maximum stress was lower than the allowable stress of SS316LN at 4 K. The stress analysis of insulator and conduit at the inboard side of the TF coil with zooming model was also carried out. It is clear from zooming analysis that the stresses of conduit and insulator are within the allowable stress. Regarding a progress of R&D, demonstration of R&W technique using a D-shaped double layer coil with the full-scale CIC conductor is planned in this year in order to confirm its designed performance.         Consideration of conductor motions in the helical coils of the Large Helical Device    S. Imagawa, N. Yanagi, H. Sekiguchi, T. Mito, T. Satow and O. Motojima Summary: A pair of helical coils of the Large Helical Device is a large pool-cooled superconducting magnet. Conductor motions are induced repeatedly at higher than about 60% of the design current of 13 kA in charging, and these disappear while holding the current or discharging halfway from the high current. This hysteresis could be caused by the friction. A normal zone can propagate at higher than 87% of the design current because of the excess heat generation by the slow current diffusion into a pure aluminum stabilizer. This propagation has been observed nine times in four years' operation. From the comparison of balance voltages of the three pairs of coil blocks, the positions of the conductor motions and the induced normal zones can be evaluated. The behavior of the conductor motions is discussed.         Simulation of dynamic stress in PF superconducting magnets for KSTAR under normal operating conditions    Qiuliang Wang, Cheon Seong Yoon, Sungkeun Baang, Keeman Kim and Wohoo Chung Summary: The PF (polodial field) superconducting magnets for the KSTAR (Korea Superconducting Tokamak Advanced Reactor) are operated in the high rates of change in the operating currents. Under the normal discharging condition of plasma, the current in superconducting magnets can generate high electromagnetic stress in CICC (cable-in-conduit-conductor) and its support structure. In order to simulate the peak value stress in PF superconducting magnet so that the support structure can be designed to bear the stress, ANSYS is used to study the variation of stress and strain distribution with time. In the paper, the detailed finite element model and numerical results are presented.         Results of preliminary testing of blip and cancellation coils for the Samsung Superconductor Test Facility (SSTF)    S. Baang, S. Lee, W. Chung, K. Kim, Q. Wang, M.P. Alexeev, O.P. Anashkin, D.P. Ivanov, V.E. Keilin, V.V. Lysenko, S.M. Miklyaev, I.O. Shchegolev, V.I. Shcherbakov, S.A. Shevchenko, I.O. Shugaev and M.I. Surin Summary: The background magnet system of SSTF (Samsung Superconductor Test Facility) for KSTAR (Korea Superconducting Tokamak Advanced Research) will be equipped with a pair of main coils (MC) and a pair of blip coils (BC). The main goal of the BC is to simulate electromagnetic disturbances (1 T amplitude and 20 T/s discharge rate), expected from the KSTAR operation. The coupling losses and magnetic interaction between MC and BC will be decreased by resistive cancellation coils (CC) wound onto a fiberglass bobbin. The BC is wound with a cable in conduit conductor (CICC) packed with Nb/sub 3/Sn strands. A set of BC and CC was tested in an open type cryostat. The BC is cooled with both boiling LHe in a container and pressurized helium passing through the CICC. The BC was charged up to 6.7 kA and discharged in 50 ms. During the discharge, the maximum field variation rate corresponds to 28 T/s in the BC center and 53 T/s on the BC conductor. No quench was observed and the BC was recharged in less than 1 minute. The measured shielding current in the CC is in a good agreement with the calculated value.         Development of CICC for KSTAR TF coil system    B.S. Lim, S.I. Lee, J.Y. Choi, W. Chung, Y. Chu, H.K. Park, K.M. Kim, S.Y. Kim and B.S. Kim Summary: The KSTAR (Korea Superconducting Tokamak Advanced Research) superconducting magnet system consists of 16 TFs (Toroidal Field) and 14 PFs (Poloidal Field) coils. Internally-cooled cabled superconductors will be used for the magnet system. The magnet systems adopt a superconducting CICC (Cable-In-Conduit Conductor) type conductor. The KSTAR TF CICC uses Nb/sub 3/Sn superconducting cable with Incoloy 908 conduit. For the fabrication of TF 1/spl sim/3 CICC, cables have been fabricated and the cable has a length of 640 m and a diameter of 22.3 mm. A continuous CICC jacketing system is developed for the CICC jacketing and the jacketing system uses the tube-mill process, which consists of forming, welding, sizing and squaring procedures. The cabling and the jacketing process is described. The welding condition of the Incoloy 908 and design specification of CICCs are also discussed. The fabrication results including the geometrical specification and the void fraction will be discussed.         Engineering design of the Mini-RT device    T. Mito, N. Yanagi, Y. Hishinuma, Y. Ogawa, J. Morikawa, K. Ohkuni, M. Iwakuma, T. Uede, S. Nose, I. Itoh and S. Fukui Summary: The plasma experiment apparatus S-RT (Superconducting Ring Trap) is planned for the purpose of high beta plasma confinement research in the University of Tokyo. As a preceding step, Mini-RT, which is the size reduction version of S-RT, has been constructed as a joint research of NIFS, the University of Tokyo, and Kyushu University. In this experiment a magnetic-levitation coil (floating coil) operated in persistent current mode has to levitate for 8 hours in the plasma vacuum vessel. The HTS floating coil wound with a Bi-2223 tape has a diameter of 300 mm and an electromotive force of 50 kA. Since any refrigerant cannot be fed to the coil during the plasma experiment, the coil is designed so that the temperature rise after 8 hours of levitation is less than 40 K with the specific heat of the coil and radiation shield. At the end of the daily plasma experiment, the coil will be drawn down to the maintenance location at the bottom of the plasma vacuum vessel, and it will be re-cooled to 20 K.         Excitation test results of the HTS floating coil for the Mini-RT project    N. Yanagi, T. Mito, Y. Hishinuma, Y. Ogawa, J. Morikawa, K. Ohkuni, M. Iwakuma, T. Uede, S. Nose and I. Itoh Summary: A magnetically levitated superconducting coil device, Mini-RT, is being developed using high temperature superconductors for the purpose of examining a new magnetic confinement scheme of high-beta plasmas. The floating coil has Bi-2223 Ag-sheathed tape conductors, which will be effectively used in the temperature range of 20-40 K. The fabrication of the coil has been completed, and excitation tests of the coil were carried out in a helium cryostat. The coil was successfully excited up to the nominal current with a proper PCS operation.         Tests of prototype quadrupole magnets for heavy ion fusion beam transport    Chen-Yu Gung, J.V. Minervini, J.H. Schultz, R.B. Meinke, C.L. Goodzeit, G. Sabbi and P. Seidl Summary: Four NbTi superconducting prototype quadrupole magnets have been built for the High Current Transport Experiment (HCX) as part of the multi-beam heavy-ion fusion research activity, led by the Lawrence Berkeley National Laboratory (LBNL). MIT performed quench training and ramp rate tests of the two prototype magnets that were designed and built by the Advanced Magnet Lab, Inc. (AML), based on a novel concept featuring cable-in-groove and multi-layer stacking. Both magnets are splice-free without inter-layer or inter-quadrant joint. Each coil was wound with a continuous NbTi round cable, placed in precise grooves machined in G-11 plates. The two magnets differ in their cable construction and their coil and yoke configuration. Each magnet was tested more than once in liquid helium bath with a room temperature thermal cycle between cold tests. This paper describes the results of the performance tests as well as the instrumentation and the quench protection system. Possible improvements for future coil winding are discussed.         Development of 10 kA Bi2212 conductor for fusion application    T. Isono, Y. Nunoya, T. Ando, K. Okuno, M. Ono, A. Ozaki, T. Koizumi, N. Ohtani and T. Hasegawa Summary: Recently, superconducting properties of high Tc superconductors (HTS) have been highly improved and using performance of HTS a conceptual design of a fusion device was performed by Japan Atomic Energy Research Institute (JAERI). HTS has a capability to produce a magnetic field of higher than 16 T, which is required in such a fusion power reactor. Aiming at development of the conductor, a trial fabrication of a 10-kA 12-T conductor was started using round Ag-alloy sheathed Bi-2212 strands, which has best performance at 4.2 K, 16 T at present. The conductor has about 34-mm diameter, and is composed of 729 HTS strands. Operating temperature is designed at not only 4 K but also 20 K. The cable of the conductor is solder-coated on the surface to use specific heat of the lead as much as possible, which at 20 K is almost comparable with specific heat of SHe at 4.5 K, 0.6 MPa. From the tests of the conductor, the fabrication of large HTS conductor and 10 kA operation at 12 T, 18 K /spl sim/ 20 K were successfully performed and the first step of developing work of HTS conductor for fusion application was achieved.         Development of novel radiation-resistant insulation systems for fusion magnets    S.W. Feucht, P.E. Fabian and N.A. Munshi Summary: The development of higher performance composite insulation systems for use in fusion magnets has been an important goal for the fusion community in recent years. Next Step Option (NSO) fusion devices, such as the Fusion Ignition Research Experiment (FIRE), are being designed with the assumption that new, better performing insulation systems will be available at the time of magnet manufacture. To address these concerns, Composite Technology Development, Inc. (CTD) has developed a new class of organic composite insulation systems designed not only to meet the performance criteria of these new magnets, but also to meet the fabrication challenges that will be encountered during magnet fabrication. These new systems, based on previous work with cyanate ester resin systems, have been developed with a focus on increased radiation-resistance, ease of processing and fabrication, and mechanical and electrical strength at cryogenic and elevated temperatures. New resin systems have been developed to enable a broad range of insulation application methods including vacuum pressure impregnation (VPI) and pre-impregnation. Processing information on these systems, along with their mechanical and electrical properties will be presented.         The DOE High Energy Physics SBIR/STTR Superconductivity Program    G.J. Peters, R.E. Berger, B.P. Strauss and D.F. Sutter Summary: The U.S. Department of Energy has over a 35-year history in the support of superconducting devices. Superconductivity is an enabling technology for its major installed particle accelerators as well as planned projects. The Small Business Innovation Research (SBIR) Program has played a most significant role in the industrial development of advanced superconducting materials and devices. This paper will give a short history of the program as well as its accomplishments in the field of superconductivity. Current development needs of the Department in High Energy Physics will be explored. Suggestions for participation in this program will be discussed.         US fusion program requirements for superconducting magnet research    J.V. Minervini and J.H. Schultz Summary: Future superconducting magnets for fusion applications require improvements in materials and components to significantly enhance the feasibility and attractiveness of fusion reactors as an energy source. These improvements will derive from research and development carried out at government laboratories, universities, and in industry. Research and development carried out under the DOE Office of Fusion Energy Sciences SBIR's and STTR's can provide a significant contribution to this effort by encouraging small businesses to focus on areas of high critical current density superconductors with low to moderate ac losses, superconductors with both high and low stabilizer fraction, superconducting cables with high copper strand fractions, insulation systems that are radiation-resistant with low gas evolution and suitable for vacuum-pressure impregnation (VPI) of coils, and novel quench detectors and other types of advanced magnet system monitoring instrumentation.         Parameters and requirements of superconducting focusing quadrupoles for heavy ion fusion    R. Bangerter, J. Barnard, T. Brown, A. Faltens, Chen-Yu Gung, E. Lee, A. Lietzke, S. Lund, R. Manahan, N. Martovetsky, R. Meinke, J. Minervini, L. Myatt, A. Radovinsky, G. Sabbi, J. Schultz, P. Seidl and S. Yu Summary: In a heavy ion fusion driver, arrays of superconducting quadrupoles will transport parallel beams through a sequence of induction acceleration cells. The development of such arrays is a unique and challenging task. Since magnetic transport is one of the most expensive subsystems, economy of fabrication is a primary consideration. A compact design is essential to limit the size and cost of induction cores. Special edge coils have to be implemented to adjust the field in outer cells and terminate the magnetic flux. The development of superconducting magnets for both near term experiments and the ultimate driver application is actively pursued by the U.S. Heavy Ion Fusion Program. The main parameters and requirements are discussed, and the R&D status and plans are presented.         Progress and plans for the U.S. HEP conductor development program    R.M. Scanlan and D.R. Dietderich Summary: Although existing accelerators utilize NbTi superconductor, it is likely that any future upgrades or new accelerators will require the use of superconductors with higher critical fields, such as Nb/sub 3/Sn. The High Energy Physics (HEP) program in U.S. Dept. of Energy (DOE) has initiated a conductor development program aimed at developing a high current density, cost-effective conductor for these new applications. The program is industry-based, with a set of target specifications that were derived from the accelerator magnet requirements. Significant progress has been made to date toward the target specifications, and the results will be presented. Plans for further development, in particular the scale-up tasks required to reduce the conductor cost, will be reviewed.         Effect of soldering on current capacity and AC loss of large superconducting solenoids    S.W. Kim, J.H. Bae, J.W. Cho, H.J. Kim, M.H. Sohn, K.C. Seong and K. Ryu Summary: A superconducting solenoid with large inner diameter has much lower current capacity than expected from short wire sample tests, and a solenoid of multi-strand cable has worse results. It is known that this degradation is observed when the inner diameter of the solenoid is bigger than a certain value (30 cm usually). However the reason is not clarified yet and some people called this just the "size effect." To obtain some clues to understand the size effect and to develop big solenoids with higher operating current, we prepared and tested two sample solenoids made of Rutherford type cables with and without soldering. Quench currents and AC losses of the two solenoid coils are measured and compared. The test results show that the soldering on the Rutherford cable improves the current capacity, but makes the AC loss much higher.         A high-temperature superconducting double-pancake insert for an NMR magnet    Haigun Lee, J. Bascunan and Y. Iwasa Summary: For a low- and high-temperature superconducting (LTS/HTS) NMR magnet, an HTS insert, comprised of 50 double pancake (DP) coils, each wound with Bi2223/Ag tape, has been built at FBML. The paper describes design, assembly, and performance data (critical current, splice resistance, field homogeneity) of the HTS insert.         A low- and high-temperature superconducting NMR magnet: design and performance results    J. Bascunan, Haigun Lee, E.S. Bobrov and Y. Iwasa Summary: A nuclear magnetic resonance (NMR) magnet comprised of low- and high-temperature superconducting (LTS/HTS) coils has been built and operated at a frequency of 360 MHz. The magnet operates at 4.2 K with the LTS background coil operated in persistent mode, while the HTS insert is in driven mode. The HTS insert is an assembly of 50 double pancakes, each wound with Bi-2223/Ag tape. The paper describes design and performance results of the LTS/HTS magnet.         Noise reduction performance of a YBCO cylinder in high-field resistive magnets    T. Asano, T. Kiyoshi, S. Matsumoto and H. Wada Summary: The field stability of high-field resistive magnets is generally inferior to that of superconducting magnets. The main reason for this is the low inductance of resistive magnets. High-precision measurements, such as those conducted using nuclear magnetic resonance, are very difficult by using high-field resistive magnets due to lack of field stability and ripples in the magnetic fields. However, recent progress in the area of high-temperature bulk superconductors indicates that it is possible to drastically improve these measurements. We used a YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) bulk cylinder made by the Nippon Steel Corporation. Its dimensions were 5 mm (inner diameter)/spl times/10 mm (outer diameter)/spl times/10 mm (height). A pickup coil was inserted into the center of the cylinder to measure ripples in the magnetic field. The bulk cylinder with the pickup coil was then inserted into a resistive magnet of the Tsukuba Magnet Laboratory. At a certain field, the bulk superconductor was cooled down from room temperature to the superconducting state. The signals of the pickup coil before and after transition to the superconducting state were compared.         Superconducting micro flux pump using a cryotron-like switch    Sangkwon Jeong, Sehwan In and Seokho Kim Summary: This paper describes a novel /spl mu/-flux (micro flux) pump using a cryotron-like switch that may be coupled to a high-temperature superconductor (HTS) insert coil of a high-field nuclear magnetic resonance (NMR) magnet. The flux pump is essentially comprised of a single superconducting cryotron-like switch loop that is intermittently open and closed by magnetic field. There is inherently only small energy dissipation in the switching action because the triggering action of the switch is made magnetically not thermally. The micro flux pump can supply precisely a small amount of current into a superconducting load magnet. The switching is stable and fast because the thermal inertia and the temperature sensitivity of the flux pump are not relevant to the operation. The /spl mu/-flux pump can be designed to generate minimum total heat input to liquid helium bath of HTS insert coil of NMR magnet.         Development of variable field-direction superconducting magnet    S. Matsumoto, T. Kiyoshi, O. Ozaki, J.-I. Fujihira, K. Koyanagi and H. Wada Summary: Magnetic field direction often has a great influence on material properties, such as critical current densities of tape-shaped superconductors. To determine the influence, an object is usually rotated in a fixed magnetic field. This method, however, is not always effective. We are developing a superconducting magnet that can change its field direction continuously in a two-dimensional plane. Two sets of split-pair coils are placed perpendicularly to each other, and the perpendicular magnetic fields generated by each split-pair coil are superimposed. By independently controlling the operating current of each split-pair coil, the direction of the superimposed magnetic field can be changed continuously. The coils are wound with Ni-Ti conductors. The variable field-direction magnet is designed to rotate a field of 1 T. The field homogeneity is estimated to be less than 1% in a 10-mm diameter sphere volume. This is a conduction-cooled superconducting magnet with 4K-GM refrigerators. Predictions derived by numerical calculations show that the electromagnetic forces among coils are quite large.         Study on AC losses of a conductive cooled HTS coil    K. Tasaki, M. Ono and T. Kuriyama Summary: We have studied ac losses of a conductive cooled high-temperature superconductor (HTS) coil. AC losses of a large stored energy HTS coil of 1.1 MJ were measured using the electrical method and the calorimetric method. The HTS coil is composed of 36 single-pancake coils using Ag-sheathed Bi2223 tapes and impregnated with epoxy resin. AC losses measured by the two methods were in good agreement. At low frequencies the experimental results were almost the same as the calculated hysteresis losses. With increasing the frequency, the measured values became larger than the calculated hysteresis losses. The extra losses were estimated to be eddy current losses generating at conduction plate made of pure aluminum and coupling losses generating between Ag sheathed tapes.         Design, manufacture, and test of a large bore cryogen-free magnet    A. Hobl, D. Krischel, M. Poier, R. Albrecht, R. Bussjaeger and U. Konopka Summary: A large superconducting cryogen-free magnet has been designed, manufactured and tested. The magnet reached 4.1 T in the 430 mm room temperature bore with a ramp time of 35 min. The magnet is cooled by a two-stage GM cryocooler. The magnet can be rotated on a support frame to be operated with either horizontal or vertical bore. The stored energy of 1 MJ can safely be handled during a quench. Homogeneity, cool down as well as quench properties confirmed the design values. The magnet is now being operated by the end user.         Conduction-cooled Bi-2212-Ag solenoid magnet system with 50-mm RT bore (III): Test results    H. Morita, M. Okada, K. Tanaka, J. Sato, K. Ohata, H. Kitaguchi, H. Kumakura, K. Togano, K. Itoh and H. Wada Summary: High-field high-temperature superconductor (HTS) conduction-cooled magnet system is considered to be the most promising system for superconducting magnets of the next generation. In order to demonstrate the feasibility, we have been developing a Bi-2212/Ag magnet system that consists of five solenoid coils fabricated with ROtation-Symmetric Arranged Tape-in-tube wire (ROSATwire). ROSATwire shows less field anisotropy on the transport current property than conventional tape conductors; therefore ROSATwire is ideal for solenoid magnets that generate high and precise uniform magnetic field. We succeeded in the fabrication of a 3.5 km long ROSATwire, and the critical current was achieved up to 500 A at 4.2 K, 10 T. Several coils were fabricated. We tested the inner two coils in the conduction cooling system. The maximum current of dc operation test was 120 A (2.17 T). However, the maximum current of ac operation test (repeat high-sweep-rate operation test) was 160 A (2.89 T) with sweep rate of 1 A/s (0.0181 T/s). This property, the maximum current of ac operation being larger than the one of dc operation, is considered to be characteristic of HTS magnets. The operation test results and the thermal stability are also reported.         Thermal stability of oxide superconductors in flux flow state    G. Nishijima, S. Awaji and K. Watanabe Summary: Transport characteristics of Bi-2212 wire in flux-flow state were experimentally investigated under a cryocooled condition in high magnetic fields up to 14 T at various temperatures. The heat balance affected the thermal stability of oxide superconductors, and the oxide superconductor with large current capacity and large n value quenched at the current that was smaller than its critical current.         Magnetization method for long high-T/sub c/ bulk superconductors used for magnetic separation    N. Nishijima, N. Saho, K. Asano, H. Hayashi, K. Tsutsumi and M. Murakami Summary: We have developed a new water-treatment system consisting of a membrane separator and a magnetic separator that uses long (>200 mm) high-temperature bulk superconductors (SCs) as permanent magnets. For magnetizing the long bulk SCs, we developed a new magnetization method. Namely, a field is applied, the bulk SCs are cooled below their transition temperature (T/sub c/), and during cooling, the bulk SCs are inserted into and withdrawn from the applied field repeatedly. As a result, the bulk SCs experience high and low fields under a gradually cooled ambient, and the trapped field gradually increases. The benefit of this method is that it can magnetize large bulk SCs by using a small field magnet. We fabricated an embedded-SC bulk magnet more than 200-mm long, and magnetized it by split-solenoid superconducting magnets with a diameter of approximately 100 mm. Field measurements showed that the developed method can magnetize a wider area over the bulk SCs than that possible with a conventional field-cooling method.         Construction of a strong magnetic field generator with use of melt-processed bulk superconductors    T. Oka, K. Yokoyama, Y. Itoh, H. Ikuta, U. Mizutani, H. Okada, K. Katagiri and K. Noto Summary: A superconducting permanent magnet system capable of generating strong magnetic fields has been constructed by using melt-processed bulk superconductors as trapped field magnets. The trapped field in the open space between two magnetic poles that are set face to face has reached 3.15 T when magnetized by a pulsed-field magnetization (PFM) technique. That was operated at 30 K attained by GM-cycle refrigerators. The performance exceeds that of conventional rare earth magnets or large scale electromagnets by far. It was found that the iteratively magnetizing pulsed field operation with reducing amplitude (IMRA) method is very effective in magnetizing the bulk superconductors. The magnet system can be used as a high field generator in various applications.         Determination of experimental conditions for HGMS magnetic separation to reduce the inorganic contents in cellulignin catalytic fuel    M.L.G. Pereira, D. Rodriguez Jr. and D.G. Pinatti Summary: Cellulignin can be generated by recycling the organic content present in the municipal solid waste. This cellulignin, in dry powder form, can be used as a highly efficient catalytic fuel. The main objective of the present work was to reduce the cellulignin inorganic contents through High Gradient Magnetic Separation (HGMS), aiming the use of the cellulignin as solid fuel in turbines and other systems. The magnetic separation was performed using a canister filled with 420 stainless steel mesh, in the region of central magnetic field, where it was pumped liquid with dispersed cellulignin. The cellulignin was characterized before and after each separation test. The magnetic separation tests were performed at the applied magnetic fields of 1 T, 2.5 T, and 4 T, and with feeding flows of 200 L/h, 300 L/h, and 500 L/h. Reduction in the inorganic contents was found in all magnetic separation tests and the efficiency increased with the decrease of the feeding flow. The highest magnetic separation efficiency for inorganic removal was found with the feeding flow of 200 L/h and at an applied magnetic field of 2.5 T.         Solid-liquid magnetic separation using bulk superconducting magnets    K. Yokoyama, T. Oka, H. Okada, Y. Fujine, A. Chiba and K. Noto Summary: Our research is to magnetize the high-T/sub c/ bulk superconductors and to supply magnetic field environment realized by superconducting bulk magnets to various applications. In this paper, we aim to apply the superconducting bulk magnets to the high gradient magnetic separation (HGMS). Using a face-to-face type superconducting bulk magnet system in which a pair of bulk superconductors are oppositely arranged, Y123 bulk superconductors are magnetized by the "IMRA" method (pulsed field magnetization), and consequently, a magnetic field of 1.6 T is achieved between the magnetic poles. Next, HGMS using superconducting bulk magnets is demonstrated. A separation pipe into which filter matrices composed by ferromagnetic wires are stuffed is set between the magnetic poles and the slurry mixed with fine powder of /spl alpha/-hematite (Fe/sub 2/O/sub 3/) particles is flown. As the results of HGMS, over 90% of the Fe/sub 2/O/sub 3/ was separated. Moreover, separation filters have to be washed so that they are not clogged with captured particles. We confirmed that the filter was briefly washed by flowing water after moving the separation pipe from magnetic poles.         Recycling of abrasives from wasted slurry by superconducting magnetic separation    S. Nishijima, Y. Izumi, S. Takeda, H. Suemoto, A. Nakahira and S. Horie Summary: Abrasives have been recovered from the slurry wasted of the factory where the silicon wafers for solar battery are processed. The slurry consists of oil and abrasives and is used in the wire saw. The viscosity of the slurry is carefully controlled to maintain a high cutting performance though it tends to be high as the silicon powder is accumulated in the slurry. The cutting performance of the slurry decreases as the amount of the silicon powder increases. The abrasives, however, still have enough performance to cut the silicon wafers. Iron segments of the wire saw were found to attach to the SiC abrasives. The iron segments magnetize the abrasives in the mechanochemical process and thus reduce the cutting performance of the abrasives. Due to the iron segments presence the abrasives with poor cutting performance could be separated from the slurry by means of superconducting magnetic separator. After the magnetic separation a centrifugal separator was used to separate the silicon powder. It was confirmed that the superconducting magnetic separation is applicable to this practical application.         The performance of high-temperature superconductors in space radiation environments    M.R. James and S.A. Maloy Summary: Space applications of high-temperature superconductors hold great promise for increasing the performance of a variety of platforms and components. One major concern for the operation of superconductors in space is their response to the specific radiation environments. These environments can be low-Earth orbits, deep space, or even radiation from on-board reactors. The influences from high-energy electrons, protons, and neutrons, as well as heavy-ion recoils, must all be considered. There exists from previous studies an extensive collection of data regarding the response of various types of superconductors to many different particles and energies. This work is a review of these data assessing changes in superconductor properties or other life-limiting factors for superconducting components in various mission profiles.         