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1992 Part 1     Front Cover (1992 - Part 1)    No author information available Summary: Not available         Table of Contents (1992 - Part 1)    No author information available Summary: The following topics were dealt with: very high field magnets; detector magnets; AC losses, cryostability and RF; superconducting magnet energy storage; MRI and special magnets; stability and quench; fusion magnets; motors and generators; leads and levitation; maglev; switches, rectifiers and current limiters; accelerator magnets; light source magnets; BSCCO wires and tapes; low temperature superconductors; YBCO film processing; surface resistance; bulk high-temperature superconductors; TBCCO thin films; critical currents and flux pinning; tunnelling; A-15 materials; NbTi alloys; flux dynamics; BSCCO films; channel phases; multilayers and heterostructures; LTS SQUIDs; multichannel SQUID instruments; HTS SQUIDs; Josephson junctions; particle and X-ray detectors; low temperature junctions; mixers; HTS junctions; Josephson oscillators; solitons; digital applications; passive devices; radiation detectors; thin films.         Conference Information (1992)    No author information available Summary: Not available         Hybrid III: The system, test results, the next step    Y. Iwasa, M.J. Leupold, R.J. Weggel, J.E.C. Williams and S. Itoh Summary: The authors describe the overall Hybrid III system, present test results, and indicate future plans. Hybrid III, completed in late 1991, has since undergone a sequence of tests in preparation for becoming a facility magnet. When first tested in December 1991, it generated a total central field of 33.5 T. The superconducting magnet (SCM), operating in a bath of superfluid helium at 1.65 K and with a current of 2200 A, contributed 12.7 T to the total. In subsequent runs it was shown that the SCM would reach a critical current of approximately 2230 A when operated at approximately 1.7 K. After the completion of improvements to the cryogenic components as described, two major goals were set: to reach 35 T in two steps and to operate Hybrid III as a facility magnet. Hybrid III is targeted to reach 35 T in the spring of 1993.         Operating experience with the Grenoble Hybrid Magnet system    M. Ohl, P. Sala, H.J. Schneider-Muntau and J.C. Vallier Summary: The Grenoble Hybrid Magnet produces fields above 30 T in a room temperature bore as big as 50 mm in diameter. It uses superfluid technology and a polyhelix insert. The authors give the main characteristics of this magnet and describe the operating conditions under which the system is run for scientific use. Only a few modifications have had to be introduced since the magnet became operational in 1986. The resistive part has been subject to two technical improvements to increase water flow and reduce operating temperature, and a fast data acquisition system was added to analyze quench behavior. The superconducting magnet quenched twice and showed a behavior exactly as calculated. No deterioration has been observed in spite of the high discharge voltage of 2.5 kV. The cryogenic system has proven to be quite reliable except for a few problems with the liquefying system and a clogged filter in front of the 1.8/4.2-K heat exchanger.         A design for the superconducting outsert of a 45-T hybrid magnet system using cable-in-conduit conductors    J.R. Miller, S.W. Van Sciver, W.D. Markiewicz, H.-J. Schneider-Muntau, E.S. Bobrov, Y. Iwasa, M.J. Leupold, R.J. Weggel and J.E.C. Williams Summary: A part of the mission of the new NHMFL is to have available for users in 1995 a hybrid magnet system capable of producing at least 45-T steady field on axis in a 33-mm working bore. Approximately 31 T of the combined field will be produced by a water-cooled insert. The superconducting outsert, which combines NbTi and Nb/sub 3/Sn conductor technologies, will provide more than 14 T. The authors describe an option for this superconducting outsert based on the cable-in-conduit-conductor (CICC) approach, where cabled strands of conductor are contained in intimate contact with helium coolant inside a strong steel sheath that also acts as distributed structure. A departure from the usual practice for CICC technology is in the application of static Hell cooling, which simultaneously provides higher conductor performance and nearly passive extraction of the rather modest heat loads during normal operation of the magnet system.         Generation of magnetic fields over 20 T using a newly developed superconducting magnet system    T. Kiyoshi, K. Inoue, K. Itoh, T. Takeuchi, H. Wada, H. Maeda, K. Kuroishi, F. Suzuki, T. Takizawa, N. Tada and H. Mori Summary: In February 1992, a newly developed superconducting magnet system at the National Research Institute for Metals accomplished generation of a magnetic field of 20.3 T in its clear bore of 44 mm in diameter. The authors give an outline of the magnet system together with the operation results. The required time to cool down from 4.2 K to 1.8 K was about 4 h. The operations carried out at 1.8 K proved that saturated superfluid helium can be applied as coolant for large scale superconducting magnets because no problems, such as a discharge in the coils, were observed even when quenches occurred. This magnet system may be useful for testing coils of new high-field superconductors.         Design of the Nb/sub 3/Sn dipole D20    D. Dell'Orco, R. Scanlan and C.E. Taylor Summary: The design of a 55-mm bore superconducting Nb/sub 3/Sn dipole with a short sample field of 13 T at 4.3 K and a current of 5500 A/turn is presented. The superconducting dipole has two layers of Nb/sub 3/Sn coils, each wound in a double pancake. The inner cable has 37 strands with a strand diameter of 0.75 mm and a Cu/Sc ratio of 0.4; the outer cable has 47 strands with a diameter of 0.48 mm and a Cu/Sc ratio of 1.15. To obtain a high transfer function and low saturation effects on the multipoles, the stainless steel collar is elliptical and the iron yoke is close in. The thin collar itself provides only a minimum prestress and the full prestress of 100 MPa is given by a 25-mm welded stainless steel shell or by winding a wire around the yoke. Aluminium spacers are used as assembly tools and as a means to control the gap size in the vertically split iron yoke. The authors present the magnetic design and the calculated stress and strain distribution in structure and coils. A 1-m model called D20 is to be built and tested at LBL.         Design concept for the GEM detector magnet    B.A. Smith, P.G. Marston, J.V. Minervini, Z.S. Piek, R. Vieira, R.D. Pillsbury Jr., J.D. Sullivan, R.J. Camille Jr., P.H. Titus, R. Stroynowski, J. Bowers, G. Deis, A. House, C. Johnson, D. Ng, G. Oberst, L. Pedrotti, R. Warren, S. Wineman, R. Yamamoto, M. Harris, N. Martovetsky and W. Wisniewski Summary: The magnet has two symmetric and independent halves, each containing a cold mass assembly operating nominally at 4.5 K, a set of vapor cooled leads, a cold mass support system, a liquid nitrogen shield system, and a vacuum vessel. Also included in each half is a forward field shaper which provides a component of magnetic induction normal to the path of low angle muons in the forward region, thereby improving their resolution. The unique features of this magnet are the conductor design itself and the large coil diameter, which demands an on-site winding and assembly operation. The use of a natural convection thermosiphon loop for thermal radiation cooling eliminates plumbing complications. Locating the aluminium sheath outside the conduit for quench protection permits optimizing the copper-to-superconductor ratio inside the conduit for stability alone. The conceptual design for the magnet, including the design for the detector dependent magnetics, the superconducting coils and coil structure (cold mass), the coil winding process, the vacuum vessel and liquid nitrogen shields, the cold mass supports, and the magnet assembly procedure, are described.         Design study of a thin superconducting solenoid magnet for the SDC detector    A. Yamamoto, Y. Doi, T. Kondo, Y. Makida, K. Tanaka, H. Yamaoka, R. Kephart, R. Fast, C. Grozis, A. Lee, R. Stanek, A.M. Stefanik, R. Wands, C.A. Collins and R. Richardson Summary: A thin superconducting solenoid magnet has been designed for the SDC detector, which is one of major colliding particle detectors for the SSC high energy particle accelerator project. Based on recent R&D efforts to develop a high strength aluminum stabilized superconductor and a honeycomb/isogrid vacuum shell, the thin solenoid has been designed to provide a central magnetic field of 2 T in a tracking volume of 3.4 m phi *8.8 m, with a magnet wall transparency 1.2 Xo. The authors describe the conceptual design and the R&D work. To minimize material in the solenoid, technical guidelines incorporated into the solenoid design are outlined, and material savings are discussed. The cryostat and cryogenic design are considered. A R&D program is in progress to develop a prototype solenoid magnet with a full diameter and a quarter length to verify the SDC solenoid design.         A large superconducting thin solenoid for the STAR experiment at RHIC    M.A. Green Summary: The author describes the 4.4-m, warm bore diameter, thin superconducting solenoid, for the proposed Solenoidal Tracker at RHIC (STAR) experiment at the Relativistic Heavy Ion Collider (RHIC). The STAR solenoid will generate a very uniform central magnetic induction of 0.5 T within a space which is 4.0 m in diameter by 4.2 m long. The solenoid and its cryostat will be 0.7 radiation lengths thick over a length of 5.45 m, about the center of the magnet, making it the largest solenoid less than one radiation length to be built. A proposed design for the solenoid and cryostat, its flux return iron, its cryogenic system, and its power supply and quench protection system is described.         Development in the design of the superconducting toroidal magnet for the Continuous Electron Beam Accelerator Facility (CEBAF) large acceptance spectrometer    J.S.H. Ross, K.D. Smith, A.J. Street, D.M. Jenkins, S.M. Harrison, R.J. Riggs, J.M. Wiatrzyk, J. O'Meara, W. Tuzel, C. Cuevas, G. Doolittle and C. Riggs Summary: The magnet system comprises six flat, kidney-shaped coils arranged radially to produce a toroidal field with a peak value of 3.5 T. Features of the design discussed include a modular coil design allowing single coil works testing, an indirectly cooled aluminum-stabilized conductor, support of coils via in-plane warm tension links to each vacuum case, out-of-plane load sensing for alignment and fault sensing, passive internal quench protection, and an integrated instrumentation and control system.         A large superconducting air-core toroid (for LHC detectors)    H. Desportes, J.M. Baze, R. Duthil, C. Lesmond, J.C. Lottin and Y. Pabot Summary: The authors present a conceptual design of a very large air-core toroid proposed for one of the detectors under study for the future Large Hadron Collider (LHC) at CERN. The magnet will produce a toroidal field around the central calorimeter in an open structure widely accessible for the installation of muon detectors inside the field area. It consists of 12 racetrack coils, 26 m long, tied together by a set of cold ring-shape structures distributed at ten locations along the length. Each coil is made of two single pancakes clamped rigidly to a solid plate and is self-contained in its own cryogenic enclosure. The design features an Al-stabilized conductor rated at 20 kA and 3.5 T, epoxy-potted windings, and indirect cooling. Special attention has been given to the mechanical design and to the winding construction which, in spite of the unusually large size, follows classical industrial techniques.         Construction of a large superconducting spectrometer dipole magnet with negative curvature    A.F. Zeller, S. Bricker, J.C. DeKamp, H. Laumer, J.A. Nolen, R.T. Swanson and B. Zhang Summary: The construction of a large superconducting dipole magnet with a negative curvature side is described. The cryostable coils consist of 350 turns each and operate at 500 A. Support links which support the coil and minimize bobbin deflections have been built and tested. A mapping system which follows the beam trajector is being built. The coil winding, the support links, the assembly, and the field mapper are discussed.         Final design and construction progress for CEBAF's cold iron quadrupoles    S.R. Lassiter, P.D. Brindza, M.J. Fowler, R.T. Wines, S.R. Milward, A.G. Day, M. Brown, G.H. Harding and J.C. Schouten Summary: The cold iron, cryostable, superconducting, large aperture magnets will operate over a decade of pole field excitation, from 0.2 T up to 2.1 T. The authors present a description of the modifications and changes to these magnets that have occurred. The use of a three-dimensional magnetostatic program, as a means of quality control for these changes, and a description of the structural modifications to the cryostat are included. The final expected magnetic performance as modeled with the program is listed for the superconducting quadrupoles. As modifications and manufacturing details have manifested, workable solutions have been implemented that preserve both the magnetic and mechanical specifications as well as keep to the delivery schedule. The current status of the project is presented.         Additional AC losses due to alternating magnetic field component longitudinal to strand axis in the armature winding of fully superconducting generators    K. Funaki, H. Kanetaka, H. Ueda, F. Yoshiya, M. Iwakuma, M. Takeo and K. Yamafuji Summary: The armature winding of fully superconducting generators will be constructed by multiply stacked cables of multifilamentary superconducting strands. In the superconducting cable exposed to an alternating transverse magnetic field, additional AC losses called longitudinal losses are generated by a field component longitudinal to the strand, because the angle between the axes of the strand and the final cable changes spatially with periods of cabling pitches. The longitudinal losses depend upon the structure of the cable, the direction and pitch in each level of cabling, etc. The additional losses are evaluated in electromagnetic environments of the armature winding. The structure of the cable is discussed to minimize the total AC loss under a stability condition.         Analysis of degradation in AC superconducting cables    S. Torii, S. Akita, R. Ishikawa, K. Uyeda, N. Amemiya and O. Tsukamoto Summary: The development of large-current-capacity AC superconducting cables is an important step in the realization of AC superconducting power apparatus. The authors have developed and tested a kA-class superconducting cable, bundled and twisted with 343 strands. The measured AC quench current was much smaller than the sum of the critical current of each strand. The authors theoretically and experimentally investigate the causes of this current degradation. Many factors were considered as the causes of this AC current degradation, and the focus is on the nonuniform current distribution among the strands of a cable was measured. The measured current distributions are compared with theoretical current distributions, and the component of AC quench current degradation is discussed.         Critical current and AC loss measurements of superconductors developed for the Super-GM project under cyclic mechanically loaded condition    S. Akita, S. Torri, H. Kasahara, K. Uyeda, Y. Ikeno, T. Ogawa, K. Yamaguchi, K. Nakanishi, S. Nakamura, S. Meguro, M. Ban, K. Takahashi and S. Sakai Summary: The design philosophy of the test facility constructed at the Central Research Institute of Electric Power Industry (CRIEPI) is described, and the test results of critical currents and AC losses of superconductors for a 200-MW-class generator rotor winding developed in the Super-GM project under a cyclic mechanically loaded condition are given. The facility can provide a sample current up to 15 kA, a DC magnetic field up to 7 T, 3 Hz of AC magnetic field up to +or-0.9 T, and a compressive mechanical force up to 100 kN to simulate the centrifugal force of the generator rotor winding. The authors evaluated the performance of three types of NbTi superconductors under 10000 applications of cyclic load.         The effect of Mn additions on the hysteresis loss and critical current density of power-metallurgy processed superconducting Nb/sub 3/Sn wires    Y. Mizomata, N. Matsukura, Y. Inoue, M. Shimada, R. Ogawa and Y. Kawate Summary: Powder-metallurgy processed Nb/sub 3/Sn conductors were fabricated using a (Cu-1 or 3 wt.% Mn)-22.5 wt.%Nb composite. Plasma rotating electrode processed powders were used to improve workability. The Mn addition to the matrix increased the critical current density. The overall critical current density was about 1.5 approximately 2 times higher than that of conductors without Mn addition. It was found that Mn addition enhanced the reaction rate of Nb/sub 3/Sn through a catalysis-like effect of Mn. The Mn addition to the matrix decreased the hysteresis loss and the effective filament diameter. The lowest hysteresis loss was about 60% of the value of conductors without Mn addition. It was found that Mn addition depressed interfilamentary coupling.         AC susceptibility and filament coupling of multifilamentary superconducting wires    K. Yasohama, Y. Kubota and T. Ogasawara Summary: The authors have studied proximity effect coupling on multifilamentary wires by measuring AC susceptibility. AC susceptibilities were measured on three kinds of samples. One was a Nb-multifilamentary wire with a Cu matrix, and the others were NbTi wires differing in the matrix, Cu or CuNi. A peak of the proximity effect coupling loss was seen as a function of temperature. It was foud that the peak temperature depends strongly on the measuring field and filament spacing. It decreased consistently with an increase in the applied field and the filament spacing. The coupling depends on the matrix, and no coupling peak was observed for the CuNi matrix wire at temperatures above 4.2 K.         Coupling losses of multifilamentary superconductors having several concentric regions and mixed matrix    G.B.J. Mulder and E.M.J. Niessen Summary: A method is presented to calculate the coupling loss in multifilamentary conductors containing a mixed matrix. The conductor geometry considered has several concentric regions with either isotropic normal material, anisotropic normal material, or superconducting filaments. In anisotropic normal regions, containing for example Cu hexagons in a CuNi environment, the effects of anisotropy and twist have to be taken into account. An interesting similarity is observed between such regions with highly anisotropic normal material and regions with superconducting filaments.         Coupling currents in Rutherford cables under time varying conditions    A.P. Verweij and H.H.J. ten Kate Summary: A network model is presented to simulate fully transposed Rutherford cables under time varying conditions. The intrinsic properties of the cable and the external applied conditions can be changed spatially. Several statistical distributions of the contact resistances are built in to investigate local differences in the coupling loss and in the eddy currents. The average loss is quite independent of the resistance distribution but locally both the loss and the eddy currents can increase significantly. The self field distribution of the cable is included, resulting in a saturation of the strands which depends on the relative direction between the magnetic field, the field sweep rate, and the transport current. Mutual inductances between strands are introduced, allowing the use of the model for nonstationary problems. Time constants can be calculated for both the coupling currents in the strands and for the local and global dissipation.         Anomalous magnetization behaviour in fine filamentary NbTi superconducting wires    M. Polak, L. Krempasky, M. Majoros, D. Suchon and H. Kirchmayr Summary: Magnetization curves of various fine filamentary superconducting wires with Cu as well as a CuNi matrix have been measured. Anomalies in the shape of these curves in a low external magnetic field were observed. A strong influence of both filament diameter and matrix type on the field above which the initial magnetization curve deviates from the straight line was detected. A considerable influence of the current flowing through the sample on the magnetization was observed as well. A model based on the proximity effect is proposed for the explanation of the magnetization anomalies.         Very sensitive electric method for AC measurement in SC coils    J. Kokavec, I. Hlasnik and S. Fukui Summary: The authors present an air-core transformer whose mutual inductance can be smoothly changed in a very large interval giving a smoothly variable secondary voltage with suppressed extraneous noise and very small phase shift with regard to dI/dt in the primary. They also describe a very sensitive method of measuring AC losses in superconducting coils based on the use of this mutual inductance with a selective nanovoltmeter. This method eliminates the need for an integrator with small drift and phase shift error, a high resolution voltage divider with a sliding contact, and a shunt resistor with small phase shift, which are required by other analog electric methods. The experimental compensating coil and its parameters as well as AC loss measurements in different superconducting coils are also described.         Quench characteristics and current distribution of multi-strand AC superconducting cables    N. Amemiya, J. Murai, K. Higashihara, K. Yamagishi, S. Shimizu, O. Tsukamoto, S. Torii and S. Akita Summary: When AC transport current is supplied to an imperfectly transposed AC superconducting cables, the current distribution among strands becomes nonuniform because of the inductance imbalance. The influence of the nonuniform current distribution on the AC quench characteristics of seven-strand cables was experimentally investigated. It was observed that the center strand carries the inverse current as compared to the total transport current. The influence of the current distribution on the quench current is discussed. The AC quench currents of the following three cases are compared: a seven-strand cable with small series impedance, a seven-strand cable with large series impedance, and a six-strand cable. The quench current of the second case was the largest, and that of the first case was the smallest. It can be qualitatively explained by the current distribution among strands, but the difference between their quench currents was smaller than expected. In a seven-strand cable with small series impedance, the magnitude of the inverse current in the center strand was smaller than the theoretical value. Its peak was eliminated when the total transport current became large.         Instabilities in multi-strand AC superconducting cables caused by longitudinal magnetic field with transverse magnetic field    N. Amemiya, T. Ohizumi, N. Ikeda, I. Hlasnik and O. Tsukamoto Summary: In multiply-twisted AC superconducting cables, strands are exposed to magnetic field with longitudinal and transverse components. The influence of such components of the magnetic field on the AC quench current degradation is investigated. The internal magnetic field is calculated in various types of cables and a winding. The AC quench current was measured in the bias magnetic field with longitudinal and transverse components simulating the internal magnetic field in the multiply-twisted cables. The influence of such a magnetic field on thermo-magnetic instabilities is evaluated.         