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1982     Front Cover (1982)    No author information available Summary: Not available         Table of Contents (1982)    No author information available Summary: Not available         Conference Information (1982)    No author information available Summary: Not available         Superconductivity research in the good old days    J. Hulm Summary: Not available         Status and trends of S.C. magnet development in Europe    W. Heinz Summary: Many applications of s.c. magnets have been proposed and considered during the last decade. They may be classified into three catagories: S.c. magnets as research tools in particle and solid state physics, in energy technology, and for various industrial applications. All these are still pursued in Europe but a considerable shift in effort to specific projects has occurred during the last decade. Some main projects are discussed: beam line magnets for new particle accelerators, high field magnets including hybrid magnets, s.c. magnets for fusion devices such as the Large Coil Project or Tore-Supra, and s.c. magnets for NMR devices or magnetic separation of weak magnetic materials. The main trend is towards very high fields and magnets with large field volume. Both are extremely challenging for improving the conductor and magnet performance with respect to stable and non-degrading operation under mechanical load conditions. Developments in the focus of present interest are improvement of the stress-strain behaviour of Nb/sub 3/Sn conductors and operation of magnets with subcooled helium. In addition, engineering and computations to predict mechanical performance are getting more and more important.         Superconducting magnet development in Japan    K. Yasukochi Summary: The present state of R & D works on the superconducting magnet and its applications in Japan are presented. On electrical rotating machines, 30 MVA superconducting synchronous rotary condenser (Mitsubishi and Fuji) and 50 MVA generator are under construction. Two ways of ship propulsion by superconducting magnets are developing. A superconducting magnetically levitated and linear motor propelled train "MAGLEV" has developed by the Japan National Railways (JNR). A large scale test track of 7 Km was constructed in Kyushu and the test vehicle reached its target speed of 517 Km/hr. The first manned test running was made by three-vehicles train on new U-shaped guideway. The superconducting magnet development for fusion is the most active field in Japan. The Cluster Test program has beer demonstrated on a 10 T Nb/sub 3/Sn coil and the first coil of Large Coil Task in IEA collaboration has been constructed and the domestic test was completed in JAERI. These works are for the development of toroidal coils of the next generation tokamak machine. R & D works on superconducting ohmic heating coil are in progress in JAERI and ETL. The latter group has constructed 3.8 MJ pulsed coil. A high ramp rate of changing field in pulsed magnet, 200 T/s, has been tested successfully, for burning tokamak device project in IPP, by joint work of Nihon University, ETL, Mitsubishi and IPP. High Energy Physics Laboratory (KEK) are conducting active works. The superconducting /spl mu/ meson channel and /spl pi/ meson channel have been constructed and are operating successfully. KEK has also a project of big accelerator named "TRISTAN", which is similar to ISABELLE project of BNL. Superconducting synchrotron magnets are developed for this project. The development of superconducting three thin wall solenoid has been started. One of them, CDF, is progressing under USA-Japan collaboration.         Status reports on ISABELLE magnets    R. Palmer, N. Baggett and P. Dahl Summary: The design of the ISABELLE "Palmer" magnets is described. The performance of thirteen such magnets is reported. Average quench fields of 55 kG at 4.5/spl deg/K have been obtained with essentially no training. The magnets can be shown to be limited only by the short sample characteristics of the cable. Required field quality was achieved in the last four magnets.         Status of the energy saver    J. Orr Summary: The one-TeV proton synchrotron which has been under construction at Fermilab is nearly complete and is now entering the commissioning phase. The assembly and testing of the ring of more than 1000 superconducting magnets with its associated cryogenic, vacuum, power, R.F., controls and safety systems has gone extremely well.         Dipole magnet development in Japan    H. Hirabayashi Summary: Recent development of superconducting accelerator dipole magnets in Japan is described. A series of NbTi/Cu dipoles in the region of 5 to 10 T is being developed at KEK. The maximum field will depend on the maximum proton energy of the TRISTAN ring from 300 to 600 GeV. On the other hand, development of a special Nb/sub 3/Sn/Cu dipole magnet in the region of 10 T has been started for the future multi-TeV pp and\bar{p}pcolliding beam accelerator.         