The medium temperature superconductor (MTS) design philosophy    J.H. Schultz Summary: This paper proposes basic principles for large-scale application design in the range 10-35 K, called medium temperature superconductor (MTS) design. Three separate categories of MTS design are analyzed, using LTS (e.g., A15), true MTS (e.g., MgB/sub 2/), and high-temperature superconductor (HTS) (e.g., BSSCO, YBCO) superconductors. Performance and limitations of each approach are quantified for critical current, stability and protection limits. The assumption that future applications will be dominated by high-temperature superconductors is challenged, arguing that MTS should be the preferred method for many energy, fusion, and high energy physics applications.         New design of a superconducting magnet for generation of quasi-uniform magnetic force field    L. Quettier and A. Mailfert Summary: The generation of uniform field of magnetic forces exerted on diamagnetic or paramagnetic particles is a problem with various applications: magnetic separation of particles with small differential magnetic susceptibility, diamagnetic levitation, material processing crystallization of proteins, etc. Superconducting magnets that are usually investigated to generate uniform field of magnetic forces are solenoids but unfortunately these designs lead necessarily to a restricted levitation domain. This paper presents a novel conceptual design of superconducting coils able to give a satisfactory solution to the problem of magnetic levitation. The symmetry of the structures allows nonrestricted levitation domain. We study the possibility of using magnetic levitation so as to compensate the gravity in deuterium in a cylinder of 5 mm in diameter and 600 mm in length. The magnetic design has been calculated thanks to one analytical model and is based on particle accelerator designs. Then the structure has been numerically optimized to reach a magnetic force as large and homogenous as possible. Simulation results with reachable values of levitation force are presented.         Design, building and testing of a 10 kW superconducting induction heater    M. Runde and N. Magnusson Summary: Conventional 50/60 Hz induction heaters for aluminum billets have very large losses. By replacing the copper windings with windings of high-temperature superconducting (HTS) tapes, there is a substantial potential for efficiency improvements, especially if low AC loss HTS tapes become available. To examine the feasibility of using HTS in induction heaters, a first, small-scale working model has been designed and built. The induction coil is made of 24 double pancake coils of Bi-2223/Ag tapes. In the initial test, a workpiece of aluminum situated in the warm bore of the coil was heated up to 300/spl deg/C.         Efficiency analysis of a high-temperature superconducting induction heater    N. Magnusson and M. Runde Summary: In an induction heater for heating of aluminum billets, the main reason for using high-temperature superconducting (HTS) tapes instead of conventional copper conductors is to reduce the large power losses in the induction coil. In this work we present how to calculate the different loss contributions of an induction heater based on HTS tapes. Calculations of these losses are used in the design of an HTS induction heater with a rated power of about 10 kW operating at liquid nitrogen temperature. The calculations predict an optimal current that yields the highest efficiency of the induction heater.         Fabrication and test of the LDX levitation coil    P.C. Michael, A. Zhukovsky, B.A. Smith, J.H. Schultz, A. Radovinsky, J.V. Minervini, K.P. Hwang and G.J. Naumovich Summary: The Levitated Dipole Experiment (LDX) was designed by Columbia University and the Massachusetts Institute of Technology to investigate plasma confinement within a dipole magnetic field. The experiment consists of a 5 m diameter by 3 m tall vacuum chamber and three superconductor coils: a Nb/sub 3/Sn Floating Coil that provides the dipole field for plasma confinement; a NbTi Charging Coil that inductively charges and discharges the Floating Coil current; and a high temperature superconductor (Bi-2223) Levitation Coil that electromagnetically supports the weight of the 620 kg Floating Coil and controls its vertical position within the vacuum chamber. LDX is the first US plasma confinement experiment to use a high temperature superconductor coil. The use of high temperature superconductor minimizes the electrical and cooling power needed for levitation, allowing additional power for plasma heating. The levitation coil is a 2800 turn, 1.3 m outer diameter, double pancake winding. It is designed to operate at up to 150 A current at 20 K and is cooled by a combination of one stage cryocooler and liquid nitrogen cooled radiation shield. This paper provides details for the design, fabrication and test of the coil.         Test results of a HTS Reciprocating Magnetic Separator    C.M. Rey, W.C. Hoffman Jr. and D.R. Steinhauser Summary: The test results of a conduction-cooled High Temperature Superconducting (HTS) Reciprocating Magnetic Separator are reported. Reciprocating magnetic separators are used in the purification of kaolin clay. The HTS coil is 0.3 m in length and has a 0.25 m (cold) bore inner diameter. The central operating magnetic field is a nominal 3.0 T with a design operating current of 126 A. In terms of combined size and magnetic field strength, this is one of the largest HTS magnets ever fabricated, possessing a stored energy >0.1 MJ. The HTS magnet is conduction cooled via one single-stage G-M cryocooler with a nominal operating temperature of 30 K. The HTS conductor uses a stainless steel reinforced Bi-2223 material. Salient design features and test results of the HTS magnetic separator are discussed.         Mine countermeasures HTS magnet    S.O. Ige, D. Aized, A. Curda, R. Medeiros, C. Prum, P. Hwang, G. Naumovich and E.M. Golda Summary: American Superconductor has designed, manufactured, and tested a model high-temperature superconducting (HTS) magnet system for airborne mine countermeasures (MCM) for the Office of Naval Research. The magnet has a magnetic moment of 80 kA-m/sup 2/, or about one-fourth that of the full-scale magnet. The magnet is a solenoid consisting of 16 layers of laminated Bi-2223 HTS wire. The coil was manufactured at Everson Electric and tested at American Superconductor. The coil has an inside diameter of 455 mm, an outside diameter of 476 mm, and is 914 mm in length. The magnet was successfully ramped to its operating current of 193 A at 30 K. It was also successfully modulated with /spl plusmn/26 A current at 0.5 Hz. The magnet is conduction-cooled with a single-stage GM cryocooler. The design, manufacture, and test results of the magnet will be presented.         First performance test of the cryogenfree hybrid magnet    K. Watanabe, S. Awaji, K. Takahashi, G. Nishijima, M. Motokawa, K. Jikihara, M. Ishizuka and J. Sakuraba Summary: We are now constructing a cryogenfree 23 T hybrid magnet at the High Field Laboratory for Superconducting Materials, Institute for Materials Research, Tohoku University. At present, an outer section coil employing NbTi multifilamentary wires for a cryogenfree superconducting magnet of the hybrid magnet was combined with an inner 15.5 T water-cooled resistive magnet, and was tested as the world's first cryogenfree hybrid magnet. The NbTi coil with 491 mm inner diameter and 584 mm outer diameter generated 4.59 T at 198 A, and the central magnetic field of 20.0 T was generated in a 52 mm room temperature experimental bore. The magnetic force field of 2030 T/sup 2//m was obtained, and a piece of paraffin was levitated at 1200 T/sup 2//m. Using a CO/sub 2/ laser combined with the cryogenfree hybrid magnet, a containerless melting experiment in magnetic levitation was demonstrated easily for paraffin.         A solid-nitrogen cooled Nb/sub 3/Sn NMR magnet operating in the range 8-10 K    Y. Iwasa, R. Wheatley, J. Bascunan, B. Haid and Haigun Lee Summary: This paper presents a reference design of a solid-nitrogen cooled 300-MHz/25 mm Nb/sub 3/Sn NMR magnet based on a novel design/operation concept. The magnet operates in the temperature range 8-10 K with its cryocooler thermally decoupled from the magnet and idled. A mass of solid nitrogen in thermal contact with the magnet prolongs the magnet warm-up time to 17 h, during which NMR measurement may be performed under a quiet environment free of the cryocooler's microphonics. At 10 K, the magnet is re-coupled to the cryocooler for recooling to 8 K and ready for another 17-h measurement.         A flux pump for NMR magnets    Haigun Lee, Ho Min Kim and Y. Iwasa Summary: A flux pump coupled to a slightly dissipative NMR magnet enables the magnet to operate effectively in persistent mode. This paper presents: 1) design and operation concept of the flux pump; 2) parameters and performance results of a prototype flux pump; and 3) a plan to couple a full-scale flux pump to two NMR magnets, one comprised of low- and high-temperature (LTS/HTS) superconducting coils in which the HTS insert is dissipative and the other an all-LTS which can be artificially made resistive. Performance results of the prototype coupled, sequentially, to two Nb-Ti magnets show that agreement between analysis and experiment is excellent.         Test of fiber-reinforced type of Nb/sub 3/Sn superconducting coils    K. Arai, J. Kondoh, H. Tateishi, K. Agatsuma, M. Furuse and M. Umeda Summary: A superconducting coil using a Nb/sub 3/Sn fiber-reinforced type of wire was fabricated and tested. Each superconducting filament of the wire was reinforced by a tantalum fiber. The coil was prepared in a wind-and-react process and was completed by epoxy impregnation. The continuous length of the wire was 250 meters, and 100-meters of it were used for the coil. The quench current in liquid helium reached similar levels to the critical current of the short sample of the wire without degradation. The strain dependence on operating current was described and compared with calculations using two-dimensional analyses. As a reference, another coil using an internally reinforced wire with the similar specifications was prepared and tested.         Negative-resistance voltage-current characteristics of superconductor contact junctions for macro-scale applications    M. Takayasu, T. Matsui and J.V. Minervini Summary: Voltage-current characteristics of mechanical pressure contact junctions between superconducting wires are investigated using a voltage-driving method. It is found that the switching regions at low voltages result from negative resistance of the contact junction. The current transport of the contact junctions is discussed from the perspective of two existing models: the multiple Andreev reflections at the two SN interfaces of a SNS (Superconductor/Normal metal/Superconductor) junction and the inhomogeneous multiple Josephson weak-link array.         Magnetic flux concentration and magnetic force enhancement using YBCO cylinders    S. Matsumoto, T. Kiyoshi, T. Asano, O. Ozaki, K. Koyanagi, J.-I. Fujihira and H. Wada Summary: In this paper, we propose new applications of bulk high-temperature superconductors in high magnetic fields. High-temperature superconductors, such as Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+d/ (BSCCO) or YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO), maintain their superconductivity over 30 T at 4.2 K. A field-cooled superconducting hollow cylinder traps the magnetic flux inside it. An increase of the applied magnetic field induces shielding current in the interior of the cylinder to maintain the magnetic flux constant. By suitably arranging the cylinders, we can concentrate the magnetic flux and enhance the gradient of the magnetic field. In order to confirm these concepts, we performed experiments using bulk YBCO hollow cylinders. The cylinders are made of YBa/sub 2/Cu/sub 3/O/sub 7-x/ quasi single-crystals containing Y/sub 2/BaCuO/sub 5/ particles. They have an inner diameter of 5 mm, an outer diameter of 10 mm, and a height of 10 mm. Using three hollow cylinders, a magnetic concentration of 0.49 T was observed in an applied magnetic field of 10.14 T. The energized hollow cylinder with a shielding current modify surrounding magnetic fields and magnetic force fields. A magnetic force field enhanced by using a hollow cylinder was calculated numerically for an applied magnetic field of 10 T and estimated to exceed 6000 T/sup 2//m.         Vertical access zero boiloff rampable superconducting magnet system with horizontal field for semiconductor crystal growth    H.B. Jin, S.J. Choi, H.J. Kim, H.H. Han, B.S. Park, B.G. Lee, K.D. Sim, Y.K. Kwon, C.H. Winter and D. Healey Summary: A magnet system has been designed and built to minimize convection mixing during the growth of 0.2 m (8 inch) diameter semiconductor crystals. Due to the size requirements of the crystal growth furnace, the magnet has a room temperature vertical access bore of diameter 1.27 m and height 1.2 m. The cold bore of the magnet is diameter 1.4 m and height 0.8 m with a 280 liter liquid helium bath. The field is perpendicular to the cylindrical bore and is provided by two saddle shaped NbTi coils. The two coils, each with 1200 turns operating at 200 A, produce a 0.2 T horizontal field at the center of the bore. The series inductance is 0.3 H for a total stored energy of 6 kJ. High Tc (BISCO in silver tape) leads were used to allow the system to be operated without persistent current switches, for ease of ramping. A 100 W at 80 K, 5 W at 20 K shield GM cooler plus a 45 W at 50 K, 1.5 W at 4.2 K helium recondensing G-M cooler were used to achieve zero boiloff. The measured shield temperatures in operation are 65 K and 17 K. Design considerations, including thermal staging of the silver tape/BISCO (HTC) current leads, lead quench protection circuit, low thermal conduction mechanical support structure and magnet construction, are discussed.         Three-dimensional analysis on time evolution of shielding current density in HTS    A. Kamitani, T. Yokono and K. Hasegawa Summary: The numerical method for calculating the shielding current density in the high-T/sub c/ superconductor (HTS) is developed by use of the element-free Galerkin method. The behavior of the shielding current density is expressed by the integro-differential equations. In order to solve the initial-boundary-value problem of the equations, the weak form is derived that is equivalent to the problem. Since the essential boundary conditions are directly incorporated into the weak form by using the Lagrange multipliers, both the test and the trial functions do not need to satisfy the conditions. The numerical code for analyzing the time evolution of the shielding current density has been developed by using the above method. The time sequence of the magnetic field is calculated by means of the code and its spectral analysis is performed.         Conceptual design of a magnetic bottle for positron containment    D. Wu, C.A. Luongo and J.R. Miller Summary: Magnetic confinement of positrons has been achieved in small scales, and the key to achieve better confinement is the design of compact and cost-efficient high field superconducting magnets. The paper describes a general algorithm to optimize a magnet design to match a pre-specified magnetic field profile needed to achieve confinement. The numerical model is used to calculate magnetic field, forces, and inductance for the superconducting magnetic bottle (magnetic mirror) based on simple solenoidal configurations. The model incorporates magnet stability and quench constraints in order to arrive at a feasible optimum design. A preliminary design for an experimental facility is presented.         A superconducting solenoid and press for permanent magnet fabrication    T.M. Mulcahy and J.R. Hull Summary: For the first time, a superconducting solenoid (SCM) was used to increase the remnant magnetization of sintered NdFeB permanent magnets (PMs). In particular, magnetic alignment of commercial-grade PM powder was improved by axial-die pressing the powder into 12.7-mm diameter cylindrical compacts in the 76.2-mm warm bore of a 9-T SCM. The press used to compact the powder is unique and was specifically designed for use with the SCM. Although the press was operated in the batch mode for this proof-of-concept study, its design is intended to enable automated production. In operation, a simple die and punch set made of nonmagnetic materials was filled with powder and loaded into a nonmagnetic press tube. The cantilevered press tube was inserted horizontally, on a carrier manually advanced along a track, into the SCM. The mechanical components and the SCM, in its liquid helium dewar, were specifically designed to allow for insertion and extraction of the magnetic powder and compacts, while operating the solenoid at 9 T. Compaction was achieved by pressing the punches between the closed end of the press tube and the hydraulic cylinder mounted on the opposite end. Improvements up to 10% in magnetization and 20% in energy products of the permanent magnets were obtained, as the alignment fields were increased above the 2-T maximum field of the electromagnets used in industry. For comparison, increases in magnetization of 3% are significant in the mature sintered magnet industry.         Magnetic shielding analysis of high-T/sub c/ superconducting plates by power law, flux-flow, and flux-creep models    T. Yokono, K. Hasegawa and A. Kamitani Summary: The magnetic shielding performance of a high-T/sub c/ superconducting (HTS) plate is investigated numerically. By taking account of the crystallographic anisotropy in the shielding current density of the melt-powder-melt-growth YBa/sub 2/Cu/sub 3/O/sub x/ plate, the multiple-layer structure is introduced to modelize the HTS plate. In this case, the shielding current density is governed by the integral-differential equation of the scalar potential. In addition, the power law is used as the J-E constitutive equation for description of the characteristics of the Type-II superconductor. When the equation is descretized by using the finite element method and the weighted average method, the resulting algebraic equation is solved by using the decelerated Newton method. A numerical code for analyzing the time evolution of the shielding current density has been developed and, by use of the code, the shielding performance of HTS plates is investigated. In addition, the results obtained by using the power law, the flux-flow and the flux-creep models are compared.         Universal magnetic inversion scheme to design novel superconducting magnet systems    N.R. Brooks and T.L. Baldwin Summary: A new computational program is developed for solving the inverse magnetic problem for determining the magnetic design necessary to produce a desired field pattern. The conception of an innovative source-modeling algorithm allows the program to be universally applied, unlike currently particularized methods. This new method termed Variable Field Generation (VFG) facilitates the synthesis of arbitrary magnetic designs and inversely defines new and unique magnetic systems for difficult three-dimensional magnetic field patterns. Such complex field patterns are necessary for proposed applications based on current advances in high-temperature superconductors. This paper reports the evaluation of VFG as a universal solution to the design challenges of magnet applications, including analysis of test cases for different magnetic applications using various solvers.         Preliminary mechanical training of thin coils    E.A. Deviatkin Summary: Bending with tension of composite superconductors during the coil winding induces a high and very nonuniform normal stress on their cross-sectional areas so that the constituent materials can be in the plastic state inside one or two extensive conductor zones already in the winding process. The removal of the bobbin from the coil results in stress redistribution. Stresses arising in components of a thin solenoidal coil after its winding, removal of the bobbin and subsequent mechanical "training" by means of internal pressure are studied. It is assumed that a multifilamentary composite superconductor is macroscopically homogeneous and its stress-strain diagram is analogous to that of a ductile material following the straight-line law in unloading and reloading whereas interlayer insulation and impregnation materials are linear elastic. The case where one plastic zone develops during the coil winding in the conductor of the rectangular cross section and a new zone does not appear after the bobbin removal operation is considered. The higher the winding pretension, the lower the tensile stress in the conductor after the removal of the bobbin. It is shown that by mechanical training of the coil it is possible to redistribute stresses between its components and decrease the conductor stress.         Current diffusion and normal zone propagation inside the aluminum stabilized superconductor of ATLAS model coil    E.W. Boxman, M. Pellegatta, A.V. Dudarev and H.H.J. Ten Kate Summary: The normal zone propagation inside the B/sub O/ model coil of the ATLAS Toroidal magnet has been measured over a large range of applied currents. Typical values for the longitudinal propagation vary from 0.3 to 15 m/s at 8 and 24 kA, respectively. A new analytical expression for the longitudinal quench propagation inside superconducting cables is presented. It describes the propagation inside superconducting wires as well as the propagation inside large stabilized superconductors. It is found that in the limit case of high currents, the stabilizer functions only as a heat-sink. The model is compared to experimental data and a good correlation is found.         Normal zone propagation model for monolith conductors with current diffusion    Yu. Lvovsky Summary: A model is presented which allows us to analyze normal zone propagation in monolith conductors taking account of current diffusion, the conductor's nonlinear properties and current sharing. An analytical description of the current diffusion heat generation is given. It is used in a first order ordinary differential equation (ODE) to determine the normal zone longitudinal velocity V/sub nz/ and temperature profile. The method is illustrated on the examples of conductors with copper and aluminum stabilizers. It also allows us to account for the heat transferred into the insulation, which can notably reduce V/sub nz/.         Quench simulation in superconducting cables using optimized DRP scheme    Shaolin Mao, C.A. Luongo and C. Marinucci Summary: A high order finite difference scheme is introduced to deal with thermo-hydraulic quench simulation in superconducting magnets, specifically in the case of cable-in-conduit conductors (CICC). Liquid helium flow in CICC is governed by the unsteady convection-diffusion conservation equations, in the low Mach number and high Reynolds number flow region. In the past several years many methods have been considered for quench simulation in superconducting magnets, for example, finite element, finite volume, and finite difference methods. One of the main challenges is the accurate simulation of flow during a superconductor quench, given the large gradients in pressure and temperature that arise during conductor normalization. These simulations are key to proper magnet protection design. The Dispersion Relation Preserving (DRP) scheme is applied to the quench simulation problem. The computational results are compared to those obtained using a well-proven commercial quench simulation code (Gandalf), as well as experimental data. Preliminary results are promising.         2-D/3-D quench simulation using ANSYS for epoxy impregnated Nb/sub 3/Sn high field magnets    R. Yamada, E. Marscin, Ang Lee, M. Wake and J.-M. Rey Summary: A quench program using ANSYS is developed for the high field collider magnet for 3-D analysis. Its computational procedure is explained. The quench program is applied to a one meter Nb/sub 3/Sn high field model magnet, which is epoxy impregnated. The quench simulation program is used to estimate the temperature and mechanical stress inside the coil as well as over the whole magnet. It is concluded that for the one meter magnet with the presented cross section and configuration, the thermal effects due to the quench is tolerable. But we need much more quench study and improvements in the design for longer magnets.         A quench management system for testing superconducting magnets    D.F. Orris, R. Carcagno, S. Feher, M.J. Lamm, J. Nogiec, P. Schlabach, M. Tartaglia and J.C. Tompkins Summary: A quench management system has been developed for the Fermilab Magnet Test Facility as part of the overall data acquisition and control system for testing superconducting accelerator magnets. The quench management system accepts a standard set of quench input signals such as magnet voltages and current, safety interlocks, and power supply status, which are multiplexed from several independent test stands. It also issues a standard set of output control signals that are used to activate the dump, the quench protection heater power supplies, and to control the magnet ramp down in the event of a quench. Triggers generated by the quench management system are used to save the logged quench data from both the fast and slow data acquisition instrumentation. The hardware architecture of the quench management system will be discussed along with analog quench detection, digital quench detection, quench logic, and the user interface for configuring and controlling this system.         Cored Rutherford cables for the GSI fast ramping synchrotron    M.N. Wilson, A.K. Ghosh, B. ten Haken, W.V. Hassenzahl, J. Kaugerts, G. Moritz, C. Muehle, A. den Ouden, R. Soika, P. Wanderer and W.A.J. Wessel Summary: The new heavy ion synchrotron facility proposed by GSI will have two superconducting magnet rings in the same tunnel, with rigidities of 200 T/spl middot/m and 100 T/spl middot/m. Fast ramp times are needed, which can cause significant problems for the magnets, particularly in the areas of ac loss and field distortion. This paper discusses the 200 T/spl middot/m ring, which will use Cos/spl theta/ magnets based on the RHIC dipole design. We discuss the reasons for choosing Rutherford cable with a resistive core and report loss measurements carried out on cable samples. These measurements are compared with theoretical calculations using measured values of inter-strand resistance. Reasonably good agreement is found, but there are indications of nonuniformity in the adjacent resistance R/sub a/. Using these measured parameters, losses and temperature rise are calculated for a RHIC dipole in the operating cycle of the accelerator. A novel insulation scheme designed to promote efficient cooling is described.         Analytical calculation of current distribution in multistrand superconducting cables    L. Bottura, M. Breschi and M. Fabbri Summary: In recent years the problem of current distribution in multistrand superconducting cables has received increasing attention for large scale superconductivity applications due to its effect on the stability of fusion magnets and the field quality of accelerator magnets. A modeling approach based on distributed parameters has revealed to be very effective in dealing with long cables made of some tens or hundreds of strands. In this paper we present a fully analytical solution equation for a distributed parameters model in cables made of an arbitrary number of strands, whose validity is subjected to symmetry conditions generally satisfied in practical cables. We give in particular analytical formulae of practical use for the estimation of the maximum strand currents, time constants and redistribution lengths as a function of the cable properties and the external voltage source.         Calculating quench propagation with ANSYS/sup /spl reg//    S. Caspi, L. Chiesa, P. Ferracin, S.A. Gourlay, R. Hafalia, R. Hinkins, A.F. Lietzke and S. Prestemon Summary: A commercial Finite-Element-Analysis program, ANSYS/sup /spl reg//, is widely used in structural and thermal analysis. With the program's ability to include nonlinear material properties and import complex CAD files, one can generate coil geometries and simulate quench propagation in superconducting magnets. A "proof-of-principle" finite element model was developed assuming a resistivity that increases linearly from zero to its normal value at a temperature consistent with the assumed B magnetic field. More sophisticated models could easily include finer-grained coil, cable, structural, and circuit details. A quench is provoked by raising the temperature of an arbitrary superconducting element above its T/sub c/. The time response to this perturbation is calculated using small time-steps to allow convergence between steps. Snapshots of the temperature and voltage distributions allow examination of longitudinal and turn-to-turn quench propagation, quench-front annihilation, and cryo-stability. Modeling details are discussed, and a computed voltage history was compared with measurements from a recent magnet test.         