A new class of AC superconducting conductors    T. Verhaege, P. Estop, W. Weber, A. Lacaze, Y. Laumond, P. Bonnet and A. Ansart Summary: Superconducting wires for 50-60-Hz applications must have very small diameters to obtain intrinsic stability and low AC losses. Concepts for the latest GEC ALSTHOM conductors that give them particular quench properties, leading to self-protection against burning or breakdown, are presented. C-type wires are industrial products with a typical diameter of 0.5 mm, presenting intrinsic performance similar to those of classically optimized wires of 0.2-mm diameter. C-type wires can be used as basic elements of larger assembled conductors. Many configurations are possible. As a first step, cables of six C-wires around one resistive insulated central wire have been realized and tested. The central wire is defined to permit rapid quench detection and a rapid phenomenon of mass quench. The mass quench transforms any possible local quench into a complete quench of the coil, after some delay which is also exploited for passive protection. Experimental results are presented.         A new method for determining the magnetization of superconducting cables and its time dependence    M. Halemeyer, P. Schmuser, H. Bruck, D. Gall, J. Krzywinski, R. Meinke and H. Preissner Summary: A method is described for determining the average magnetization of several meters of Rutherford-type cable used in the superconducting magnets of the proton-electron collider HERA. Fifty-six cable sections of 300-mm length are mounted in two 90 degrees sectors on a stainless steel tube and inserted in a superconducting dipole coil, providing a magnetizing field of up to 5 T. The magnetized NbTi filaments in the sample generate dipole and decapole fields inside the tube of 1-2 mT. The dipole component is obtained from a longitudinal scan with a nuclear magnetic resonance (NMR) probe, subtracting the background field of the magnet. The superconductor magnetization was determined with a precision of 3%. The decapole field of the magnetized cable sample, measured with a fivefold rotating pickup coil, was well suited to study time dependences as it was almost two orders of magnitude larger than the persistent-current decapole of the dipole magnet. A weak logarithmic time dependence was observed, compatible with thermally activated flux creep in the superconductor.         Cryostabilization of high-temperature superconducting magnets with subcooled flow in microchannels    Y.S. Cha, J.R. Hull and U.S. Choi Summary: Subcooled flow of liquid nitrogen in microchannels is proposed as a means to enhance the stability of superconducting magnets. An analysis shows that high current density or a low stabilizer fraction can be obtained in a cryostable magnet. An increase in stability (with the Stekley criterion as a measure) is directly related to coolant velocity and coolant channel aspect ratio. However, it is accompanied by a corresponding increase in pressure drop of the system. In addition, the coolant temperature rises as a function of coolant residence time and coolant-to-conductor ratio.         Magnetic shielding properties of NbTi/Nb/Cu multilayer composite tubes    I. Itoh, T. Sasaki, S. Minamino and T. Shimizu Summary: Magnetic shielding properties have been investigated using Hall plates at 4.2 K in a parallel magnetic field up to 4 T for superconducting cylinders with and without a bottom, which are multilayer composites consisting of NbTi, Nb, and Cu. These composite cylinders were fabricated by deep drawing a multilayer composite sheet made by cladding and rolling. It was found that a sample of five concentrically stacked cup-shaped cylinders, with a thickness of 1 mm, an inside diameter of 20-40 mm, and a length of 45 mm, can reduce the external magnetic field of 3 T to less than 10 G.         Improvement in magnetic shielding by the superposition of a magnetic cylinder over a copper-oxide superconducting cylinder    M. Itoh, T. Ohyama, K. Hoshino, H. Ishigaki and T. Minemoto Summary: Magnetic shielding was shown to be improved by superimposing a magnet cylinder over a superconducting cylinder. Examples of such configurations are soft iron and electromagnetic steel cylinders over a copper-oxide superconducting cylinder. The value of the magnetic shielded field for the superimposed cylinder was found to be several times more than that of single superconducting cylinders such as YBCO or a BPSCCO cylinder. Experimental results reveal good characteristics which include the effects of the excitation magnetic field on the inner magnetic field within both the single superconducting and superimposed cylinders, the temporal change of the trapped magnetic field within the superconducting cylinder, the distribution of the magnetic shielded field along the axial direction of the superimposed cylinders, and the relationship between the length of the magnetic cylinder and the shielding effect.         High temperature superconductors for low frequency magnetic shielding    J. Wang and M. Sayer Summary: The authors report the results of magnetic shielding measurements on pure YBa/sub 2/Cu/sub 3/O/sub 7- delta /, silver-doped YBa/sub 2/Cu/sub 3/O/sub 7- delta / packed powder, laser ablated thin film, and copper. The shielding factors of bulk ceramics were much higher than those of other materials and were not a function of frequency in the range from 10 Hz to 3000 Hz. Simply packed superconducting powder did not show any shielding. While polycrystalline ceramics were effective as shields, the thickness of the ceramic played a crucial role in shielding. The breakthrough field increased with thickness. The influence of DC fields on the shielding behavior depended on the magnitude of the fields.         Magnetic shielding by Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7- delta / thick films    D.B. Opie, M.E. Read, S.K. Remillard, M.J. Brown, W.J. Kossler, H.E. Schone, T.W. Button and N. McAlford Summary: The magnetic shielding properties of YBCO thick-film shielding structures have been calculated using the Bean model, and these numerical results are compared to measured data. The numerical results were obtained with a three-dimensional finite-element code that performed a nonlinear, transient analysis of the superconducting material as a function of applied magnetic field. The superconducting properties of the Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7- delta / (YBCO) are included in this model by defining a nonlinear response of the high-temperature superconductor material to the applied field. The measurements were performed on superconducting, melt textured thick YBCO films deposited on cylindrical and planar substrates, which together formed a closed shielding structure. The YBCO shields were measured at various temperatures from 12 K up to T/sub c/. At 50 K these shields were found to completely shield a centrally placed magnetic probe up to an external field of 5 G.         Superconducting niobium thin film sputtering onto copper quarter wave resonators for heavy ion accelerators    V. Palmieri, V.L. Ruzinov, S.Y. Stark, R. Preciso, L. Badan and A.M. Porcellato Summary: Niobium sputtered copper quarter wave resonators (QWRs) represent an innovative and promising alternative to lead electroplated copper cavities, or to those made of niobium, both bulk and explosively bonded on copper. The authors describe the R&D efforts of the first niobium sputtered copper prototypes. The results obtained and the progressive improvements achieved test by test make Nb sputtered QWRs an intriguing possibility for the acceleration of heavy ions whenever the need for changing from Pb to Nb is encountered. A prototype with a Q-value of 7*10/sup 8/ and maximum accelerating field of 4 MV/m has been produced.         First measurement of a NbTi RF cavity    P. Fabbricatore, G. Gemme, R. Musenich, R. Parodi, M. Viviani, B. Zhang and R.J. Sinko Summary: The first measurement of a NbTi superconducting accelerating cavity at 4.5 GHz is reported. As a first step of a R&D project for the study of new promising superconducting materials for future applications to RF accelerating structures, a NbTi cavity was built using the same technique developed for niobium cavities. The cavity was electron beam welded, chemical polished, and rinsed with high purity water. A first test has shown very good agreement between measured and computed RF surface resistance down to 1.8 K. The authors used the Halbritter's code for RF loss computation in superconductors to obtain from measured data information about the coherence length, the penetration depth, the mean free path, and the strong coupling coefficient of the material.         Cost savings and prospects for applications of micro superconducting magnetic energy storage (SMES) using high temperature superconductors    S.M. Schoenung, R.L. Bieri, W.R. Meier and T.C. Bickel Summary: Recently, interest in superconducting magnetic energy storage (SMES) systems of approximately 1-MJ storage capacity has grown among potential industry and utility users. A large fraction of the cost is in the refrigeration system which is required to maintain a superconducting coil. The objective of the project described was to determine possible cost savings from the use of high-temperature superconductors (HTSs). An additional goal was to identify development needs for HS materials to be useful in small SMES systems. The approach to this assessment was to build a computer model with assumed HTS conductor properties to establish coil configurations for a small SMES (1-MJ/1-MW) system. A second computer model was developed to estimate refrigeration requirements. A third model was used to estimate and sum component costs. A conventional low-temperature superconductor (LTS) system was also modeled for comparison.         SSD operating experience    M.A. Daugherty, W.E. Buckles, G.A. Knudtson, D.L. Mann and P.W. Stephenson Summary: A self-contained system called the SSD that uses the energy stored in a superconducting magnet to provide voltage support for large electrical loads was developed. Operating experience gained during the development and first two years of SSD field operation is reported. The SSD delivers energy from its superconducting magnet to a customer's load using a current-to-voltage converter which feeds an inverter. Two different systems were developed based on different inverter topologies. One configuration supports an adjustable speed motor load. The other supports diverse AC loads and incorporates a static isolation switch. These systems were installed at customer sites. Each system successfully carried industrial loads through numerous voltage sags. Field operating data on both system configurations are reported.         Testing plant with a small fast superconducting energy storage at TU Munchen    P.J. Birkner, U. Brammer, H.W. Lorenzen, J.F. Karner, W. Rehm, J. Schaller and R. Schottler Summary: The authors describe a small energy storage plant for experimental tests. The centre of this energy storage plant is a small, fast acting superconducting magnetic energy storage (SMES) of 1.4 MJ. The SMES is composed of six superconducting (SC) coils arranged in a torus. The SC coils are cooled indirectly by supercritical He. To avoid eddy currents as far as possible all important parts are made of glass-fiber reinforced plastic. Calculations show the losses of the small, fast acting SMES during periodical load cycles depending on different charge and discharge times.         Development of superconducting magnet with low electric power loss for SMES    K. Hayakawa, T. Nakano, M. Minami, M. Fujiwara, T. Kanzawa, S. Terai, E. Haraguchi, A. Ryouman and Y. Murakami Summary: A superconducting magnet with a 0.01% electric power loss was developed. This magnet is used to store electric power as magnetic energy and to stabilize an electric power system. This magnet of 78-cm outer diameter and 27-cm width consists of 18 double-pancake-type coils and was designed with a 10-T/s pulse-discharge speed and 350-A transportation current. To reduce energy loss caused by the eddy current, the copper wire stabilizer surrounding the superconducting material was subdivided by a cupronickel layer. To prevent quench, cooling channels were arranged between pancakes of the magnet and between turns of the coil. Elementary analysis and tests of mechanical strength, insulation, cooling and quench were performed, and the performance of this magnet was confirmed with high-speed charge-discharge tests and forced-deenergizing tests.         The comparison of single- and multi-solenoidal windings for superconducting storage device performance    S.I. Kopylov Summary: The author compares a scheme utilizing multisolenoidal windings (MSW) in a superconducting storage device to the traditional single solenoidal winding (SSW). It has been found that in the case of a MSW assembled from a number of solenoids smaller in diameter than those used in the SSW with the same storage capacity, the stored energy per unit volume is higher than in the SSW. It is shown that there is a parameter space where MSW is preferable to SSW. This scheme also offers additional advantages such as higher reliability, controllability and durability.         Power system stabilization by superconducting magnetic energy storage connected to rotating exciter    Y. Mitani and K. Tsuji Summary: The authors describe a combination of a rotating exciter and a superconducting magnetic energy storage (SMES) system for efficient power system stabilization. A SMES system connected to an exciter rotating with a turbine-rotor shaft is proposed. The exciter is installed exclusively to supply current for the SMES. Since electrical power output from the SMES is converted into a mechanical torque of the generator directly by the exciter, it is expected that power swings of the generator will be damped efficiently. Several numerical studies demonstrate that the proposed control system is capable of stabilizing torsional oscillations as well as electromechanical oscillations in power systems significantly.         Damping of current oscillation in superconductive line applied for high voltage direct current transmission system    N. Kimura, T. Funaki and K. Matsu-ura Summary: The application of a superconductive transmission line to a high-voltage direct-current transmission system is considered. However, unstable phenomena similar to an AC system are introduced. The authors suggest installing a damper circuit, which consists of an inductor and a resistor in parallel, to prevent such instabilities. In a steady state, most of the DC current flows into the damper inductor and generates little loss, but once oscillation in the DC current is induced, voltage appears across the damper inductor, and the resistor generates the loss for the current. The loss dissipates the energy of the oscillation and damps it. The effectiveness of proposed damper circuit was shown by using computer simulation.         Disturbance energy of a forced flow cooled superconducting coil    M. Shimada, M. Ono, Y. Wachi, T. Hamajima and M. Yamaguchi Summary: The disturbance energy of a forced flow cooled superconducting coil (FCC) is discussed. The authors built a FCC and carried out stability and quench tests. The test coil had a 36-m-long cooling path with a 0.37-mm hydraulic diameter. It was cooled by supercritical helium at 4.1 K. The stability margin of the FCC was evaluated by using RF heating. In addition, the coil quench test was performed. The disturbance energy at quench is estimated by the stability margin characteristics. The disturbance energy obtained agrees well with that of a simple analytical model.         Field coil protection for a SMES-supported all-purpose compensator    J.F. Karner and A. Nitsche Summary: The use of superconducting coils to complete static volt ampere reactive (VAr) controllers provides an efficient protective system which detects quenches and saves the quenched coil from being damaged by thermal and electrical stresses. The authors deal with the peculiarities of designing the protective system of a 1.36-MJ experimental superconducting magnetic energy storage (SMES) system which will form part of a static compensator for multiple use in public power supply networks. A concept for selective use of the available protective devices which serves to achieve maximum energy recovery at a minimum thermal load of both field coils and cooling circuit in case of a quench is presented.         Design aspects of mid-size SMES using high temperature superconductors    S.M. Schoenung, W.R. Meier, J.R. Hull, R.L. Fagaly, M. Heiberger, R.B. Stephens, J.A. Leuer and R.A. Guzman Summary: Conceptual designs of modular, cold-supported superconducting magnetic energy storage (SMES) units using high-temperature superconductors (HTSs) were investigated over the mid-size energy range of 2 to 200 MWh. This size range covers many utility, industrial, and military applications. Both toroidal and solenoidal configurations were analyzed to determine physical dimensions, heat loads, and cost of major components. Among the effects considered were the impact of critical current density on feasible configurations, mass of conductor, and cost: the effects of magnetic field and strain limits on physical parameters and structural mass; and the savings in refrigeration from operating at a higher temperature. The design of the HTS conductor, stability criteria, and coolant selection are also discussed.         Vertically rippled flat coil configuration for SMES    X. Huang, Y.M. Eyssa and R.W. Boom Summary: A novel vertically rippled flat coil design concept for superconductive magnetic energy storage (SMES) is presented. The coil consists of two or more horizontal layers that are rippled in the vertical direction. The thermal strains of the coil are accommodated by vertical bending and the magnetic forces are taken up by radial bending. The coil is very stiff in the radial direction to transfer magnetic forces to the external warm structure, which causes very small structure bending stresses and results in essentially a strain-free conductor during operation. The vertically rippled coil is very flexible in the vertical direction and accommodates large thermal strains occurring during a cool-down or warm-up process with only small stresses. The impact of this concept upon the SMES design is discussed.         New conductor designs for superconductive magnetic energy storage systems    X. Huang Summary: The study separates high purity aluminum stabilizer design and superconducting strand design. The author discusses the impact of each conductor design parameter on the conductor transient (recovery) stability and dynamic (nonpropagation) stability. The transient stability requirement determines the size of stabilizer and the dynamic stability requirement determines strand design. Examples of 50-kA and 100-kA conductors are given. Design guidelines are established for each of the stability requirements, which lead to cheaper and more efficient conductor designs. A normal zone propagation stopper concept is presented.         On the design of superconducting magnetic energy storage systems    P.J. Birkner Summary: With respect to the available technology and the total costs a first significant step in developing superconducting magnetic energy storage (SMES) plants will be to design a device that is characterized by a small content of stored energy as well as by a high charging power, which is called a small fast-acting SMES unit. It is shown that a small fast-acting SMES unit should be designed as a toroidal coil operating at low induction and high current. The effects of the SMES design and the operating cycle on the cryogenic AC losses are investigated. The quench pressure and cooling concept are discussed.         Superconducting magnetic energy storage (SMES) for industrial applications-comparison with battery systems    P.G. Therond, I. Joly and M. Volker Summary: The authors have considered using a superconducting coil to store energy as an impulsive high power supply for industrial applications such as smoothing of short power interruptions, and smoothing of varying load. They present the results of an economic and technical evaluation of such a system for two applications. The applications are (1) as substitution for the flywheels of the primary pump motors of nuclear power stations and (2) related to the design of magnetic energy storage for load smoothing. A general evaluation of costs is given, and they are compared to those of battery systems.         Passive shimming of MR magnets: algorithm, hardware, and results    B. Dorri, M.E. Vermilyea and W.E. Toffolo Summary: An improved method for allowing a magnetic resonance (MR) magnet to meet its stringent field homogeneity requirements has been developed. The method is called passive shimming and involves the placement of pieces of ferromagnetic material in the magnet bore at locations which are determined from an initial field map. Software and hardware which facilitate this shimming procedure have been developed at GE and successfully implemented in MR scanners around the world. The software uses a linear programming algorithm to minimize the thicknesses of shims at each of a number of allowable locations which will bring the peak-to-peak field error in the volume of interest to its minimum level. The hardware consists of arc-shaped drawers on each of which shim packages may be built up to a predetermined maximum thickness. This shimming technology represents a major cost reduction from the superconducting or resistive electromagnetic correction coils which are typically used to shim a magnet's field.         Transverse stress on Nb/sub 3/Sn conductors in high field NMR magnets    W.D. Markiewicz, S.R. Voleti, N. Chandra and F.S. Murray Summary: For a thin coil section of a solenoidal magnet, the relationship between the reduction in axial stress and the reduction in tangential stress for a given quantity of lumped reinforcement is determined. The axial compression in solenoids originates toward the end of the solenoid in the region of greatest radial field. For the axial load to accumulate on the conductor in the midplane, the reinforcement will be placed in compression axially. The result is a redistribution of the axial load and a reduction of the axial stress on the conductor. It was a primary objective of the present work to examine this mechanism and to determine the effectiveness of the lumped reinforcement in reducing the axial stress on the windings. The general picture of axial stress in long thin solenoids which has emerged in the course of this investigation is described. The axial and radial stress distribution in a coil of a high field magnet is computed and related to the performance of the Nb/sub 3/Sn conductor in the coil.         A NbTi split magnet directly cooled by a cryocooler    S. Masuyama, H. Yamamoto and Y. Matsubara Summary: A novel system consisting of a NbTi coil directly cooled by a G-M cryocooler was successfully constructed. The quench was simulated, focusing on the role of the copper bobbin as the secondary coil. Under the optimum conditions, a maximum field of 6.3 T was achieved. It was demonstrated that the critical current can be attained in the temperature range 6 approximately 9 K. After a quench the increment of the coil temperature was less than 50 K and safe operation of the system was demonstrated. The results indicate good possibilities for realization of a split magnet which produces a very high field.         Construction of 8 T magnet test stand for cyclotron studies    J. Kim, H. Blosser, S. Hickson, L. Lee, F. Marti, J. Schubert, G. Stork and A. Zeller Summary: A superconducting magnet designed to study cyclotron central regions and ion sources is under construction. Two split coils were used to provide an approximately flat field in the range of 2-8 T. The coils were epoxy potted and banded by stainless steel wire, and the winding form was removed from the coil to reduce the shear stresses. The horizontal and vertical support links were attached to the median plane structure. The pairs of the coils were weakly connected for independent excitations. The stresses in the coils and quench protection have been studied to ensure coil safety.         