Mo base superconducting materials prepared by multi-target reactive sputtering    M. Ikebe, N. Kazama, Y. Muto and H. Fujimori Summary: With an aim of developing new types of superconducting materials, Mo-N films and Mo/Si multi-layered films were fabricated by reactive and two-target sputtering methods, respectively. The superconducting properties such as T/sub c/, H/sub c2/and J/sub c/were examined. The crystal structure of Mo-N films changed from bcc to fcc with increasing N/sub 2/gas flow rate during sputtering and a homogeneous fcc Mo/sub 2/N superconductor was obtained. On the other hand, the superconducting characteristics of the Mo/Si multi-layered film with a layer spacing 32.3 /spl Aring/ were confirmed to be similar to those of amorphous Mo-Si alloys except the occurrence of anisotropic vortex pinning.         Effect of rapid quenching and with Carbon and Nitrogen on the structure and superconducting properties of the Nb/sub 3/Ge compound    E. Savitsky, M. Bychkova, V. Sumarokov, G. Grabylnikova, K. Kieinschtuk and G. Fosterling Summary: The effect of rapid quenching and alloying with carbon and nitrogen on the superconducting properties of the Nb/sub 3/Ge compound has been studied. The quantitative phase X-ray analysis of the studied specimens depending on the content of alloying components has been carried out. The temperature at which the transition into the superconducting state occurs as well the parameters of the alloy lattices have been investigated.         Quenches of formvar - coated NbTi/Cu caused by step input in power    Li-He Lin, C. Chuang, Y. Kim and T. Frederking Summary: We have investigated the stability of the composite Nb48Ti/Cu coated with a formvar layer (30 /spl mu/m thick). Starting from thermal equilibrium in the superfluid liquid He II range below the lambda temperature (T = T/sub /spl lambda//), the composite temperature is found to rise first monotonically with time t, upon onset of energy dissipation. However, restricted stability is visible as a relative temperature maximum (T/sub max/) of the composite at the time t/sub max/, followed by a relative minimum in T at t/sub min/. These coated composite phenomena are similar to stability conditions of bare composites in the same "conductor-in-box " geometry employed. However at a specified power the times t/sub max/and t/sub min/are shifted in comparison to the bare composite. Diagnosis is based on power-time functions whose tangents are characterized by power law exponents (m) . The m-values found are re - presentative of strong, localized solid - coolant interaction, of a caloric condition, or of locally turbulent fluid motion. In the range covered by the present transients, stability is available by creation of entropy - rich buffer domains of fluid, below the superconducting transition temperature, between He II and the heated composite. The latter is quench - protected in an intermediate power range.         An attempt to reduce training using filled epoxy as an impregnating material    S. Nishijima, K. Shibata, T. Okada, K. Matsumoto, M. Hamada and T. Horiuchi Summary: Selection of impregnating materials has been made in order to reduce training of superconducting magnets based on their mechanical and/or thermal properties. Race track shaped coils which are assumed to show marked training, are impregnated with several materials and energized. Epoxy resin filled with alumina powder is found to show superior behavior to those of wax or epoxy resin itself as an impregnating materials.         Computer analysis of transient heat transfer from coated surfaces    A. Menard and D. Holmes Summary: The transient thermal response of internally heated, coated surfaces in contact with liquid helium was investigated with a previously developed computer model. The coatings were found to affect the time required to initiate film boiling or to quench a superconductor in the substrate. The energy which can be absorbed without an unacceptably large temperature rise depends most strongly upon the coating thermal property group (kpC/sub p/)/sup 1/2/and on the peak nucleate boiling heat flux. Dielectric materials for electrical insulation usually have low thermal property group values, but a new class of ceramic materials shows great promise for application with superconducting devices aselectrical insulations with good thermal properties. Coating materials with thermal property group values greater than that of OFHC copper at liquid helium temperatures provide the same thermal stability as a bare copper surface exposed to the helium bath. Possible applications of the new materials to potted windings are also discussed.         Nb/sub 3/Sn-composite conductors with Aluminum as electrical stabilizer and stainless steel as mechanical reinforcement    P. Turowski and L. Lin Summary: Three-component conductors composed of a preheat-treated Nb/sub 3/Sn flat cable, aluminium, and stainless steel were soldered together in a straight alignment and then wound in a single-layer coil with a diameter of 90 mm. The performance of the composite conductor was determined mainly by the position of the steel, because the steel shifts the neutral plane considerably due to its high modulus of elasticity and can generate high compressive forces on the Nb/sub 3/Sn with a consequent reduction of critical current density. The aluminum stabilizer developed its full stabilizing performance only in close contact with the superconductor, because resistive layers between them cause partial resistivity in the superconductor.         