Effect of thermo-mechanical stress during quench on Nb/sub 3/Sn cable performance    L. Imbasciati, P. Bauer, G. Ambrosio, M.J. Lamm, J.R. Miller, G.E. Miller and A.V. Zlobin Summary: Several high field magnets using Nb/sub 3/Sn superconductor are under development for future particle accelerators. The high levels of stored energy in these magnets can cause high peak temperatures during a quench. The thermo-mechanical stress generated in the winding during the fast temperature rise can result in a permanent damage of the brittle Nb/sub 3/Sn. Although there are several studies of the critical current degradation of Nb/sub 3/Sn strands due to strain, little is known about how to apply the strain limitations to define a maximum acceptable temperature in the coils during a quench. Therefore, an experimental program was launched, aimed at improving the understanding of the effect of thermo-mechanical stress in coils made from brittle Nb/sub 3/Sn. A first experiment, reported here, was performed on cables. The experimental results were compared to analytical and finite element models. The next step in our experimental program will be to repeat similar measurements in small racetrack coils and later in full size magnets.         Current redistribution and thermal history due to ramp-rate limitation of a superconducting cable    Seokho Kim and Sangkwon Jeong Summary: RRL (Ramp-Rate Limitation) is caused by current nonuniformity during magnetic field change. Although current nonuniformity is determined only by contact resistance between strands, cable inductance and field ramp rate, current redistribution process is induced by joule heating from current sharing mode and heat transfer to adjacent liquid helium. Experiment was performed to investigate electro-magnetically and thermo-hydraulically coupled RRL with 2.6 m long two-strand superconducting cable at maximum field to 6 T with a rate of 3 T/s. This paper describes the detailed strand current redistributions during quench process under magnetic field ramps. Heat transfer effect as well as electrical characteristics to current redistribution was also investigated with the measured strand temperatures, currents and quench voltages.         Measurements of temperature dependence of the stability and quench propagation of a 20-cm-long RABiTS Y-Ba-Cu-O tape    R. Grabovickic, J.W. Lue, M.J. Gouge, J.A. Demko and R.C. Duckworth Summary: Thermal stability and quench propagation in a composite tape made of YBa/sub 2/Cu/sub 3/O/sub x/ (YBCO) superconductor were studied experimentally. Quench propagation in each test was initiated by applying a sequence of a short overcurrent pulse followed by a longer pulse at a typical operating current for the tape. The resulting change in resistivity due to internal heating was measured through voltage taps across different zones of the tape. Measurements were performed as a function of both initial overcurrent and operating current for several operating temperatures between 45 and 80 K. These experimental results provided the thermal stability margin, the minimum propagation current, and the quench propagation velocity for the tape. Experimentally obtained temperature dependence of normal zone propagation velocity was compared with the adiabatic theory taking into account minimum propagation current. It was noted that the measured normal zone propagation velocity compared favorably with the theory at each operating temperature.         Analysis of AC loss in superconducting power devices calculated from short sample data    J.J. Rabbers, B. ten Haken and H.H.J. Ten Kate Summary: A method to calculate the AC loss of superconducting power devices from the measured AC loss of a short sample is developed. In coils and cables the magnetic field varies spatially. The position dependent field vector is calculated assuming a homogeneous current distribution. From this field profile and the transport current, the local AC loss is calculated. Integration over the conductor length yields the AC loss of the device. The total AC loss of the device is split up in different components. Magnetization loss, transport current loss and the loss due to the combined action of field and current all contribute to the AC loss of the device. Because ways to reduce the AC loss depend on the loss mechanism it is important to know the relative contribution of each component. The method is demonstrated on a prototype transformer coil wound from Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x//Ag superconducting tape. Differences between the model assumptions and devices are pointed out. Nevertheless, within the uncertainty margins the calculated AC loss is in agreement with the measured loss of the coil.         AC losses in YBCO coated conductors carrying AC transport currents in perpendicular AC external magnetic field    J. Ogawa, M. Shiokawa, M. Ciszek and O. Tsukamoto Summary: The paper reports an experimental study on AC loss characteristics of a YBCO coated tape conductor carrying AC transport current in AC external magnetic field. In the experiment we electrically measured total losses that were transport current losses plus magnetization losses in AC external magnetic fields perpendicular to the tape surfaces. The transport current losses were measured by a four terminal method and the magnetization losses by a method using a pick-up coil. To measure the total losses electrically we need to pay proper attentions to prevent electromagnetic coupling between the sample currents and the external magnetic fields and to suppress inductive voltage in signals from the pick-up coil and voltage taps. The total losses were purely hysteretic for the amplitude of the external field up to 20 mT and the peak transport current up to the critical current. The loss characteristics can be explained by a theory based on the Bean model if the dependence of the critical current on the external magnetic field is taken into consideration.         Investigation of degradation mechanisms in CICCs    C. Meinecke and A.M. Miri Summary: The performance of cable-in-conduit conductors often does not meet the anticipation extrapolated from the data of single strands. Various mechanisms are currently discussed as potential causes of this degradation. However, their quantitative influence in real-scale conductors remains to be determined. We investigated several mechanisms such as self-field effect, joint resistance scatter, and local strand degradation (e.g., by a local strain maximum in Nb/sub 3/Sn strands), using a recently presented model for the coupled electromagnetic and thermo-hydraulic analysis of forced-flow cooled multi-strand conductors. The significance of the electromagnetic diffusion length for the current distribution processes in multi-strand conductors is emphasized.         Monte Carlo simulation of strand position in CIC conductor    K. Aoki, Y. Izumi, S. Nishijima, K. Okuno and N. Koizumi Summary: The strand position in CIC conductor has been calculated three dimensionally by using Monte Carlo method. The 1152 (3 /spl times/ 4/sup 3//spl times/ 6) Nb/sub 3/Sn superconducting strands were packed in the conduit. The manufacturing process of CIC conductor was simulated. The six 4th-stage cables were cabled with a spiral tube and then packed into the conduit. The conduit was compressed with the cable to fix the size and the shape. The conduit was compressed from one end and so that the strands were stretched along the axis unevenly. The contact energy between strands and the strain energy in the strands were considered. It was confirmed that the strand positions were changed by compressing the conduit and the obtained strand positions were similar to those in actual CIC conductor.         Case studies in reconstruction efficiency of current distribution in CICC's by self field measurements    Yu.A. Ilyin and A. Nijhuis Summary: The measurements of the self magnetic field by means of Hall sensors (HS) in the vicinity of a superconducting cable-in-conduit conductor (CICC) is often used to study current distribution effects. It is possible that current imbalance may affect the performance of CICC's and therefore knowledge of the current distribution is needed. Recently a model was presented to approximate the current distribution inside a conductor. Basically, the inverse problem must be solved in which the input data usually are the experimentally measured values of the local magnetic field, the location and orientation of the HS's and the geometry of the line or segment currents. All these, together with the adopted algorithm, determine the accuracy of the reconstruction procedure. In the present study the impact of two basic orientations of the HS: polar-symmetric and plane-parallel on the current reconstruction efficiency is performed for the analytical model developed in Twente. For the case study, a 36 strands CICC and a mock-up conductor are considered. The influence of the experimental errors and geometrical errors on the model output is also investigated.         Self field measurements by Hall sensors on the SeCRETS short sample CICC's subjected to cyclic load    Yu.A. Ilyin, A. Nijhuis, H.H.J. Ten Kate, B. Stepanov and P. Bruzzone Summary: An imbalance in the transport current among the strands of a Cable-in-Conduit conductors (CICC) can be associated with the change of their performance. In order to understand and improve the performance of CICC's, it is essential to study the current imbalance. This paper focuses on the study of the current imbalance in two short samples of the SeCRETS (Segregated Copper Ratio Experiment on Transient Stability) conductors subjected to a cyclic load in the SULTAN facility. The self field around the conductors was measured on four locations by 32 miniature Hall sensors for a reconstruction of the current distribution. The results of the self field measurements in the DC tests are presented and discussed.         Relation between frictional loss and combination of thermal coefficient of bobbins and winding tension in AC superconducting coils    N. Sekine, T. Takao, Y. Kojo, Y. Yamaguchi, S. Tada, T. Higuchi, M. Takeo, S. Sato, A. Yamanaka and S. Fukui Summary: Frictional losses in windings are one of the loss types in AC superconducting coils. When an AC current is supplied to the coil, a superconducting wire in the winding start to vibrate. And frictional heat generates at contact segments between the wire and a coil bobbin. And hence, the losses are not electromagnetic losses such as coupling losses but mechanical losses in superconducting coils. We prepared four types of bobbin materials. Two bobbins expanded during a cooling process from room temperature to liquid helium temperature. The other two bobbins contracted during the cooling down. Winding tensions for the four kinds of coils were 0.5, 3.5, and 5.0 N. And then, the AC losses of the twelve coils were measured. When the coils whose bobbins have thermal expansion were used, the AC losses increased with the gain of the winding tensions, in spite that the experimental conditions such as coil currents and background magnetic field were same. On the contrary, in case of the contraction bobbins coils were used, the losses decreased with the tensions increased. To analyze the experimental cases of the winding tensions of the sample coils at the liquid helium temperature were calculated, and the relation between the tensions at the cryogenic temperature and the frictional losses was discussed.         Effect of helium convection on cryogenic stability of superconducting magnet    Y. Tatsumi and S. Nishijima Summary: The convection of liquid helium in the superconducting magnet was analyzed by means of lattice Boltzmann method in order to study the cryogenic stability of the magnet. Since the cooling capability is determined by the convection of liquid helium, the cryogenic stability of the superconducting magnet should be analyzed considering the effects of the convection. In the calculation, we applied the lattice Boltzmann method which is suitable for the analysis of the complex flows and the heat transfer. By calculating both the convection of liquid helium and the heat transfer, the propagation of the normal state zone was studied.         Joint resistances between two parallel high Tc superconducting tapes    M.H. Sohn, S.W. Kim, S.K. Baik, Y.S. Jo, M.G. Seo, E.Y. Lee and Y.K. Kwon Summary: Eight different types of joining between two parallel high Tc superconducting (HTS) tapes were prepared and current-voltage (I-V) characteristic curves were investigated at 77 K, liquid nitrogen temperature. Contact resistances of joint parts with 25 mm in length were estimated from I-V curves. Lowest contact resistance among eight samples having different types of joining was 0.497 /spl mu//spl Omega/. The best joining method is to do crossly joining with HTS tapes on two parallel HTS tapes after filling solder paste into their gap. In this case, lowest joint resistance was 0.15 /spl mu//spl Omega/ at 77 K and 0.05 /spl mu//spl Omega/ at 28 K. Joule heat of a joint sample generated at 30 K and at 100 A was calculated 0.492 mW. Also, in I-V curve of samples crossly joined with HTS tapes, it was found that joint resistance does not depend on variation of magnetic fields (0/spl sim/7000 G) at 77 K. From consideration of Joule heat generation, such joining method is available for fabricating the field winding of superconducting rotating machine.         The role of nickel substrates in the quench dynamics of silver coated YBCO tapes    R.C. Duckworth, J.W. Lue, D.F. Lee, R. Grabovickic and M.J. Gouge Summary: A pair of silver coated YBCO tapes with varying degrees of electrical contact between the silver and the YBCO nickel substrate were studied to examine the impact of nickel on normal zone formation and stability. The YBCO tapes were fabricated using the rolling assisted bi-axially textured (RABiTS) method and 15-cm-long samples with 2 /spl mu/m of silver were prepared. The samples were place in a conduction cooling environment at 45 K to study quench or recovery when a series of dc transient over-current pulses were applied. We used a series of voltage taps on both the silver and nickel to characterize the nature of the contact between the silver and the nickel through the measured voltages. In as-manufactured samples and those sample with continuous contact between the nickel and silver, we found that the silver and nickel can not be treated as conductors in parallel when a normal zone is present because of current present in the nickel even while sections of the sample remains superconducting. This nonparallel contact makes stability characterization difficult although the samples with intentional contact were able to withstand larger current pulses. In addition, the samples with intentional electrical contact between the silver and nickel exhibited normal zone propagation in both the silver and the nickel with speeds between 4 mm/s and 8 mm/s.         Quench and recovery of YBCO tape experimental and simulation results    Y. Iwasa, Haigun Lee, Jiarong Fang and B. Haid Summary: This paper presents quench/recovery results, both experimental and simulation, of a 10-cm long YBCO test sample subjected to an over-current pulse. The sample was cooled by liquid nitrogen, either in a bath or forced through a narrow channel. Bath provides a better cooling than flow, at least for velocities of 3 and 5 cm/s used in the experiment.         Investigation of cooling effects on conduction cooled HTS tape due to high thermal conduction plastics    T. Takao, A. Kawasaki, M. Yamaguchi, H. Yamamoto, A. Niiro, K. Nakamura and A. Yamanaka Summary: Local temperature rise due to insufficient cooling is one of the important problems in conduction-cooled high-temperature superconducting (HTS) coils. Assuming two types of plastics having high thermal conductivity as spacers in HTS coils, we measured temperature rises of a conduction-cooled HTS tape under various contact conditions between the plastics and the HTS tape. The cooling performance from the Zylon fiber reinforced plastic to the HTS tape was not so good, since the fibers in the plastic were oriented in one direction. The Dyneema fiber reinforced plastic effectively cooled the HTS tape, because the fibers in the plastic were two dimensions. The possibility to use the plastics with high thermal conductivity as the spacers in the conduction-cooled HTS coils was demonstrated.         Copper stabilization of YBCO coated conductor for quench protection    Y. Fu, O. Tsukamoto and M. Furuse Summary: The required amount of copper stabilizer to protect a YBCO conductor coil from damage caused by a hot spot due to a quench is studied in this paper. YBCO coated conductors which are made by deposition of thin YBCO film on high resistance metal substrates are highly resistive when they are quenched. Therefore, stabilization and quench protection are more important for YBCO conductors than Bi/Ag sheathed tapes which have low resistance silver matrix. In the work we numerically calculated maximum temperature rise of a YBCO conductor quenched by a local disturbance during the sequence of quench detection and energy dump. In the analysis, necessary amount of copper to keep the maximum temperature of the conductor below a threshold value is calculated for cases of conduction cooled coils of dry windings. Based on the analysis, optimum conductor design is discussed to protect the coil from a quench reliably.         Soldered double pancake winding of high temperature superconducting tape    S.W. Kim, M.H. Sohn, S.K. Baik, Y.S. Jo, M.G. Seo, E.Y. Lee, R.K. Ko and Y.K. Kwon Summary: To make a superconducting coil by winding a High Temperature Superconductor (HTS) tape conductor on a bobbin, the double pancake winding technique is widely used to reduce number of splicing contacts between conductor pieces. However, this makes some Ic (critical current) degradation on kink points of the conductors, which is unavoidable. Soldered double pancake can be an alternative way to overcome the Ic degradation. This paper describes and compares the two ways of winding; usual double pancake, and soldered double pancake. Characteristics of the windings are measured and compared. The soldered double pancake winding has resistance on the contact points, but the estimated Joule heating on the contacts is much smaller than heat leak of cryostats.         Thermo-mechanical characterization of insulated and epoxy-impregnated Nb/sub 3/Sn composites    L. Imbasciati, G. Volpini, G. Ambrosio, D.R. Chichili, D. Pedrini, V. Previtali, L. Rossi and A.V. Zlobin Summary: Nb/sub 3/Sn is, at present, the best superconductor for high field accelerator magnets. Several models using Nb/sub 3/Sn are under development in many laboratories. Knowledge of the thermo-mechanical properties of the impregnated coils is of crucial importance for the design of these magnets. In fact, the performance of epoxy-impregnated coils is sensitive to the thermal conductivity value, especially in case of heating caused by hysteretic losses, which are usually relevant in Nb/sub 3/Sn magnets, and in the case of continuous heat deposition, such as in magnets near the interaction region of a collider. Thermal contraction measurements are necessary to estimate the stresses during the magnet thermal cycle. Different insulation materials have been studied at Fermilab utilizing various design approaches and fabrication methods. Thermal conductivity and thermal contraction measurements, at cryogenic temperatures, have been performed respectively at INFN-LASA and Fermilab. The results are reported and discussed in this paper.         Investigation of alternative materials for impregnation of Nb/sub 3/Sn magnets    D.R. Chichili, J. Hoffman and A.V. Zlobin Summary: Insulation is one of the most important elements of magnet design, which determines the electrical, mechanical, and thermal performance as well as lifetime of the magnet. The exposure to high radiation loads especially for the proposed LHC second-generation interaction region Nb/sub 3/Sn quadrupoles further limits the choices of the insulation materials. Traditionally Nb/sub 3/Sn magnets were impregnated with epoxy to improve both the mechanical and electrical properties. However, the acceptable radiation limit for epoxy is low which reduces the lifetime of the magnet. The paper presents the results of the feasibility study to replace epoxy with high radiation-resistant material during vacuum impregnation. The mechanical, thermal and electrical properties of samples impregnated with Matrimid were measured and compared with epoxy-impregnated samples.         Development of CCVD ceramic insulation for Bi-2212 superconducting wires and Rutherford cables    Yibin Xue, S. Mark, S. Shoup, K.R. Marken Jr., Hanping Miao, M. Maarten, S.A. Gourlay and R. Scanlan Summary: A low cost, open-atmosphere deposition technique, Combustion Chemical Vapor Deposition (CCVD) is used to deposit zirconia-based, multi-component insulation films on Bi-2212 tapes for fabricating high temperature superconducting magnet coils. The insulation coatings were investigated in detail in terms of composition, microstructure, and insulation strength versus the deposition temperature and other parameters. Dielectric and mechanical properties and chemical compatibility with BSCCO have been characterized and optimized. The advantage of the CCVD technique in producing multi-component insulating materials with the desired properties are described. A brief evaluation of this insulation coating on Rutherford cables fabricated from Bi-2212 wires is also reported.         A 100 MJ SMES demonstration at FSU-CAPS    C.A. Luongo, T. Baldwin, P. Ribeiro and C.M. Weber Summary: The Center for Advanced Power Systems (CAPS) at Florida State University (FSU) was recently established to pursue research and education in power engineering. Development and demonstration of superconducting technologies is one of the cornerstones of the CAPS program. Important aspects of the program are the test of superconducting equipment at power levels up to 5 MW, and the creation of a reconfigurable network that will support pulsed power testing. A 100 MJ SMES system is being completed at BWX Technologies for integration to the CAPS test facility, to allow pulsed power operation of the testbed. The SMES coil, scheduled for completion in 2003, is based on cable-in-conduit technology and NbTi superconductor. The full system (including cryostat and power converter) will be integrated at CAPS and be operational in late 2004.         Interaction between a superconducting coil and the power electronics interface on a 100 MJ SMES system    M. Steurer, C.A. Luongo, P.R. Ribeiro and S. Eckroad Summary: Although numerous studies have focused on the connection of SMES to the utility power grid, fewer have addressed in detail the interactions between the power electronics interface and the SMES coil. While electromagnetic transient models are available from classical transformer studies, little work has been done on how these models apply to SMES coils. This paper presents the computer modeling of the interaction between a 100 MJ/100 MW LTS SMES coil now under construction and its power electronics interface. It is concluded that frequency domain modeling methods are applicable to study SMES coil-converter interactions and to recommend preferred operating frequencies of the power converter provided that certain characteristics unique to SMES systems are accounted for.         Design and test results of CIC conductor for a cost reduced 100 MW/500 kWh SMES    S. Hanai, M. Shimada, T. Tsuchihashi, T. Kurusu, M. Ono, K. Shimada, S. Koso, K. Tsutsumi and S. Nagaya Summary: Cost reduction study of 100 MW/500 kWh SMES for load compensation and frequency regulation is performed under Japanese national project. A newly designed CIC (Cable In Conduit) Conductor is developed for the SMES (Superconducting Magnetic Energy Storage). The number of superconducting strand in the cable is reduced with segregated Cu strands. The cross-sectional structure of a strand with CuNi sheath is simplified from the previous design. To reduce AC loss time constant, strands are twisted up to second degree, which is much lower than that of the previous cable design. A short sample of the conductor is manufactured and tested. The test results show that the conductor has good performance for the SMES.         Magnet power supply with power fluctuation compensating function using SMES for high intensity synchrotron    T. Ise, K. Furukawa, Y. Kobayashi, S. Kumagai, H. Sato and T. Shintomi Summary: The power supply for high intensity synchrotron magnet draws large amount of power from utility network. The JHF 50-GeV main ring will require 104 MW of total active power and 28.8 MW of dissipation power by estimation. Moreover, the charging and discharging cycle is repeated with 3.64 s of the cycle time at the initial operation, and the repeating frequency will be raised up by twice in future. Taking this situation into consideration, energy storage system using adjustable speed type flywheel and IGBT power converter are studied in the JHF project. In this paper, the power supply using SMES is proposed. The power supply can absorb the fluctuation of active and reactive power caused by charging and discharging the synchrotron magnet. The system is composed of current source ac/dc converter, chopper circuits and superconducting magnets. The chopper circuits for superconducting magnets and synchrotron magnets can be connected to the same dc bus of the power supply and this feature can reduce the power rating of ac/dc converters.         Analysis on the impact of HTS cables and fault-current limiters on power systems    L.F. Martini, L. Bigoni, G. Cappai, R. Iorio and S. Malgarotti Summary: Power system studies on potential applications of superconducting cables and fault-current limiters and their impact on utility networks were performed by digital models developed in ATP (Alternative Transients Program). Simulation results from lightning overvoltage and fault analyses on 132 kV cable and 3-phase faults on 20 kV current limiter are reported.         Simulation study on operating characteristics of superconducting fault current limiter in one-machine infinite bus power system    Y. Shirai, M. Taguchi, M. Shiotsu, H. Hatta and T. Nitta Summary: A simulation model of a Superconducting Fault Current Limiter (SCFCL) based on the experimental results was proposed. Simulation studies were performed in one-machine infinite bus system with parallel transmission lines, which corresponds to the experimental system. The simulation results agree well with the experimental ones. Power system operating characteristics of the SCFCL were investigated and discussed by simulation results Effects of the SCFCL to the power system are verified from the simulation results. It is shown that the SCFCL's make critical clearing time longer and improve the system stability.         Optimal location assignment and design of superconducting fault current limiters applied to loop power systems    K. Hongesombut, Y. Mitani and K. Tsuji Summary: Short-circuit current is strongly related to the cost of apparatus and the efficient use of power transmissions. Therefore, the introduction of Superconducting Fault Current Limiters (SFCL's) becomes an effective way for suppressing such a high short-circuit current in loop power systems. Firstly, a method to obtain a smaller SFCL capacity by observing the SFCL behavior including sub-transient and transient effects during a short circuit is proposed. Secondly, we propose using a micro-genetic algorithm (micro-GA) combined with a hierarchical genetic algorithm (HGA) to simultaneously search for the optimal location and the smallest SFCL capacity. The efficiency of the proposed method is shown by numerical examples with a loop power system.         Experimental study of solenoid using Bi2223/Ag tape with ferromagnetic disks    J. Kondoh, M. Furuse and M. Umeda Summary: We have studied a disk-set solenoid: a superconducting solenoid that uses Bi2223/Ag tape and has ferromagnetic disks set on both its ends. A magnetic field applied to the tape conductors at the edges turns so it is parallel to the tape surface. We manufactured a solenoid made of 10 double pancakes and investigated differences in its characteristics with and without the ferromagnetic disks. The results showed that setting the disks increased the critical current of a double pancake on the edge 1.3 times. And measurements using the Hall elements demonstrated that the magnetic field applied perpendicularly to the tape surface near the edge was reduced to the same degree as indicated by the numerical calculation.         Topology optimization method for superconducting system with critical current condition    Il-Han Park, Jin-Kyu Byun, J.S. Kang and W.S. Nah Summary: A new design scheme is developed to use the topology optimization method in the superconducting system. The critical current condition is considered in the sensitivity calculation for accurate analysis and design of the system. The density method is used to model the design space, and the normalized density of superconducting filament in each cell is used as design variables. The designs of SMES (superconducting magnetic energy storage) coil and MRI (magnetic resonance imaging) coil are given as numerical examples.         Distribution of stress in force-balanced coils on virial theorem    H. Tsutsui, S. Nomura, N. Watanabe, C. Suzuki, S. Kajita, Y. Ohata, S. Tsuji-Iio and R. Shimada Summary: Distributions of stress on a device with helical coils for the superconducting magnetic energy storage (SMES) are analyzed experimentally and numerically. In the previous work, we showed a theoretical limit of stored energy in a toroidal SMES system by the virial theorem. To verify the theoretical limit, we designed and construct a small device which is composed of two sets of helical superconducting coils and a toroidal frame of aluminum alloy. Strains by electromagnetic force on the frame were obtained experimentally. Distributions of stress on a toroidal shell with a similar configuration to the device are numerically calculated. Comparing the results of the experiments and the numerical calculations, a qualitative agreement of stress distribution between the calculation and the experiment is obtained in the toroidal direction, while discrepancies of stress in the poloidal direction are not negligible.         