Study of impregnating materials for stable superconducting magnets    A. Iwamoto, S. Nishijima and T. Okada Summary: The cryogenic properties of impregnating resins were measured, and the instability of superconducting magnets was studied with reference to these properties. As impregnating materials, alumina powder filled, nonfilled, and irradiated nonfilled epoxy resins were studied. Cryogenic properties such as mechanical strength, thermal contraction, and thermal conductivity were measured. The minimum quench energies of impregnated short samples were measured. The training behavior of small sized impregnated coils was also studied by using the acoustic emission technique to estimate epoxy cracking in the coils. It was found that the mechanical, not the thermal, properties of the impregnating materials were the important factors for the stability of superconducting magnets.         Voltage detection and magnet protection    J.M. Pfotenhauer, F. Kessler and M.A. Hilal Summary: Voltage detection is routinely used to identify resistive regions within superconducting magnets so that a protection circuit can trigger a safe magnet discharge. Nonresistive voltage signals, for example inductive voltages, can, however, produce false signals, causing the magnet protection system to trip prematurely. An experimental verification is given of a quench detection method which eliminates sensitivity to inductive voltages in multiple magnet systems. In addition, a specific application of these ideas for the University of Wisconsin proof-of-principle experiment demonstrated the need for incorporating a microprocessor in the quench detection system. The shortcomings of the traditional quench detection techniques were demonstrated explicitly.         Experimental investigation of the dynamic stability of BI 2223 tapes    A. Abeln, A. Minor, E. Klemt, W. Knaak and H. Reiss Summary: Bi 2223 tapes were loaded with current pulses to observe transitions to instability (quench). It was found that, if a sample was overloaded by a current the magnitude of which was several times the critical current, the time interval during which the sample withstands a quench was longer for samples with smaller critical current densities than for those with larger ones, the samples developed hot spots, which reduce the resistance against overloading and therefore reduce the dynamic stability of this material.         Normal-zone propagation in adiabatic superconducting magnets. II. Quench properties of a 12 coil 17.6 T 750 MHz NMR magnet    Z.P. Zhao, Y. Iwasa, J.E.C. Williams, E.S. Bobrov, A. Zhukovsky and R. Hirose Summary: For pt.I see ibid., vol.31, p.817 (1991). A quench simulation code was developed for multisection, epoxy-resin-impregnated, superconducting solenoids. The analysis of a 12 coil, 17.6 T, 750 MHz nuclear magnetic resonance (NMR) magnet shows that the overloading stress and strain in a heater-induced simultaneous quench are much lower than those in a sequential quench unaided with heaters. The analytical quench results are generally consistent with the experimental data for the five outer NbTi coils in the system. The analysis indicates that the magnet insulation strength should be no less than 1 kV, the maximum internal quench voltage of the system.         Experimental study on quench current of superconducting coils for 50-60 Hz use    T. Ise, K. Moriyasu and Y. Murakami Summary: The quench current of a superconducting coil wound with a multifilamentary superconducting wire for 50-60 Hz use was measured for various frequencies by using a variable-voltage variable-frequency power supply composed of a cycloconverter or an inverter circuit to investigate characteristics of the superconducting AC coil and solve the current degradation problem. The test coil was wound by using wire containing no copper. Because of the instability of the wire, the effect of wire motion was observed, and quench current of the coil varied significantly. Generally, superconducting wires for AC use are unstable because the copper content of the wire is lower than for wires for DC or pulse use. From experimental results, it has become clear that a fixing method for wires to a bobbin keeping a good cooling condition is the key to solving the current degradation problem.         Origination of propagating normal domains in large composite superconductors    V.S. Kovner, R. Kupferman and R.G. Mints Summary: The origination of propagating normal domains in large superconducting composites is studied numerically by means of an effective circuit model. The initial perturbation is considered to be a thermal pulse. The minimum energy required to form a propagating normal domain is calculated as a function of the dimensionless transport current, and three parameters characterizing the cooling conditions and the conductor. An analytical expression is proposed to determine this energy in the region of parameters of practical interest.         Computer simulation of thermal process during quench in superconducting winding of solenoid    A.V. Gavrilin Summary: A precise computer code was developed to model nonstationary 3D thermal processes, in particular during quench, in an adiabatic solenoidal winding of a superconducting magnet. The code solves, with desired precision, the set of 1D nonlinear nonstationary heat balance equations, each of which treats, in a section of winding, dynamically interdependent processes of heat propagation along a helix-shaped wire and transverse heat transfer across interturn insulation. For a fixed current, a dimensionless analysis of normal zone propagation within a single solenoid layer was carried out with the code to demonstrate the peculiar influence of the wire helicity on longitudinal and transverse velocities of the normal zone and the layer temperature profile.         Explanation of main features of superconducting windings training by balance of acting and permissible disturbances    V.E. Keilin Summary: Training of superconducting windings is considered by comparison of energies of acting disturbances mainly due to Lorentz forces and maximum permissible (critical) energies. Each quench can be interpreted as an intersection point of the curves of acting and critical energies vs. operating current. The transformation of the former curve in the course of consequent quenches changes the point of intersection and hence the operating current. With this model all main features of training behavior can be qualitatively explained. Critical energies depend on conductor properties and on cooling conditions. They can be either computed or experimentally determined for any disturbance type. The quantitative determination of the current dependence of acting disturbance energies is a much more complex problem. However, the dependence can be deduced from the results of model winding tests.         Monitoring system of superconducting magnet introducing fuzzy theorem    A. Ninomiya, Y. Kanda, Y. Uriu, T. Ishigohka, T. Mito, K. Takahata, M. Sakamoto and J. Yamamoto Summary: For quench detection or the monitoring of a superconducting magnet the authors introduce a fuzzy theorem for a new monitoring system to obtain overall diagnostic information synthesized from a number of fundamental detection items. The present operating condition of a superconducting magnet is given as a numerical amount. This numerical index (dangerous rate) can be used to indicate that the magnet is in dangerous state, and it may be possible to detect a quench very quickly or give an alarm before the quench. The fundamental idea of this method is presented. This method is applied to a superconducting magnet system in the NIFS called the TOKI-MC module coil. Some experimental results show that this method can be used for monitoring large superconducting magnets.         Study of quenching and recovery for superconducting wires and cylinders    A. Unal and M.-C. Chyu Summary: The operational instability of a cylinder/wire-type superconductor subjected to an instantaneous linear thermal disturbance is investigated. The mechanism of loss and recovery of superconductivity is studied by calculating the instability parameter, Joule heating rate, and convective cooling rate based on a solution of the transient heat conduction equation with or without volumetric heating. The effects of operational current density and wire diameter on stability are investigated. A criterion is developed for the maximum current density in stable operation under thermal disturbance and the maximum current density for recovery after quenching. Data for NbTi superconductors are presented, and the results are compared with those for tape/film-type superconductors.         A research for application of HTSC to high magnetic field at 4.2 K    L.Z. Lin and L.Y. Xiao Summary: Some high-temperature oxide superconductors (HTSCs) exhibit their best electromagnetic transport property at 4.2 K, which can be applied to produce high magnetic fields. The adiabatic stability of Bi-2212 at 4.2 K is analyzed. A configuration of the composite Bi-2212 conductors which can be used in a high magnetic field magnet is suggested. The stability performance of bi-2212 silver-sheathed tape was studied experimentally. By using composite conductors, a 10 T HTSC coil which can be inserted into a NbTi-Nb/sub 3/Sn magnet of 15 T was designed, and the possibility of the application of HTSC to 30-40 T superconducting magnets is discussed.         Racetrack coil instability resulting from friction heat generation at fixtures    T. Yazawa, M. Urata, G.R. Chandratilleke and H. Maeda Summary: A series of experiments on the instability resulting from mechanical disturbance at the coil surface of a small racetrack coil is described, along with a preventive measure against its instability. Epoxy-impregnated racetrack coils sometimes experience premature quenches due to frictional heat produced by coil slides at fixtures. The first experiment confirmed coil slides during coil charging. These slides were about 10 mu m, an equivalent of 20 mJ in fractional heat generation. One effective preventive measure against this mechanical disturbance is the utilization of a thermal barrier method. The thermal barrier is an insulation layer at the interface between the coil and the fixtures. The second experiment examined the thermal barrier effect on the stability margin on the racetrack coil. A thicker insulation layer substantially increased the coil stability margin. The margin increased from 105 mJ to 200 mJ by thickening the insulation layer from 0.36 mm to 1.00 mm. The two experiments showed that the racetrack coil was stabilized if the thickness of the insulation layer exceeded 0.20 mm. Charging a racetrack coil with a 0.36 mm-thick insulation layer confirmed this criterion.         Stabilization of dry-wound high-field NbTi solenoids    P.C. Michael, E.S. Bobrov, Y. Iwasa and M. Arata Summary: Dry-wound, Formvar-insulated NbTi superconducting solenoids are frequently used for small-bore and low-field applications because of their low manufacturing costs. The more widespread use of dry-wound coils for large-bore and high-field applications has been limited by their tendencies toward conductor-motion-induced degradation. Simple models for estimating the occurrence of conductor-motion disturbances in dry-wound solenoids are described. These models were used to design and analyze the training behaviors of three small, high-field NbTi test coils. The experimental results suggest that stabilization is best achieved by forcing all potential conductor motions to occur during low-field portions of the magnet's energization sequence, where its stability margin is greatest.         The UW-SMES design    R.W. Boom Summary: The evolution of the University of Wisconsin (UW) superconducting magnetic energy storage (SMES) designs for electric utility use is traced from 1970 to the present. The UW-SMES design principles were used in the 1987-90 ETM competition by the EBASCO team of subcontractors (UW, Westinghouse, CBI, and Teledyne). Some recent post-ETM design improvements are discussed. The Wisconsin emphasis on 1.8 K pool cooling, cryogenic stability, and ripple design is stressed.         The SSD: a commercial application of magnetic energy storage    W.E. Buckles, M.A. Daugherty, B.R. Weber and E.L. Kostecki Summary: A magnetic energy storage system, SSD, has been developed to provide power to industrial electric loads subjected to short-term voltage disturbances. An overview of the SSD system as presently installed at customer sites, including magnet, cryostat, refrigeration, and power conditioning equipment, is provided. Electric power interruptions are unpredictable in time but are typically of short duration. The SSD system provides rapid response backup power by means of a superconducting magnet connected to the load through a current-to-voltage converter and a DC-to-AC inverter. Power flows from the magnet to the load when the line voltage drops below a preset value. The magnet was designed with terminal characteristics matched to the inverter DC voltage, connected load, and required carryover time. Cryogen inventory is maintained through use of a Collins cycle liquefier. All system components were designed for long-term unattended operation and can be mounted in a semitrailer. Remote monitoring provides information on system performance and status.         SMES conductor selection: an engineering perspective    C.A. Luongo, R.J. Loyd and S.D. Peck Summary: The authors discuss the engineering considerations driving the selection of a conductor concept for large-scale SMES (superconducting magnetic energy storage). There are five areas that require special attention: current diffusion effects, stability margin, AC losses, cooldown stress sustained by the conductor, and helium containment. From a magnet design perspective, there is a strong premium in SMES on utilizing conductors with as high a current as possible. It is difficult to scale up a particular monolithic design to achieve higher current. Overall magnet design issues are also more difficult to tackle with monolithic conductors. It is concluded that cable-in-conduit conductors are more attractive for large-scale SMES.         Investigating thermal hydraulic quenchback in a cable-in-conduit superconductor    J.W. Lue, L. Dresner, S.W. Schwenterly, C.T. Wilson and M.S. Lubell Summary: Quench propagation of a cable-in-conduit force-cooled superconductor plays a very important role in the protection of a magnet built with such a conductor as in a superconducting magnetic energy storage (SMES) system. Some thermal analysis showed that the compressional and frictional heating exerted by the expanding hot helium could heat the helium away from the normal zone above the superconductor current sharing temperature. Thus, an acceleration of the quench propagation could be realized. This phenomenon is called thermal hydraulic quenchback (THQ). A setup was built specifically to investigate this phenomenon. The test sample consists of a 50 m long NbTi superconducting cable enclosed in a stainless steel conduit. Heaters 0.2 to 8 m long are provided to quench the conductor. The authors report experimental finding of THQ and its dependence on the initial normal zone length, the conductor current, the magnetic field, and the coolant temperature.         US perspective on the ITER magnetics R and D program    D.B. Montgomery and R.J. Thome Summary: The overriding issue for ITER magnetic systems is the very high reliability requirement, coupled with significant scale-up in size from present experience. An international R&D program is being planned for the next six years, to prepare for a decision to construct the device. The conductors will use an internally cooled cabled approach, using A-15 conductors in the toroidal field coils, and in major portions, if not all, of the poloidal field coil system. It is planned to support two approaches to Nb/sub 3/Sn production, and to give parallel consideration to NbAl and other advanced strands. Several approaches to conductor jackets will be considered, both circular and rectangular, with alternative methods of fabrication and alternative materials. The selected conductors will be incorporated into significant scale model coils and tested in one or more common test facilities. Development of connectors, leads, and quench protection systems will be important parallel activities.         The configuration development of the superconducting magnets for the SSAT-S tokamak device    T.G. Brown, D.D. Lang, J. Mueller and J. Schultz Summary: The Steady State Advanced Tokamak (SSAT) device will be developed to demonstrate steady-state tokamak operations and optimize plasma conditions in a steady-state environment. The authors describe the configurational development of the SSAT device to meet the physics objectives and subsystem design requirements. Superconducting toroidal field (TF) and poloidal field (PF) coils are planned, as they are well suited for the long-pulse, high-duty-factor operation of the SSAT mission. A two-coil TF module forms the basis of the tokamak core. PF coils, consisting of a solenoid and six ring-coils, surround the TF coils. The physics requirement of low field ripple and sufficient plasma access for tangential neutral beams influenced the configuration in determining the size and number of TF coils. Further configuration influences included low activation considerations, divertor pumping, service line access, requirements for remote maintenance, and compatibility with the existing TFTR test cell facility.         Test result of full size 40 kA NET/ITER conductor in the FENIX test facility    P. Bruzzone, N. Mitchell, H. Katheder, E. Salpietro, M.R. Chaplin, S.S. Shen, D.S. Slack, J. Rauch, W. Brehm, S. Ceresara, M. Ricci and A. Bonito Oliva Summary: Three Nb/sub 3/Sn cable-in-conduit prototype conductors have been manufactured in the framework of the European conductor development program for NET. They have been tested in the FENIX test facility at the Lawrence Livermore National Laboratory, beyond their operating conditions, with current up to 40 kA, magnetic field up to 13.5 T, and supercritical helium up to 8 K. The testing procedure is described and the test results are discussed. The main objective of the test was the measurement of temperature margin under DC operation and the hydraulic pressure drop.         First performance test of the 12 T split coil test facility SULTAN III    B. Blau, E. Aebli, B. Jakob, G. Pasztor, I. Rohleder, D. Trajkovic, G. Vecsey, M. Vogel, A. Della Corte, G. Pasotti, M. Ricci, N. Sacchetti, M. Spadoni and E.P. Balsamo Summary: The test facility SULTAN III at PSI is primarily devoted to qualification of full-size conductors developed for the next generation of fusion experimental devices. Very recently, the facility generating magnetic fields in excess of 11 T was completed and successfully tested. The split coil arrangement with a radial access of 94 mm*144 mm is ready to perform tests of superconductors carrying currents up to 50 kA at temperatures between 4.5 K and 7 K. First results on a fusion dedicated prototype conductor are presented. The main features of the SULTAN III facility are summarized.         Present status of design and manufacture of the superconducting magnets for the Large Helical Device    T. Satow, J. Yamamoto, K. Takahata, S. Imagawa, H. Tamura, N. Yanagi, T. Mito, A. Nishimura, S. Satoh, K. Yamazaki, H. Kaneko, H. Yonezu, H. Hayashi, M. Takeo and O. Motojima Summary: The Large Helical Device (LHD) is a nuclear fusion experimental device with superconducting magnets. Manufacture of the cryostat, the inner vertical coils, and the helical-coil winding machine are now being carried out. Designs for constructing two helical coils and two other pairs of poloidal coils are in progress. The outside diameter of the torus-shaped cryostat is 13.5 m. There are two operational stages for the LHD. Phase I and Phase II. The helical coils will have a magnetic energy of 1.6 GJ and an overall current density of 53 A/mm/sup 2/ in Phase II. The rated current is 13.0 kA in Phase I, and the maximum magnetic field in the helical coil winding in Phase I was calculated to be 6.9 T. Three pairs of poloidal coils are cooled by forced-flow supercritical helium because of the necessity of having no metal coil vessel. The rated current of one inner vertical (IV) poloidal coil is 20.8 kA, and its stored energy is 80 MJ. The maximum magnetic field of the two IV coils was calculated to be 5.8 T. The type of superconductor for the IV coils is a cable-in-conduit conductor.         Recent progress of development of 70 MW class superconducting generators    N. Higuchi, H. Fukuda, T. Ogawa, Y. Nakabayashi, Y. Kobayashi, M. Ogihara, H. Sawazaki, Y. Yagi, A. Ueda and T. Kitajima Summary: The authors describe the R&D program and recent results for the 70 MW-class superconducting generator called the model machine in the Super-GM project based on an eight-year program started in FY 1988. Super-GM (Engineering Research Association for Superconductive Generation Equipment and Materials) has been researching and developing three kinds of 70 MW-class model machines. The R&D objectives are to research basic elemental techniques for components of superconducting generators and to conduct technical development by using various partial models for the rotor and stator in the first half of the eight-year period, and then to develop 70 MW-class model machines in the latter half of that period. In FY 1991, the design methods and manufacturing techniques for the 70 MW-class model machines were successfully verified.         Design and fabrication of high temperature superconducting field coils for a demonstration DC motor    C.H. Joshi and R.F. Schiferl Summary: The design, fabrication, and characterization of field coils for a DC motor operating at 77 K are described. The DC motor uses an iron core to impress the field from the stationary superconducting coils onto a conventional armature which is nominally at room temperature. The motor has a total mechanical power output of 25 W. The coils were fabricated from BSCCO ceramic superconductor using a react and wind process. Each coil was extensively characterized both in terms of the motor configuration and individually. The tests indicated that robust superconducting coils can be produced by using ceramic superconductors. The durability of these coils as illustrated by the testing of the motor showed that high-temperature superconductors have reached a level of performance to be considered for demonstration motors.         Stability characteristics of fully superconducting and damperless generator connected to power grid    O. Tsukamoto, J. Chen and S. Akita Summary: The damperless fully superconducting generator can more efficiently use the magnetic flux produced by the field windings and be more compact and have a rotor of simpler structure than a partially superconducting generator, because both the field and armature windings can be placed in the same cryogenic region and the gap between the windings can be minimized. However, a damperless machine causes a dynamic instability problem when interconnected to an electric power system, and a device to stabilize the system is required. The authors propose a method to stabilize the operation of the generator by controlling the excitation voltage of the field winding. Details of the method are explained. Its effectiveness is shown by numerical simulation.         