Studies on deformation of a 600 kJ modified D-shaped superconducting coil caused by electromagnetic force    H. Hayashi, K. Tsutsumi, T. Esaki, Y. Horiuchi, K. Funaki, S. Hanai, H. Takigami, T. Kobayashi and T. Bohno Summary: As the mechanical causes for instability and loss in superconducting coils become more pronounced as coils increase in scale, it is important to understand the physical behavior of such failure when developing highly reliable and efficient SMES's of a practical scale. However, it is difficult to understand the mechanical behavior of superconducting coils, especially the local deformation or displacement of coil components. It is helpful to use a model to simulate the mechanical behavior of superconducting coils when discussing the instability and mechanical loss caused by such mechanical factors. A simulation model was developed to show the nonlinear mechanical deformation of a modified D-shaped elemental coil with a Rutherford type conductor in a 1 kWh SMES. The nonlinear characteristics of the conductor were explained by the frictional slip between two layers in the conductor. FEM analysis conducted using this model explained well with the mechanical deformations measured in the coil.         A study on performance improvements of HTS coil    M. Yamaguchi, A. Honma, S. Ishiguri, S. Fukui, I. Muta and T. Nakamura Summary: It is of great concern for magnet designers to address their critical currents at a given field and bore size. In the case of high temperature superconducting magnets wound with BSCCO Ag-sheathed tapes, they have a strong magnetic anisotropy and therefore the critical current of magnets defined by an average voltage drop over an entire coil cannot be easily determined like low temperature superconducting magnets. An analytical way to obtain the critical current of HTS magnets is described by means of the electric and magnetic field analyzes based on the measured data of BSCCO Ag-sheathed tapes. A performance improvement of HTS magnet is studied by pursuing an optimum coil cross section.         Demonstration of the stress-minimized force-balanced coil concept for SMES    S. Nomura, H. Tsutsui, N. Watanabe, C. Suzuki, S. Kajita, Y. Ohata, T. Takaku, E. Koizumi, S. Tsuji-Lio and R. Shimada Summary: Strong electromagnetic force caused by high magnetic field and coil current is a serious problem in SMES systems. In facing this problem, we proposed the concept of Force-Balanced Coil (FBC) which is a helically wound toroidal coil. Based on the virial theorem, the FBC can minimize structure requirements for energy storage by selecting an optimal number of poloidal turns. We designed and fabricated a small experimental device which is composed of inner and outer helical coils mutually wound in opposite toroidal directions using NbTi superconductors. The distribution of the working stresses in this device can be changed by selecting the optimal current ratios between inner and outer coil currents. From the experimental results, we demonstrated the validity of the FBC concept.         An optimization method for design of SMES coils using YBCO tape    S. Noguchi, H. Yamashita and A. Ishiyama Summary: Recently, the properties of high temperature superconducting (HTS) tapes have been in advance and HTS magnets have been constructed and demonstrated. However, the HTS tapes have thermal different characteristics compared with the low temperature superconducting (LTS) wires. Moreover, Bi2223/Ag tapes and YBCO coated conductors have the different properties about the dependence on the degree of external magnetic field. Therefore it is necessary to consider these characteristics of HTS tapes at magnet design stage. We proposed an optimal design method for superconducting coils using Bi2223/Ag tapes. And the proposed configuration is optimized by using the simulated annealing (SA), which is one of the optimization algorithms, under a lot of constraints such as B-I characteristic, storage energy, and so on. The details of the optimization method and an example of its application to SMES coils (72 MJ) using YBCO coated conductors are shown.         Design of a 150 kJ high-Tc SMES (HSMES) for a 20 kVA uninterruptible power supply system    R. Kreutz, H. Salbert, D. Krischel, A. Hobl, C. Radermacher, N. Blacha, P. Behrens and K. Dutsch Summary: A High temperature Superconducting Magnetic Energy Storage (HSMES) system has been designed and is being built by ACCEL Instruments GmbH in cooperation with the German companies AEG SVS GmbH, and EUS GmbH, and the utility company E.ON Bayern AG. The magnet is designed for an energy of 150 kJ. The superconducting coil is composed of twenty double pancakes wound of a high temperature superconductor tape with BSCCO-2223 filaments. The coil and the shield are conduction-cooled using a cryocooler; the cryostat is free of cryogens. The current leads are composed of a resistive part and a high temperature superconducting BSCCO-2212 MCP element. The HSMES will be integrated in a 20 kVA uninterruptible power supply (UPS) system coupled to the electrical grid for enhancing the power quality of a selected grid user. The design of the HSMES UPS system is described. A test module composed of two double pancakes wound from pre-series superconductor tapes was manufactured and tested at 77 K in order to check the magnet design and the coil manufacturing technique.         Fabrication and test of a superconducting coil for SMES systems    H.J. Kim, K.C. Seong, J.W. Cho, S.W. Kim, Y.K. Kwon and K. Ryu Summary: To develop a stable and compact small-sized superconducting magnetic energy storage (SMES) coil, which provides electric power with high quality to sensitive electric loads, we fabricated a SMES coil and tested it. Because such a large-sized superconducting coil quenches far away from its critical current, the recovery current is frequently used as a stability criterion in the coil fabrication. Therefore, we first investigated the recovery current characteristics of the large current conductor, which was used in our SMES coil fabrication. The test results indicate that the recovery currents measured in the conductor are nearly identical to those based on the single wire. This implies that the recovery current is affected by the conductor's cooling condition rather than its size and current capacity. In the SMES coil test the first quench occurred at 1250 A, which is equivalent to the stored energy of about 2 MJ. It corresponds to the quench current density of about 130 A/mm/sup 2/. This value is much higher in comparison with that reported in the other work. In addition, the first quench current of the coil agrees well with the measured recovery current of the conductor having similar cooling condition with it. This means that to determine the recovery current of a conductor is, first of all, important in the design and fabrication of a large-sized superconducting coil.         Fabrication and test of a 4 kJ Bi-2223 pulse coil for SMES    H. Hayashi, H. Kimura, Y. Hatabe, K. Tsutsumi, A. Tomioka, T. Bohno, S. Nose, Y. Yagi, T. Ishii, M. Iwakuma and K. Funaki Summary: We designed and fabricated a 4 kJ conduction-cooled high-Tc superconducting (HTS) pulse coil. The coil is wound with an interlayer-transposed 6-strand parallel conductor which is composed of Bi-2223 silver alloy-sheathed multi-filamentary wires. We had developed a complete 3.6 MJ/1 MW low-Tc superconducting (LTS) SMES system for testing on a power line at Imajuku substation. Aiming at the feasible operation of SMES applying a HTS coil, we made a SMES system set-up in which HTS coils were serially connected to 3 LTS coils of the SMES. The SMES including the HTS coil was connected to Imajuku substation's power system, to made operational tests of compensation for load fluctuation at the 6 kV power line. The test results lead to the feasibility of the HTS SMES for practical use in future power systems.         Development of a solenoidal HTS coil cooled by liquid or gas helium    Xiaohua Jiang, Xu Chu, Jie Yang, Nengqiang Jin, Zhiguang Cheng, Zhenmin Chen, L. Gou and Xiaopeng Ren Summary: A small HTS coil was developed that is cooled by liquid or gas helium. The coil temperature can be adjusted from 4.2 to 77 K by pulling the coil in or above liquid helium (LHe). The coil has a short solenoid structure. It is made of six Bi-2223 tapes with cross-section dimensions of 3.1 mm /spl times/ 0.168 mm. The single tape length is about 200 meters. Experiments were carried out to measure the critical currents of the coil at different temperatures from 4.2 to 77 K. To investigate the applicability of the HTS coil to superconducting magnetic energy storage (SMES), the coil was charged at various rates by a current source IGBT AC/DC converter with temperatures ranging from 20 to 55 K.         HT-SMES operating at liquid nitrogen temperatures for electric power quality improvement demonstrating    A. Friedman, N. Shaked, E. Perel, F. Gartzman, M. Sinvani, Y. Wolfus, D. Kottick, J. Furman and Y. Yeshurun Summary: We have developed and tested a laboratory scale High-T/sub C/ Superconducting Magnetic Energy Storage (HT-SMES) system with storage capacity of up to 1.2 kJ. It was designed to improve the power quality for a consumer supplied by 3-phase standard commercial electric power grid at a consumer power of up to 20 kW. This SMES is based on a high-T/sub C/ superconducting coil with a ferromagnetic core, immersed in liquid nitrogen at 65 K to provide efficient thermal contact with the coolant. We also developed a cryogenic DC-DC converter based on low resistance power MOSFET transistors, providing low losses in the stored energy and high operational efficiency. The power conditioning capability of our HT-SMES was proved, and compensation of voltage drops in the electric grid was successfully demonstrated.         RF pulse triggered superconducting switches    A. Hiebl, K. Numssen, H. Kinder, W. Weck, A. Muller and H. Scholderle Summary: In recent years, we have studied the possibility of using YBCO thin films not only for passive switching, as in resistive fault current limiters, but also as actively switchable devices at high power levels and millisecond time scales. As a trigger, we previously used heat pulses which were launched from the backside of the substrate. This requires relatively high trigger power, however. More recently, we have used RF pulses which are directly applied to the superconducting strip itself. The RF magnetic field was applied by various types of coils at frequencies in the MHz range. The samples were prepared by thermal co-evaporation on sapphire substrates in the form of strips with dimensions 10 mm /spl times/ 42 mm. They were submersed in liquid nitrogen and biased by a dc current. Simultaneously with the leading edge of the RF pulse, we observe the onset of a dc voltage drop along the superconductor which continues to increase during some milliseconds until the YBCO film eventually switches into the normal state. We have measured the switching time as a function of bias current, RF field direction, and RF power. The latter is considerably less than the heat pulse power required for our previous trigger method. The optimum field direction turned out to be perpendicular to the film.         AC loss properties of a 4 kJ conduction-cooled pulse coil wound with a Bi2223 6-strand parallel conductor for SMES    M. Iwakuma, H. Miyazaki, Y. Fukuda, K. Kajikawa, K. Funaki, K. Tsutsumi, H. Hayashi, H. Kimura, A. Tomioka, T. Bohno and Y. Yagi Summary: We designed and fabricated a 4 kJ conduction-cooled superconducting pulse coil with a 6-strand interlayer-transposed parallel conductor composed of Bi2223 multifilamentary tapes. We adopted the helium gas forced-flow cooling system where the helium gas flowed inside a copper pipe soldered with the flanges of brass. We succeeded in the continuous pulse operation with an amplitude of 500 A-1.6 T at a sweep rate of 140 A/s at 30 K as designed. Even in the ac operation with an ac loss of 120 W, the difference in temperature inside the winding was only 5 K and it was possible to hold the coil temperature around 30 K. In this paper, we report the design and the test results of the coil system from the aspect of ac loss and thermal properties.         Numerical modeling of a HTS cable    F. Grilli, S. Stavrev, B. Dutoit and S. Spreafico Summary: The finite element method has been employed in order to simulate the behavior of a HTS cable for transport current applications. The E-J model includes an anisotropic dependence of the critical current density J/sub c/ and power index n on the local magnetic field, whose magnitude is nonnegligible and determines the effective critical current of the cable. The cable consists of four electrically insulated layers, each of them composed by 20 superconducting tapes, providing a total critical current of about 4 kA. In order to obtain a uniform repartition of the current among the layers, a sufficiently high contact resistance has been inserted in the electric circuit. The ac losses and the field distribution have been computed. A comparison is also made with a simple electric model of a HTS cable.         Equivalent circuit model for superconductors    M. Sjostrom, B. Dutoit and J. Duron Summary: We propose an equivalent circuit model that describes the behavior of a superconductor viewed by an external user, for whom the global variables voltage and current are of interest. It is used in time-continuous simulations and it treats well both the subcritical and supercritical current regime. The model is based on Maxwell's equations, measurement results as well as on the physical structure of a superconducting tape. The incorporated circuit elements have been described in mathematical expressions: a nonlinear resistance and a nonlinear inductance (superconducting core) in parallel with a linear resistance and a linear inductance (silver sheath or by-pass material). The simplicity of the model makes it fast and easy to apply compared to existing numerical models of superconductors, based on finite element methods. Furthermore, it is wide-ranging and may represent a superconductor in many different applications depending on parameter values. Examples of applied voltage and current with nonstationary waveforms on a HTS tape are given. Calculated are the hysteresis losses (due to flux pinning) and resistive losses (due to flux creep and flux flow) in the tape in the range 0.1 to 1.8 I/sub c/.         Efficient finite element analysis of electromagnetic properties in multi-layer superconducting power cables    S. Honjo, N. Hobara, Y. Takahashi, H. Hashimoto, K. Narita and T. Yamada Summary: It is highly beneficial to reduce AC losses in multi-layer superconducting power cables. For this purpose, each superconducting layer is wound with a different twist pitch on a former so as to balance current distribution among layers. Finite element analysis makes it possible to show electromagnetic properties in superconducting layers visually, which is useful for discussing methods to enable further loss reduction. However, making a numerical analysis model of a multi-layer cable which is faithful to its geometry is highly complicated and troublesome as the model requires a correction each time the set of twist pitches needs to be changed. The authors have developed a new method to analyze such a cable by introducing anisotropy on the conductivity. In this paper, the method and the effects are discussed and compared with experimental results.         Dependence of current carrying capacity and AC loss on current distribution in coaxial multi-layer HTS conductor    M. Tsuda, Y. Ito, T. Harano, Y.S. Kim, H. Yamada, N. Harada and T. Hamajima Summary: We had developed a simulation method of current distribution in coaxial multi-layer HTS conductor and investigated influence of the nonlinear voltage-current characteristic of HTS tape on current distribution. It had been reported that homogeneous current distribution, especially the same layer current, is effective in terms of reducing AC loss. There are, however, many sets of cable parameters to achieve homogeneous current distribution in such the coaxial multi-layer cables. Therefore, using our developed evaluation method, we numerically investigated the relationship between AC loss and the cable parameters such as twisting pitch, radius, and direction in coaxial three- and four-layer conductors. We evaluated both hysteresis loss and flux flow loss as AC loss using the Norris's model and V-I characteristic of HTS tape, respectively. The critical current of whole cable and current density of each tape are key parameters in terms of reducing AC loss. The larger twisting pitch is better for increasing the critical current of cable due to the greater number of usable tapes and the shorter tape-length per unit length of cable in longitudinal direction. Alternate twisting pitch, however, is ineffective for increasing the critical current due to small twisting pitch and small number of tapes for realizing homogeneous current distribution. There is no effect of the degradation of the critical current caused by magnetic field generated by the other layers on AC loss in the cable with the current carrying capacity of the order of at least 1 kA.         Measurement of AC losses of superconducting cable by calorimetric method and development of HTS conductor with low AC losses    M. Yagi, S. Tanaka, S. Mukoyama, M. Mimura, H. Kimura, S. Torii, S. Akita and A. Kikuchi Summary: To achieve compact and highly efficient HTS power transmission cables, reducing and evaluating AC losses is important. Furukawa is developing conductors with low AC losses of 1 W/m at 3000 Arms for the 66/77 kV class HTS cables as a part of the Super-ACE project. Specifically, we aim to achieve a superconducting conductor with minimum AC losses by optimizing the winding pitches and twisted filaments in the tape. The electrical method is generally used to evaluate AC losses in HTS cables. However, measures of AC losses were uncertain using only the electrical method of evaluation. Therefore, the calorimetric device was developed and was used for determining AC losses. Consequently, results from the two methods almost agreed. Moreover, AC losses in the fabricated HTS conductors were measured at the lowest levels ever achieved.         DFBX boxes - electrical and cryogenic distribution boxes for the superconducting magnets in the LHC straight sections    J.P. Zbasnik, C.A. Corradi, S.A. Gourlay, M.A. Green, A.Q. Hafalia Jr., Y. Kajiyama, M.J. Knolls, R.F. LaMantia, J.E. Rasson, D. Reavill and W.C. Turner Summary: DFBX distribution boxes provide cryogenic and electrical services to superconducting quadrupoles and to a superconducting dipole at either end of four of the long straight sections in the LHC. The DFBX boxes also provide instrumentation and quench protection to the magnets. Current for the quadrupole and the dipole magnet is delivered through leads that combine HTS and gas cooled leads. Current for the 600 A and 120 A correction magnets is provided by pure gas-cooled leads. The bus bars from the leads to the magnets pass through low leak-rate lambda plugs between 1.8 K and 4.4 K. The heat leak into the 1.9 K region from the liquid helium tank is determined by the design of the lambda plugs. This paper describes the DFBX boxes and their function of delivering current and instrumentation signals to the magnets.         Characteristics of Peltier current lead system for alternating current mode    T. Yamaguchi, H. Okumura, K. Nakamura and S. Yamaguchi Summary: Since the Peltier current lead (PCL) was proposed to reduce heat leakage in low-temperature systems, numerical calculations and experimental studies have been performed. However, these studies were done for the direct current (DC) mode because the applications of superconducting systems are mainly used in DC mode. On the other hand, since commercial electric power is mainly used in the alternating current (AC) mode, future studies for superconducting application should move towards the AC mode. The topics to study in alternating current PCL (AC-PCL) are switching devices, transportation phenomena in thermoelectric semiconductors in the AC mode, and thermal transportation of current lead under AC operation. We study the AC-PCL numerically.         Multi-stage Peltier current lead system for liquid helium free magnets    T. Yamaguchi, H. Okumura, K. Nakamura and S. Yamaguchi Summary: After the Peltier current lead (PCL) was proposed to reduce heat leakage into a low-temperature system and demonstration experiments were performed for liquid helium systems, we study in this paper a PCL application to a liquid helium free magnet (HFM). Numerical calculation codes have been developed previously to optimize the current lead and to analyze the experimental data for single stage PCL. Since multi stage Peltier elements are often used in various kinds of scientific fields, this configuration is applied to the PCL, a computer code is developed and finally a numerical calculation has been performed for several types of multistage PCL. Heat leakage is reduced at the high-temperature end of the HTS, and therefore the stability of the magnet is enhanced, the cooling time of the system shortened and the magnitude of the current increased.         Construction and operation performance of the 80 kA current leads used for the test of the ITER toroidal field model coil in the TOSKA facility    R. Heller, G. Friesinger, A. Kienzler, P. Komarek, A. Lingor, A. Ulbricht and G. Zahn Summary: For the test of the ITER TFMC in the TOSKA facility of the Forschungszentrum Karlsruhe, two 80 kA current leads were designed and manufactured. Based on the experience coming from the performance of the 30 kA forced-flow current leads, the 80 kA leads were designed in a continuous manner. During the TFMC experiment, various optimization runs were performed at 0, 40 and 80 kA. It could be demonstrated that the leads were operated with the designed mass flow rates. Especially, the Nb/sub 3/Sn inserts used in the lower part of the heat exchanger behave as expected. The slightly different mass flow rate of both terminals can be explained by different RRR of the copper of the heat exchanger. The 80 kA current leads display the highest operating sc coil current reported up to now.         A superconducting DC transmission system based on VSC transmission technologies    G. Venkataramanan and B.K. Johnson Summary: High voltage direct current transmission (HVDC) based on current sourced converters has been in use for 50 years. Voltage sourced converter (VSC) HVDC transmission has come into use in the last five years. These systems, referred to as HVDC Light and HVDC Plus by leading vendors, are based on a modular design, reducing the installation time. VSC transmission is often used in cases where an ac system is not practical, generally due to long underground or undersea cables, and excessive losses. Such a system could be married to superconducting transmission cables in many of these applications and possibly expanded into new arenas where the cable losses in a standard VSC transmission system would have cost disadvantages. Issues related to the impact of voltage sourced converter on superconducting cables are presented along with computer simulation results.         Test results of a 30 m high-Tc superconducting power cable    S. Mukoyama, H. Hirano, M. Yagi, H. Kimura and A. Kikuchi Summary: Furukawa Electric is developing technologies for reducing the AC losses in and cooling HTS cables as part of the Super-ACE project. These technologies are important to facilitate the introduction of HTS cable into the electric power network. Furukawa executes research on these topics under the support of Chubu Electric Power Company, Tokyo Electric Power Company and Kansai Electric Power Company. We report on the progress of technology development for cooling long scale superconducting cables. The HTS cable is designed as a single core, 77 kV cable with cryogenic dielectric. A 30 m long cable was manufactured and tested to obtain design data for the 500 m long cable that will be tested in CRIEPI in 2004. The cable manufactured here used transposition tape twisted by six tapes of Bi2223. In the 30 m-cable tests, the influence of thermal contraction on critical current and heat invasion was examined. The tests confirmed that our cable can withstand thermal contraction. Moreover, useful data for cable design such as pressure drop and thermal contraction stress were obtained. We started manufacturing and preparing for substantive tests of 500 m-cable based on the success of these tests.         Cryostat vacuum thermal considerations for HTS power transmission cable systems    J.A. Demko, J.W. Lue, M.J. Gouge, D. Lindsay, M. Roden, D. Willen, M. Daumling, J.E. Fesmire and S.D. Augustynowicz Summary: The use of high-temperature superconducting (HTS) materials for power transmission cable applications is being realized in several utility demonstration projects. Both room-temperature and cold-dielectric cable systems rely on a vacuum cryostat to keep the ambient thermal loads at a minimum. For long-term installations, operating 30 years or longer, the thermal-insulating vacuum pressure may increase in sections of a long length installation. Even if only a small section of the total length of the HTS cable system is affected, localized heating of the cable may reduce the performance of the HTS cable system. A study is presented of the effects of degraded vacuum levels on the operation of HTS cables for different cryogenic thermal insulation systems.         Study of the HTS coaxial cable models    V.E. Sytnikov, P.I. Dolgosheev, N.V. Polyakova, G.G. Svalov, I.I. Akimov, A.I. Boev, A.N. Ivanov, V.E. Keilin, I.A. Kovalev, S.A. Lelekhov, S.I. Novikov, M.S. Novikov and V.I. Shcherbakov Summary: The results of the experimental studies of the short HTS cable models with the length of 1.2 and 2.4 meters under the DC and AC modes are presented. The electrical resistance of the soldered and the mechanical joints between the copper current-lead and the superconducting tape layer and between the superconducting tape layers were studied. The internal conductor of these models has three layers twisted with the left direction and with various values of the twist pitch. The influences of the total current ramp rate, the model length and the value of the electrical resistance between the layers on the current redistribution in the cable model were experimentally studied. The results are in a good agreement with the theoretical results predicted earlier. Some cryogenics test results at different temperatures in the range of 65 K-78 K are presented also.         Design, analysis, and fabrication of a tri-axial cable system    P.W. Fisher, M.J. Cole, J.A. Demko, C.A. Foster, M.J. Gouge, R.W. Grabovickic, J.W. Lue, J.P. Stovall, D.T. Lindsay, M.L. Roden and J.C. Tolbert Summary: Encouraged by the positive test results of a /spl sim/1.5-m long prototype tri-axial cable, the Southwire Company/Oak Ridge National Laboratory (ORNL) team has conceived, designed, and built a 5-m tri-axial cable with three-phase terminations. The three concentric superconducting phases are made of BSCCO-2223 high-temperature superconducting (HTS) tapes, separated by layers of cold-dielectric (CD) tape. A copper braid is added as the grounding shield. The completed tri-axial cable is enclosed in a flexible cryostat. Cooling of the cable and terminations is achieved by liquid nitrogen flowing through the annulus between the cable and the cryostat. A challenging analysis and design problem was development and implementation of an insulator material between the concentric phases with high enough thermal conductivity to meet temperature gradient requirements and acceptable mechanical performance (strength and contraction on cool down). The resulting three-phase, CD cable and termination design is nearly as compact as the single-phase, co-axial design developed previously by Southwire/ORNL and represents the highest cable current density achievable in an electric alternating-current power cable.         Quench development in long HTS objects - the possibility of "blow-up" regimes and a heat localization    A.L. Rakhmanov, V.S. Vysotsky and N.V. Zmitrenko Summary: The qualitative analysis of the quench development in long HTS objects has been performed based on the general physical study of so-called "blow-up" regimes. Blow-up processes with strong heat localization in HTS objects with overcurrent are possible. Heat localization appears due to general instability in a media with nonlinear parameters that is valid for HTS. The sizes of overheated area and time of the heat localization development has been evaluated for typical parameters of HTS power cables.         R&D of a 500 m superconducting cable in Japan    K. Ueda, O. Tsukamoto, S. Nagaya, H. Kimura and S. Akita Summary: Super-ACE project started to research and develop the superconducting AC power equipment as a national project in 2000 fiscal year. This project is R&D of the basic technologies of high temperature superconducting (HTS) cable, HTS fault current limiter (FCL), HTS magnet for reactor and transformer. Main subjects of the cable are to develop an HTS conductor rated 3 kA, cooling technology of a 500 m HTS cable of 700 A rated current, and the analysis of integrated HTS power system. The paper describes the background of this project, its target, major results of studies, and testing schedule of 500 m cable.         Electric properties of a 66 kV 3-core superconducting power cable system    S. Honjo, M. Shimodate, Y. Takahashi, T. Masuda, H. Yumura, C. Suzawa, S. Isojima and H. Suzuki Summary: A 100 m-long, 66 kV, 3-core high temperature superconducting power cable system prototype has been developed and installed in order to verify its properties and performance for practical use. The cable is a cold dielectric type with three cable-cores placed in co-axial stainless corrugated pipes. After cooling the cable to LN/sub 2/ temperature, long duration tests, such as that for nominal current-voltage loading and that for load fluctuation, were performed for a one-year period. The cable was warmed to room temperature after each test to investigate the influence of the heat cycle. Critical current was more than 2.7 kA at 77.3 K, and AC loss was 0.7 W/m/phase at 1 kArms. The magnitude of shielding current was almost equal to the transport current. Capacitance, dielectric losses and other electric properties were also measured. All values showed no change during the tests, and were in good agreement with calculated expectations.         Thermo-mechanical properties of a 66 kV superconducting power cable system    M. Watanabe, T. Masuda, Y. Ashibe, M. Hirose, S. Isojima, S. Honjo, T. Uchiyama, M. Shimodate, Y. Takahashi and H. Suzuki Summary: To verify the practicability for intended application, TEPCO and SEI have jointly developed a 100 m, 66 kV class High Temperature superconducting power cable system and tested for a long duration one year at the CRIEPI test site. The cable has three cores in a cryostat and a cold dielectric configuration. The three cores are stranded loosely to manage thermal contraction during the cooling process. The cable is warmed to room temperature after each test to investigate the influence of the cooling cycle. At the initial cooling of the system, the tension of the cable due to thermal contraction during the cooling process was measured to be about 8 kN, which is considerably lower than 50 kN measured in a short length model cable without measures against thermal contraction. System properties, such as critical current, AC loss, shield current and so on are measured during each test after the cooling cycle. During the test program, the system shows no change in its properties.         AC losses in prototype multistrand conductors for warm dielectric cable designs    J.O. Willis, M.P. Maley, H.J. Boenig, G. Coletta, R. Mele and M. Nassi Summary: We report on multiphase ac losses in four-layer prototype multi-strand conductors (PMC's) wound from HTS tape provided by American Superconductor Corporation. These conductors are prototype warm (near room temperature) dielectric cable designs, such as for the US Dept. of Energy's Superconductivity Partnership Initiative Project at Detroit Edison. We report on single phase "two phase" (no current in the PMC but with an external ac magnetic field generated by the two normal conductors arranged at the remaining corners of an equilateral triangle forming a three-phase configuration), and balanced three phase losses. Losses were also measured using a set of saddle coils to apply an ac magnetic field to the PMC. The losses were measured as a function of temperature, frequency, and current. We compare the losses for three PMC's, one (4LA) wound conventionally with equal pitch angles for all layers and the two others (4LB and 4LC) wound to achieve equal current distribution (UCD) among the layers, and thus lower single-phase losses in the operating region. In addition, 4LC was wound with a newer generation tape having a higher critical current. The PMC 4LC was found to have the lowest single, two-phase, and three-phase losses.         The current test results for two models of HTS cables on CASAT project    V.E. Sytnikov, P.I. Dolgosheev, M.G. Soloviev, D.I. Belij, L. Nieto, A. Perez, A. Gonzalez, M. Maya, F. Ortiz, C. Falcony, M. Jergel and A. Morales Summary: Two models of HTS power cables were made and tested. The cable of Nordic Superconductor Technology (NST, Denmark) tape has 4 layers and length of 1 m, and the cable of Vacuumschmelzc (VAC, Germany) tape has 6 layers and length of 5 m. The test of the cables was performed at currents up to 6 kA (AC) and 10 kA (DC). Temperature was 78 K, uniform along the models' length. The critical current was more than 10 kA for 6 layers cable at 78 K. Main attention was paid for current distribution study in the cable models. Measurements of the current distribution between layers showed uniform current distribution and high level of superconducting tapes current currying capacity utilization. The comparison of the experimental and theoretical results showed reasonable coincidence. The tests will be continued at a various temperatures up to 100 K.         Measurement of DC critical current in superconducting cable with non-uniformities    F. Gomory, L. Frolek, J. Souc, G. Coletta and S. Spreafico Summary: We investigated the effect of nonuniform current distribution on the critical current experimentally determined on a superconducting cable. In theoretical model, the cable is considered as a set of parallel current paths, each containing one single tape. Critical currents, n-factors and contact resistances between each tape and current termination are the input data of the model. Spread in these parameters results in a nonuniform distribution of DC current among tapes. Then, the voltages on different tapes would vary, and the determination of cable's critical current by a standard procedure becomes difficult. This was shown on a single-layer cable model, manufactured by placing 16 straight Bi-2223/Ag tapes in parallel on a cylindrical epoxy fiberglass mandrel. With the help of brass shunts connected in series with each tape, the currents in all the tapes can be measured simultaneously. Experimental signals registered on different tapes were in excellent agreement with theoretical predictions. We found the spread in contact resistances to be rather critical issue for our 1 m long model.         SUPERPOLI fault-current limiters based on YBCO-coated stainless steel tapes    A. Usoskin, H.C. Freyhardt, A. Issaev, J. Knoke, J. Dzick, M. Collet, P. Kirchesch and J. Lehtonen Summary: Tubular modules of fault-current limiter (FCL) have been developed, manufactured and industrially tested in the framework of the European SUPERPOLI Project. The modules of /spl phi/55 mm /spl times/ 500 mm are based on YBCO-coated stainless steel tapes exhibiting an excellent critical current of >150 A per cm-width at 77 K. A specific FCL architecture enables i) a "soft" current transfer from the YBCO film to the steel tape at over-critical currents, ii) double-sided cooling of the tape, and iii) protection against temperature shocks. The tubular configuration of the modules allows suppression of the normal component of the self magnetic field, and, as a result, gain of total critical current. Critical currents above 3000 A (78 K) have been realized in these modules in the course of industrial tests. A limitation of the fault current with an amplitude of 50 kA lead to a limited current of 3-4 kA, a voltage drop of 50 V (per module) and a power dissipation of about 100 kW. At sub-critical currents, the module introduces a negligible power loss. A quenching time of only 0.1-0.4 ms was observed.         Testing bulk HTS modules for resistive superconducting fault current limiters    M. Noe, K.-P. Juengst, F.N. Werfel, S. Elschner, J. Bock, F. Breuer and R. Kreutz Summary: Recent investigations show that high Tc bulk material is an attractive material option in resistive superconducting fault current limiters. Our investigation focuses on the short-circuit behavior of long samples of MCP-BSCCO2212 and polycrystalline melt-textured YBCO. The experiments have been performed for different operating temperatures, short-circuit duration and prospective short-circuit currents. The measurements demonstrate that a metallic bypass is needed to avoid destructive hot spots during quench. Quench and limitation tests of MCP-BSCCO2212 bifilar coils with integrated high resistive metallic shunt down to 65 K have successfully been performed. This type of module will be used for construction of a 10 MVA power system demonstrator.         Manufacturing and testing of MCP 2212 bifilar coils for a 10 MVA fault current limiter    S. Elschner, F. Breuer, M. Noe, T. Rettelbach, H. Walter and J. Bock Summary: A very promising option within the German 10 kV/10 MVA superconducting fault current limiter project CURL 10 is melt cast processed (MCP-) BSCCO 2212 bulk material. With tube shaped samples cut to bifilar coils and contacted in series, the required long lengths (160 m per phase) can easily be achieved. At the operating temperature of T=65 K the critical current density is near 4000 A/cm/sup 2/ and the voltage under limiting conditions reaches E/sub p/=0.5 V/cm. The contribution describes the design, manufacturing and testing of the superconducting components. In particular the development and characterization of a suitable electrical shunt is focused. Finally the finished components are characterized with respect to electrical homogeneity and under various limiting conditions. It could be confirmed that the single components each meet all the requirements defined within the project.         Restoration and testing of an HTS fault current controller    J.A. Waynert, H.J. Boenig, C.H. Mielke, J.O. Willis and B.L. Burley Summary: A three-phase, 1200 A, 12.5 kV fault current controller using three high temperature superconducting, HTS 4 mH coils, was built by industry and tested in 1999 at the Center Substation of Southern California Edison in Norwalk, CA. During the testing, it appeared that each of the three single-phase units had experienced a voltage breakdown, one externally and two internally. Los Alamos National Laboratory (LANL) was asked by DOE to restore the operation of the fault current controller provided the HTS coils had not been damaged during the initial substation tests. When the internally-failed coil vacuum vessels were opened it became evident that in these two vessels, a flashover had occurred at the high voltage bus section leading to the terminals of the superconducting coil. An investigation into the failure mechanism resulted in six possible causes for the flashover. Based on these causes, the high voltage bus was completely redesigned. Single-phase tests were successfully performed on the modified unit at a 13.7 kV LANL substation. This paper presents the postulated voltage flashover failure mechanisms, the new high voltage bus design which mitigates the failure mechanisms, the sequence of tests used to validate the new design, and finally, the results of variable load and short-circuit tests with the single-phase unit operating on the LANL 13.7 kV substation.         Studies of YBCO strip lines under voltage pulses: optimization of the design of fault current limiters    M. Decroux, L. Antognazza, S. Reymond, W. Paul, M. Chen and O. Fischer Summary: We present experimental results on the behavior of a superconducting YBCO/Au meander of length L submitted to short circuit tests with constant voltage pulses. The meander, at the beginning of the short-circuit, is divided in two regions; one, with a length L/sub 1/ proportional to the applied voltage, which first switches into a highly dissipative state (HDS) while the rest remains superconducting. Then the rest of the meander will progressively switch into the normal state due to the propagation of this HDS (few m/s) from both ends. The part L/sub 1/ has to initially support a power density proportional to /spl rho//spl middot/J/sub p//sup 2/ (/spl rho/ is the resistivity of the bilayer and J/sub p/ the peak current density). To avoid local excessive dissipation of power and over heating on one part of the wafer in the initial period, we have developed a novel design in order to distribute the dissipating section of the meander into many separated small dissipative zones. Furthermore the apparent propagation velocity of these dissipative zones is increased by the number of propagation fronts. We will show results obtained on 3 kW (300 V, 10 A) FCL on a 2" wafer which confirm the benefits of this new design.         Waveform analysis of the bridge type SFCL during load changing and fault time    K.M. Salim, T. Hoshino, A. Kawasaki, I. Muta and T. Nakamura Summary: DC reactor type superconducting fault current limiter (SFCL) has drawn the interest of some researchers in developing such device and more research work is being carried out in order to make it practically feasible. We have pointed out one issue that is not properly examined yet on such a device during load changing time. As we know, it is very difficult to introduce DC bias voltage to the reactor coil of the bridge type SFCL and some researchers are developing such device without using DC bias current. In such a case, the voltage drop occurs at the load terminal during the load increasing time caused by the DC reactor's inductance. By using the Electro-Magnetic Transients in DC systems which is the simulator of electric networks (EMTDC) software we carried out analysis of first few half cycles of the voltage and current waveforms after the load is increased. We also performed the same analysis for fault conditions. The peak value of the waveforms is considered in calculating the voltage drop at load terminal during the load changing time. The analysis can be used in selecting an appropriate inductance value for designing such SFCL.         Electrical insulation performance under thermal and electrical combined stress for resistive fault current limiters    N. Hayakawa, M. Noe, K.-P. Juengst and H. Okubo Summary: This paper discusses the electrical insulation performance of resistive superconducting fault current limiters (SFCL) under quench condition exposed to thermal and electrical combined stress. Electrical stress of 50 Hz AC was applied to parallel ring electrodes molded with epoxy resin. Thermal stress simulating the quench of the resistive SFCL was simultaneously applied to the ring electrode by an electromagnetic induction current. Experimental results revealed that breakdown (BD) or precursory partial discharge (PD) could be induced under such combined stress. A criterion for determining electrical insulation design of the resistive SFCL was proposed as a function of temperature of the ring electrode.         Improved design and system approach of a three phase inductive HTS fault current limiter for a 12 kVA synchronous generator    I. Vajda, A. Gyore, A. Szalay, V. Sokolovsky and W. Gawalek Summary: A further development of the high temperature superconducting (HTS) mini power plant (MPP) concept designed earlier by one of the authors is presented in the paper. HTS fault current limiters (FCL) will be inserted at the terminals of the synchronous generator. Joint operation of HTS generators (including fully superconducting generators) and HTS FCL's provide additional benefits viz. a significant increase of the generator's unit power rating as well as of its dynamic stability, shown in the paper. A three-phase inductive HTS FCL designed and built for the protection of a generator is made up of three one-phase units, each containing YBCO rings as secondary "windings." A new design idea was applied for the primary winding to further reduce the leakage reactance of the FCL resulting in low reactive power consumption. Simulations of the electromagnetic processes in the HTS FCL are shown. Theoretical studies on the joint operation of a fully superconducting generator and an HTS FCL are presented.         Inductive type fault current limiter with Bi-2223 thick film on a MgO cylinder    M. Ichikawa, H. Kado, M. Shibuya and T. Matsumura Summary: Fault current limiters for electric power systems have been researched. We have studied a inductive type superconducting fault current limiter. The limiter has superconducting cylinder as active element. We developed a high Jc Bi-2223 thick film on a MgO cylinder. Jc was over 5800 A/cm/sup 2/ at 77 K. We made a inductive type superconducting fault current limiter with the Bi-2223 thick film cylinder and investigated limiting performances.         Design, fabrication and testing of superconducting DC reactor for 1.2 kV/80 A inductive fault current limiter    Hyoungku Kang, Min Cheol Ahn, Yong Ku Kim, Duck Kweon Bae, Yong Soo Yoon, Tae Kuk Ko, Jung Ho Kim and Jinho Joo Summary: A superconducting DC reactor protects a power system by limiting the amplitude of fault current with its inductance. Therefore, it is very important to design and simulate the DC reactor precisely for making the power system stable and effective. In this paper, we designed the superconducting DC reactor of an inductive superconducting fault current limiter conceptually and acquired the optimal design parameters by using Finite Element Method (FEM). We manufactured the superconducting DC reactor and tested its characteristics at cryocooler-cooled 20 K temperature. Moreover, we compared experimental characteristics with simulation results and analyzed them. We introduced the design method of the superconducting DC reactor and the fabrication method of a 1.2 kV/80 A class DC reactor for an inductive superconducting fault current limiter. Finally, we performed the short circuit test and discussed the results.         Design of 6.6 kV, 100 a saturated DC reactor type superconducting fault current limiter    T. Hoshino, K.M. Salim, A. Kawasaki, I. Muta, T. Nakamura and M. Yamada Summary: Proposed saturated DC reactor type superconducting fault current limiter (SFCL) was designed and fabricated. The rated value was 100 V and 10 A for small scale experiment. The relationships between the one-turn voltage and the cross section of the core, the inductance value are obtained. The optimized cross section of the core was 90 mm /spl times/ 45 mm under restriction of the core manufacturer. The core material was ultra fine grain steel named FINEMET/sup /spl reg// FT-3H. The number of main winding turns was 100 and that of the control winding was also 100 turns. The wires are of NbTi superconductor with different filament diameter. We enhanced this design scheme to 6.6 kV, 100 A SFCL. The core cross section size and core gap and core length of 6.6 kV design are presented.         Design and test of modified bridge type superconducting fault current limiter with reverse magnetized core    Seungje Lee, Chanjoo Lee, Min Cheol Ahn, Hyoungku Kang, Duck Kweon Bae and Tae Kuk Ko Summary: To develop a DC reactor type Superconducting Fault Current Limiter (SFCL), the most important elements are superconducting magnets or inductors. Recently large size magnets have been developed, according with the improvement of high temperature superconducting wire. In the DC reactor type SFCL, the purpose of a magnet is to store the generated electric energy of the power system immediately after a fault. Therefore most inductors are designed with an air core since the magnetic core inductor is too easy saturated to absorb the energy. Therefore the inductor consumes so much superconducting wire to make a large inductance and these expensive coils are a weak point of the DC reactor type SFCL. To solve this problem, the Reverse Magnetization Bias (RMB) method is introduced. The energy capacity of magnetic core is expanded to several times. With a shorter length of HTC superconducting wire, a much improved effect was obtained in the 40 V prototype SFCL.         FEM analysis of current limiting characteristics of a superconducting thin film current limiting device by the current vector potential method    S. Sugita and H. Ohsaki Summary: Numerical analysis of a resistive superconducting fault current limiter (SFCL) using superconducting thin film has been performed. The finite element method (FEM) based on the current vector potential with the thin plate approximation was used to study current limiting characteristics and current imbalance phenomenon of a single SFCL device. Transport current and temperature dependence were also taken into account by solving a three-dimensional coupled problem of electromagnetic field, an electric circuit and thermal field. An E-J relation based on the power law was adopted for modeling the electromagnetic property of superconductor. This analysis method enables us to calculate not only current limiting characteristics but also current density, flux density, and heat generation at any point in the superconducting thin film at any time.         Fundamental performance of flux-lock type fault current limiter with two air-core coils    T. Matsumura, A. Kimura, H. Shimizu, Y. Yokomizu and M. Goto Summary: This paper proposes a superconducting fault current limiter (FCL) which is a modified version of the flux-lock type fault current limiter developed by us. This FCL consists of a high T/sub c/ superconductor (HTS) and two coaxial air-core coils. One coil is connected in parallel with another one through the HTS. The HTS is arranged inside the coils. Under fault condition, the HTS generates resistance by a overcurrent. The limiting impedance appears in the FCL so that the overcurrent can be reduced. Furthermore, the resistance of the HTS increases because the HTS is exposed the magnetic field of the coils. As a result, we can obtain a larger limiting impedance in the current limiting phase. We concretely designed a 200 V class FCL with Bi2223 bulk and estimated the transient behavior in current limiting operation. It is confirmed that the magnitude of fault current was suppressed significantly by this type of FCL with Bi2223 bulk and that the limiting effect was slightly improved by the application of the magnetic field induced by two air-core coils.         An empirical correlation for E(J,T) of a melt-cast-processed BSCCO-2212 superconductor under self field    Y.S. Cha Summary: An empirical correlation is developed for the electrical field strength E(J, T) of a melt-cast processed BSCCO-2212 superconductor. The empirical correlation is based, in part, on the theory of magnetic relaxation and on experimental data at 77 and 87 K. It is developed for temperatures in the range between 77 and 92 K, which is the range of interest for practical devices such as the superconducting fault current limiters. The general form of the correlation may be applicable to other high-T/sub c/ superconductors.         Resistance development in superconducting fault current limiters prior to quench completion    Hye-Rim Kim, Ok-Bae Hyun, Hyo-Sang Choi, Sang-Do Cha and Je-Myung Oh Summary: We investigated the resistance development in resistive superconducting fault current limiters (SFCLs) based on YBa/sub 2/Cu/sub 3/O/sub 7/ thin films prior to quench completion. The behavior of resistance during this time period is important for the development of SFCLs since it is closely related to the current limitation speed of SFCLs. The 0.3 /spl mu/m thick film of 2 inch diameter was coated with a gold layer of 0.2 /spl mu/m thickness and patterned into 2 mm wide meander lines. The SFCL was subjected to simulated AC fault current for resistance measurements. It was immersed in liquid nitrogen during the experiment. The resistance first increased rapidly and the increase slowed down. It was a superposition of an oscillatory component to a slowly varying background. The background increased rapidly and then slowly with time, and linearly with source voltage. The oscillatory component was small, of constant amplitude, and independent of source voltage. These results could be explained quantitatively with the concept of quench propagation, which was caused by heat transfer within the film and a transition to a resistive state. A simulation function was derived from a heat balance equation. Data fit well to this function.         Modeling of the transient behavior of a resistive type high T/sub c/ fault current limiter    R. Petranovic and A.M. Miri Summary: The potential distribution in electrical equipment during transient excitation is an important criterion for the design of the insulation. Transients in electric power networks can be caused by lightning strikes, disconnecting operations or system disturbances. In this work the transient behavior of a resistive superconducting fault current limiter (SFCL) based on Bi-2212 tubes, which are connected in series, has been modeled. The SFCL will be used in a 10 kV bus tie of a German utility. A lumped network model of the limiter has been developed and implemented in PSpice to investigate the transient behavior. The model includes inductive- and capacitive coupling, respectively. An AC analysis is performed to obtain the frequencies which will cause the highest overvoltages between the windings of the limiter. Furthermore a lightning impulse voltage and a lightning stroke current are applied to the limiter to investigate its transient behavior. A simplification of the model is performed to reduce the computing time. Both models are compared and a good agreement of the results is obtained.         66 kV-class high-T/sub c/ superconducting fault current limiter magnet model coil experiment    T. Yazawa, H. Koyama, K. Tasaki, T. Kuriyama, S. Nomura, T. Ohkuma, N. Hobara, Y. Takahashi and K. Inoue Summary: As a part of the Super-conductive AC Equipment (Super-ACE) project being performed from 2000 to 2004, an AC magnet for a fault current limiter is being developed. This research focuses on fundamental technical items essential for a 66 kV class fault current limiter magnet wound with high-T/sub c/ superconductors operating at around 65 K. These items are high current capacity, high voltage insulation and sub-cooled nitrogen cooling. This paper describes experimental results obtained for a model coil wound with four-parallel Bi2223 tape conductors. Voltage-current characteristics, equal current distribution among tape conductors and overvoltage behavior are evaluated.         Switching behavior of YBCO thin film conductors in resistive fault current limiters    H.-P. Kraemer, W. Schmidt, B. Utz and H.-W. Neumueller Summary: The quenching process of YBCO thin film conductors designed for resistive fault current limiters has been analyzed by electrical and optical measurements. The influence of the switching voltage as well as the critical current and normal resistance of the thin film conductors on the quench propagation has been studied in detail. The experimental results show that homogeneous quenching can be achieved. The YBCO parameters can not be varied independently of the shunt layer thickness.         Test results and analysis of current limiting characteristics in conduction cooled Bi2223 fault current limiter    K. Sasaki, C. Nishizawa and T. Onishi Summary: Current limiting characteristics in conduction cooled high-T/sub c/ superconducting fault current limiter (SFCL) have been calculated numerically. These calculations have been performed based on the measured results of the E-J characteristics in the region of I/sub c/ to several tens of I/sub c/. With decreasing operating temperature of the SFCL, the current limiting characteristics are improved, especially at the first peak after the fault, in addition to the decrease of the required volume of superconductor. The improvement is caused by the high resistance of superconductor associated with the reduction of cross-sectional area and the discrepancy of E-J characteristics between different temperatures of superconductor in the high electric field region. Such improvement of current limiting characteristics has been observed in the experiment using a small model of conduction cooled SFCL.         A study on required volume of superconducting element for flux flow resistance type fault current limiter    H. Shimizu, Y. Yokomizu, M. Goto, T. Matsumura and N. Murayama Summary: We have proposed a fault current limiter (FCL) suppressing an overcurrent only by a flux flow resistance of a high temperature superconductor (HTS). If the fault current is interrupted within an allowable time t/sub a/ after the fault occurs, the flux flow resistance type FCL can instantly recover to the superconducting state and pass a load current. In this paper, the volume V/sub r/ of the HTS in the FCL required to satisfy the specified limiting effect and t/sub a/ was investigated theoretically. The volume V/sub r/ depends on the critical current density and the flux flow resistivity of the HTS. As the flow resistivity and/or critical current density increase, V/sub r/ can be reduced to obtain a certain current limiting effect. When t/sub a/ is specified, V/sub r/ has a maximum value at a certain flux flow resistance. If both the limiting effect and t/sub a/ are given, the required volume is constant and independent of critical current density or flux flow resistance.         Current limiting characteristics of flux-lock type high-T/sub C/ superconducting fault current limiter with control circuit for magnetic field    Sung-Hun Lim, Hyeong-Gon Kang, Hyo-Sang Choi, Seong-Ryong Lee and Byoung-Sung Han Summary: A flux-lock type superconducting fault current limiter (SFCL) can change the amplitude of the magnetic field by adjusting either the inserting resistance or the phase adjusting capacitor. However, the magnetic field coil cannot generate enough magnetic field for some time after a fault happens due to resonance between the phase adjusting capacitor and the magnetic field coil. It is also required for the magnetic field generated to be controlled for the application to high-T/sub C/ superconducting (HTSC) elements which have different critical characteristics. This paper proposes a flux-lock type SFCL with a control circuit for the magnetic field, which is composed of solid state switches connected with the magnetic field coil. A current limiting experiment of this model was carried out. We showed that the amplitude of the fault current as well as the magnetic field could be controlled by the sinusoidal pulse width modulation (SPWM) operation, one of the switching techniques for controlling the magnetic field.         Shunt-assisted simultaneous quenches in series-connected resistive SFCL components    Ok-Bae Hyun, Sang-Do Cha, Hye-Rim Kim, Hyo-Sang Choi and Si-Dol Hwang Summary: We investigated shunt-assisted quenches in resistive superconducting fault current limiter (SFCL) components based on YBCO thin films when they are connected in series. Slight differences in Ic between the components induces significant power imbalance, which causes uneven quenches between the components. The extremely fast superconductor-normal transition causes the uneven quenches. Therefore, an appropriate quench delay is needed for synchronized switching of all components. In addition to the currently practised ways, an alternative way was demonstrated for simultaneous activation of components (or units) connected in series, the shunt-assisted quench. The shunts of equal resistance across individual components are to increase the current over Ic to each of the superconducting components. This design successfully produced simultaneous quenches, resulting in equal voltages over all components, while the YBCO films were protected from excessive heating. The shunts are found to be somewhat insensitive to differences in Ic. This design provides a wide selection of shunt resistance and film uniformity, allowing practicality, particularly in engineering application.         