Superconducting permanent magnet motor design and first tests    P. Tixador, C. Berriaud and Y. Brunet Summary: A permanent magnet motor with a superconducting armature has the high current densities of superconductors and the simplicity of a cooled rotating permanent magnet inductor to benefit from the better magnetic properties of rare earth magnets when the temperature decreases. A small-scale model has been developed to prove the experimental feasibility and to study its behavior. The layout of this eight-pole, 750-rpm, 15-kW machine is conventional with a horizontal axis and a rotating inductor. The three-phase winding was made with (6+1) cable of 0.25-mm-diameter strands comprising 597102 NbTi filaments. This model required a fiber glass composite helium cryostat. The helium enthalpy recovery from the helium vessel cools the NdFeB magnets. The cantilevered rotating part inside the armature facilitates the cooling. The machine has been assembled. The main cryogenic and first electrical tests are reported. The experimental demonstration of a superconducting permanent magnet motor has been proved with satisfactory operation.         Field winding model test of 70 MW class superconducting generator    K. Yamaguchi, Y. Yagi, R. Shiobara, S. Ohashi, H. Sato, K. Nakanishi, K. Tanaka, M. Ohi, Y. Matsunobu, H. Tomeoku, N. Maki and M. Ogihara Summary: A national project for development of a superconducting generator has been continuing since 1988 in Japan. In this project, the authors have been developing a superconducting field winding. An aluminium stabilized double standard superconducting cable has been developed for the winding. In the rotor, the centrifugal force field is 5000 G, and consequently liquid helium has a cooling ability ten times larger than that in the 1-G gravitational field. Therefore, a cryostable winding design can be used. A field winding model having 40% of the 70-MW-class generator field winding was tested in a nonrotated cryostat. The specification and structure of the cable and the test results are outlined.         Application of high temperature superconductors on levitation bearings, torque transmissions and vibration dampers    K.B. Ma, C.K. McMichael, M.A. Lamb and W.K. Chu Summary: The transfer of momentum between a permanent magnet and a type II superconductor without mutual physical contact is the central theme behind many mechanical applications of the new class of high-temperature ceramic superconductors. The properties of this momentum transfer and its applications were studied in a series of experiments as a proof of principle. The authors discuss the application of the force between permanent magnets and high-temperature superconductors (HTSs) in three different mechanical devices-a torque coupler, a magnetic bearing, and a vibration damper-based on the following two broad features of this forces. (1) A restoring force is generated by a piece of HTS material to oppose the motion of a magnet if and only if the magnet moves in such a way as to produce a change in the magnetic field in the space occupied by HTS material. (2) Back and forth cyclic motion of a magnet relative to a piece of HTS in the vicinity experiences hysteretic forces with loss of mechanical energy as a result. All the studies refer to melt-textured HTS material.         Performance measurements of superconducting current leads with low helium boil-off rates    R.C. Niemann, Y.S. Cha and J.R. Hull Summary: A performance-measurement facility for current leads has been developed as a part of Argonne National Laboratory's program to develop applications for high-temperature superconductors. The facility measures the rate of helium vapor boil-off due to current-lead heat input to liquid helium and the pressure drop across a current lead for a pair of leads operating at currents up to 100 A. The facility's major components are a liquid-helium dewar with low background-heat input; a dewar insert that incorporates the current leads and associated instrumentation or connections for flow, pressure, level, temperature, and voltage measurements; and a computer-driven data-acquisition system. Background heat input is low enough so that boil-off rates one-tenth that of an optimized conventional lead can be characterized. The facility has been operated with conventional leads, and with leads incorporating high-temperature superconductors at their cold ends. Details of the facility design, construction, and operating experience are presented.         Testing of high temperature superconductors for cryogenic current lead applications    J.L. Wu Summary: As part of a developmental effort to bring the technology of high-temperature superconducting current lead to practical applications, device-size high-temperature superconductor (HTSC) samples supplied by various vendor sources were tested. The tests include measurements of DC transport critical current I/sub c/, current density (J/sub c/), and electrical joint resistance (R/sub c/) under externally applied magnetic field in a LN/sub 2/ bath, as well as the effects of thermal cycling on these parameters for one selected sample. Dependence of R/sub c/ on temperature was also evaluated. Based on these tests, a set of HTSC bars was ordered and used in a prototype multiple lead assembly. This lead assembly demonstrated experimentally a two to one reduction in heat leak. The work related to the testing of the HTSC samples is addressed.         Design and testing of a pair of current leads using bismuth compound superconductor    K. Ueda, T. Bohno, K. Takita, K. Mukae, T. Uede, I. Itoh, M. Mimura, N. Uno and T. Tanaka Summary: The thermal behavior of current leads using an oxide superconductor for the low-temperature portion has been studied. Numerical calculations predict a reduction of the necessary coolant flow rate and refrigerator input power. A pair of current leads has been manufactured where the low-temperature portion consists of six sintered Bi compound cylindrical bars and the high-temperature portion consists of a Cu wire bundle. The lead, cooled by gaseous helium along its entire length, is 0.9 m long and designed to carry 1 kA. The leads have been tested in the same arrangement as practical applications. The helium flow rate necessary to hold thermal equilibrium was about 80% of that for conventional copper leads. The calculation shows that power consumption of the refrigerator needed to cool high-temperature superconductor current leads with an optimum cooling scheme will be about one-third of that for conventional current leads.         Magnetic coupling by using levitation characteristics of YBCO superconductors    H. Ishigaki, H. Ito, M. Itoh, A. Hida and R. Takahata Summary: A mechanical system which uses high lateral restoring forces of high-T/sub c/ materials as the driving force for a magnetic coupling is proposed. As the basic study of the superconducting magnetic coupling, the relationship between the lateral restoring force and levitation force, transmitted torque characteristics as a function of a twisting angle and clearance, and damping characteristics of the coupling were examined. Superiorities of the coupling such as high damping coefficients and high stability against time and twisting angle were revealed. A magnetic force sensor system was used to evaluate the superconducting characteristics of materials, and nonuniform distribution of repulsive force was observed for the YBCO pellet fabricated by the melt-powder-melt-growth process. The improvement of the homogeneity was achieved by compensating for the composition rate which had changed during the quenching process.         Thermal optimum analyses and mechanical design of 10-kA, vapor-cooled power leads for SSC superconducting magnet tests at MTL    Q.S. Shu, J. Demko, R. Dorman, D. Finan, D. Hatfield, I. Syromyatnikov, A. Zolotov, P. Mazur and T. Peterson Summary: Spiral-fan, 10-kA, helium vapor-cooled power leads have been designed for Superconducting Super Collider superconducting magnet tests at the Magnet Test Laboratory. To thermally optimize the parameters of the power leads, the lead diameters, which minimize the Carnot work for several different lengths, two different fin geometries, and two RRR values of the lead materials were determined. The cryogenic refrigeration and liquefaction loads for supporting the leads have also been calculated. The optimum operational condition with different currents is discussed. An improved mechanical design of the 10-kA power leads was undertaken, with careful consideration of the cryogenic and mechanical performance. In the design, a new thermal barrier device to reduce heat conduction from the vacuum and gas seal area was used. Therefore, the electric insulation assembly, which isolates the ground potential parts of the lead from the high-power parts, was moved into a warm region to prevent vacuum and helium leakage in the O-ring seals due to transient cold temperature. The instrumentation for testing the power leads is also discussed.         Inductance characteristics of pipe-type oxide superconductor for various configurations    K. Nakamura, Y. Abe, E. Inukai and M. Sone Summary: The authors present the magnetic inteeeons of pipe-type superconductors which may be used as the current lead in the cryogenically cooled power cable and magnet. Bi-system superconductors were successfully fabricated by a glass-ceramic process. Inductance characteristics for a simple configuration of a single bar-type superconductor are discussed. The inductance was evaluated from the measurements of reactive voltage and alternating current. The magnetic interactions for coaxial and parallel configurations of the pipe-type superconductor are considered.         Electromagnetic force and eddy current loss in dynamic behavior of a superconducting magnetically levitated vehicle    T. Saitoh, N. Maki, T. Kobayashi, M. Shibata and T. Takizawa Summary: A magnetically levitated vehicle is being designed to travel between Tokyo and Osaka in about 1 h at a 500-km/h speed. When the car runs at a high speed, it moves laterally and vertically from its balanced position at low frequencies. The authors present calculations of electromagnetic forces and eddy currents generated in the onboard cryostat containing the superconducting magnet as a result of these motions. They show that the electromagnetic forces, eddy current losses and damping constants of the motion, especially for the lateral and vertical motions, depend on the materials of the radiation shield and the inner vessel in the magnet and change with the frequencies of car motion. The magnitudes of forces, losses, and damping constants in lateral motion are compared with those in vertical motion. To evaluate these quantities, numerical calculations were performed with a two-dimensional finite-element method.         MPZ stability under time-dependent, spatially varying heat loads    E.A. Scholle and J. Schwartz Summary: Although the on-board superconducting magnets (SCMs) are a relatively small fraction of the cost and weight of magnetic levitation systems their performance is critical to the success of the entire system. The velocity of the MLU 002 vehicle in Japan had been limited by quenching of the SCMs due to track induced vibrations at high speed. Superconductor stability is discussed assuming time-dependent spatially varying heat loads. The one-dimensional minimum-propagating zone (MPZ) model has been extended to include time-dependent disturbances. The MPZ has been determined as a function of the disturbance frequency, amplitude, and length. The spatial variation of the initial disturbance is modeled as a sinusoidal function. Results for the MLU 002 and cable-in-conduit conductors are compared.         General expressions of propulsion force in EDS-MAGLEY transport systems with superconducting coils    F. Albicini, M. Andriollo, G. Martinelli and A. Morini Summary: The propulsion force produced by air-cored long-stator linear synchronous motors with superconducting coils propelling magnetically levitated vehicles with electrodynamic suspension (EDS-MAGLEV) is determined by means of an analytical three-dimensional method which takes into account different coil arrangements and the harmonic spectrum of the armature currents. The resulting analytical expressions take into account the actual coil thicknesses as well as the approximation of filiform coils and armature coils arranged both in a single layer and in two overlapped layers. The expressions have been utilized to calculate the propulsion force acting on an EDS-MAGLEV vehicle.         Analysis of superconducting magnet (SCM)-ground coil interactions for EDS Maglev coil configurations    E.E. Burkhardt, J. Schwartz and S. Nakamae Summary: The performance of electrodynamic magnetic levitation systems is dominated primarily by the electromagnetic interactions between the onboard superconducting magnets (SCMs) and the normal levitation and propulsion coils situated on the guideway. Alternative designs are examined for coil configurations in terms of the resulting SCM-ground coil interactions. In particular, the modified null flux configuration and the ladder-on-box-beam approach are compared. Magnetic drag, levitation, and guidance forces are considered on an absolute and per (kg/m) of ground coil basis.         Design of a superconducting magnet system for Maglev applications    B. Gamble, D. Cope and E. Leung Summary: The superconducting magnet system for magnetic levitation (Maglev) transportation system has been analyzed as part of a DOT system concept definition study. The magnet design requirements are developed based on a locally commutated linear synchronous motor propulsion system and sidewall null-flux levitation. The characteristics of this electromagnetic system were used to develop the superconducting magnet system requirements which would lead to an optimal overall system. A preliminary design based on these requirements is summarized and recommendations for future work are discussed. Significant results of the study are that the required magnet system technology is available today and can be utilized to develop a Maglev transportation system between major population centers operating at speeds in excess of 135 m/s.         Application of superconducting cable-in-conduit conductors to coil systems for Maglev vehicles    R.J. Thome, D.B. Montgomery, J.V. Minervini, J.R. Hale and M. Ferri Summary: Significant system advantages result if the superconducting levitation and propulsion coils can be operated at temperatures higher than 4.2 K, which can be achieved with cable-in-conduit conductors (CICCs) using Nb/sub 3/Sn and supercritical helium as the working fluid. The authors compare the relative advantages of NbTi and Nb/sub 3/Sn for this application. They also discuss the system aspects surrounding the selection of operating temperature, current density and number of modules. The features of a suitable CICC Nb/sub 3/Sn conductor which has been manufactured are described.         A cryogen-free superconducting magnet design for Maglev vehicle applications    M.E. Vermilyea and C. Minas Summary: A novel refrigerated superconducting magnet design for application to magnetic levitation vehicles for US transportation is presented. The magnet requires no liquid cryogens and offers improved size, weight, and reliability relative to conventional liquid helium pool cooled magnets. Niobium tin superconductor allows the magnet to be operated at a nominal temperature of 8 K, which is attainable at design heat loads with a conventional Gifford-McMahon cryogenic refrigerator. The magnet and the single thermal radiation shield are cooled by conduction from the two stations of the refrigerator. Higher temperature operation minimizes the likelihood of a magnet quench by virtue of the relatively high material heat capacity. The electromagnetic structural, and thermal design of the magnet and cryostat are presented.         AC loss time constant measurements on Nb/sub 3/Al multifilamentary superconductors    T.A. Painter, Y. Iwasa, T. Ando, H. Tsuji and S. Shimamoto Summary: AC loss time constants have been measured by an inductive method developed at the Japan Atomic Energy Research Institute. Measurements were performed on four multifilamentary Nb/sub 3/Al test wires, manufactured by the jelly-roll method and one multifilamentary NbTi test wire. The theoretical AC loss time constants were calculated and compared with the measured values. The time constants of the Nb/sub 3/Al wires were found to vary as the square of the twist pitch as predicted. The Nb/sub 3/Al wires have time constants that are higher than the lower limit predicted by theory, suggesting that the contact resistance between the copper matrix and superconducting filaments is lower than that in the NbTi wire.         Comparison of AC losses of superconducting wires for ramped-field applications    C.Y. Gung, M. Takayasu, J.V. Minervini, M.A. Ferri and M.M. Steeves Summary: A local maximum at a slow field variation was measured in the AC-loss profile vs. field ramping rate in a double-stacked wire, which is not predicted by the existing AC-loss models. The AC losses of three important superconducting wires, manufactured mainly for superconducting magnets running at large amplitudes and slowly ramping fields, have been measured. These three single-strand samples, including a NbTi, an internal-tin, and a modified jelly-roll internal-tin wire, have different cross sectional constructions. A model taking into account the saturation of the filament bundle walls caused by strong local interbundle coupling currents in the inner multifilament region is proposed to provide a possible explanation to this special loss dependency.         Measurements of ramp-rate limitation of cable-in-conduit conductors    M. Takayasu, M.A. Ferri, C.Y. Gung, T.A. Painter, M.M. Steeves and J.V. Minervini Summary: The ramp-rate limitation found in the US-demonstration poloidal coil (US-DPC) test was studied in a laboratory scale experiment. The ramp-rate sensitivity has been identified on a 27-strand cable-in-conduit conductor at a background ramped field to 9.5 T with various ramp rates of 0.5 T/s to 2 T/s, simulating the US-DPC test conditions. A model assuming the existence of periodic disturbances is proposed in which the disturbance frequency is directly proportional to the ramp rate of the square of field. A semi-empirical formula was developed which fits the ramp-rate limitation data of both the US-DPC large coil and the 27-strand cable. The ramp-rate limitation does not occur for currents below the conventional limiting current.         Calculation of magnetization, hysteresis and power dissipation in a superconductor during bipolar field cycles    L. Bottura and J.V. Minervini Summary: A method for the calculation of the hysteresis loss in a superconducting slab for large, bipolar changes of the applied magnetic field is presented. The method is purely analytical and uses the Kim model for the critical current density J/sub c/. Arbitrary change in the external magnetic field can be handled, before or after full penetration. Magnetization, dissipated power and energy are computed as a function of time, independent of the presence of closed loops in the magnetic field change. Scaling relations are given to extend the results to the hysteresis loss in a superconducting cylinder in a changing transverse field. An example of an application shows excellent agreement between measured and computed dissipated energy.         Status report on a 0.6 m bore Nb/sub 3/Sn, wind and react, CICC solenoid    A. Bonito-Oliva, A. Della Corte, S. Parodi, G. Pasotti, S. Patrone, R. Penco, R. Renzetti and N. Valle Summary: Ansaldo and ENEA have carried out the design of a Nb/sub 3/Sn solenoid, 0.6-m bore, wound with a cable-in-conduit conductor (CICC) and manufactured with the wind react technique. A general overview of the work done is presented. The solenoid will be tested in the SULTAN facility where, under operating conditions, it will be subjected to a magnetic field of 12 T on the inner radius, with a current of 6 kA. An accurate description, including the critical energy calculation, the quench behavior, and the stress analysis, is reported. A verification analysis of the final design has been carried out. In particular, the authors analyzed the problem of the quench evolution in the coil and the mechanical behavior of the winding. The final design has been checked by manufacturing a model coil. The model coil has been successfully tested.         Development and tests of electrical joints and terminations for CICC Nb/sub 3/Sn 12 Tesla solenoid    A. Bonito Oliva, P. Fabbricatore, A. Martini, R. Musenich, S. Patrone, R. Penco and N. Valle Summary: Ansaldo Componenti, under a contract with ENEA, has developed the interlayer electrical points and coil terminations for a 12-T solenoid, 0.6-m bore, Nb/sub 3/Sn, wound with the wind and react technique with a cable-in-conduit (CIC) conductor. Both the interlayer joints and terminations under the coil's operating conditions, will be subjected to a magnetic field of about 8-10 T with a 6-kA current. Tests on shorter length interlayer joints and terminations, at different magnetic fields and currents, were carried out. The resistance of a 140-mm-long interlayer joint at magnetic field B=8 T and I=6 kA was 2.4*10-9 Omega . The measured resistance for a joint between two terminations, under the same conditions, was 1.5*10-8 Omega.         Coupling time constants for modified jelly roll Nb/sub 3/Sn wires    J.C. McKinnell, M.B. Siddall and D.B. Smathers Summary: Measurement of the coupling time constant allows an estimate of the coupling loss in AC applications. The authors report the coupling time constants of modified jelly-roll niobium-tin (Nb/sub 3/Sn) wires which were measured using a modified version of the technique described by T. Ando et al. (1985, 1988). The coupling time constant is reported for over 200 km of wire at zero applied field. If the pulse field was large enough, two characteristic time constants were observed at zero field. The longer of the two time constants was not observed when a DC magnetic field of >or=0.1 T was applied to the sample. The field behavior of the coupling time constant from 0 to 6 T is also reported.         Losses in cable-in-conduit superconductors used for the poloidal coil system of the large helical device    F. Sumiyoshi, S. Kawabata, Y. Kanai, T. Kawashima, T. Mito, K. Takahata and J. Yamamoto Summary: The authors discuss the loss features of the NbTi cable-in-conduit (CIC) superconductor for the Large Helical Device (LHD) poloidal coil system. Eight conductors were prepared. The conductors differ in the matrix or in the surface condition of the strands. The interstrand coupling losses tend to increase during the pulsive operation of the poloidal coil. Short and straight samples of about 500 mm in length were provided for this experiment since bending may change the interstrand contact condition. The authors measured the loss-frequency characteristics of the short sample conductors with various types of strands to clarify their loss properties. The measurement was carried out in the transverse AC ripple field superposed on bias fields, in the frequency range from 0.1 Hz to 200 Hz. The measurements showed that the replacement of the CuNi matrix strands in the conductor by the Cu-matrix strands did not increase the intrinsic coupling loss significantly, but that noninsulation of the strands caused considerably higher interstrand coupling losses.         Charging test results of the DPC-TJ, a high-current-density large superconducting coil for fusion machines    M. Ono, Y. Wachi, M. Shimada, Y. Sanada, H. Mukai, T. Hamajima, T. Fujioka, M. Nishi, H. Tsuji, T. Ando, T. Hiyama, Y. Takahashi, K. Yoshida, K. Okuno, T. Kato, H. Nakajima, K. Kawano, T. Isono, M. Sugimoto, N. Koizumi, K. Koizumi, E. Tada, F. Hosono, S. Iwamoto, T. Sasaki, H. Hiue, H. Ishida, A. Miyake, Y. Kamiyauchi, H. Ebisu, J.R. Armstrong, M. Oshikiri, H. Hanawa, H. Ohuchi, F. Tajiri, M. Seki, T. Ohuchi, J. Okayama, Y. Takaya, Y. Kon and S. Shimamoto Summary: The authors describe the electromagnetic results and the quench phenomena of the DPC-TJ large cable-in-conduit Nb/sub 3/Sn coil experiment which took place in the summer of 1991. The DPC-TJ coil was developed by Toshiba and JAERI in collaboration to demonstrate the realization of (NbTi)/sub 3/Sn superconducting coils for fusion with high average current density of 40 A/mm/sup 2/. The coil was charged up to its rated current of 24 kA (40 A/mm/sup 2/) at 7.6 T without quench in the DPC test facility. Thereafter, the electromagnetic performance was tested by measuring I/sub c/ and T/sub cs/, and the critical current at 12 T was estimated to be 41 kA. The quench phenomena of the DPC-TJ coil were also tested by measuring normal-zone propagation velocity to get the protection design. In these experiments, very slow and very fast propagation were observed. Many other electromagnetic results were also obtained, which are necessary for the design of fusion machines such as International Thermonuclear Experimental Reactor.         Study on fluctuations in supporting force of conductors caused by fluctuations in conductor dimensions    T. Takao, O. Tsukamoto, N. Amemiya, A. Nishimura, T. Mito, H. Tamura, J. Yamamoto and O. Motojima Summary: The authors are investigating fluctuations of contact force between a conductor and a spacer, and the possibility of local conductor motion in the helical coils of the Large Helical Device (LHD) which will be installed in National Institute for Fusion Science (NIFS). They performed an experiment to study the rigidity of the helical coils and fluctuations in the contact force caused by the irregularity of conductor bends and spacer dimensions by making a model coil pack. A theory is proposed to statistically estimate the fluctuations in the contact force. The theory is explained and the experimental results are shown and compared with the theory. The theory agrees well with the experimental results.         The effect of Ti conduit on the critical current in (NbTi)/sub 3/ Sn cable-in-conduit conductors    T. Ando, H. Nakajima, H. Hiue and Y. Wadayama Summary: The authors investigated the effect of Ti conduit on the critical current in (NbTi)/sub 3/Sn cable-in-conduit conductors in comparison with stainless steel and copper-nickel alloy conduits. Ti has a coefficient of thermal expansion closely matching (NbTi)/sub 3/Sn and is expected to prevent the compressive thermal prestrain introduced in (NbTi)/sub 3/Sn filaments. As samples, two kinds of conductors were prepared, one consisting of seven (NbTi)/sub 3/Sn strands and the other of 36 (NbTi)/sub 3/Sn strands. The (NbTi)/sub 3/Sn strands produced by a bronze process had a diameter of 1.0 mm and a copper ratio of 2. The experimental results indicated that the critical current density in conductors with a Ti conduit and void fraction in the range of 5-46% nearly matched that of a single strand. From these results, Ti appears to be attractive as a practical conduit material for (NbTi)/sub 3/Sn cable-in-conduit conductors.         Development of Nb/sub 3/Al cable-in-conduit fusion superconductors    T. Ando, Y. Takahashi, M. Sugimoto, M. Nishi, H. Tsuji, Y. Yamada and M. Nagata Summary: The present status of Nb/sub 3/Al cable-in-conduit conductor development is described. Nb/sub 3/Al cable-in-conduit conductors have been developed for application to the International Thermonuclear Experimental Reactor (ITER) magnet. Several conductors were fabricated having a full size and a sub-size with current capacity of 5-40 kA at 11.2 T. Their performance was examined by critical current and mechanical property tests. The full-size 40 kA-11.2 T conductor consisted of 324 Nb/sub 3/Al strands inserted in a CuNi conduit. The Nb/sub 3/Al strands were made by the Jelly Roll process and had a diameter of 1.22 mm and a copper ratio of 2. The non-copper current density was over 600 A/mm/sup 2/ at 11.2 T and 4.2 K. The effective filament diameter was less than 20 mu m.         Development of a (NbTi)/sub 3/Sn strand for the ITER CS scalable model coil    T. Isono, F. Hosono, N. Koizumi, M. Sugimoto, H. Hanawa, Y. Wadayama, H. Tsukamoto, T. Sasaki, M. Nishi, K. Yoshida, T. Ando and H. Tsuji Summary: As the first step in development of the center solenoid (CS) scalable model coil for the International The monuclear Experimental Reactor (ITER), development of a (NbTi)/sub 3/Sn strand with characteristics of high current density and low AC loss was started by the Japan Atomic Energy Research Institute (JAERI). One of the targets of strand development was set at the point where current density (J/sub c/) was more than 800 A/mm/sup 2/ at 12 T and effective filament diameter (d/sub eff/) was less than 10 mu m. The other target decided by JAERI was the point of more than 600 A/mm/sup 2/ for J/sub c/ and less than 3- mu m d/sub eff/, because it is possible to design the coil by using this strand performance. The 0.92-mm-diameter (NbTi)/sub 3/Sn strands were fabricated by a bronze process, a Nb tube process, and an internal tin diffusion method to attain one of two targets. Strand performance of about 800-A/mm/sup 2/ J/sub c/ at 12 T and about 5- mu m d/sub eff/ was obtained. The results from critical current measurements and effective filament diameter measurements are presented.         Characterization of flow in sub-scale cable-in-conduit conductors    M.A. Daugherty, R. Maekawa and S.W. Van Sciver Summary: The authors measured the pressure drop of supercritical helium and He II counterflow heat transport in subscale cable-in-conduit conductors (CICCs) at a variety of different temperatures. These measurements were made on various conductors with different flow areas, void fractions, and strand diameters. Classical friction factor analysis was used to correlate the pressure drop results. The results of this analysis revealed systematic variations in the friction factor which appear to be dependent on the temperature of the helium. In a separate experiment heat transport in He II contained in the CICCs was analyzed in terms of the Gorter-Mellink relationship to obtain an independent determination of the flow cross-sectional area. These cross-sectional areas were used to reanalyze previously reported pressure drop data on the same conductors. Use of He II counterflow measurements as a general method to characterize the hydraulics of these conductors is discussed.         Instability of NbTi/CuNi superconducting wires    M. Tsuda, H. Takamatsu and A. Ishiyama Summary: The quench current degradation in multifilamentary NbTi superconducting wires with a CuNi matrix have been measured and analyzed by the finite-element method. The authors measured the degradation of the quench current as a function of the current sweep rate in the range of 10 A/s to 100 kA/s, and the initial current, which was a transport current just before current changing. Experimental data are compared with analytical results taking the magnetic and the thermal diffusion in the radial direction of wire cross-section into account. From these comparisons, the relation between the rate of current changing and the degradation of the quench current in superconducting wires is discussed.         Stability of a length of cable-in-conduit conductor submitted to a rapidly changing field    D. Ciazynski, A. Martinez and B. Turck Summary: The authors present a stability experiment on a NbTi triplet in conduit conductor, 10 m long. This cable was cooled with helium forced flow. An inductive heating system allows deposition of large heat quantities over the whole length of the conductor. In one experiment, the AC losses of the conductor were calibrated by measuring the dissipated energy in a superfluid helium bath, for different magnetic field variations and pulse durations. In another experiment, with supercritical helium, the minimum energy needed to quench the conductor in relation to the transport current, for a given external magnetic field and given refrigeration conditions, will be studied. The results of the first experiment are given, and the second experiment is described.         Stability of cable-in-conduit superconductors for Large Helical Device    K. Takahata, T. Mito, T. Satow, N. Yanagi, M. Sakamoto, S. Yamada, A. Nishimura, J. Yamamoto, O. Motojima, S. Mizumaki, K. Nakamoto, T. Uchida, Y. Wachi, M. Shimada, S. Itoh and S. Ioka Summary: The stability of cable-in-conduit superconductors has been experimentally investigated as part of a poloidal field coil program for the Large Helical Device (LHD) project. A new conductor was designed and fabricated, focusing on the stability. As a result of a zero-dimensional stability analysis, it was found that the conductor had a high stability, 5*10/sup 5/ J/m/sup 3/, at the design condition of 20.8 kA and 6.5 T. Current transfer performance after partial quenching has been investigated by using a short sample of the conductor for the poloidal field coil. The effects of the current transfer among the strands on the conductor stability are discussed.         The cable-in-conduit Nb/sub 3/Sn conductor for the EURATOM-ENEA 12 T wind-and-react magnet    R. Bruzzese, S. Ceresara, S. Chiarelli, A. Della Corte, P. Gislon, T. Pietrobon, S. Rossi and M. Spadoni Summary: A 12-T wind-and-react magnet using a 6-kA Nb/sub 3/Sn cable is being contributed by ENEA within the framework of R&D in the European Fusion Program. The authors present results on the strand, jacket, and manufacturing of the cable-in-conduit (CIC) conductor. Data on critical current, AC losses, and RRR on the Nb/sub 3/Sn strand are reported, as well as the mechanical properties at 300 K and 77 K of the modified 316LN jacket before and after heat treatment. The approach used at Europa Metalli-LMI for cabling, compaction, and insertion of the superconducting cable into the circular tube and the method used to reach the final square cross section with the desired void fraction are illustrated and discussed.         Numerical analysis of stability and quench characteristics of superconductors for the LHD coils    T. Fujiwara, T. Ohnishi, T. Mito, M. Matsukawa, K. Noto, K. Sugita and J. Yamamoto Summary: A numerical analysis has been performed on the stability and quench characteristics of superconductors for helical coils of the Large Helical Device. Two types of conductors are dealt with, both of which consist of a NbTi/Cu superconducting cable stabilized by pure aluminium. The analysis is based on a two-dimensional model and the heat conduction equation was solved numerically. The distributions of temperature and current density are clarified for the cases of recovery and quench. The minimum input energies required to initiate a quench are calculated and compared with the experimental values.         Stability performance of the DPC-TJ Nb/sub 3/Sn cable-in-conduit large superconducting coil    T. Sasaki, N. Koizumi, M. Nishi, K. Okuno, K. Yoshida, H. Tsuji, H. Mukai, Y. Wachi, T. Hamajima, S. Nakayama and T. Fujioka Summary: The DPC-TJ test coil was developed in the collaboration between the Japan Atomic Energy Research Institute (JAERI) and Toshiba for the Demo Poloidal Coil (DPC) project at JAERI to obtain key technologies required for the construction of superconducting coils of a fusion experimental reactor. The DPC-TJ is a 1-m-bore, 40-A/mm/sup 2/ forced-flow cooled superconducting coil wound with a double-walled 24-kA, 12-T (NbTi)/sub 3/Sn cable-in-conduit conductor. The DPC-TJ was tested to investigate stability performance at operating conditions between 15 kA, 2.3 T and 30 kA, 4.5 T. Another test was carried out with a 1/18 reduced-scale model of the DPC-TJ conductor to investigate stability margins at the designed field of 12 T. Results indicated the limiting current of the DPC-TJ was around 25 kA. The DPC-TJ coil was stably charged up to 30 kA without any normal transitions because only a small mechanical disturbance could occur in the newly developed type of conductor.         A stability and quench experiment using a NbTi forced flow cooled conductor in a two-dimensional winding pack    E.P. Balsamo, L. Bottura, O. Cicchelli, P. Gislon, M.V. Ricci and M. Spadoni Summary: Experiments of quench propagation and stability margin have been performed on a NbTi hollow conductor test module allowing heat conduction only between adjacent layers, while the turns in a layer were thermally insulated. Some of the experimental data on heat propagation and stability margin are reported, and the results of two selected runs are compared with the prediction of a 2-D version of the SARUMAN code. It is shown that the simulation can reproduce the general features of the quench propagation experiments, in one case reaching a quantitative agreement.         Test results of the toroidal model pancake for ITER/FER toroidal field coils    M. Sugimoto, F. Hosono, T. Isono, N. Koizumi, K. Yoshida, T. Ando, Y. Takahashi, M. Nishi, K. Okuno, H. Nakajima, H. Tsukamoto, T. Kato, K. Kawano, T. Hiyama, H. Hiue, S. Iwamoto, A. Miyake, T. Sasaki, H. Ebisu, T. Takahashi, K. Yamamoto, Y. Yasukawa, H. Hanawa, M. Oshikiri, S. Seki, F. Tajiri, M. Seki, T. Ouchi, J. Okayama and H. Tsuji Summary: Development of a hollow cooling monolithic (TMC-FF) conductor has been carried out by Japan Atomic Energy Research Institute (JAERI) since 1988. Manufacture of the toroidal model pancake (TMP) made of the TMC-FF conductor was completed in August, 1991, after trial manufacturing and verification tests. Experiments on the TMP started in January, 1992, in the Demo Poloidal Coil (DPC) test facility. Results of cooldown, pressure drop, stability, and mechanical performance of the TMP are presented.         AC losses of the toroidal model pancake (hollow conductor type)    F. Hosono, M. Sugimoto, H. Tsukamoto, M. Oshikiri, H. Hanawa, S. Seki, T. Sasaki, N. Koizumi, T. Isono, Y. Takahashi, K. Okuno, M. Nishi, H. Nakajima, T. Kato, K. Yoshida, T. Ando and H. Tsuji Summary: The conductors of the toroidal field (TF) coil are being developed for the tokamak fusion reactor ITER International Thermonuclear Experimental Reactor. While the TF coil will be operated in the DC mode, the reduction of AC losses is important from the viewpoint of the plasma disruption. The Toroidal Model Pancake (TMP) is a test coil for investigating the applicability of a hollow conductor for the TF coil. The TMP has a 90-m-long hollow conductor, and AC loss measurements were carried out. This pancake has an inner diameter of 1 m and an outer diameter of 1.5 m. The results show that the effective diameter of (NbTi)/sub 3/Sn and NbTi corresponds to the nominal filament diameter of 4 mu m and 39 mu m, respectively, and that the coupling losses depended on the direction of the applied magnetic field. The time constant of the coupling current was 1.6 s when a magnetic field was applied in the perpendicular direction.         Optimum conditions of stabilizer ratio and critical current margin for maximizing the current density of a tightly-wound superconducting magnet    T. Satow Summary: A new stability criterion for a tightly wound superconducting magnet is proposed. In a tightly wound superconducting magnet such as a resin-impregnated or a nonimpregnated magnet, conductor motion within the winding or cracking of epoxy resin often causes a quench of the magnet. Based on an experimental result and theoretical analysis of conductor motion, their time constants were 200 to 500 mu s. The time constant of temperature rise due to heating in a conductor was calculated to be about 20 mu s so that conductor motion can be regarded thermally as a steady-state phenomenon. In a model where the heat due to local steady disturbance is cooled by conduction to both ends of the conductor with a heated length l, the optimum stabilizer ratio and critical current margin for maximizing the current density of the tightly wound superconducting magnet are obtained theoretically. In this theoretical analysis, the stability parameter B, the limited disturbance l/sup 2/ p, and evaluation factor EF are proposed. Stability evaluations on some magnets that were constructed and tested are presented.         Excitation experiments of module coil (TOKI-MC) as an R&D program for Large Helical Device    M. Sakamoto, T. Mito, K. Takahata, A. Nishimura, N. Yanagi, S. Yamada, J. Yamamoto, O. Motojima, T. Minato, T. Ichihara and M. Hasegawa Summary: Excitation experiments for one of the R&D coils called TOKI-MC have been carried out to simulate the condition of excitation of helical coils for the Large Helical Device (LHD). TOKI-MC is a pool-cooled twisted solenoid coil with aluminum stabilized superconductors that were obliquely wound around an elliptical bobbin. In all nominal current excitations, quenches were initiated around 17 kA while the design current was 20 kA. There was no training effect. Signals of acoustic emission (AE) sensors indicated that the quenches were triggered by mechanical perturbations. It was found that the conductor of TOKI-MC moved freely without restriction due to the electromagnetic force, and that the winding moved reversibly.         Stability tests of module coil (TOKI-MC) wound with an aluminum stabilized superconductor    T. Mito, M. Sakamoto, K. Takahata, N. Yanagi, A. Nishimura, S. Yamada, O. Motojima and J. Yamamoto Summary: The module coil TOKI-MC is a twisted solenoid coil wound with an aluminum stabilized superconductor developed as an R&D program for the Large Helical Device (LHD). The TOKI-MC can simulate the conductor and winding structure cooled by pool boiling helium, the twisted winding and the large electromagnetic force of the helical coils for LHD. The TOKI-MC was designed as a cryostable coil at an operating current of 20 kA, but the coil quenched around 17 kA in excitation tests. The cause of quenches was thought to be the result of wire movement. Stability tests were also carried out and the measured recovery current was less than the designed value. The degradation of recovery current was due to the excess magnetoresistivity of the copper clad aluminum stabilizer. The stability of TOKI-MC was evaluated and compared with the data of short sample tests.         Superconducting magnet system for high power gyrotron    M. Konno, Y. Yasukawa, K. Sakaki, T. Kumagai, H. Hiue, M. Tsuneoka, S. Maebara, A. Kasugai and K. Yoshida Summary: A superconducting magnet system was designed and fabricated for a 1-MW gyrotron in a frequency range of 110-140 GHz. The system consists of superconducting magnets, a cryostat, a two-stage cooler, and power supplies. The diameter of the gyrotron bore is 220 mm. A magnetic field of 5.0 T in the resonance region was obtained with a 340-mm bore superconducting split coil. A magnetic field of 0.25 T in the gun region was obtained with two solenoid coils. A persistent current switch, removable current leads, and a two-stage cooler were adopted to decrease the heat load of liquid helium. The superconducting magnet system has successfully achieved a 110% rated current without quenching.         Fiber-reinforced-superconductors for a 15 T-class high-field pulsed magnet and their conceptual design    K. Arai, H. Tateishi, M. Umeda and K. Agatsuma Summary: The authors are developing a novel type of Nb/sub 3/Sn superconductor with high elastic modulus fibers for application to high field pulsed superconducting magnets, called the fiber-reinforced superconductor (FRS). They describe the conceptual design of a conductor for a pulsed magnet using FRSs and present superconducting characteristics for monofilamentary FRS samples. Each monofilamentary FRS supports hoop stress under operation of the magnet. Short lengths of monofilamentary FRSs using tungsten fiber were prepared by RF-magnetron sputtering. Critical current measurement up to 15 T and a uniaxial strain test at 10 T have been carried out. The data support the conceptual design of the 15-T-class pulsed superconducting magnet using FRSs.         The reduction of the critical current in Nb/sub 3/Sn cables under transverse loads    J.M. van Oort, R.M. Scanlan, H.W. Weijers, S. Wessel and H.H.J. ten Kate Summary: The degradation of the critical current of impregnated Rutherford type Nb/sub 3/Sn cables was investigated as a function of the applied transverse load and magnetic field. The cable is made of modified jelly-roll-type strand material and has a keystone angle of 1.0 degrees . The voltage-current characteristics were determined for the magnetic field ranging from 2 to 11 T and transverse pressure up to 250 MPa on the cable surface. It was found that the 48-strand cable, made of strands with six elements in the matrix, showed a larger critical current degradation than the 26-strand cable with 36 elements per strand. The global degradation of the 48-strand cable was 63% at 150 MPa, and 40% at 150 MPa for the 26-strand cable. Microanalysis of the cross-section before and after compression is presented, showing significant permanent damage to the superconducting strands.         Applications of high-temperature superconducting coils as inductors in switching power supplies    E. Schempp and C. Russo Summary: Chokes and inductors made from high-temperature ceramic superconducting (HTS) wires offer a new range of design and performance possibilities for high-power converters by making possible near-lossless inductances. Cryogenically cooled inductors and cryogenically integrated electronics offer substantial design advantages in high-power converters that are discussed. Such power supplies can operate efficiently at low frequencies, thereby reducing semiconductor switching losses, decreasing heat sinking requirements, and lowering demands on circuit capacitors. Use of HTS inductors results in power converters up to 50% smaller in size in multimegawatt installations, while still achieving considerably improved operating efficiencies and greatly simplified heat rejection. The installed cost may be 30-50% less than for conventional designs.         Application of high-T/sub c/ superconductor to current limiting devices    T. Ikegami, Y. Yamagata, K. Ebihara and H. Nakajima Summary: Resistive characteristics of YBa/sub 2/Cu/sub 3/O/sub 7-x/ superconductor thin film quenched by a current was investigated. Thin films prepared on MgO substrates by the laser ablation method were used, and their current-resistance characteristics under current-quenching were investigated. A resistance appeared quickly above a critical current and then increased to about 8 Omega within few milliseconds, which depended on input power to the film. To investigate characteristics of the current-quenched superconducting film, a one-dimensional heat transfer equation was numerically solved using a finite-difference method. By comparing these experimental and numerical results it was found that nonuniformities in current density or temperature may exist in the quenching thin film.         Design considerations for an inductive high T/sub c/ superconducting fault current limiter    L.S. Fleishman, Y.A. Bashkirov, V.A. Aresteanu, Y. Brissette and J.R. Cave Summary: The authors investigate the design feasibility of an inductive iron core superconducting fault current limiter. A simplified thermo-electromagnetic analysis of the operating behavior of the fault current limiter is presented. This design is based on a high temperature superconducting shield surrounding a magnetic circuit with a primary winding generating an AC magnetic field. During fault conditions the field penetrates the core resulting in a large impedance, and thus a limitation of the fault current. In the analysis of this design, for voltages and currents up to 25 kV root-mean-square (RMS) and 2000 A RMS, it is shown that recuperation times for superconductors operating at liquid nitrogen temperatures are acceptable.         