Over-voltage suppression in a fault current limiter by a ZnO varistor    Y. Shirai, Y. Miyato, M. Taguchi, M. Shiotsu, H. Hatta, S. Muroya, M. Chiba and T. Nitta Summary: A superconducting fault current limiter (SCFCL) of the transformer type with a ZnO varistor (metal oxide varistor) in parallel was investigated to determine the effects of the ZnO varistor as an over-voltage suppressor for the SCFCL. An SCFCL of the transformer type, which has an adjustable trigger current level, has been studied. A small model of this type of SCFCL was designed and built with NbTi superconductors. Since a fault current is reduced by its inductive component, a large over-voltage is observed at the beginning of the current limiting event. It is important to suppress the over-voltage to avoid any damages to the power system apparatus. Experimental results on the fault current limiting operation of the SCFCL with ZnO varistor in parallel are shown. It was confirmed that the surge voltage that appears at the terminal of the SCFCL can be successfully suppressed by ZnO varistor. Current limiting and recovery characteristics of the SCFCL with a ZnO varistor are investigated and discussed. The trigger current level of the SCFCL is not affected by the ZnO varistor. The recovery time is a little longer with the ZnO varistor than that without it. Energy dissipation in the ZnO varistor and the SCFCL is discussed.         Physical and numerical models of superconducting fault current limiters    S. Kozak and T. Janowski Summary: The physical and numerical models of the inductive type superconducting fault current limiter (SFCL) were made. The physical models consist of superconducting Bi2223 tubes (diameter = 0.059 m, height = 0.05 m and critical current at 77 K = 625 A), iron cores (cross-section area = 0.02 m /spl times/ 0.02 m and 0.02 m /spl times/ 0.03 m) and the plastic cryostat with copper primary winding (236 turns). The voltage-current characteristics of these physical models were used for verification of the geometry and properties of regions in numerical model of SFCL. The numerical model using the magnetodynamics physical domain of the CAD package FLUX2D coupled with circuit equations was used to analyze the influence of selected parameters on SFCL voltage-current characteristics. The paper shows that the changes of the iron core and the superconducting tube geometry influence these characteristics significantly.         Properties comparison of superconducting fault current limiters with closed and open core    T. Janowski, S. Kozak, H. Malinowski, G. Wojtasiewicz, B. Kondratowicz-Kucewicz and J. Kozak Summary: The high-T/sub c/ superconducting fault current limiter (SFCL) can be classified into resistive, inductive and hybrid types. The inductive type HTSFCL seems to show most prospect due to the simple design (construction) of the secondary superconducting winding in the form of ceramic type BSCCO and for the reduction of current leads. In an inductive type SFCL, ferromagnetic cores for magnetic flux are applied, however open cores are also taken into consideration in order to simplify the construction. The results of experimental and computational investigations of inductive SFCL parameters are presented in this paper.         Effects of thermal exchanges on the YBCO transition and the superconductivity recovery    D. Buzon, L. Porcar, P. Tixador, D. Isfort, X. Chaud and R. Tournier Summary: The influence of the current slope (dI/dt) and thermal exchanges on the magneto-thermal transition of textured bulk YBCO are analyzed within the framework of the resistive Fault Current Limiter (FCL). This study was carried out at 90.5 K both in pressurized liquid nitrogen, in vacuum and when the YBCO sample is in contact with alumina plates. The superconductor U(I) response is governed by a power law, depends on dI/dt and is influenced by the thermal surroundings. These phenomena can be justified if the dissipated energy during the transition is concentrated in a small volume of the conductor. The second part of this paper deals with the thermal recovery of bulk materials. Even in the case of film boiling where the exchanges are poor, a thermal gradient due to the weak thermal conductivity of HTc materials appears in the section of the conductor. This point and its consequences are described and discussed by using a finite element software.         Characteristics of critical current of high-T/sub c/ superconducting magnets wound with various tensions    Min Cheol Ahn, Min Chul Kim, Duck Kweon Bae, Seungje Lee, Yong Soo Yoon, Sang Jin Lee and Tae Kuk Ko Summary: High-T/sub c/ superconducting fault current limiters (SFCLs) with a DC reactor limit fault currents using the inductance of the DC reactor. Therefore, manufacture of the DC reactor is very important in developing this type of SFCL. The DC reactor makes use of high-T/sub c/ superconducting (HTS) magnets. Because high-T/sub c/ superconducting wires are rectangular tape and contain ceramic compounds, the winding method and the tension control of the HTS magnet are different from those of normal conductor magnets. In this research, we design and manufacture a winding machine for HTS magnets. We fabricate four HTS magnets wound with various tension. Characteristics of the fabricated magnets are observed through measurements of critical currents. This paper suggests an optimal winding method of HTS magnets.         Relation between critical current density and flux flow resistivity in Bi2223 bulk element for fault current limiter    T. Aritake, T. Noda, H. Shimizu, Y. Yokomizu, T. Matsumura and N. Murayama Summary: The relationship between the critical current density and flux flow resistivity in a Bi2223 bulk for fault current limiter application was experimentally investigated. The distributions of J/sub c/ and voltage along the longitudinal direction were measured as well as the transport current. As a result, it was found that the flux flow resistivity is higher at positions of lower critical current. Measured results were numerically analyzed to obtain an empirical expression for the flux flow resistivity as a function of the critical current density, accumulated Joule heat and transport current.         A study on DC S/N transition type superconducting fault current limiting interrupter    Takao Sato, M. Yamaguchi, S. Fukui, Y. Watanabe, T. Matsumura and H. Shimizu Summary: The proposed DC S/N transition type superconducting fault current limiting interrupter (SCFCLI) uses a high temperature superconducting (HTS) element made of Bi-2223 bulk material. This SCFCLI comprises a device that can not only limit fault current but also interrupt it in a three-phase power system. The current limitation and interruption characteristics of this SCFCLI were numerically analyzed. The confirmation tests were made by a small-scale model in the case of a fault of lines to ground, and test results agreed relatively well with analyses. An SCFCLI for a 6.6 kV-1000 A power system was analyzed based on these achievements.         Quench behavior of YBaCuO films for fault current limiters under magnetic field    K.B. Park, J.S. Kang, B.W. Lee, I.S. Oh, H.S. Choi, H.R. Kim and O.B. Hyun Summary: The resistive superconducting fault current limiters (SFCLs) are very attractive devices for the electric power network. But they have some serious problems when the YBCO thin films were used for the current limiting materials due to the inhomogeneities caused by manufacturing process. When the YBCO films have some inhomogeneities, simultaneous quenches are difficult to achieve when the fault current limiting units are connected in series for increasing operating voltage ratings. In order to solve these problems, vertical magnetic fields varied from 0 to 130 mT were applied to the YBCO elements. Then, extensive electric field-current (E-I) and quench characteristics were investigated for all elements by using both electrical measuring method and observations of bubble behaviors. The experimental results were compared with the quench properties of YBCO elements, which were connected in series. From the experiment works, it was revealed that applied magnetic fields generated by surrounding coils could induce uniform quench distribution for all strips and simultaneous quenches were realized in all YBCO elements. Finally, by applying vertical magnetic fields perpendicular to the limiting devices, 1.2 kV/sub rms/ rated resistive fault current limiter were realized using five YBCO films in series.         Study on recovery current of transformer type superconducting fault current limiter    H. Hatta, T. Nitta, S. Muroya, T. Oide, Y. Shirai, M. Taguchi and Y. Miyato Summary: To introduce Superconducting Fault Current Limiters (SCFCL's) in a power system, some specifications such as the impedance, the trigger current level, the recovery time and so on are requested. Fault analyses point out that the accuracy of the trigger current level is required in several percents. Therefore, an SCFCL with adjustable trigger current level was proposed, designed and made. Adjustability of the trigger current level was confirmed experimentally. In addition, the SCFCL has good limiting and recovery characteristics. The SCFCL can recover in several tens of msec. It suggests that the SCFCL can recover when the current becomes small enough. In this paper, experimental and theoretical studies on recovery current of the SCFCL are described. Recovery current of the SCFCL was measured and the current of the secondary coil at the recovery operation was calculated. The minimum propagating current of the superconducting wire was calculated and it was compared to the current of the secondary coil just after recovery. Then, it is confirmed that the recovery current of the SCFCL's of proposed type can be calculated at designing.         Investigation on reduction of required superconductor volume in a resistive fault current limiter with Bi2223 bulk superconductor    T. Onishi, K. Sasaki and R. Akimoto Summary: The bulk high temperature superconductor of low J/sub c/ is difficult to be heated up over T/sub c/ quickly within a period of the initial 1/4 cycle during a fault. Therefore, a large volume of superconductor will be required to obtain the required current limiting impedance, because a short-circuited current has to be limited by the flux flow resistance. Even in case of J/sub c/ of 2000 A/cm/sup 2/, the volume will amount to around 0.1 m/sup 3/ in order to limit a fault current to less than 3 times the J/sub c/ value for 6.6 kV-1000 A fault current limiter. In this paper, a method in which a perpendicular magnetic field is applied automatically to the bulk superconductor during a fault is proposed. And it is revealed that the volume of superconductor will be reduced by three times less than the one required in the conventional method.         Current transport and FCL properties of polycrystalline melt textured YBCO    U. Floegel-Delor, T. Riedel, R. Rothfeld, D. Wippich, B. Goebel and F.N. Werfel Summary: Toward demonstrating the potential of resistive HTS fault current limiting behavior bulk polycrystalline melt textured (pmt) YBCO devices in meander-like shape were developed and tested by using 50 Hz AC pulses at 77 K. Meander fabrication is based on high-dense and temperature gradient growth textured YBCO plates, which were mechanically stabilized, diamond tooling CAD cut and prepared with low resistive Cu contacts in lengths between 1-5 m. The nonideal I-V characteristics at normal operation due to the residual grain boundary resistivity was measured to a few tens of microvolts per centimeter at 1000 A. Due to additional metallic shunt layer the conditions for quench protection of inherently inhomogeneous material have been derived, tested and substantially improved. We investigated the feasibility, technical performance and economy of employing robust pmt YBCO to take decisions about the material line of future superconducting fault current limiter (FCL) modules.         Quench characteristics of fault current limiting element with YBCO thin film    K. Shimohata, S. Yokoyama, T. Inaguchi, S. Nakamura and K. Yasuda Summary: It is important with a resistance type current limiting element to make quench occur uniformly over the whole area of the element. Current limiting experiments were carried out to find out the quench characteristics of some specifications of elements with YBCO thin films. In the experiments, applied voltage, fault duration and short-circuit phase were changed. As a result, uniform or local quench was observed. The films were damaged at about 500 K. Moreover, a current limiting simulation considering the dispersion of critical current was compared with the experimental results. The calculated results agreed with the experimental results.         The improved magnetic shield type high T/sub c/ superconducting fault current limiter and the transient characteristic simulation    Guoqiang Zhang, Zanji Wang and Ming Qiu Summary: Based on the equivalent circuit of a power transformer, considering both the nonlinear magnetizing characteristic of an iron-core and the nonlinear resistance of a superconducting secondary winding (V-I characteristic), the simulation of a magnetic shield type high T/sub c/ superconducting FCL was carried out by Simulink module of Matlab software. The transient response, especially the primary short circuit current is obtained. The influence of the saturation of an iron-core, and the specified structure of the magnetic circuit are analyzed. Based on the simulation, an improved magnetic shield type HTS FCL, a cross section adjustable power transformer with a multi-turn superconducting secondary winding is proposed. Its advantages include stable apparent impedance during the occurrence of a fault, shorter recovery time and lower voluminal energy dissipation during controlled S-N transition.         The feasibility study on the combined equipment between micro-SMES and inductive/electronic type fault current limiter    Zanji Wang, Guoqiang Zhang and Ming Qiu Summary: The concept of the combined equipment between micro-SMES and inductive/electronic type FCL is proposed in this paper. Having the multifunction for a superconducting device, the new equipment can serve as the protective component for a dual power system. The specification of a testing model was determined and the transient performance was analyzed by Matlab software. The results show that the combined equipment is realizable for a dual power system application, where it has the major function of limiting fault current (FCL function) and the minor function of maintaining power fluctuation (SMES function).         Long-term operational experience with first Siemens 400 kW HTS machine in diverse configurations    M. Frank, J. Frauenhofer, P. van Hasselt, W. Nick, H.-W. Neumueller and G. Nerowski Summary: Siemens has built a synchronous machine consisting of an HTS rotor and an air-cored stator. Rotor cooling is provided by a Gifford-McMahon (GM) "off the shelf" cryocooler, the typical requirement being about 30 W @ 25 K. The machine was designed for a rated power of 380 kW (rated voltage 3 phases 400 V Y), but achieved a maximum continuous power of 450 kW and a short term maximum power of 590 kW at 1500 rpm. In all cases, output power was limited by stator cooling. Characteristic parameters such as reactances, inductances, and time constants were determined to obtain a consistent overview of the machine properties. The machine was tested under different operational modes, including motor mode as well as generator mode. In the generator mode, it was operated on water cooled resistors or connected to the grid. The properties of motor mode have been determined synchronized to the grid as well as via an inverter. Special attention was taken to investigate the influences of asymmetric loads, grid and inverter harmonics on rotor cooling requirements. Numerical calculations were performed and compared to the experimental data showing good correlation.         A new project for superconducting generator (SCG)    K. Nishijima, M. Asada, A. Izumi, R. Takahashi, H. Sato and S. Maeda Summary: We have started a new project (Phase-II) on the development for superconducting generators, which is scheduled from 2000 to 2003, following Phase I project. For commercialization, cost competitiveness of superconducting generators against conventional machines should be strongly pursued. From this viewpoint, the new project focuses onto mainly two targets; downsizing with improved generator output density, enhancement of the generator capacity with intention of cost reduction by the scale merits. In the first half of Phase-II, 2000-2001, primary fundamental design studies of 200 MW and 600 MW class machines were conducted reflecting and reviewing the Phase-I results. NbTi superconducting wires for the field windings are also under development.         A cosmic microwave background radiation polarimeter using superconducting bearings    S. Hanany, T. Matsumura, B. Johnson, T. Jones, J.R. Hull and K.B. Ma Summary: Measurements of the polarization of the cosmic microwave background (CMB) radiation are expected to significantly increase our understanding of the early universe. We present a design for a CMB polarimeter in which a cryogenically cooled half wave plate rotates by means of a high-temperature superconducting (HTS) bearing. The design is optimized for implementation in MAXIPOL, a balloon-borne CMB polarimeter. A prototype bearing, consisting of commercially available ring-shaped permanent magnet and an array of YBCO bulk HTS material, has been constructed. We measured the coefficient of friction as a function of several parameters including temperature between 15 and 80 K, rotation frequency between 0.3 and 3.5 Hz, levitation distance between 6 and 10 mm, and ambient pressure between 10/sup -7/ and 1 torr. The low rotational drag of the HTS bearing allows rotations for long periods of time with minimal input power and negligible wear and tear thus making this technology suitable for a future satellite mission.         The man-loading high-temperature superconducting Maglev test vehicle    Suyu Wang, Jiasu Wang, Xiaorong Wang, Zhongyou Ren, Youwen Zeng, Changyan Deng, He Jiang, Min Zhu, Guobin Lin, Zhipei Xu, Degui Zhu and Honghai Song Summary: The first man-loading high-temperature superconducting (HTS) Maglev test vehicle in the world was successfully developed on Dec. 31, 2000 in the Applied Superconductivity Laboratory, Southwest Jiaotong University, China. Heretofore over 24 500 passengers took the vehicle, and it has been operating back and forth for about 400 km. The HTS Maglev vehicle provides inherent stability both in the vertical and lateral direction, so no control system is needed. The only control system is used for linear motor driving devices. The melt-textured YBaCuO bulk superconductors are fixed on the bottom of a liquid nitrogen vessel and cooled by liquid nitrogen. The bottom thickness of the rectangle liquid nitrogen vessel with its thin wall is only 3 mm. The onboard HTS Maglev module is placed over the guideway. The guideway consists of two parallel permanent magnetic tracks, whose concentrating magnetic field at 20 mm height above the surface is about 0.5 T. The levitation forces of 8 HTS Maglev modules were measured. The total levitation force of 8 onboard Maglev modules was 10431 N at the levitation gap of 10 mm, and 8486 N at the levitation gap of 15 mm, respectively. These results were measured on May 28, 2002.         Lift-to-weight ratio dependence of lift and stability in an active-Maglev system    M. Tsuda, M. Tamura, H. Yamada, N. Harada and T. Hamajima Summary: In an active-Maglev system composed of YBCO bulk and electromagnets, lift-to-weight ratio dependence of lift and stability was investigated experimentally and theoretically. A bulk was levitated by an electromagnet after a field-cooling process for magnetization. It has been shown that lift and stability of the bulk are closely related to both the magnitude of trapped magnetic field and the magnetic field distribution generated by the electromagnet. Minimum field-cooling current for stable levitation, the operating current of electromagnet at initial levitation, and maximum stable-levitation height were measured as a function of the load on the top surface of the bulk. It was observed that the minimum trapped field for stable levitation increased with the load. Maximum permissible displacement in the radial direction was also investigated experimentally as a function of the load and levitation height. The maximum permissible displacement decreases with levitation height and stable-levitation range decreases with weight of load. Numerical analysis based on the three-dimensional finite element method was performed to investigate electromagnetic behaviors within bulk, especially stability at initial levitation. The stability depends on the ratio of operating current at initial levitation to field-cooling current.         Effects of the field dependent J/sub c/ on the vertical levitation force between a superconductor and a magnet    Gang Li, Meng Jun Qin, Hua Kun Liu and Shi Xue Dou Summary: The vertical levitation force between a superconductor disk (SC) and a permanent magnet disk (PM) has been calculated from first principles using different J/sub c/(B) relationships of the magnetic field. Based upon the first principles, the current distribution inside the SC induced by the applied inhomogeneous magnetic field generated by the PM and the field profiles have been calculated with a power law E /spl sim/ J relationship: E(J) = E/sub c/(J/J/sub c/(B))/sup n/. The levitation force is highly hysteretic for the approaching and the retreating branches. The saturated current value, magnetization, and levitation force are found to depend strongly on the J/sub c/(B) relations. Features of the supercurrent distribution, the force loop, and the levitation force density are discussed.         Optimization of energy conversion in monolithic superconducting magnets    P.T. Putman and K. Salama Summary: As part of an effort to develop an electromagnetic launcher, the authors have studied magnetic to kinetic energy conversion in a system of monolithic superconducting magnets. They present the dependence of optimal shapes on design parameters such as speed, scale, and critical current density, as well as an optimized shape.         Liquid hydrogen tank with cylindrical superconducting bearing for automotive application    H. Walter, S. Arsac, J. Bock, S.O. Siems, W.-R. Canders, A. Leenders, H.C. Freyhardt, H. Fieseler and M. Kesten Summary: Using the concept of superconducting suspension of the inner tank in an outer vessel, the authors have designed and constructed a prototype of a liquid-hydrogen storage tank for automotive application. In contrast to the earlier model with planar design of the bearing, they used a rotationally symmetric arrangement with the inner tank suspended over a central frame bar. The bearing consists of superconducting rings fixed to the central tube of the inner tank and a system of permanent magnets mounted on the frame bar. No additional cooling of the superconductors (YBaCuO rings prepared by a modified multi-seeding process and Bi-2212 rings prepared by the melt cast process) is required. For suspension of the tank in the warm state above Tc, they used newly developed actuators with main springs made of shape-memory alloy. When the tank is filled with liquid hydrogen, the actuators release the tank, thereby providing absolutely passive activation of the bearing.         Guidance forces on high temperature superconducting Maglev test vehicle    Jiasu Wang, Suyu Wang, Zhongyou Ren, Xiaorong Wang, Min Zhu, He Jiang, Honghai Song, Xingzhi Wang and Jun Zheng Summary: The levitation force between superconductors and permanent magnets is directly proportional to the gradient of the magnetic field over the guideway. However, the lateral guidance force is dependent on the trapped flux in the superconductors. The stronger the trapped flux, the larger the guidance force. The guidance force provides stability to the vehicle in the lateral direction. In order to obtain both larger levitation force and guidance force, superconductors must be cooled in an appropriate applied magnetic field. A man-loading high temperature superconducting (HTS) Maglev test vehicle levitating over a permanent magnet (PM) guideway, the first such in the world, was developed and equipped with guidance force measurement instrumentation and the guidance force acting on the entire vehicle are experimentally investigated. The dependence of the entire vehicle guidance force on the field cooling height (FCH) is reported. The experiment results have proved that the guidance force of the entire vehicle is large enough for the lateral stability at an FCH height of 20 mm.         A new type of active-Maglev system using YBCO bulk and multiple electromagnets    R. Kamoshida, H. Ueda and A. Ishiyama Summary: We have been developing a new type of active-Maglev system that is a transporter in the vertical direction, consisting of high-temperature bulk superconductors and multiple electromagnets piled up on the vertical axis. In a previous paper, using an active-Maglev system composed of a disk-shaped YBCO bulk and five electromagnets, we have demonstrated continuous levitation and verified that its levitation height, as well as stability, can be remarkably improved by adjusting the operating current of the electromagnets individually. Electromagnetic behavior within the bulk has been also investigated numerically by a newly developed computer program based on the finite-element method adopting the Bean model. Agreement of levitation force and height between experiments and numerical analyses was good. The levitation force properties strongly depend on the field-cooling condition and the distribution and magnitude of the external magnetic field generated by the electromagnets. We clarify electromagnetic phenomena within the bulk superconductor by the computer program developed to improve the levitation properties for applications of continuous levitation to real Maglev systems.         Characteristics of levitating X-Y transporter using HTS bulks    T. Akamatsu, H. Ueda and A. Ishiyama Summary: High-T/sub c/ superconducting bulk has been used for magnetic levitation systems such as a flywheel energy storage system and noncontact transport system. We have been investigating the electromagnetic behavior of high temperature superconductor (HTS) bulks to realize a X-Y (two-dimensional) magnetic levitating transporter without any fixed guides. We have investigated qualitatively the characteristics of the lift and the restoring force of an YBCO bulk under various field-cooling conditions and permanent-magnet arrangements. In this paper, we evaluate the most suitable four-permanent-magnet arrangement through lift and restoring force measurements and numerical analysis by the finite element method (FEM) using the current vector potential.         Effect of a passive magnetic damper in a flywheel system with a hybrid superconductor bearing set    Tae-Hyun Sung, Young-Hee Han, Jun-Sung Lee, Sang-Chul Han, Nyeon-Ho Jeong, Kwang-Seok Oh, Byung-Sam Park and Je-Myung Oh Summary: A flywheel energy storage system with a hybrid bearing set was designed. The hybrid bearing system consisted of a superconductor bearing and a permanent magnetic bearing. The flywheel was suspended by the permanent magnetic bearing and stabilized by the superconductor bearing. The range of stable levitation was experimentally determined for the vertical magnetic force. A new type of damper designed to provide essential damping for the permanent magnetic bearing was tested by an impact test. The damper using eddy current loss showed good performance.         Investigation of joint operation of a superconducting kinetic energy storage (flywheel) and solar cells    I. Vajda, Z. Kohari, L. Benko, V. Meerovich and W. Gawalek Summary: Superconductors provide unique possibilities for storage of electricity, which is especially important for the reliability of networks supplied by renewable energy sources such as solar energy and wind energy. A system consisting of an HTS-based levitated flywheel as the energy storage unit and solar cells as the power supply was installed and investigated as a model of a viable variant of the mini-power plant concept. Measurements were performed to obtain information about relevant storage characteristics such as efficiency and stability. Possibilities of fitting the storage unit to the solar supply were also investigated in order to get maximum charge and discharge efficiency.         Progress toward 500 kg HTS bearings    F.N. Werfel, U. Floegel-Delor, T. Riedel, R. Rothfeld, D. Wippich, B. Goebel, P. Kummeth, H.-W. Neumueller and W. Nick Summary: We have tested a heavy load HTS radial bearing dedicated for use in motors, generators, and flywheels. The HTS bearing is of radial type design providing both radial and axial support. The stator and rotor are modular assemblies which allows up-scaling in size. The superconducting stator is made of polycrystalline melt-textured (pmt) YBCO 200 mm inner diameter hollow cylinder grown in cylinder-like a-b texture. The stator assembly is composed of axially stacked YBCO rings in a Cu tube and cooled from the outside by LN/sub 2/. The rotor consists of stacked annular PM rings in compression on a shaft. This results in a high radial magnetic field gradient. Three such YBCO stators have been fabricated, assembled, and tested for use with a 380 kW superconducting motor developed by SIEMENS. Maximum radial forces of more than 3.7 kN were measured (at a temperature of 68 K) with the shaft at center radial position. The goal is to demonstrate safe operation of heavy rotors in a desired frequency range by providing sufficient forces, stiffness, and damping at critical modes.         