Experimental 7.2 kV/sub rms//1 kA/sub rms//3 kA/sub peak/ current limiter system    T. Verhaege, J.P. Tavergnier, C. Agnoux, C. Cottevieille, Y. Laumond, M. Bekhaled, P. Bonnet, M. Collet and V.D. Pham Summary: A current limiter system based on GEC ALSTHOM's kA-class AC superconducting conductors was realized. Its active components are two parallel noninductive superconducting windings, a shunt resistor, and a detection box which triggers the opening of a fast circuit breaker. The current limiter system has to withstand in the superconducting state current up to 1 kA/sub rms/, and to provide without damage an immediate limitation at 3 kA/sub peak/, in the various fault conditions which could to appear on one of the three phases of a 7.2-kV/sub rms/ network. The conductor definition guarantees complete transitions, and therefore maximal protection, whether in the case of a short circuit or of an accidental quench. Applications to the AC power network are examined for protection against excessive short-circuit currents. The current limiting system reduces considerably the fault current, its destructive effects, and the switching capacity of the required circuit-breaker. The current limiter system has been tested in a 600-MVA power station.         Equivalent circuit and leakage reactances of superconducting 3-phase fault current limiter    S. Shimizu, O. Tsukamoto, T. Ishigohka, Y. Uriu and A. Ninomiya Summary: The authors have been studying a novel type of superconducting fault current limiting reactor (SCFCLR). The SCFCLR is a reactor which has three superconducting windings with the same numbers of turns wound on a single iron core. An equivalent circuit is proposed for the SCFCLR. Using this equivalent circuit, the leakage reactances of the SCFCLR were calculated, and they agree well with the experimental data. Ground fault tests in a model power system were carried out. When the SCFCLR was inserted in the model transmission line, a ground fault was not observed.         Reduced mass persistent switches for large superconducting magnets in space    M.A. Green Summary: Superconducting magnets in space must operate in the persistent mode. The author describes the characteristics of low mass niobium titanium persistent switches for low mass superconducting magnets which were designed to quench protect themselves through the quench back process. The whole coil is driven normal shortly after the quench has started and the magnet stored energy is taken up by the coil and the persistent switch. The concept of using a resistor and diode in parallel with the persistent switch to reduce the overall mass of the persistent switch system and the helium consumption during magnet charging is discussed. A 1.4-m-diameter free-flyer version of the 11.6-MJ stored energy ASTROMAG magnet and its persistent switch is presented as an example.         Stabilization of Cu-Ni based persistent current switch    M. Urata, T. Yazawa, H. Maeda, T. Tomisaki, S. Kabashima, K. Sasaki and T. Kumano Summary: Stabilization of a persistent current switch with a parallel connection is described. The current transfer behavior for a seven-strand conductor, wound as a persistent current switch, was studied. Each strand current was measured by using Rogowski coils. In the current ramp, negative current flowed into the center strand, which was inverted to a positive direction in about a 2-min time constant. Strand quench was induced by a heater wound in each strand. When one of the outer strands was quenched by its heater, the current was mainly transferred to the nearest three strands including the center strand in about 2 ms. These experimental results agreed well with the calculated results considering the self/mutual inductance for a parallel conductor and the joint resistance. The transferred current of several tens of amperes, which flowed with a few orders of 10000 A/s ramp rate, resulted in the degradation of the whole switch quench current from the conductor critical value.         Development of a 50-60 Hz thermally switched superconducting rectifier    O.A. Shevchenko, H.H.J. ten Kate, H.J.G. Krooshoop, N.V. Markovsky and G.B.J. Mulder Summary: A full-wave thermally switched superconducting rectifier, able to operate directly from the mains at the 50-60-Hz frequency, has been developed. Typical design output values of this device are a current of 300 A, a voltage of up to 1 V, an average power of up to 100 VA, and an efficiency better than 95%. The rectification is achieved by means of fast-response switches and an iron core transformer. A simple and reliable algorithm for the rectifier operation, based on the measured current change across the switches, was developed and tested while powering a small magnet. The new features of the rectifier allow for a simplification of the construction and a significant reduction of cost, mass, and volume.         AC losses and current distribution in 40 kA NbTi and Nb/sub 3/Sn conductors for NET/ITER    D. Ciazynski, B. Turck, J.L. Duchateau and C. Meuris Summary: General working formulas usable for calculations of AC losses in superconducting multistage twisted cables have been developed. In situ contact resistances between subcables of different cabling levels as well as AC losses have been measured on full-size steel jacketed 40-kA NbTi and Nb/sub 3/Sn conductors developed for NET/ITER (International Thermonuclear Engineering Reactor) applications. In addition to the strand resistive barriers, stainless steel spacers have been used inside these cables to reduce the AC losses. Theory and measurements demonstrate the role played by the steel spacers in the reduction of the total AC losses of this kind of conductor. The authors give conditions for a good compromise between low AC losses and sufficient current transfer to ensure a correct current distribution among strands.         AC loss performance of 1-m-bore, large-current Nb/sub 3/Sn superconducting coils in JAERI Demo Poloidal Coil project    K. Okuno, Y. Takahashi, H. Tsuji, T. Ando, M. Nishi, K. Yoshida, M. Sugimoto, N. Koizumi, F. Hosono and M. Shimada Summary: The Demo Poloidal Coil (DPC) project at JAERI started in 1985, and four forced-flow, large-current-capacity, 1-m-bore Nb/sub 3/Sn coils have been fabricated and tested. Two of them, DPC-EX and US-DPC, have been tested in pulsed charging at several teslas per second. Their coupling loss time constants were measured to be 2 ms, and quite good AC loss characteristics were obtained owing to chromium plating on the surface of their strands. The other two, DPC-TJ and the Toroidal Model Pancake (TMP), were designed to be DC coils, and revealed a much larger coupling time constant (a few seconds). An increase in the coupling time constant of the bundle-type conductor with regard to a coil current was observed.         Quench propagation through manifolds in forced flow cooled coils    L. Bottura Summary: The hydraulic connections of the cooling channels of a forced-flow cooled coil can provide an effective means for propagating a quench in the winding pack by recirculating the hot helium expelled from the normal zone. This propagation mode can be exploited to decrease thermal gradients and increase the coil mass where energy is dumped during an accident. A model for the analysis of such a system is presented using a simplified approach for the hydraulic network formed by the manifolds and the distribution lines also including valves and pumps. The procedure has been coupled to a sophisticated quench analysis code. Results of simulations are presented to show that the manifold propagation of quench is of relevance and has beneficial effects in the case of switching or coil failures.         Experimental results of stability and current sharing of NbTi cable-in-conduit conductors for the poloidal field coils    Y. Takahashi, N. Koizumi, Y. Wadayama, K. Okuno, M. Nishi, T. Isono, K. Yoshida, M. Sugimoto, T. Kato, T. Sasaki, F. Hosono, T. Ando and H. Tsuji Summary: Japan Atomic Energy Research Institute has developed and tested the 30-kA NbTi Demo Poloidal Coils whose stored energy and inner diameter were 30 MJ and 1 m, respectively. The conductor of these coils consists of Formvar-coated NbTi strands inside the stainless steel conduit. During the charging test, an instability was observed. Stability and current sharing of the cable-in-conduit conductor were studied to solve the problem. These experimental results clarified that the cause of the instability was the low stability margin of the conductor due to the nonuniformity of current distribution between the strands. Therefore, the surface of the strand of the new conductor was designed to be chromium instead of the Formvar. Two types of the new 30-kA conductors were fabricated. One of these conductors was tested, and good results were obtained. These new conductors can be used for the conductor of the outer ring coils of the International Thermonuclear Experimental Reactor (ITER) with minor modifications.         Test results on 10 T LHC superconducting one metre long dipole models    D. Leroy, J. Krzywinski, L. Oberli, R. Perin, F. Rodriguez-Mateos, A. Verweij and L. Walckiers Summary: Superconducting twin-aperture dipole model magnets for the CERN future superconducting collider, the Large Hadron Collider (LHC), were built. The authors report on the magnet quench behavior and the field measurements at low and high magnetic induction. They describe the results obtained with 1-m-long models which have been made in industry. To test different design ideas, four magnets were built with a number of technical variants relating to the type of cable and electrical insulation, details in coils, material, shape and assembly method of the collars and the material of the outer shrinking cylinder. Tests performed on two magnets called MTA-JS and MTA-H are discussed. Measurements of the losses in the superconducting cables and the quenching field at various field ramp rates are used to investigate the temperature margin in superfluid helium under steady-state losses.         Half cell operations test of the Superconducting Super Collider Laboratory    A.D. McInturff, S. Augustynowicz, W. Burgett, R. Coombes, C. Dickey, T. Dombeck, W. Feitz, R. Flora, J. Gannon, D. Haenni, P. Kraushaar, M. Levin, M. McAshan, G. Mulholland, D. Murray, W. Robinson, T. Savord, F. Spinos, G. Tool, J. Weisend II, D. Wallis, D. Voy and J. Zbasnik Summary: Preparations and tests are underway at the N-15 site in Waxahachie, Texas, to obtain operational parameters and characteristics for the 100-m-long 50-mm-aperture half cell of the Superconducting Super Collider Laboratory (SSCL) collider. The first power phase of this test refers to the accelerator system string test. The experimental procedure is described. These measurements are being added to the previous information obtained during the thousands of hours of operating the 40-mm-aperture half cell minus the quadrupole string. These data are being compared to each other and to various computer models to obtain optimum operating scenarios for the final collider components and their use. The last run on the previous string emphasized the mid-cell spool piece recooler components; i.e., bypass leads, recooler, cool down valve, quench valve, etc., and their operation. Problems previously reported and their proposed solutions or proven fixes are discussed. Future tests with the present half cell and possible plans for its expansion to a full cell plus are presented. Heat loads from previous runs are compared with their design values.         Quadrupole magnets for the SSC    A.F. Lietzke, P. Barale, R. Benjegerdes, S. Caspi, J. Cortella, D. Dell'Orco, W. Gilbert, M.I. Green, K. Mirk, C. Peters, R. Scanlan, C.E. Taylor and A. Wandesforde Summary: The authors have designed, constructed, and tested four short (1-m) models and six full-size (5-m) models of the Superconducting Super Collider (SSC) main-ring 5-m focusing quadrupole magnet (211 T/m). The results of this program are summarized. The magnet construction, test procedures, and test results are discussed. Except for modest training above the SSC operating point, the magnets performed very well and proved to be self-protecting. Some design flaws, e.g., inadequate end-clamping and pole shimming, were identified and corrected sufficiently so that the later magnets exceeded specifications.         A 50 mm bore superconducting dipole with a unique iron yoke structure    D. Dell'Orco, S. Caspi, J. O'Neill, A. Lietzke, R. Scanlan, C.E. Taylor and A. Wandesforde Summary: A 50-mm-bore superconducting dipole with a thin stainless steel collar and a close-in elliptical iron yoke was designed to obtain a high transfer function and low saturation effects on the multipoles. A 1-m model was built and tested. The training behavior of the first 1-m model is presented at 4.3 K and 1.8 K. At 1.8 K it reached the record field of 10.06 T. The two layer cos theta winding uses 30 and 36 strand cables identical to the cables of the 50-mm-bore Superconducting Super Collider (SSC) dipole, and it has an operating field of 6.6 T at 4.35 K with a current of 5800 A. To evaluate behavior at high fields, the mechanical structure for the model was designed for 10 T. The thin collar itself provides only a minimum prestress of 10 MPa, and the full prestress of 70 MPa is given by the iron yoke. An aluminum spacer is used to control the gap size in the vertically split iron yoke. The tapered gap in the yoke is determined by the size of the Al spacer so that during cooldown there is no loss of coil prestress and the gap remains closed when the magnet is energized.         Effects of manufacturing errors on the magnetic performance of the SCC dipole magnets    L.V. Nguyen, C.E. Abel and H.F. Gurol Summary: The authors summarize the work performed to evaluate the effects of manufacturing errors on the field quality of the Superconducting Super Collider dipole magnets. The multiple sensitivities to the conductor displacements were computed. There are two types of magnetic field multipole specifications: systematic (average over the entire ring) and RMS (standard deviation of the multipole distribution). The RMS multipoles induced by random variations in the magnet cross section were predicted using VSA software and the current design tolerances. In addition, the effects of variations in the beam tube, yoke and cryostat dimensions were also analyzed.         Locating the magnetic center of the SSC CDM using a temporary quadrupole field    C.R. Gibson, D.W. Bliss, R.E. Simon, A.K. Jain and P. Wanderer Summary: For the Superconducting Super Collider (SSC) to meet its physics requirements, the magnetic center of each collider dipole magnet (CDM) must be accurately aligned. A technique has been developed to determine the magnetic center of the SSC dipole magnet under ambient test conditions. This technique involves flowing current in the upper half of the coils in the direction opposite to the current in the lower half. This is done using a temporary lead connected to the splice joining the two coil halves and two matched power supplies. The resulting field is primarily skew quadrupole and has high field gradients which allow the center to be accurately located. The viability of this method has been verified by analysis using a Taylor series expansion of the resulting magnetic field. The analysis has also verified that off-the-shelf power supplies have low enough mismatch to be used in this technique. The analytical results have been verified through the test of a short dipole magnet at the Brookhaven National Laboratory.         Analysis of SSC dipole quench behavior as a function of quench protection heater configuration    D.J. Kinzie and S.D. Peck Summary: Analytic modeling tools have been developed to predict the quench behavior of the Superconducting Super Collider (SSC) dipole coils for a wide range of quench protection heater designs and configurations. Computer modeling tools have been developed to predict the time between heater firing and the initiation of conductor normal zones, and the maximum heater temperature for parametric variations in the heater strip geometry, resistance, material, protection circuit configuration, and conductor current and temperature. Verification of the modeling results has been accomplished by comparison of analysis results with data obtained from quench heater tests of DCA 311-321. Predictions for effective conductor enthalpy and time to normal zone initiation were found to correlate well with actual test data. Predictions have been made for the performance of heater designs for the GDSS prototype dipole magnets.         Enhanced quench propagation velocity    R.G. Mints, A.A. Akhmetov and A. Devred Summary: Quench propagation velocity in conductors having a large amount of stabilizer outside the multifilamentary area is considered. It is shown that the current redistribution process between the multifilamentary area and the stabilizer can strongly affect the quench propagation. A criterion is derived for determining the conditions under which the current redistribution process becomes significant, and a model of effective stabilizer area is suggested to describe its influence on the quench propagation velocity. As an illustration, the model is applied to calculate the adiabatic quench propagation velocity for a conductor having a multiply connected stabilizer consisting of an inner core and an outer sheath.         Quench characteristics of 5-cm-aperture, 15-m-long SSC dipole magnet prototypes    W. Nah, A. Akhmetov, M. Anerella, R. Bossert, T. Bush, D.W. Capone II, J. Carson, R. Coombes, J. Cottingham, S.W. Delchamps, A. Devred, J. Di Marco, G. Ganetis, G. Garber, C. Goodzeit, A. Ghosh, S. Gourlay, A. Greene, R. Gupta, R. Hanft, A. Jain, S. Khan, E. Kelly, W. Koska, M. Kuchnir, J. Kuzminski, M.J. Lamm, P. Mantsch, P.O. Mazur, G. Morgan, J. Muratore, T. Ogitsu, D. Orris, J. Ozelis, T. Peterson, E.G. Pewitt, A. Prodell, M. Puglisi, P. Radusewicz, M. Rehak, E.P. Rohrer, J. Royet, W. Sampson, P. Sanger, R. Scanlan, R. Schermer, R. Shutt, R. Stiening, J. Strait, C. Taylor, R. Thomas, P. Thompson, J.C. Tompkins, J. Turner, M. Wake, P. Wanderer, E. Willen, Y. Yu, J. Zbasnik, Y. Zhao and H. Zheng Summary: The quench performance and ramp rate sensitivity of 18 5-cm-aperture, 15-m-long Superconducting Super Collider (SSC) dipole magnet prototypes are discussed. All the magnets appear to reach a quench plateau near their extrapolated short sample current limit and well in excess of the operating current with very little training. Most of the magnets, however, exhibit a dramatic degradation of their quench current as a function of ramp rate, which, for the most part, can be attributed to large cable eddy currents.         Quench temperature excursion predictions for the SSC higher energy booster dipole and quadrupole magnets (HDM and HQM)    O. Christianson Summary: A coupled numerical procedure and MIITS calculation are used to estimate temperature excursions in the HDM and HQM. The MIITS tabulation for copper and niobium-titanium used in this work were given by M.S. McAshan (1988). The increasing size of the normal zone is based on measured propagation velocities. The temperature is calculated from the MIITS integrals. Current decay in the magnet is dependent upon the temperature and time varying resistance of the normal zone. Quench heater performance is included by varying the time delay between quench heater firing and the resulting transition to the normal state. The quench heater delay is also calculated with a numerical model incorporating heater, insulation, conductor, and coolant elements, temperature dependent physical properties, and superconducting properties. Quench projections for magnets in a half cell are made.         Test results of post-ASST design Fermilab built 1.5 meter, SSC collider model dipole magnets    T.S. Jaffery, J. Carson, S.W. Delchamps, W. Kinney, W. Kosaka, M.J. Lamm, J.P. Ozelis, J. Strait and M. Wake Summary: A series of 1.5-m-long and 50-mm-aperture model Superconducting Super Collider (SSC) dipole magnets was built and tested at Fermilab. Later models were built to test several extensions to the Fermilab design and variations in the manufacturing parameters. Some of the variations tested included a conductor insulation scheme, alternate materials for coil end parts, and coil winding. The coils were instrumented with voltage traps for the pppes of quench localization and with strain gages to measure the stresses and deflections in the coil and magnet support structure. Data from the quench performance, coil stress, end force, and harmonics are presented and compared with design expectations and correlated with changes in the magnet design and assembly methods.         Magnetic performance of the SSC dipole magnets    H. Gurol, D.W. Bliss, J.L. Elliott, L.V. Nguyen, R.E. Simon, C.E. Abel and M.P. Krefta Summary: The authors report on the status of the magnetic design of the Superconducting Super Collider (SSC) dipole magnets. A two- and three-dimensional design optimization was performed that included the effects of permeable collar, yoke, cryostat, beam tube, crescent yoke end pieces, cool-down, and Lorentz loads. A field quality plan was developed that represents the approach to tuning the design for satisfying the systematic and RMS multipole specifications. The VSA tool is being used to simulate the effects of random parts, tool and process variations on the expected multipole distributions, both between many magnets, and within a single magnet.         Current dependence of harmonic field coefficients of 5-cm-aperture, 15-m-long SSC dipole magnet prototypes    Y. Zhao, A. Akhmetov, M. Anerella, R. Bossert, T. Bush, D.W. Capone II, J. Carson, R. Coombes, J. Cottingham, S.W. Delchamps, A. Devred, J. Di Marco, G. Ganetis, M. Garber, C. Goodzeit, A. Ghosh, S. Gourlay, A. Greene, R. Gupta, R. Hanft, A. Jain, S. Kahn, E. Kelly, W. Koska, M. Kuchnir, J. Kuzminski, M.J. Lamm, P. Mantsch, P.O. Mazur, G. Morgan, J. Muratore, W. Nah, T. Ogitsu, D. Orris, J. Ozelis, T. Peterson, E.G. Pewitt, A. Prodell, M. Puglisi, P. Radusewicz, M. Rehak, E.P. Rohrer, J. Royet, W. Sampson, P. Sanger, R. Scanlan, R. Schermer, R. Shutt, R. Stiening, J. Strait, C. Taylor, R. Thomas, P. Thompson, J.C. Tompkins, J. Turner, M. Wake, P. Wanderer, E. Willen, Y. Yu, J. Zbasnik and H. Zheng Summary: Eighteen 5-cm-aperture, 15-m-long Superconducting Super Collider (SSC) dipole magnet prototypes have been produced and cold tested. On each prototype, the dependence of harmonic field coefficients on magnetic current was measured as part of a study of the magnetic field quality. For most of the magnets, the observed behavior conforms to what can be expected from the effects of persistent magnetization currents and iron yoke saturation. A few prototypes, however, exhibited anomalies during current ramp at 4 A/s which can be attributed to large cable eddy currents.         AC loss measurements of model and full size 50 mm SSC collider dipole magnets at Fermilab    J.P. Ozelis, S. Delchamps, S. Gourlay, T. Jaffery, W. Kinney, W. Koska, M. Kuchnir, M.J. Lamm, P.O. Mazur, D. Orris, J. Strait, M. Wake, J. Dimarco, J. Kuzminski and H. Zheng Summary: Tests have recently been performed at Fermilab in order to measure the energy losses due to eddy currents and iron and superconductor magnetization. These measurements were performed on six 1.5-m-long model magnets and eight 15-m-long full-scale collider dipole magnets. AC losses were measured as a function of ramp rate using sawtooth ramps from 500 to 5000 A for both types of magnets, while bipolar studies were additionally performed on some of the short magnets. The measured magnet voltage and current for a complete cycle were digitally integrated to yield the energy loss per cycle. Measurement reproducibility was typically 5%, with good agreement between long magnet measurements and extrapolations from short magnet measurement results. Magnetization loss measurements among similar magnet types agree to within experimental error, while eddy current losses correlate strongly with the observed dependence of quench current on ramp rate.         Yoke magnetic analysis for the SSC collider quadrupole magnet (CQM)    Y.M. Eyssa, M.W. Hiller, M.-F. Xu and J.A. Waynert Summary: The authors investigate some options that can improve the design and performance of the Superconducting Super Collider (SSC) collider quadrupole magnet (CQM). They concentrate on the effect of the CQM magnetic material (yoke) on the design. Among these options are reduction of the amount of iron used; transfer function improvement to match that of the collider dipole magnets (CDM); yoke hysteresis effects; and shaping yoke or inserted magnetic material in the CQM collar to correct for some multipoles. PE2D software and FORTRAN codes were used to conduct the analysis.         Mechanical performance of 5-cm-aperture, 15-m-long SSC dipole magnet prototypes    T. Ogitsu, A. Akhmetov, M. Anerella, R. Bossert, T. Bush, D.W. Capone II, J. Carson, R. Coombes, J. Cottingham, S.W. Delchamps, A. Devred, J. Dimarco, G. Ganetis, M. Garber, C. Goodzeit, A. Ghosh, S. Gourlay, A. Greene, R. Gupta, R. Hanft, A. Jain, S. Kahn, E. Kelly, W. Koska, M. Kuchnir, J. Kuzminski, M.J. Lamm, P. Mantsch, P.O. Mazur, G. Morgan, J. Muratore, W. Nah, D. Orris, J. Ozelis, T. Peterson, E.G. Pewitt, A. Prodell, M. Puglisi, P. Rodusewicz, M. Rehak, E.P. Rohrer, J. Royet, W. Sampson, P. Sanger, R. Scanlan, R. Schermer, R. Shutt, R. Stiening, J. Strait, C. Taylor, R. Thomas, P. Thompson, J.C. Tompkins, J. Turner, M. Wake, P. Wanderer, E. Willen, Y. Yu, J. Zbasnik, Y. Zhao and H. Zheng Summary: The authors summarize the mechanical performance of the most recent 5-cm-aperture, 15-m-long SSC dipole magnet prototypes. The magnets were produced at Brookhaven National Laboratory (BNL) and Fermi National Accelerator Laboratory (FNAL) under contract with the Superconducting Super Collider Laboratory (SSCL). The BNL magnets rely on a horizontally split yoke with collared ends, while the FNAL magnets rely on a vertically split yoke with collet-style end clamps. Magnets of both designs are equipped with strain gauges enabling measurement of the azimuthal pressures exerted by the coils against the collar poles as well as the axial forces transmitted from the coil ends to the end plates. A comparison of the mechanical behaviors measured by the strain gauges is presented. How the behavior of the 5-cm-aperture magnets compares to that of the 4-cm-aperture prototypes is also discussed.         Magnetic and mechanical considerations in the design of the SSC collider dipole magnet end region    D.W. Bliss, H.F. Gurol and M.P. Krefta Summary: The end regions of the Superconducting Super Collider (SSC) collider dipole magnets. (CDMs) were designed to meet both magnetic and mechanical requirements. The authors present an optimized end design for CDM magnets that is mechanically producible and possesses desirable magnetic field quality, peak field, and magnetic length properties. A three-dimensional magnetic field distribution was calculated for this end-turn design using the finite element program TOSCA. The effective magnetic length, integrated multipole content, and peak fields are extracted from the results of the finite element model. These results compare favorably with those from a second analysis program, ENDTURN, that is based on an analytic solution to the defining field equations.         Magnetic field angle changes during manufacture and testing of SSC collider dipoles    M. Kuchnir, M. Bleadon, S.W. Delchamps, E. Schmidt, R. Bossert, J. Carson, S. Gourlay, R. Hanft, W. Koska, M.J. Lamm, P.O. Mazur, D. Orris, J. Ozelis, J. Strait, M. Wake, A. Devred, J. Dimarco, J. Kuzminski, T. Ogitsu, Y. Yu and H. Zheng Summary: Measurements of the magnetic field angle along the length of collider dipole magnets are discussed. These superconducting magnets were built at Fermilab for the Superconducting Super Collider (SSC) by Fermilab and General Dynamics personnel. These measurements were made at four stages in the assembly and test sequence. The data show that changes can occur both during installation in the cryostat and as a result of cold testing. Most of the changes during installation are correlated with the welding of the tie bar restraints, but the changes observed as a result of the cold testing can be attributed to changes in the magnetization of the iron laminations.         Mechanical performance of full-scale prototype quadrupole magnets for the SSC    J.M. Cortella, A. Devred and A. Wandesforde Summary: Six 5-m-long prototype quadrupole magnets have been built and cold-tested at Lawrence Berkeley Laboratory for the Superconducting Super Collider. The authors report on the mechanical behavior of the magnets, focusing on measurements made during cold-testing. Each of the magnets contained instrumentation to monitor the mechanical performance on the magnets during assembly and cold-testing. In addition, the instrumentation was used along with physical measurements as aids during magnet assembly. Quantities measured include coil pressures during assembly, cooldown, and magnet energization; axial thermal contraction of the magnets during cooldown; and axial force transmitted to the magnet end-plates. For the most part, mechanical measurements have proven repeatable and agree well with analysis.         SSCL phase 1 inner cable development program at IGC Advanced Superconductors, Inc    P. Valaris, H. Kanithi, D. Alderson, F. Krahula, W. Wiegert, R. Macri, G. Sorvillo, J. Rinaldi, D. O'Heron and B.A. Zeitlin Summary: Nearly 1500 tons of 8000 filament superconductor are required for the Superconducting Super Collider Laboratory (SSCL) main ring dipole magnets. IGC Advanced Superconductors' (IGC-ASI's) major accomplishments in achieving the goals included in the SSCL Phase 1 program are presented. Under the Phase 1 contract, IGC-ASI has assembled 12 Phase 1A and 9 Phase 1B multifilament billets. As required by the program, all the Phase 1B billets, containing one alloy 'source X', were identically processed under the IGC-ASI baseline. An analysis of data generated in the program is given. All data published are based on alloy source X. The authors discuss mechanical properties, including final die draw parameters, superconducting properties, and cable performance, including data affecting strand residual resistivity ratio (RRR).         Results of SSC vendor qualification program at Outokumpu superconductors    J. Teuho, T. Erkolahti, P. Haasjoki, E. Heikkila, J. Lehto, R. Liikamaa and V. Vanhatalo Summary: Outokumpu Superconductors is engaged as one of the suppliers in the developing of Superconducting Super Collider (SSC) dipole outer cable in the vendor qualification program. In the program, the authors used a billet size of 278 mm in the outer diameter. In phase IB, 15 billets were extruded and drawn down to the final diameter. The phase IA goal was to optimize some production process parameters. In this phase, 18 billets were processed. The wires for the phases IA and IB have been finished, and a summary of the results of phase IB is presented, focusing on the uniformity of quality. Some results of the different optimizing programs of phase IA are presented.         Discussion of results achieved during the SSC Vendor Qualification Program    J.J. Lichtenwalner and J.D. Scudiere Summary: Oxford Superconducting Technology has been producing niobium-titanium superconducting wire with nominal 6- mu m-sized filaments for the Superconducting Super Collider (SSC) Vendor Qualification Program. Results from the program are presented. Phase I of the program was divided into two sections: the development phase and the preproduction phase, referred to as Phase IA and Phase IB, respectively. For Phase IA, NbTi from two different suppliers was evaluated and process optimizations were performed. For Phase IB, the process parameters were fixed to provide a statistical basis for evaluating process uniformity. The preproduction phase conductor exhibited very uniform performance both within a billet and among the entire set of billets. The developmental phase conductor provided interesting information regarding the use of NbTi alloy from two different suppliers.         SSC-VQP-status of the manufacture at AISA of SSC outer wire and cable    H.G. Ky, P. Sulten, G. Grunblatt and P. Mougenot Summary: Single stacking billets were processed to manufacture Superconducting Super Collider (SSC) outer wire and cable as part of the SSC vendor qualification program. The authors report the production results and the main performance parameters of the wire manufactured. Phase IA and Phase IB results are discussed. Phase IA of this program related to manufacturing 15 different versions of SSC outer wire to investigate the effects of design and process parameters, e.g., NbTi source, billet design, Nb thickness, etc., on the wire critical current density and piece length as well as on the production yield. With regard to phase IB, 23 multifilament billets were processed to produce SSC outer cable with the Alsthom Intermagnetics SA (AISA) baseline design and process.         Critical current properties of fine filament superconducting wires for the SSC    K. Susai, H. Ii, K. Ogawa, T. Suzuki, M. Ikeda and S. Shiga Summary: Nb-Ti superconducting wires with high performance were developed and manufactured at the Furukawa Electric Co., Ltd. under the Superconducting Super Collider (SSC) vendor qualification program. The authors report the result of the experiment intended to enhance the superconductivity performance. This experiment was intended specifically to examine the effects of the heat treatment schedule on the critical current density (J/sub c/), effects of production conditions, other than heat treatment conditions, as represented by extrusion of monofilament and multifilament billets, and the difference in NbTi sources and difference in the thickness of the Nb barrier used as a diffusion preventive material while using mass-produced superconducting wire. The correlation between J/sub c/ and the resultant wire drawing performance is summarized.         The outer cable phase IB results at Hitachi Cable, Ltd., for the SSC-VQP    K. Kamata, Y. Suzuki, H. Moriai, G. Iwaki, S. Sakai, T. Kamiya, H. Oota and H. Noda Summary: Hitachi has been qualified to proceed to the phase II portion of the VQP (Vendor Qualification Program) from the standpoint of QA (quality assurance) as a result of the second QA survey practiced by the SSCL (Superconducting Super Collider Laboratory). The authors describe the fabrication procedures for Phase IB SSC outer strands and cables and summarize the strand production and the strand test results for the 0.648-mm-diameter outer strands fabricated from the first five pieces of the multibillets among the 20 pieces required to be processed in Phase IB. The first run for the 930-m-long cabling operating is discussed by considering a record of the inline cable measuring machine used for monitoring the cable dimensions. The QA program for Phase IB is also reviewed.         Image analysis of superconducting composites    J.M. Seuntjens, F.Y. Clark, T.J. Headley, F.E. Geulich and N.Y.C. Yang Summary: Image analysis of multifilament superconducting materials can yield quantitative analysis of many critical parameters that affect conductor performance. The techniques for analysis are described, and examples of each of the techniques applied to samples from the Superconducting Super Collider Laboratory (SSCL) vendor qualification program are presented. SSCL has image analysis capabilities over the range of 0.5* to 10,000*. Transmission electron microscopy (TEM) analysis equipped with the same image analysis system at Sandia National Laboratory extends these capabilities to over 150,000*. Among the analysis routines for composite materials are the local area ratio, barrier volume fraction, barrier inside perimeter, barrier outside perimeter, barrier thickness filament roundness, filament area, filament perimeter, transmission X-ray negative analysis, and feature position analysis TEM work also provides analysis of alpha -phase titanium precipitate volume fraction, precipitate thickness, and precipitate spacing.         Cold work loss during heat treatment and extrusion of Nb-46.5 wt.% Ti composites as measured by microhardness    J.A. Parrell, P.J. Lee and D.C. Larbalestier Summary: The authors utilized the simple technique of hardness measurement as a probe of the retained cold work in variously treated Nb-Ti monofilament rod stock, and they compare these results on extruded multifilament rod stock. In this experiment the cold work loss which occurs during monofilament heat treatment and multifilamentary extrusion was directly measured by comparing the Vickers hardness of the same Nb-46.5wt.%Ti alloy stock which had been cold drawn at room temperature, heat treated and cold drawn, and warm extruded. Depending on the strain state of the filaments prior to extrusion, a strain loss between 1.4 and 5.4 was determined in the extruded billet filaments. This is a very significant loss range given that the total strain space of most multifilamentary stacks lies in the range of 11-12.         Development of ductile, high current density multifilament niobium-titanium superconducting wire for SSC corrector magnets    D. Frost, R. Randall and J. Wong Summary: A superconducting corrector magnet wire was developed for the Superconducting Super Collider (SSC) which surpassed all performance specifications. Critical current requirements were met while maintaining the high degree of ductility necessary for manufacturing the intricate magnet coils. Data suggest that ductility specifications can be met with current densities exceeding 3000 A/mm/sup 2/ at 5 T. Indications are that electrical performance can be further increased without compromising piece length, ductility, or manufacturability.         A facility to test short superconducting accelerator magnets at Fermilab    M.J. Lamm, J. Butteris, K. Coulter, C. Hess, D. Lewis, T. Jaffery, W. Kinney, A.D. McInturff, J.P. Ozelis and J. Strait Summary: The superconducting magnet R&D facility at Fermilab (Lab 2) has successfully tested superconducting dipole, quadrupole, and correction coil magnets less than 2 m in length for the Superconducting Super Collider (SSC) project and the Tevatron D0/B0 Low- beta Insertion. The authors describe the Lab 2 facility and the several upgrades which were developed to accomplish these successful test programs. Several improvements have been made to the facility that have greatly enhanced its magnet testing capabilities. Among the upgrades have been a new rotating coil and data acquisition system for measuring magnetic fields, a controlled flow liquid helium transfer line using an electronically actuated cryo valve, and stand-alone systems for measuring AC loss and training low current Tevatron correction coil packages. Tests are performed in vertical dewars of boiling liquid helium.         Results of AC loss measurements on heat treated SSC cables    G.T. Mallick Jr., D. Natelson, W.J. Carr Jr., G. Snitchler and V. Kovachev Summary: Dipole magnets designed for the Superconducting Super Collider (SSC) have shown anomalous ramp rate dependence, and it is thought that interstrand coupling may contribute to this effect. The authors describe measurements made on cable samples which were prepared and measured under circumstances which approximate those which an actual magnet conductor will experience. The object of this experiment was to investigate the sensitivity of eddy current loss to applied pressure, and to observe the loss in a sample prepared under conditions which actual SSC conductors experience during magnet fabrication. Subjecting the cable to pressure during heat treatment and during measurement significantly increased the eddy current loss, but it is not altogether clear that the increase results primarily from interstrand coupling.         AC loss measurements of Rutherford type superconducting cables under mechanical stresses    Y.Z. Lei, T. Shintomi, A. Terashima and H. Hirabayashi Summary: Experimental apparatus for measurements of AC losses in Rutherford type cable conductors has been constructed. A number of compacted cable samples have been measured. Hysteresis loss, loss from coupling within strands and loss from interstrand coupling are distinguished from each other. The results show that even for cables without soldering and coating, the AC losses may be quite different from each other due to interstrand coupling loss. As the curing temperature increases, interstrand coupling loss tends to increase. For some cables, interstrand coupling loss increases nearly geometrically with the increase of curing temperature. Most of the samples did not show dependence of loss on mechanical pressure.         Enhanced static magnetization and creep in fine-filamentary and SSC-prototype strands via helical cabling geometry enhanced proximity effects    M.D. Sumption, K.R. Marken Jr. and E.W. Collings Summary: Helical-cabling-geometry enhanced proximity effect (PE) magnetization and creep have been found in multifilamentary NbTi/Cu superconductive composites with filament diameters (interfilamentary spacings) of 2.0 (0.39) mu m and 6.0 (1.14) mu m. Single strands were wound into helical coils to simulate round-cable geometry. Additionally, oval coils were wound to verify the existence of enhanced PEs in 6.0 mu m filament diameter material with a large effective coupling length. For the helical coils, when the strand twist pitch was nearly equal to the cable perimeter, PE related magnetization was enhanced, and this magnetization creeps at a significantly greater rate than that of bare NbTi.         Nonuniform deformation of niobium diffusion barriers in niobium-titanium wire    R.W. Heussner, P.J. Lee and D.C. Larbalestier Summary: A major source of extrinsic limitation to the critical current density in Nb-46.5 wt.% Ti superconductors has been sausaging initiated by the formation of hard intermetallics of Cu-Ti-Nb at the Cu-superconductor interface during precipitation heat treatment. The main defense against this is the use of a diffusion barrier (normally Nb foil) between the Cu and the Nb-Ti, which has a tendency to deform in a nonuniform manner even prior to heat treatment. Initial examination of Superconducting Super Collider (SSC) R&D composites indicated that most of the nonuniform deformation of the barrier occurred at the interface between the Nb barrier and the Nb-Ti. The authors have examined the effect of varying the starting Nb-Ti grain size on the uniformity of barrier thickness reduction during wire drawing. For all the wires tested the nonuniformity of the barrier increased with drawing strains and with increasing initial Nb-Ti grain size. They also compared the barrier of cold drawn monofilament to that of warm extruded filaments. The extruded filaments had a significantly more nonuniform barrier.         Conceptual design of a 70 mm aperture quadrupole for LHC insertions    R. Ostojic and T.M. Taylor Summary: Due to their detrimental effect on the Large Hadron Collider (LHC) dynamic aperture, the random multipole errors of the LHC insertion quadrupoles need to be lower by a factor of five than the corresponding errors in the lattice. For achieving this level of random errors, the authors propose to increase the aperture of the insertion quadrupoles. A novel approach for achieving a quadrupole strength of 250 T/m in an aperture of 70 mm, based on a graded multilayer coil wound from NbTi conductor cooled at 1.8 K, has been investigated. The design concept of the coil, which incorporates a shell-like structure composed of a high current density block imbedded in a low density shell, is developed. The coil design, parameters of the superconducting cable, and the yoke and collar design are described, both for a two-in-one and a single quadrupole geometries.         Fabrication and test results of a twin-aperture superconducting dipole model magnet for LHC    H. Boschman, H.J. Israel, R.L. Dubbeldam, D. Leroy and P. Rohmig Summary: In the research and development program for the Large Hadron Collider (LHC) project at CERN the construction of superconducting dipole magnets with a twin aperture plays an important role. The design value of the magnetic field produced by these magnets is 10 T at superfluid helium temperatures below 2 K. One of the 1-m-long model magnets in the program has been built by HOLEC. The behavior of this magnet under cryogenic conditions has been investigated twice: first, after the collaring of the superconducting coils had been completed and, second, after the completion of the magnet, i.e., after assembling the iron yoke and aluminum shrinking cylinder. This procedure has made possible a study of the influence of the iron yoke and shrinking cylinder on the training behavior of the magnet. The test results of this model magnet show that the design value of the magnetic field is feasible and that the mechanical structure can withstand the forces.         Development of 10 T dipole magnets for the Large Hadron Collider    A. Yamamoto, H. Hirabayashi, H. Yamaoka, S. Kawabata, G. Brianti, D. Leroy, R. Perin, L. Walckiers, M. Hirano, S. Ito, I. Inoue, M. Ikeda and M. Kondo Summary: Development of high field dipole model magnets for future high energy accelerators has been carried out as a part of the cooperative accelerator program between CERN and KEK. A single aperture dipole model magnet was completed and tested. The magnet reached 8.0 T at 4.3 K and 9.87 T at 1.8 K. A twin aperture dipole model magnet with an identical coil design is being assembled. The development status and test results are described.         Test results of the prototype combined sextupole-dipole corrector magnet for LHC    A. Ijspeert, R. Perin, L. Walckiers, E. Baynham, P. Clee, R. Coombs, M. Begg and D. Landgrebe Summary: The corrector magnet for the Large Hadron Collider (LHC) contains a 1.5-T dipole for orbit correction and a 8000 T/m/sup 2/ sextupole for chromaticity correction. The dipole has for compactness been mounted around the sextupole coil. A full-scale prototype of 1.3-m length has been fabricated and tested. The coils were first tested at 4.2 K. It appeared that the training of the impregnated coils could be strongly reduced by increasing the radial precompression. The coils were subsequently cooled to the operational temperature between 1.8 and 2 K and the field quality was measured with a harmonic rotating coil. The results of the tests show that the combined dipole-sextupole corrector magnet does meet the desired field strengths.         Cryogenic and magnetic tests of the twin aperture prototype dipole in the Saclay test facility    J. Deregel, P. Genevey, J.P. Jacquemin, F. Kircher, J. Le Bars, A. Le Coroller, K.N. Henrichsen, P. Lebrun and J. Vlogaert Summary: The authors describe the test facility and the cryogenic and magnetic measurements performed on the twin aperture prototype (TAP) dipole for the CERN Large Hadron Collider (LHC). The magnet, designed by CERN and built by European industries, was tested in a facility built at CE Saclay. The focus is on the cryogenic system, which enables prototype magnets to be tested in superfluid helium; on the data acquisition systems, including a system for magnetic measurements; and on the results which were obtained during the tests.         Quench observation in LHC superconducting one meter long dipole models by field perturbation measurements    D. Leroy, J. Krzywinski, V. Remondino, L. Walckiers and R. Wolf Summary: A novel method to localize and characterize the origin of a quench in a superconducting dipole has been developed during the tests of the Large Hadron Collider (LHC) 1-m-long superconducting dipole models. It consists of an extended analysis of the voltage signals generated at the onset of a quench in pickup coils distributed along the inside of the magnet bore in conjunction with the pole voltage signals. The authors discuss the measurement method and the main results obtained during the training of these magnets, reaching a bore field of 10 T.         