Temperature and frequency effects in a high-performance superconducting bearing    A.C. Day, J.R. Hull, M. Strasik, P.E. Johnson, K.E. McCrary, J. Edwards, J.A. Mittleider, J.R. Schindler, R.A. Hawkins and M.L. Yoder Summary: A high-temperature superconducting (HTS) bearing was fabricated and tested by itself and as a component in a 1-kWh and a 10-kWh flywheel energy system (FES). The rotational losses of the HTS bearing as a function of rotational rate and HTS temperature were determined. The 1-kWh FES was tested with a motor/generator and with an eddy current clutch to determine the motor/generator losses.         Lateral force in permanent magnet-superconductor levitation systems with high critical current    C. Navau, A. Sanchez and E. Pardo Summary: The force generated when a zero-field-cooled superconductor is displaced laterally from an initially cylindrically symmetric situation is numerically calculated. An unstabilizing lateral force, according to previous measurements, is obtained. Approximate analytical expressions for both lateral and vertical force are also presented for small lateral displacements. In this case, it is concluded that the lateral stiffness is independent of the lateral disturbance, whereas the cross-stiffness is zero.         A levitated motor with superconducting magnetic bearings assisted by self-sensing AMBs    M. Komori and C. Shiraishi Summary: This paper describes newly developed superconducting magnetic bearings (SMBs) assisted by self-sensing active magnetic bearings (AMBs). The self-sensing AMBs detect the gaps between rotor and electromagnets. The principle of the self-sensing sensors is based on a differential transformer. The sensitivity in liquid nitrogen is almost equal to that in air. The sensor is found to be useful in liquid nitrogen at 77 K (-196 /spl deg/C). Moreover, the sensors are applied to the SMBs. Dynamics of the SMBs with self-sensing AMBs are discussed. From the results, it is found that the system is useful and promising.         Calculation of AC loss in an HTS wind turbine generator    M. Fee, M.P. Staines, R.G. Buckley, P.A. Watterson and Jian Guo Zhu Summary: In order to achieve lower cost of energy the typical power rating of large wind turbine generators has steadily increased over recent years. However, with the mast-top weight of multi-megawatt generators exceeding 100 tonnes, installation becomes increasingly costly and difficult. Direct drive turbine designs can give significant weight and cost reductions. We have developed a design for a lightweight direct drive transverse flux generator with a rating of 2 MW. The design features a multi-pole permanent magnet rotor with a single global HTS stator coil of between 4 and 6 m diameter for each phase. As one consequence of this design approach, the HTS conductor is exposed to leakage field from the magnets and the self-field of the generated current. The magnitude of the loss associated with these time-varying fields is crucial to the viability of the HTS generator concept. The stator design seeks to minimize exposure of the HTS tape to alternating magnetic fields perpendicular to the face of the tape in order to reduce the AC loss in the stator coils to an acceptable level. For a coil operating at 50 Hz, the total AC loss is calculated as 15.1 W/m. Thus, AC losses within each of the three 6 m diameter HTS global coils of a 2 MW generator would be 285 W. The thermal load for the cryogenic system of the 2 MW generator is estimated to total 936 W, with the majority (90%) due to AC loss. Assuming a cryogenic specific power of 20, the energy required to cool the 2 MW generator represents less than 1% of total output.         Design and electrical characteristics analysis of 100 HP HTS synchronous motor in 21st Century Frontier Project, Korea    Hyun-Man Jang, I. Muta, T. Hoshino, T. Nakamura, Seog-Whan Kim, Myung-Hwan Sohn, Young-Kil Kwon and Kang-Sik Ryu Summary: A 100 hp class superconducting motor in the 21st Century Frontier R&D Program of Korea has been designed. A theoretical model of high temperature superconducting (HTS) motor was presented by two-dimensional electromagnetic field analysis. The motor is composed of HTS field winding, cold damper shield, air-gap armature winding and laminated machine shield. The HTS field winding consists of racetrack type double pancake coils wound with Bi-2223 HTS tapes operated at about 30 K. The operating current of the HTS tape conductor could be determined by the magnetic field distribution calculated in the HTS field winding and the I/sub c/ - B characteristics of a practical HTS conductor, taking account of its anisotropy.         Characteristics of axial-type HTS motor under different temperature conditions    Hun-June Jung, T. Nakamura, I. Muta and T. Hoshino Summary: We tested an axial-type Bi-2223 bulk motor under different magnetic field and temperature conditions. Distributed armature windings with a pole number of four were used in order to compensate for the harmonic components in the air-gap magnetic flux density. The temperature was varied by evacuating the metal cryostat with a rotary vacuum pump. The fabricated motor demonstrated hysteresis characteristics when the temperature of the system was decreased and the magnetomotive force was adjusted to appropriate values. Then, synchronous speed at no-load condition was fulfilled. On the other hand, slip of rotational speed as well as inductive torque was induced when temperature and magnetic conditions were not satisfied. These results can be explained based on the pinning properties and AC loss inside the bulk rotor.         Influences of superconducting fault current limiter (SFCL) on superconducting generator in one-machine double-line system    I. Muta, T. Doshita, T. Nakamura, T. Egi and T. Hoshino Summary: Analysis of superconducting generator in single machine double-line infinite-bus transmission system equipped with SFCL's has been performed by use of EMTDC/PSCAD. When some faults occur in one transmission line, the SFCL in the fault line operates and then the peak fault current can be limited to expected value by use of a function of the SFCL. However, in some cases, the SFCL in the other sound line has been also proved to occasionally operate due to the interaction through each transmission line. Problems due to an installation of the SFCL's in such a model system and the influences on the superconducting generator have been pointed out by simulation analysis.         Torque characteristics of a motor using bulk superconductors in the rotor in the transient phase    Y. Tsuboi and H. Ohsaki Summary: A motor using bulk superconductors in the rotor (bulk superconducting motor) is considered to achieve higher power density than conventional machines. When the bulk superconducting motor is operated with slip, for example at startup or during overload operations, traveling electrical fields are applied to the bulk superconductors. In slip operation, the characteristics of the motor are complex because, under the traveling field, flux flow occurs in the bulk superconductors, which causes the increase in the current but at the same time generates heat, which decreases the critical current density of the bulk superconductors. In order to analyze the characteristics of the bulk superconducting motor in the transient phase and those of a bulk superconductor in traveling fields, pull out tests and locked rotor tests were performed using an experimental apparatus for a hysteresis motor with bulk superconductors in the rotor. Numerical analysis when operated with slip was also performed to know the electromagnetic phenomena in the bulk superconductor used in the motor when the effect of the heat is ignored.         Design of field coil for 100 hp class HTS motor considering operating current    J.J. Lee, Y.S. Jo, J.P. Hong and Y.K. Kwon Summary: The value of critical current (I/sub c/) in High Temperature Superconductor (HTS) tape is greatly influenced by perpendicular magnetic flux density B/spl perp/. Therefore, I/sub c/ of HTS magnet is determined by not only operating temperature but also the B/spl perp/. In this paper, flux distribution and operating current are calculated according to the field coil change in 100 hp class HTS motor. The magnetic flux density of field coil is calculated by changing the outer radius and inner width of field coil. Biot-Savart equation is used as analytic method for the characteristic analysis of magnet. 3D FEA (Three Dimensional Finite Element Analysis) is used for the magnetic field distribution in the HTS motor. The operating current of 100 hp class HTS motor is calculated by using I/sub c/-B/spl perp/ curve.         HTS motor shape optimization for its maximum critical current of the field winding    Joonsun Kang, Joon-Ho Lee, W. Nah, Il-Han Park, Jinho Joo, Young-Kil Kwon, Myung-Hwan Sohn and Seog-Whan Kim Summary: Superconducting motors have high efficiency as well as reduced size and weight. In superconducting motors, the field winding is composed of HTS tapes (Bi-2223) without any iron core because of magnetic saturation, and the current in the field winding is limited by the maximum magnetic field in the field winding. To enhance the performance of superconducting motor, we need to maximize the critical current of field winding as much as possible. This paper introduces the shape optimization method with the constraint of HTS characteristic (I/sub c/-B curve), and proposes a shape that improves the critical current of the field winding. Finite element analysis and discrete sensitivity approach are used for calculating the magnetic field of coil and shape optimization.         Determination of equivalent circuit parameters of the low-T/sub c/ superconducting power supply for charging of superconducting magnet    Yong Soo Yoon, Min Cheol Ahn, Ho Min Kim and Tae Kuk Ko Summary: This paper deals with determination of equivalent circuit parameters of the Low-T/sub c/ Superconducting (LTS) power supply for charging of the LTS magnet, as well as analysis of its characteristics as determined through experiments. The power supply consists of two exciters, a rotor, a stator, and an LTS magnet. In this experiment, a 25.8 mH LTS magnet was used, and rotor revolutions from 30 to 300 rpm were used. The magnetic flux distribution analysis of the system was carried out. Based upon this analysis, maximum 150 A DC excitation current was optimally derived. In order to measure the pumping-current with respect to the magnet flux changes, a Hall sensor was installed at the center of the LTS magnet. The experimental observations have been compared with the theoretical predictions. In this experiment, the pumping-current has reached about 372 A.         Characteristic analysis of a heater-triggered switching system for the charging of Bi-2223 double-pancake load    Duck Kweon Bae, Yong Soo Yoon, Min Cheol Ahn, Hong Soo Ha, Tae Kuk Ko and Sang Soo Oh Summary: In this paper, characteristics of a heater-triggered switching system for the charging of Bi-2223 double pancake load with 1.7 mH has been analyzed through the simulations and experiments. Two heaters were used to store the energy in high-T/sub c/ superconducting (HTS) load. The timing of the sequential control and the heating current with two heaters are important factors to generate pumping-current. The thermal analysis of the switch considering the heater input and time was carried out. Based on the analysis just mentioned, the heater-triggered switch was fabricated. Characteristic analysis was carried out through two modes having different sequential timing controls. Maximum current stored in the HTS load reached 18 A and the pumping rate was 113 mA/s at that time.         Test of an induction motor with HTS wire at end ring and bars    Jungwook Sim, Myungjin Park, H. Lim, G. Cha, Junkeun Ji and Jikwang Lee Summary: Motors with HTS wires or bulks have been developed recently. These are a large synchronous motor with HTS wires at the field winding in the rotor, hysteresis and reluctance motors with HTS bulk in the rotor. This paper presents the fabrication and test results of an HTS induction motor. Conventional end rings and short bars were replaced with HTS wires in the motor. Stator of the conventional induction motor was used as the stator of the HTS motor. Rated capacity and rpm at full rotor of the conventional motor were 0.75 kW and 1710 rpm. Two HTS wires are used in parallel to make the end rings and bars. The critical current of the BSCCO-2223 HTS wire which was used in the bars and end rings were 115 A. An electrodynamometer was coupled directly to the shaft of the rotor with HTS wires.         A superconducting induction motor using double-helix dipole coils    C.L. Goodzeit, R.B. Meinke and M.J. Ball Summary: The double-helix dipole configuration, which uses concentric pairs of oppositely-tilted helical windings to generate a dipole field, is the basis of a design for a unique high-torque, low-rpm, compact superconducting motor. We describe an analysis method that uses coupled mutually-inductive equivalent circuits for each phase for computing the performance and operating characteristics of such a device. We discuss the performance and limitations of an example motor that uses NbTi superconducting cables for the stator and rotor. The example device is a 4-pole, 2-phase induction motor that produces typically 10 000 HP for a 1-m effective length rotor with a 0.4 m diameter rotor operating at /spl sim/300 rpm. In addition, the relatively large minimum bend radius of the double-helix coil configuration also facilitates the use of brittle superconducting materials such as HTS or A-15 for this application.         Experimental study of a new kind of superconducting inductor    P. Masson, J. Leveque, D. Netter and A. Rezzoug Summary: Electrical motors need a spatial variation of the flux density created by their inductors to make torque. We propose to achieve this angular repartition of the induction with bulk high temperature superconducting plates and two low temperature superconducting solenoids. These solenoids have the same axis and are fed with opposite currents in order to create a radial magnetic induction. Four superconducting plates placed on the cylindrical surface, situated on the same axis and having the same radius as the solenoids, concentrate the magnetic field. This device provides a spatial variation of the flux density, and can be considered as an inductor for a synchronous motor with eight poles. This paper presents the experimental study of our prototype at 4.2 K. We compare the experimental results with calculation. Ten Hall probes permit us to reconstitute the angular variation of the flux density. The paper shows the feasibility of this new kind of superconducting inductor.         A new driving method for superconducting levitated stepping motor    M. Komori and S. Nomura Summary: A magnetically levitated stepping motor using high T/sub c/ superconductor has been studied. The levitated stepping motor consists of a cylindrical rotor with superconductors and a stator with eight electromagnets. The rotor measures 10 mm in diameter, 46 mm in length, and 18 g in mass. The superconductors of the rotor are field-cooled in liquid nitrogen with various field-cooling currents. The levitated rotor is driven by an four-phase excitation with various driving currents. The rotation angle by each step is 45 deg. The rotor spins for every step as the excitation phase shifts. This paper discusses the dynamics of the motor driven by a new driving method.         Parametrically excited horizontal and rolling motion of a levitated body above a high-T/sub c/ superconductor    T. Sugiura, T. Aoyagi, H. Ura and M. Yoshizawa Summary: This research deals with a kind of parametric excitation of a permanent magnet freely levitated above a high-T/sub c/ superconductor excited in the vertical direction. We find the magnet has two vibration modes of linearly coupled horizontal translation and roll motion. These two modes are coupled nonlinearly with the vertical motion by the magnetic force and torque. Through nonlinear analysis and numerical simulation, this research discusses parametric resonance of each mode caused by vertical excitation at the frequency in the neighborhood of twice the natural frequency of that mode. Analytical and numerical results show qualitative agreement with experimental ones.         Trial production and experiment of linear synchronous actuator with field-cooled HTS bulk secondary    A. Takahashi, H. Ueda and A. Ishiyama Summary: It is expected that HTS bulk materials can be applied to various electric devices. We have fabricated and tested a linear actuator with a single-sided primary and an HTS bulk secondary. The linear actuator was comprised of a zero-field-cooled YBCO bulk plate for the secondary (mover) and copper windings with iron core for the primary. In this study, to improve the characteristics of the linear actuator, we designed and fabricated a double-sided and short-secondary type of linear synchronous actuator which has a field-cooled YBCO bulk plate as a secondary (mover). The static synchronous thrust forces were measured. To evaluate the static characteristics of the linear actuator, we also numerically investigated the electromagnetic behavior within the bulk in an operational environment of the linear actuator by using a computer program based on the finite element method (FEM). The influence of the supercurrent distribution in the bulk on the thrust-angle characteristics of the model linear actuator are discussed.         Investigation of magnetic characteristics in HTS bulk materials for motor applications    T. Nakamura, K. Fukui, H.-J. Jung, I. Muta and T. Hoshino Summary: Magnetic characteristics of a Bi-2223 bulk rotor that was used for the HTS motor was investigated at 77.3 K. Spatial distribution of the magnetic flux density in the air-gap of axial-type HTS motor was measured in a rotating magnetic field at 60 Hz frequency. Numerical simulation based on 3D finite element method was also performed. It was shown that the pinning property of the bulk rotor influences the harmonic components of the air-gap flux density as well as motor characteristics.         An effective hysteresis loss computation for HTS bulk material    Seung-Yong Hahn, Song-Yop Hahn and Chang-Seop Koh Summary: This paper describes an effective method to calculate hysteresis loss of high-temperature superconducting (HTS) bulk material under time varying magnetic field. In the proposed method, the inner product of current and electric field in a HTS bulk is integrated to calculate hysteresis loss. To consider the nonlinear relation between the current and the electric field of HTS bulk material, critical state model and iteration method are adopted. According to the critical state model, if different types of time varying magnetic field are applied, the current distribution in a HTS bulk is affected not by applied field types but by peak-to-peak field values on the assumption of same critical current density regardless of different field types. This is the basic idea to compute hysteresis loss more effectively. This paper shows how to reduce total calculation time using the suggested method. To verify the validity of the suggested method, numerical results are compared with experimentally measured ones.         A micro HTS renewable energy/attitude control system for micro/nano satellites    Eunjeong Lee Summary: This paper proposes an energy storage and attitude control system for micro-electromechanical systems in spacecraft using a high-temperature superconductor-magnet bearing system. This system consists of an HTS-magnet flywheel energy storage system and a brushless motor/generator. The HTS flywheel, which permits high angular momentum storage since its drag torque is nearly velocity-independent and extremely small, facilitates high-speed rotation. It can also perform the dual function of a power/attitude control system using flywheel elements for both power storage and attitude control. This dual function capability further reduces the mass of the spacecraft. The HTS flywheel has an angular momentum capacity of 0.083 J.s and stores 2.32 kJ at 530 krpm. Its energy storage capacity is approximately 45 Wh/kg with an energy density of around 370 kJ/L. The system is ideally suited for low earth orbit energy storage, power generation and attitude control of spacecraft such as nano satellites.         Axial and journal bearings for superconducting flywheel systems    A. Rastogi, D.R. Alonso, T.A. Coombs and A.M. Campbell Summary: Axial and journal bearings have been investigated for use in superconducting flywheel systems. Our test rig comprises of an Evershed type magnetic bearing used to levitate a 35 kg rotor. The stabilizing forces are provided by superconducting axial and journal bearings. In this study we focus on the vertical stiffness measurements and explore the use of journal bearings. The journal bearing consists of radial magnets with alternating polarities. Our results indicate that this type of journal bearing can effectively stabilize the rotor. Spin-down test shows a linear behavior.         Performance of Nd-Fe-B and ferrite magnets in superconducting linear bearings with bulk YBCO    R. de Andrade Jr., J.A.A.S. Cardoso, G.C. dos Santos, L.B. de Cicco, A.F.G. Fernandes, M.A.Pd. Rosario, M.A. Neves, A.P. de Souza, A. Ripper, G.C. da Costa, R. Nicolsky and R.M. Stephan Summary: The performance of two different magnets has been tested in linear bearings with YBCO bulk superconductors, prepared by seeded melt texturing technique. Two different rails have been assembled with opposite magnetic polarization and intercalation of ferromagnetic flux concentrators. One rail has been mounted with Nd-Fe-B magnets and the other one, with Ferrite magnets. The levitation force of the Nd-Fe-B permanent magnets rail is more than one order of magnitude larger than that one of Ferrite. The stiffness of the linear bearing and the vibration damping were measured in the field cooling procedure for several cooling heights from the rail. The different cooling heights result in different gaps between the YBCO blocks and the magnets, for the same load. The stiffness increases with the decrease of gap, for the same load, in both cases, but is higher in the Nd-Fe-B rail. The vibration damping is rather low in both systems (/spl sim/0.01). We conclude that the Nd-Fe-B magnets are the most suitable for applications on linear levitating bearings.         HTS bearings for space applications: reaction wheel with low power consumption for mini-satellites    K.B. Ma, Yong Zhang, Y. Postrekhin and Wei-Kan Chu Summary: Superconducting bearings have very low coefficients of friction. It is promising to exploit this feature of HTS bearings in the construction of reaction wheel systems that consume meager power. Reaction wheel systems that consume little power are particularly suitable for use on mini-satellites where both energy and power are scarce resources. Thus, these mini-satellites can still have attitude control capabilities without prohibitive requirements for total volume and weight of hardware, and power consumption. Here, we will present the design and discuss the performance of a prototype with a 1.9 kg stainless steel wheel of diameter 82.5 mm, and height 75 mm, which can store 3.5 J-sec of angular momentum when it rotates at an angular speed of 15000 RPM. We have performed spin down tests from 7000 RPM down and measured the input power required to sustain rotational speed under a vacuum of 0.01 torr. Implications of the results are discussed.         Numerical and experimental analysis of the rotation speed degradation of superconducting magnetic bearings    R. Shiraishi, K. Demachi, M. Uesaka and R. Takahata Summary: The suppression of the rotation speed degradation of the Superconducting Magnetic Bearing (SMB) with the Permanent Magnet (PM) rotor including the layered insulator thin films is studied. The SMB system consists of the superconductor stator and the PM rotor, and is a no-contact bearing system using the levitation force between them. The SMB was expected to be applied to the electric power storage flywheel system because friction causes the rotation speed degradation and decreases the energy storage capability. However, it was found that the electromagnetic friction of the SMB was not zero, due to electromagnetic forces; 1) the magnetic force interaction between the inhomogeneous magnetic field of the PM rotor and the eddy current it induces in the cryostat, 2) the magnetic force between the inhomogeneous magnetic field of the PM rotor and the shielding current it induces in the superconductor, 3) the magnetic force between the magnetic field of superconductors yielding the levitation force and the eddy current induced in the PM rotor. This magnetic field of superconductor is inhomogeneous too, because the superconductors consist of several HTSC bulks. In this research, it was found that the 3rd phenomenon is most significant. So, we use the advanced PM rotor including the layered insulator thin films to suppress its eddy current and the degradation of the rotation speed. Using our SMB equipment, the rotation speed degradation was measured using the PM rotors with/without the insulator thin films and the electromagnetic frictions were compared to each other.         Trapped field characteristic of HTS bulk in AC external magnetic field    H. Ueda, M. Itoh and A. Ishiyama Summary: Although immutable trapped field is required in superconducting bulk applications as a quasipermanent magnet, the trapped field is influenced and changed by time-varying external magnetic field in a realistic operational environment of electrical devices. This means that shielding current distribution within bulk is changed by the time-varying magnetic field and the transient magnetic flux movement results in temperature rise and finally reduction of the trapped field. In this paper, we experimentally investigated the transition of trapped field while applying external AC magnetic field with various amplitude and frequency to a disk-shaped YBCO bulk. And we also numerically investigate the relationship between characteristic of trapped-field attenuation and shielding current distribution within the bulk using a newly developed simulation program. This program is based on the finite element method (FEM) considering the voltage-current (E-J) characteristics. It is found that the shielding current distribution is dependent on frequency of AC external field and trapped field attenuation is closely related to the shielding current.         A high-temperature superconductor energy-momentum control system for small satellites    T.L. Wilson Summary: A method for angular momentum management in flywheel energy storage systems that employ superconducting bearings for spacecraft attitude control is presented. Success with high-temperature superconductor momentum wheels as practical energy storage systems has led to increased interest in their dual function for providing electrical power as well as attitude control of small satellites. The physics of angular momentum management is used to quantify how superconductor magnetic bearing flywheels as electro-mechanical devices serve as both energy storage and angular momentum storage systems within an end-to-end architecture. The result is a compound energy-momentum attitude and electrical power control system for satellites.         Design of a 1 MVA high T/sub c/ superconducting transformer    Woo-Seok kim, Song-Yop Hahn, Kyeong-Dal Choi, Hyeong-Gil Joo and Kye-Won Hong Summary: A 1 MVA transformer using BSCCO-2223 high T/sub c/ superconducting (HTS) tapes was designed. The rated voltages of each sides of the transformer for primary and secondary are 22.9 kV and 6.6 kV respectively. Double pancake HTS windings, which have advantages of insulations and distribution of high voltage, were adopted. Four HTS tapes were wound in parallel for the windings of low voltage side. Each winding was composed of several double pancake windings and four parallel conductors of secondary winding were transposed in order to distribute the currents equally in each conductor. The core of the transformer was designed as a shell type core made of laminated silicon steel plate and the core is separated from the windings by a cryostat with a room temperature bore. Configuration of the cryostat made of nonmagnetic and nonconducting material and a liquid nitrogen sub-cooling system were used in order to maintain the coolant's temperature of 65 K.         Optimization of 1 MVA high T/sub C/ superconducting transformer windings    Chan-Bae Park, Woo-Seok kim, Kyeong-Dal Choi, Hyeong-Gil Joo, Gye-Won Hong and Song-Yop Hahn Summary: It is common practice to wind coils in pancake shape for conventional high voltage transformers because of electrical insulation problems. In HTS superconducting transformers, the perpendicular component of magnetic flux density (B/sub r/) applied to HTS tapes of pancake windings becomes larger than that of solenoid winding, thereby decreasing the critical current in the HTS tapes. This paper introduces several methods to reduce B/sub r/ applied to the HTS tapes in the transformer with double pancake windings by changing winding arrangements and the relative permeability of flux diverters. We have conducted a winding design for a single-phase 1 MVA 22.9 kV/6.6 kV HTS transformer. The magnetic field in the spaces occupied by the windings and its vicinity was numerically simulated. We observed a change of B/sub r/ due to various gap arrangements of high voltage and low voltage windings and various reciprocal arrangements. We also observed a change of B/sub r/ on the HTS tapes due to variation of relative permeability of flux diverters placed between the high voltage winding and the low voltage winding.         Cryogenic cooling temperature of HTS transformers for compactness and efficiency    Ho-Myung Chang, Yeon Suk Choi, S.W. Van Sciver and T.L. Baldwin Summary: A comprehensive thermal design to optimize the cryogenic cooling temperature of HTS transformer is presented, aiming simultaneously at compactness and efficiency. As small size and low power consumption are conflicting in determining the operating temperature, we develop a general and systematic model to quantify the effects of the temperature on compactness and efficiency. The procedure includes modeling of the critical property of HTS and the winding size, a heat transfer analysis for cooling load estimate, and a thermodynamic evaluation for cryogenic refrigeration. We demonstrate that there exists an optimum for the operating temperature that minimizes the overall power consumption, while taking into account the size effect of HTS windings. The optimal temperature turns out to be slightly above 77 K for two specific systems considered here: liquid-cooled pancake and conduction-cooled solenoid. The operation at temperatures well below 77 K can be justified, if the amount of ac loss is substantially reduced or the saving in capital investment earned by the compactness is significant in comparison with the operational cost.         