Electric insulation in bath cooled superconducting magnets with bare conductors    H. Kofler, J. Sammer, P. Bogensberger and F. Ramsauer Summary: Electric insulation of bare superconductors in bath cooled magnets is a requirement for safe operation of such magnets. Electric insulation of such conductors is accomplished by spacer constructions. The authors consider a spacer construction which is built up by spacer bars attached to a straplike girder mounted in a slot of the conductor surface. Typical electric load at these spacers can be defined as flash over load. Different operating conditions of the coil drive the cooling fluid into various states, in which electric insulation must sustain the possible ultimate voltages at the coil. The insulation system of a large dipole is described. Experimental performance of the insulation system is outlined at different temperatures of the cooling helium. The test equipment and experimental results are described and discussed.         Concept of quench protection and automatic control for the HMS dipole magnet system for CEBAF    H. Kofler, G. Krainz, J. Sammer, R.K. Maix, F. Ramsauer and P. Brindza Summary: Unattended operation of the CEBAF high momentum spectrometer (HMS) magnet system is considered. Beside quench detection, several vital system information and actions of the HMS dipole magnet are handled by a local computer and an intelligent industrial control system. The overall concept is described and hardware components are introduced. The operation of the system is shown by an example of some different performance states. Potential advantages of such interlinked control and monitoring systems are discussed.         Structural analysis of the 7.5 GeV superconducting dipole for the CEBAF High Momentum Spectrometer    R. Wines, P. Brindza, M. Fowler, S. Lassiter, F. Baumann, P. Bogensberger, R.K. Maix, F. Ramsauer and A. Umschaden Summary: CEBAF's High Momentum Spectrometer, (HMS) dipole cryostat has been optimized in collaboration with the subcontracting manufacturer, ELIN-EA, to minimize the deformation of the cryostat and thus the stress on the coil under load conditions. The structural behavior of the cryostat was analyzed using the finite-element codes I-DEAS and ANSYS. The HMS dipole cryostat was designed to withstand the load conditions of cooldown, energization, and warm-up of the magnet. The cryostat is subject to the effects of thermal contraction during cooldown from ambient, 293 K, to 4.2 K. The energization of the magnet to the maximum current subjects the cryostat to the load of the Lorentz forces. The load conditions apply to the structural members of the cryostat, requiring modifications to the design to achieve minimum deformation and stress concentration in the cryostat. An extensive analysis of the dipole cryostat has been carried out to optimize the design. The finite-element analysis has been used throughout the design and fabrication process for quality control of the design.         Design and manufacture of the dipole coil for the CEBAF High Momentum Spectrometer    P. Bogensberger, R.K. Maix, F. Ramsauer, A. Umschaden, H. Kofler, K. Piswanger and P. Brindza Summary: The superconducting coil for the CEBAF High Momentum Spectrometer is under construction. The coil is a bath cooled system with an external coolant reservoir tank. Design and manufacturing procedures of the bobbin structure and coil are described. The overall coil/cryostat dimensions are about 7.3*3.9*1.9 m. The cooling system works on the thermal siphon principle. An outline of the conductor layout and its physical performance are shown. Bare conductors separated with special glass epoxy insulation spacers are used to get a sufficient surface for cryogenic stability. A special method for coil clamping has been developed to get sufficient mechanical prestress after cooldown and during operation up to nominal current.         Cable-in-conduit conductor concept for the GEM detector magnet    J.V. Minervini, P.G. Marston, B.A. Smith, R. Camille, M.A. Ferri, J.R. Hale, Z.S. Piek, S. Pourrahimi, R.F. Vieira and P. Titus Summary: A conceptual design for a conductor based on cable-in-conduit (CIC) technology is presented for application to the proposed GEM detector magnet for the Superconducting Super Collider. The conductor design is driven by the enormous scale of the magnet, which will be composed of two coil halves each approximately 19 m in diameter and 14 m long. Each coil half will be assembled from 12 winding modules, each comprising of a single layer winding. The nominal operating current of 50 kA generates a central field of 0.8 T and a peak field at the winding of 1.6 T. Although the field requirements are low and operation is DC, the CIC concept is preferred because of its large intrinsic stability. The GEM detector requires the highest level of stable, quench-free operation to minimize risk and maximize reliability. The conductor consists of a 450 strand multistage cable made from NbTi/copper composite wires enclosed in a stainless steel tube which is surrounded by a large rectangular block of low resistivity aluminum. The aluminum sheath offers quench protection for the 2.5-GJ coil system, while the fast transient stability is provided by copper in the strand and the supercritical helium inside the conduit. Details of the conductor design, operating performance, and manufacturing process are described.         Stability of indirectly cooled conductors with large cross section    D.E. Baynham, N.V. Festisov and N.N. Martovetsky Summary: Results of a theoretical stability analysis of indirectly cooled conductors with a large cross section of the stabilizer are presented. The geometry of the superconducting (SC) cable was varied from a compact Rutherford type cable surrounded by aluminum stabilizer to distributed cable over the cross section. The cable geometry strongly affects the transient heat generation during the process of distribution of the transport current over the cross section of the stabilizer when a heat pulse raises the temperature above the current sharing temperature. The effect of heat transfer between adjacent turns was taken into consideration and found to be very important. Stability analysis shows that with proper design of the SC cable geometry inside the stabilizer and proper design of the coil, the stability of an indirectly cooled conductor may be enhanced by at least an order of magnitude to ensure an adequate stability margin for use in large magnets.         Test result of individual ASTROMAG test coils with aluminum stabilized superconductor    Y. Makida, Y. Doi, T. Haruyama, H. Inoue, N. Kimura, K. Nakai, S. Saito, K. Tanaka, A. Yamamoto and H. Yamaoka Summary: The development of an ASTROMAG test coil has been carried out at KEK to find the optimum parameters for the ASTROMAG main coil through an experimental study. Test results are reported. The test coil consists of a pair of windings, and their individual performance has been examined. The objectives of the test coil are to confirm the high stability of the conductor, safety of the coil at quench and cryogenic characteristics. Training phenomena have been observed and quench characteristics have been measured.         The development of a superconducting 6T wiggler magnet for the Daresbury SRS    J.S.H. Ross and K.D. Smith Summary: The 6-T wiggler is an iron-cored, warm bore, superconducting dipole magnet destined for the SERC Daresbury (UK) Laboratory's 2-GeV synchrotron radiation source to enhance the available radiation spectrum. The authors describe the major features of the magnet and include a discussion of detailed magnetic and cryogenic tests. The magnet provides a peak field of 6 T on the beam line, which was reached after four training quenches. The design and manufacturing contract for this magnet was started in September 1989 and was preceded by a feasibility study, presented in mid-1988. At the end of the feasibility study the recommendation was for a design incorporating a room temperature beam pipe and soft magnetic iron pole pieces. The magnet was cooled and successfully tested at Daresbury in February 1992. The ease with which reliable operation at 6 T was obtained and the good comparison between predicted and measured magnetic fields were results arising from the works tests.         Stability and training of a high field superconducting wiggler    J.T. Eriksson, L. Kettunen, R. Mikkonen, L. Soderlund, H. Collan and K. Hjelt Summary: A three pole superconducting wiggler with six racetrack NbTi coils kept together by iron yokes has been constructed and tested. The high field wiggler will provide photons of high intensity, high photon flux, and high degree of circular polarization with a beam life time of 10 h. The authors give an overview of the training procedure of the wet layer impregnated magnet. The tests indicated an obvious improvement of the critical current by training, although an excessive number of quenches were required. Quench analysis and some other cryogenics are also included in the discussion. Measurements are compared to the calculated values.         Superconducting bending magnets for compact synchrotron radiation source    S. Yamamoto, T. Kawaguchi, T. Matsuda, T. Takeuchi, I. Kodera, T. Amano, M. Morita, S. Yokoyama, K. Shimohata, S. Nakamura, T. Yamada and M. Iwamoto Summary: A 180 degrees superconducting magnet has been constructed for a synchrotron radiation source. The authors describe the superconducting magnet design and some component test results for the compact synchrotron radiation source. The magnetic field at the electron orbit is 4.5 T. The bending radius is 0.593 m. The magnet has several features such as low liquid helium consumption ratio, persistent current operation, high homogeneous magnetic fields, and leakage flux shielding by the iron core surrounding the cryostat. Component tests of persistent current switches of 15 Omega and 3 Omega and a superconducting joint test have been performed.         Superconducting X-ray lithography 180 degrees bending dipole magnet design and material selection    E.M.W. Leung, G.A. Albert, K.L. Agarwal, D.D. Madura, D.J. Silva, S.K. Sharma, J.B. Murphy, R. Heese and S. Kalsi Summary: The Superconducting X-ray Lithography Sources (SXLS) being built at Brookhaven National Laboratory requires two superconducting bending magnets. The selection of the material for the coldmass structure, i.e. the superstructure around the magnet coils, is most crucial because of its immense size and close proximity to the beam. The authors describe the selection process for the coldmass structure material in detail, and for the high strength structural bolts, the weld rods for the structural welds, and various components within the cryomagnetic system. Results of the verification testing are outlined. Nitronic 40 was the selected material for the coldmass structure. MP35N was used for making the compression bolts, aluminum 5083-0 for making the thermal shields, and AISI 316LN for making the room temperature vacuum vessel. In each case, a balance between performance and cost was carefully considered. The final design of the SXLS magnets was completed in February, 1992.         Superconducting X-ray lithography 180 degrees bending dipole magnetics analysis methodology    D.D. Madura, E.M. Leung, L.V. Nguyen, H. Gurol, J.B. Murphy and S.K. Sharma Summary: The Superconducting X-ray Lithography Source (SXLS) being built at Brookhaven National Laboratory requires two superconducting bending magnets. The authors describe the magnetic analyses completed to support and direct the design of magnets capable of successfully meeting the system requirements. Because of the diversity of the effects investigated a number of analytical techniques were necessary. Each of the effects and the analytical approach chosen are outlined. The magnetic field calculation approach and verification are presented. To verify the satisfaction of requirements, field calculations to seven significant digits were necessary. The effects of magnetic permeability of magnet materials, eddy currents, superconductor magnetization, current leads, splices, structural deflection, and manufacturing tolerances were calculated in addition to the current density field calculations.         An examination of the properties of SSC Phase II R&D strands    P.J. Lee and D.C. Larbalestier Summary: The authors summarize a detailed characterization of the Superconducting Super Collider (SSC) Phase II R&D billets, samples of which were supplied to the University of Wisconsin (UW). An important part of the SSC Phase I and II strand R&D programs was an extensive sampling scheme that covered the entire fabrication process of the strand. Samples were sent to UW, where complete microstructural and physical property analysis could be performed. In addition, sufficient extruded pre-heat-treatment multifilamentary material was provided to OW so that parallel processing to strand could be performed. In Phase I material it was found that the 2 vol% Nb diffusion barrier thickness was insufficient to prevent extrinsic limitation of the critical current density (J/sub c/). This contrasted with the Phase II strand which incorporated 4% barriers and showed intrinsic behavior. The intrinsic nature of the Phase II conductor has made it possible to probe the basic microstructure property relationships of the strand and provide insight into improvements in future processing.         The evolution of tooling, techniques, and quality control for accelerator dipole magnet cables    R.M. Scanlan Summary: The author summarize the results of the Superconducting Super Collider (SSC) R&D program from 1984 to 1990. The SSC R&D program has led to a significant improvement in critical current, piece lengths, and overall manufacturing capability for multifilamentary NbTi superconductors. The requirements for current density, filament size, dimensional control, long lengths, and low current degradation are much more stringent for the present accelerators compared with the earlier Tevatron and HERA accelerators. Also, to achieve higher field strengths with efficient use of the superconductor, the new designs require wider cables with more strands. These requirements have stimulated an active research effort which has led to significant improvements in critical current density and conductor manufacturing. In addition, they have stimulated the development of new cabling techniques, improved tooling, and better measurement techniques. The need to produce over 20 million meters of cable has led to the development of high speed cabling machines and online quality assurance measurements. These new developments are discussed, and areas still requiring improvement are identified.         Analysis of monofilament and multifilament samples obtained from Phase I of the SSCL Vendor Qualification Program    J.M. Seuntjens, V.A. Bardos, D. Christopherson, D.W. Capone II, F.Y. Clark, E.S. Coleman, M.J. Erdmann, T.J. Headley, B. Jones, V. Levy and D.K. Washburn Summary: Select samples from each cable vendor in the Superconducting Super Collider. (SSC) Laboratory Vendor Qualification Program were characterized by a series of mechanical and metallographic tests. Samples were chosen to cover the spectrum of monofilament types in each vendor's process. The tests performed were NbTi alloy hardness, tensile strength of the restack element, tensile properties of the restack element, without the copper, copper to superconductor ratio, barrier X-ray line scans, and NbTi alloy and Nb barrier image analysis. Process data supplied by each cable vendor are also analyzed to obtain extrusion k factor for monofilament and multifilament billets. The data available to date are summarized.         Continuing results of systematic error in I/sub C/ testing    M.J. Erdmann, D.W. Capone II and J.M. Seuntjens Summary: Critical current (I/sub C/) testing of the superconducting wire for the Superconducting Super Collider Laboratory (SSCL) is an important concern due to its significance in magnet variability. Established procedures to quantify measurement variability have been adapted to I/sub C/ measurements. To implement these ideas, a round robin experiment was developed and all vendor qualification program participants were required to become certified before the end of Phase II. The authors include updated results from all vendors, including foreign suppliers. The definition of each component of variability, test plan procedure quantifying each component, minimum SSCL certification requirements, current results, and future plans, are reported. Results show that all of the round robin participants have accuracy within the SSCL certified limit of +or-2% of the National Institute of Standards and Technology critical current Standard Reference Material value. Reproducibility results show that all of the test sites have less than a 2% uncertainty with the repeatability results falling between 1 and 3.5%. Cumulative uncertainty is determined to be between 1.5 and 5%.         Transverse and longitudinal resistivities in NbTi multifilamentary strands with Cu and CuMn matrices    M.D. Sumption, D.S. Pyun and E.W. Collings Summary: Transverse and longitudinal resistivities have been measured for a pair of multifilamentary strands with filament diameters of 2 mu m, interfilamentary spacing to filament diameter ratio of 0.19, and about 5000 filaments. One of these strands has a Cu matrix and the other has a CuMn matrix. 4.2-K transverse resistivities were extracted from the per cycle eddy current loss and also the magnetization of samples of various twist pitches. Longitudinal resistivities were measured with a four-terminal method at T=12 K. These results are interpreted in terms of size, proximity, and current-path effects. It is found that size effects significantly enhance both the transverse and longitudinal resistivities of the Cu matrix material, and that current-path effects significantly decrease the transverse resistivity of the CuMn material. Additionally, the proximity effect causes the resistivity of the Cu matrix to vary with magnetic field. Resistivity for the Cu matrix at high fields is about 0.6-0.8 that of the CuMn.         US maglev: status and opportunities    H.T. Coffey Summary: Recognizing the development of magnetic levitation (maglev) systems in Germany and Japan, and the growing congestion, air pollution, and energy consumption resulting from the current transportation system, the US, in 1990, embarked on a program to evaluate the potential usefulness of these systems in the US. The utility of maglev systems in alleviating some of these problems, progress in the current program, and opportunities for participation by the superconductivity and cryogenic communities are discussed.         High-temperature superconducting current leads    J.R. Hull Summary: The author reviews major high-temperature superconductor (NTS) current-lead concepts and presents several new considerations that should affect design of HTS leads. Considerable advantage is achieved by operating these leads with an intermediate-temperature heat sink. The HTS part of the lead can be made from pressed and sintered powder. Powder-in-tube fabrication is also possible, but the normal metal part of the lead acts as a thermal short and cannot provide much stabilization without increasing the refrigeration requirement. For lead stability, designs with low current density are favored. Such leads can be manufactured with today's technology, and refrigeration requirements are lower for the same allowable burnout time. Higher current densities result in lower helium boil-off for the same lead length, but burnout times can be very short. In comparing experiment to theory in open systems, the density of helium vapor must be accounted for in calculating the expected boil-off. For very-low-loss leads, two-dimensional heat transfer and the state of the dewar near the leads may play dominant roles in lead performance.         European project for the development of high T/sub C/ current leads    P.F. Herrmann, C. Albrecht, J. Bock, C. Cottevieille, S. Elschner, W. Herkert, M.-O. Lafon, H. Lauvray, A. Leriche, W. Nick, E. Preisler, H. Salzburger, J.-M. Tourre and T. Verhaege Summary: A European BRITE/EURAM project for the development of current leads in the kA range using high-T/sub C/ superconductor parts has been started recently. The partners in this two-year project are two chemical companies, Hoechst and Rhone-Poulenc, and two companies in the field of electrical engineering, Siemens and Alcatel Alsthom. The goal of these four companies is to develop current leads for 4.2-K systems making use of high-T/sub C/ superconducting materials, to manufacture them, to demonstrate their performance in comparison with conventional all-metal current lead, and to develop relevant models. The objective is the realization of a demonstration current lead toward the end of the project. This device will operate at a steady-state current of 1000 A and an insulation voltage of 20 kV. The losses will be reduced to one-third of the losses of a conventional metallic current lead. First results are given on Y- and Bi-based current lead models, including calculations and the characterization of large bulk high-T/sub C/ samples up to a length of 200 mm with a I/sub C/ value reaching 2000 A.         He I-He II electrical lead transition    X. Huang, T.M. Eyssa, J. Photenhauer and O. Lokken Summary: The authors address a new lead concept. This design would apply to electrical leads between superfluid helium (He II) baths and ordinary 4.2-K He I baths. The lead consists of a plug made of alternating copper/stainless steel (SS) thin laminates with attached superconducting strands. The laminates minimize thermal conduction from 4.2 K to He II and provide large heat capacity for protection compared to a solid SS transition. The authors have constructed and tested a 50-kA transition lead that is fully stable up to about 35 kA. Between 35 and 55 kA, the lead will have a stable temperature profile if it becomes normal. Between 55 and 75 kA, its temperature will increase slowly enough with time following a disturbance so that the protection circuit can turn off the connected power supply.         Resistive fault current limiters with HTSC-measurements and simulation    M. Lindmayer and M. Schubert Summary: The results reported concern polycrystalline Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub x/ and Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ bulk material. The transition between superconducting and normal-conducting state of YBCO and BSCCO high-T/sub C/ superconductors (HTSCs) was investigated experimentally. By using these results, simulations of the behavior of HTSC current limiters in electrical power networks were carried out. Assuming a homogeneous conductor, the self-quenching initialized by exceeding the critical current is calculated for conductors with different critical current densities. Questions of inhomogeneity along the conductor, current pulse triggering, and transient overvoltages are discussed.         A study on a coreless superconducting transformer    M. Yamamoto, N. Okada, T. Ishigohka and I. Ishii Summary: A conceptual design for a 1000-MVA-class coreless superconducting autotransformer (CLSCAT) has been developed. For a preliminary experimental study, a small 2.5-kVA CLSCAT has been manufactured and tested. The test result shows that though the exciting current of the CLSCAT is very large, its voltage drop is relatively small compared with the cored transformer. The dielectric strength of liquid helium has been tested using an insulation model. From the insulation test, the availability of the fundamental insulation structure composed of the lamination of small liquid helium gaps separated by solid barriers has been confirmed. From the conceptual design of a 1000-MVA-class CLSCAT, it becomes clear that the CLSCAT has an additional reactive power of about one-third of its rated capacity. This large reactive power can be utilized for the compensation of the capacitive charging current of a cable line or a UHV transmission line. The operating loss, was calculated to be about two-thirds of the conventional transformer. However, this figure is reduced to one-half if the additional reactive power of the CLSCAT is considered.         Author Index (1992 - Part 1)    No author information available Summary: Not available

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