Magnetic field analysis of HTS transformer windings with high currents    Min Chen, Y.J. Yu, L.Y. Xiao, Q.L. Wang, Wooho Chung, Keeman Kim and Sungkeun Baang Summary: The leakage magnetic field in HTS transformer windings fabricated by Bi-2223 tapes decreases the critical current and increases the ac losses in the tapes. Because of the anisotropy of the HTS tape, the numerical analysis of the radial component of the leakage field is especially important. In this paper the influence of the core structure and the winding configuration on the stray field is studied by finite element method, and some suggestions for improving the leakage field distribution are presented to make HTS transformers more efficient.         Conceptual design of 100 MVA high temperature superconducting auto-transformers    T. Nagasawa, M. Yamaguchi and S. Fukui Summary: This paper describes the conceptual design of 100 MVA high temperature superconducting (HTS) autotransformers as well as coreless ones having the rating of three-phase, 50 Hz, and 132 kV/66 kV. Each one is compared with conventional oil-immersed autotransformers. The HTS autotransformers with core will provide a percent impedance of 11.7% close to the conventional one and require an air gap field of 0.33 T, while the coreless HTS autotransformers require 25.8% and 0.7 T respectively. HTS autotransformers with a core have a 22% smaller window size and 0.3% higher efficiency than conventional ones. The coreless HTS autotransformers need HTS tapes about two times the length required for the HTS autotransformer with a core.         Test results of 14 kVA superconducting transformer with Bi-2223/Ag windings    Z. Jelinek, Z. Timoransky, F. Zizek, H. Piel, F. Chovanec, P. Mozola, L. Jansak, J. Kvitkovic, P. Usak and M. Polak Summary: Single phase 14 kVA, 400 V/200 V superconducting transformer with Bi/2223/Ag winding immersed in liquid nitrogen and with laminated ferromagnetic core was designed and manufactured. The core of the transformer was at room temperature, both windings were placed in a nonmetallic toroidal cryostat. The aim of the work was to verify the calculated values of critical currents and AC losses in primary and secondary windings which were based on short sample measurements. Standard short circuit test, open circuit test and load test were performed and evaluated. To reduce AC losses of primary and secondary winding laminated ferromagnetic rings attached to both ends of the windings were designed. Their influence on the radial magnetic field component in the windings was computed. The resulting effect of the rings on AC losses was verified experimentally. The issue of AC losses is discussed in another contribution of these proceedings. The residual basic parameters are presented here.         The magnetic properties of the ferromagnetic materials used for HTS transformers at 77 K    Min Chen, Y.J. Yu, L.Y. Xiao, Q.L. Wang, Wooho Chung, Keeman Kim and Sungkeun Baang Summary: The properties of the magnetic materials, such as the amorphous alloys and the grain-oriented silicon steels, are essential to the design of high-temperature superconducting transformers. In this paper the magnetic properties and the loss characteristics of different ferromagnetic materials are measured at liquid nitrogen temperature. It is shown from experimental results that at 77 K the saturation flux density of the amorphous metal is about 0.3 T lower than that of the silicon steel, and the loss of amorphous metal is 4 times less than that of the silicon steel. Since the losses of materials at 77 K are higher than those of at room temperature, it is not economical to immerse the transformer core in liquid nitrogen.         Electrical breakdown properties of liquid nitrogen for electrical insulation design of pancake coil type HTS transformer    S.M. Baek, J.M. Joung, J.H. Lee and S.H. Kim Summary: In the electrical insulation design of a pancake coil type high temperature superconducting (HTS) transformer, knowledge of the dielectric behavior of both liquid nitrogen (LN/sub 2/) and gaseous nitrogen (GN/sub 2/) is very important. Also, the breakdown strength under a quench conditions is an important factor of the insulation engineering. Since spacers are used in the pancake coil type HTS transformer, the liquid nitrogen and the spacer must be considered together in the design of the insulation and cooling of this type transformer. This paper describes the results of an experimental study on the electrical breakdown phenomena and properties of liquid nitrogen with the electrode of the pancake coil made with Ag sheathed Bi-2223 HTS tape. When bubbles occur, the breakdown characteristics of LN/sub 2/ in a simulated cooling channel are examined to understand the optimal dimensions of the cooling channel. Open and closed cooling channels were made to compare the breakdown voltage to each other. The breakdown voltage in the open cooling channel appeared higher than the breakdown voltage in the closed cooling channel. The open cooling channel type is recommended for higher stability of equipment. This research will be useful in the electrical design of pancake coil type HTS transformers that are cooled by LN/sub 2/.         Electrical insulation characteristics in the simulated electrode system of HTS double pancake coil    J.M. Joung, S.M. Baek, C.S. Han and S.H. Kim Summary: For the experiment four types of spacer were distinguished by an arrangement that could improve the dielectric strength by making the path of flashover longer. One of the spacers could be applied to an insulator between windings of a high temperature superconducting (HTS) transformer. The flashover characteristic of each type was investigated and the flashover phenomena were observed to understand breakdown mechanism in liquid nitrogen (LN/sub 2/). In the first, the flashover characteristic in LN/sub 2/ was compared with that in air using the simulated electrode made from five turns of HTS tape. The dielectric strength of spacers was improved with an arrangement in air but not in LN/sub 2/. Through the observation of flashover phenomena, a micro gap between the spacer and the coil electrode generating bubbles was regarded as the main cause. In the second, the effect of the micro gap on flashover was investigated with a plane-plane electrode system. The micro gap decreased the flashover voltage by 70 percent. Finally, the dielectric strength of the spacer in LN/sub 2/ also could be improved by filling of a small amount of epoxy in the gap between the coil and the spacer.         Development of high-temperature superconducting transformers for railway applications    R. Schlosser, H. Schmidt, M. Leghissa and M. Meinert Summary: We describe the high-temperature superconducting (HTS) transformer project run by Siemens. The project started in October 1996 and ended in September 2001. The aim of the project was to show the future prospects for superconducting railway transformers. To study the principle behavior of such a transformer, as a first step we designed, constructed and tested a nominal single-phase transformer of 100 kVA, 50 Hz, 5.5 kV/1.1 kV. After this was successfully tested, we started the design and construction of a single-phase transformer of 1 MVA, 50 Hz, 25 kV/1.4 kV. This unit already has the full ratings of a commercial transformer in many respects, e.g., power range, nominal voltage, 2-limb core with horizontal orientation, two secondary windings and an impedance of 25% at nominal current. Further innovative features are transposed conductor and a closed cooling cycle with sub-cooled nitrogen. The report describes the 1-MVA transformer's detailed design, and presents the results of electrical and thermal transformer routine tests (e.g., measurement of load losses and no-load losses). The conclusion highlights the future perspective of HTS transformers for railway applications.         Design and construction of a 41 kVA Bi/Y transformer    P. Tixador, G. Donnier-Valentin and E. Maher Summary: High Temperature Superconducting (HTS) materials bring to transformers benefits such as weight reduction and improvements in efficiency as well as the electrical behavior in the network. In the context of a European project (READY) we designed and built a 41 kVA single phase transformer that will use the first lengths of YBCO coated conductors for the secondary winding. Project partners are developing this conductor. The primary winding uses a PIT-Bi-2223 tape and we designed the transformer as a complete device with integrated cooling. The refrigerator is a large cooling capacity (100 W at 80 K) single stage coaxial pulse tube cooler developed by Air Liquide. We chose a cold magnetic circuit with low iron loss laminations. The cryostat is then very simple with metallic vessels and only one interface with the refrigerator. The cooling fluid is helium in order to investigate a large temperature range (40-80 K). Thermal simulations were made to minimize heat transfers to the HTS conductors and experiments provided some necessary data. The transformer design and optimization is presented as well as its construction.         Fabrication of winding model of high-T/sub c/ superconducting transformer for railway rolling stock    H. Kamijo, H. Hata, H. Fujimoto, T. Bohno, K. Sakaki, H. Yamada, M. Iwakuma and K. Funaki Summary: We fabricated two high-T/sub c/ superconducting coils that simulated the winding of a traction transformer for railway rolling stock. The multi-layer solenoid coil to simulate the primary winding of the transformer had five layers with a single Bi2223 superconducting tape. The closed solenoid coil to simulate the secondary winding of the transformer had one layer with eight parallel Bi2223 superconducting tapes. We measured the voltage-current, AC loss and current sharing characteristics of these coils cooled in saturated liquid nitrogen at 77 K. As a result, we concluded that the multi-layer solenoid coil is applicable to the primary winding and the closed solenoid coil is also applicable to the secondary winding.         AC losses in a toroidal superconducting transformer    B. Perez, A. Alvarez, P. Suarez, D. Caceres, J.M. Ceballos, X. Obradors, X. Granados and R. Bosch Summary: In order to study the viability of coreless AC coupled coils, a superconductor transformer based on BSCCO-2223 PIT tapes was constructed. To achieve the minimum flux leakage, a toroidal geometry was selected. Both secondary and primary coils were wound around a glass fiber reinforced epoxy torus, obtaining a solid system. The field inside the transformer, the coupling factor, and the losses in the system were computed and measured, providing suitable parameters for new improvements in these systems.         Design optimization of high-temperature superconducting power transformers    T.L. Baldwin, J.I. Ykema, C.L. Allen and J.L. Langston Summary: As HTS transformers begin to move into utility and commercial applications, engineering must optimize the designs for AC losses and total ownership costs while meeting the performance criteria and application requirements. Transformer manufacturers use cost optimization techniques during the design phase to minimize material costs and satisfy the utility's loss evaluation requirement. This paper presents the modifications necessary in transformer design and optimization to handle high-temperature superconductors as the winding material. These changes include AC losses, short-circuit stresses, and cooling loads. Design results are presented for a five-legged core, three-phase, 3.5-MVA power transformer optimized for reduced weight and footprint space for electrical distribution onboard ships.         System test of a 1-MVA-HTS-transformer connected to a converter-fed drive for rail vehicles    M. Meinert, M. Leghissa, R. Schlosser and H. Schmidt Summary: Railway companies aim to realize environmentally friendly revenue operations with high efficiency. High Temperature Superconducting (HTS)-transformers offer advantages regarding less mass and volume and considerably higher efficiency in drive systems. Siemens has developed a 1-MVA-HTS-transformer with typical characteristics for railway applications. For a successful introduction in the market, it is essential to guarantee the operational behavior of drive systems in well-known manner. So, Siemens realized the 1st operation of an AC-converter fed by a HTS-transformer. System test measurements of losses, tests of cooling redundancy as well as drive cycle operation were performed to compare the converter operation to sinusoidal operation, to analyze the losses depending on the harmonics of nonsinusoidal current and to investigate the behavior of the whole system under realistic drive cycles of a current rail vehicle.         Loss analysis of a model transformer winding    L. Jansak, F. Zizek, Z. Jelinek, Z. Timoransky, H. Piel and M. Polak Summary: In the paper we present an analysis of AC losses in windings of a 14 kVA superconducting transformer with Bi-2223/Ag winding. AC losses of individual pancake coils of the secondary winding were measured. Discussion of the meaning of AC loss measurements in individual pancakes is presented. Measurement of loss in short samples (critical current in external magnetic field, transport current losses) was done and the results were compared with losses in the winding under operating conditions using available published data. An effect of temperature on winding losses was also studied.         AC loss measurement of HTS coils with ferromagnetic disks    M. Furuse, J. Kondoh, H. Tanaka and M. Umeda Summary: Manufacturing techniques for low AC loss high-T/sub c/ superconducting coils are necessary to realize high efficiency superconducting power equipments. High-T/sub c/ superconducting tape conductors have anisotropic magnetic field dependence on critical current and AC magnetization loss. A magnetic field component perpendicular to the tape surface degrades HTS coil performance. We numerically investigated a magnetic field adjusting method and AC loss reduction effects by attaching ferromagnetic materials to both ends of HTS coils. We also measured total AC loss of an HTS coil comprising 10 HTS double pancake coils by the boil-off method. Total AC loss of the coil was dominated by mechanical loss due to vibration and movement of conductors and pancake coils. In this paper, methods to reduce total AC loss of HTS coils are discussed.         Magnetization loss characteristics in a stack of Bi-2223 tapes    K. Ryu, B.J. Choi and Y.H. Chun Summary: The AC loss is an important issue in the design of high-T/sub c/ superconducting power devices such as transformers and cables. In these devices many Bi-2223 tapes are closely stacked together and exposed to alternating magnetic fields that can have different orientations with respect to a tape. In such arrangement the magnetization loss is influenced by the screening current induced in adjacent tapes and thus different from that in a single tape. This stacking effect was experimentally investigated by measuring the magnetization loss in a stack, which consists of a number of tapes. First the magnetization loss in the single tape was measured in order to confirm the reliability of the loss data measured in the stack. The results for the single tape coincide well with the loss characteristics described in other previous works. For the stack in parallel and longitudinal magnetic fields the measured loss is independent of both the number of tapes and stacking type. The longitudinal magnetization loss is well explained rather by the slab model for decoupled filaments. For the tall stack in perpendicular field the measured loss at low fields is greatly decreased, compared to the loss of the single tape. However the loss at high fields is unaffected. These loss behaviors in the tall stack are well described by the slab model for full coupling.         AC loss characteristics of twisted multifilament Bi2223/Ag sheathed tapes carrying AC transport currents in AC longitudinal magnetic fields    J. Ogawa, M. Shiokawa and O. Tsukamoto Summary: This paper reports on the total AC loss characteristics of a twisted multifilamentary Bi2223/Ag sheathed tape carrying AC transport current in longitudinal AC magnetic field in phase with the transport current. The tape was specially made for the experiment and had wider space between superconducting filaments than a usual multifilamentary Bi/Ag sheathed tape to suppress superconducting bridgings between the filaments. In our experiment the total losses were measured by the electric method. The losses supplied from the longitudinal magnetic field were measured by using a pick-up coil and the losses supplied from the power supply for the transport current by a four terminal method. The measurement results showed that the total losses depended on the direction of the longitudinal magnetic field. In the case that the combined magnetic field produced by the transport current and the external longitudinal magnetic field was nearly parallel to the filaments of the twisted wire, the losses were smaller than those in the case that the combined field was nearly perpendicular to the filaments. This was observed when the amplitude of the longitudinal magnetic field was larger than the full penetration magnetic field of the wire.         Theoretical and experimental study on AC loss in HTS tape in AC magnetic field carrying AC transport current    H. Tonsho, S. Fukui, T. Sato, M. Yamaguchi, S. Torii, T. Takao and K. Ueda Summary: AC loss characteristics of high temperature superconducting tape in external AC magnetic field carrying AC transport current were theoretically and experimentally studied. We measured the AC transport current and magnetization losses in a conventional Bi2223/Ag multifilamentary tape in the external AC magnetic field carrying the AC transport current. The measured AC magnetization loss, AC transport current loss and total AC loss were compared with the numerical results. The measured AC loss characteristics of the tape can not be explained by the critical state model. Numerical calculations on the AC losses in the tape were performed by using our analytical model introducing the electric field and current density relation locally determined in the filamentary region of the tape. The numerical losses by our model reasonably agree with the measured data.         AC loss characteristics of Bi2223 twisted multifilamentary tape in AC longitudinal magnetic field    T. Yoshida, S. Fukui, M. Yamaguchi and T. Sato Summary: AC loss characteristics of the twisted multifilamentary high temperature superconducting tape with different twist pitches in external AC longitudinal magnetic field as well as those of the nontwisted tape were experimentally investigated. We measured the AC transport current loss and the AC magnetization loss in the twisted and nontwisted Bi2223 multifilamentary tapes in the external AC longitudinal magnetic field. The measured transport loss and magnetization loss in the twisted tapes were affected by the amplitude and the direction of the AC longitudinal field. It was also shown that the AC losses in the tapes under the external AC longitudinal field depended on the twist pitch.         AC loss of Nb/sub 3/Sn-based Rutherford cables with internally and externally added Cu    M.D. Sumption, E.W. Collings, R.M. Scanlan and A. Nijhuis Summary: Calorimetric measurements of AC loss and hence interstrand contact resistances (ICR) were measured on various stabilized (Cu-added) Nb/sub 3/Sn Rutherford cables. The cable variations formed two sets; externally added Cu and internally added Cu (mixed strand cables). In the first set, Cu strips were diffusion bonded onto a pre-existing cable. Two distinct variants were made, in the first a Cu strip was added to the "upper" and "lower" cable surfaces and then diffusion bonded during a reaction heat treatment (RHT) of 180 h/650/spl deg/C under a "cold-applied pressure" of 20 MPa. The second was formed by diffusion bonding a helically wrapped Cu strip along the cable. A control cable with no strip was included in this set. The second set consisted of a cable with approximately 1/3 of the strands replaced with pure Cu wires during the cable winding, and here also a control cable was fabricated for comparison. Calorimetric measurements of AC loss were made on all cables at 4.2 K in a transverse sinusoidal field of amplitude 400 mT, frequency 5 to 90 mHz, applied both parallel and perpendicular to the face of the cable. The loss data were interpreted in terms of an effective interstrand contact resistance, R/sub /spl perp/,eff/.         Inter-strand resistance measurements in cored Nb-Ti Rutherford cables    R. Soika, M.D. Anerella, A.K. Ghosh, P. Wanderer, M.N. Wilson, W.V. Hassenzahl, J. Kaugerts and G. Moritz Summary: Cored Nb-Ti Rutherford cables with high crossover resistance R/sub c/ are being investigated to minimize ac losses in a set of superconducting dipole magnets for the proposed rapid cycling heavy ion synchrotron facility at the Gesellschaft fur Schwerionenforschung (GSI) in Darmstadt, Germany. This ring of magnets is based on the Relativistic Heavy Ion Collider (RHIC) design. R/sub c/ in cored cables is significantly larger than the contact resistance between adjacent strands R/sub a/. The latter, however, dominates the voltage profile when the interstrand contact resistance is measured via the usual VI technique. This makes the extraction of the magnitude of R/sub c/ out of the voltage profile very difficult. Knowledge of R/sub c/ is important to predict ac losses, because if R/sub c/ and R/sub a/ were equal, perpendicular field induced losses due to R/sub c/ would be around 50 times greater than those induced by R/sub a/. Because of the importance of the crossover resistance, we have developed a novel measurement technique for R/sub c/ in cored Nb-Ti Rutherford cables. The procedure involves removing the edges of the conductors along the region to be measured. We have measured the cables using the new technique and the usual VI technique. We describe the novel measurement technique and present results for cables made with different core materials. While measuring R/sub c/, we found evidence that R/sub a/ is nonuniform over the length of a twist pitch and is in fact significantly lower at the cable edge. We report on this as well.         Irregular AC losses with long time constants in large cable-in-conduit conductors    T. Hamajima, Y. Kakusho, K. Hoashi, M. Tsuda, N. Harada, H. Yamada, K. Takahata and T. Satow Summary: A large superconducting coil wound with Cable-in-Conduit (CIC) conductor causes both irregular AC losses that cannot be estimated from short conductor sample test results, and regular AC losses that are proportional to cable twisting pitch squared. We proposed a mechanism forming loops that generated the irregular losses. The CIC conductor is composed of several stages of sub-cables. If one strand on the surface of a sub-cable contacts another strand on the surface of the adjacent sub-cable, the two strands must encounter each other again at the LCM (Least Common Multiplier) distance of all staged cable pitches, and thereby a long loop is formed. We orderly labeled all strands in CIC conductors for the SMES and the LHD. It was found that strands in a triplet were widely displaced from their original positions on one cross section, but contacted each other tightly on the other cross section. This fact suggests that the loop with the large displaced strand links irregularly with external field so that the loops cause the irregular AC losses. Moreover, it indicates that a contacting length of the large displaced strands can be quite long, giving rise to a low contact resistance for the loop, and leading to the long time constants. It is believed that the widely displaced strand are inherent in a CIC conductor. It was demonstrated that the strand surface coated with CuNi was effective to suppress the irregular AC losses.         Evolution of contact resistance and coupling loss in prototype ITER PF NbTi conductors under transverse cyclic load    A. Nijhuis, Yu. Ilyin, W. Abbas and H.H.J. Ten Kate Summary: Cyclic energizing of a magnet coil with Cable in Conduit Conductors (CICC), as for fusion applications, results in an anomalous change of the interstrand contact resistance (R/sub c/) and coupling loss (n/spl tau/) due to the alternating transverse forces. Previously, three Nb/sub 3/Sn ITER conductors have been tested in a cryogenic press, up to 40 cycles. Now, for the first time, the behavior of NbTi conductors under cyclic load is investigated and results are presented for three full-size prototype ITER Poloidal Field (PF) Coil conductors. One conductor has bare copper strands and no petal wrapping while the others have a Cr and solder strand surface coating. The press can transmit a maximum transverse force of 800 kN/m directly to a cable section of 400 mm length at 4.2 K. Each conductor is tested up to 220 kN/m and 40,000 full loading cycles. The magnetization of the conductors and the R/sub c/ between combinations of strands and strand bundles is measured at various number of cycles. It appears that the R/sub c/ can vary for up to orders of magnitude during cyclic loading.         Influence of intersecting angles of strands on contact resistance in cable-in-conduit conductors    K. Nakamura, M. Yamanouchi, M. Yamaguchi, T. Obana, K. Hashimoto, T. Takao, A. Nishimura and T. Mito Summary: We have measured contact resistance between superconducting strands that was a parameter of coupling losses in cable-in-conduit conductors. Assuming some kinds of twist pitches of sub-cables in the multi-stranded cables, we measured the contact resistance under the condition of the intersecting strands. Since not only the resistance but also mechanical properties of the strands (applied force to the strands and deformation of the strands due to the force) were measured, the contact area could be precisely estimated, and then the surface resistance was also evaluated. The experimental results showed that the surface resistance hardly depended on the twist pitches of the sub-cables at both liquid nitrogen and liquid helium temperatures. The results become fundamental data to estimate the coupling losses caused by current loops including more than one sub-cable with long-time constants of current decay.         Energy loss measurements in the CICC short samples and model coil    I. Rodin, S. Egorov, A. Lancetov, M. Astrov and S. Fedotova Summary: The AC performance of the superconducting magnets of thermonuclear tokamak reactors and superconducting magnetic energy storages (SMES), made of the cable-in-conduit conductors (CICC), is greatly influenced by the deposition of the electromagnetic and mechanical energy losses in the conductor. The paper describes the electromagnetic techniques used for the measurements of these losses in the CICC short samples with and without transport current and in the International Thermonuclear Experimental Reactor (ITER) Toroidal Field Conductor Insert Coil (TFCI).         Combined modeling of cables and joints/terminations for the electromagnetic analysis of superconducting cables    M. Breschi, M. Fabbri, F. Negrini and P.L. Ribani Summary: The electromagnetic models developed in the recent years to study current distribution and ac losses in superconducting magnets have focussed on detailed descriptions of either cables or joints/terminations, usually considered separately. A more accurate physical description of the magnet system requires to model simultaneously the different parts of cable, the joints between them and the cable terminations. In this work we present the coupling of a distributed parameters circuit model of the cable with a simple lumped parameters resistive model of the joints and terminations. The principles and results of the coupling strategy are illustrated and validated by means of a comparison with the analytical solution of the problem found for triplex cables.         A new winding method to reduce AC losses in stable LTS pulse coils    A. Kawagoe, F. Sumiyoshi, M. Nakanishi, T. Mito and T. Kawashima Summary: A new winding method was proposed to reduce ac losses in stable LTS pulse coils. The suitable conductor for this winding method is a multi-layer type conductor composed of stacked Rutherford type cables with low resistive contact between strands. In this winding method, the twist angle around axis of the conductor is controlled during winding process to adjust the direction of edge-on orientation to stacked cables to direction of local magnetic fields applied to the conductor in winding areas. Inter-strand coupling losses in this coil are expected to be small in spite of low resistive contact between strands in the wound conductor. In order to clarify the effect of this winding method, firstly, a test conductor was fabricated and ac losses in short samples of the conductor were measured. This was an aluminum stabilized conductor, and a Rutherford cable composed of 8 Cu/Nb-Ti strands was used as the core of this conductor. The loss is measured with the transverse magnetic fields applied either perpendicular or parallel to the broad cable face, the "face-on" (FO) and "edge-on" (EO) orientations, respectively. From observed data, it is found that EO loss is 0.12 times FO loss . Secondly, ac losses in test coils wound with this conductor were calculated. The result showed that this winding method was very effective.         Author Index (2002 - Part 2)    No author information available Summary: Not available

© Copyright 2009 All Rights Reserved. Developed for IEEE Applied Superconductivity Conference by InControl Productions, Inc..