Oxygen-free Copper at 4 K: Resistance and magnetoresistance    F. Fickett Summary: Oxygen-free copper is the most common material used for stabilizing practical superconductors. This type of copper may show residual resistance ratios (RRR) that vary from 50 to 700 in the full soft condition. Knowledge of the exact RRR value is often essential for optimum system design. We have investigated the effect of stress, temper, and reanneal on the RRR and magnetoresistance of several hundred samples of oxygen-free copper from many sources. In this paper we describe the program and present a sampling of the results obtained to date.         Normal zone stationary distribution in superconducting composites with contact resistance    A. Akhmetov and R. Mints Summary: Heat and electrical contact resistances exist in composite superconductors between the normal metal and the superconductor in most cases. Frequently by some reasons these resistances are high enough. It is shown in this paper that in composite superconductors with noticeable contact resistance the existence of the resistive regions of finite size is possible. Such regions (resistive domains) are stable in the regime of fixed current and the temperature and the current density are non-uniform in the cross-section of the composite superconductor in the vicinity of the resistive domain. We find the I-V characteristic of a sample with a resistive domain and the minimum domain existence current i/sub r/. It is shown that the current i/sub r/is much less than the minimum normal zone propagation current i/sub p/. We investigate the process of the resistive domain formation due to the heat pulse. Note that the resistive domains are unstable in the regime of fixed current in uniform composite superconductors without the contact resistance and are stable in non-uniform ones. The existence of the stable resistive domains largely regulates the process of the superconductivity destruction and the following recovery of the superconductivity in the presence of the transport current. Moreover the resistive domains existence is responsible for some hysteresis phenomena accompanying the superconductivity destruction and recovery. Some previous results were published in the short note.         Origination and oscillations of normal zone in superconductors    V. Baev, A. Gurevich, R. Mints and M. Ushomirsky Summary: Dynamics of normal (N) zone regions (resistive domains) in uniform and nonuniform superconductors has been investigated both theoretically and experimentally. An analytical theory has been proposed to describe the resistive domains (RD) dynamics in nonuniform superconductors with the alternating current. The origination and localization of RD have been considered. The self-exited relaxation oscillations of the voltage were observed experimentally. The oscillations are due to the self-exited ones of the RD length when the inductance of the circuit is large enough. The superconducting sample in our experiment was made from the multifilament Nb-40%Ti cable, the characteristic values of the oscillations frequency f and the inductance L were of the order of 1 Hz and 20 /spl mu/H respectively. The theory proposed is in a good agreement with the experiment.         Current-carrying capacity of composite superconductors    V. Andrianov, V. Baev, S. Ivanov, R. Mints and A. Rakhmanov Summary: The maximum transport current I/sub m/of the composite superconductors is investigated both theoretically and experimentally. It is shown that the high values of the transport current observed in these materials is due to the non-linear part of the current-voltage characteristic in the range of low electric fields (E /spl lsim/ 10/sup -6/ Vcm/sup -1/). The conductors of rather different structure with Nb-Ti superconducting filaments were tested in a wide range of the external parameters. It is shown that in the external magnetic fields B/sub a/ /spl gsim/ 1 Tthe ratio I/sub m//I/sub c/(where I/sub c/is the critical current) is the universal function of the single dimensionless parameter which depends on the sample properties and the external conditions. The theory and experiment are in a good agreement.         The effect of field orientation on current transfer in multifilamentary superconductors    L. Goodrich Summary: Experimental data and discussion are presented on the current distribution along the length of a superconducting wire when subjected to multiple parallel and perpendicular magnetic fields. The experimental data were taken on a rectangular pancake coil with the applied magnetic field in the plane of the coil. These data indicate that significant current transfer occurs in the first and last perpendicular magnetic field sections and little transfer occurs between these two sections. The implication for superconducting magnet design will also be discussed.         A low loss NbTi multifilamentary composite conductor for A.C. use    T. Ogasawara, Y. Kubota, T. Makiura, T. Akachi, T. Hisanari, Y. Oda and K. Yasukochi Summary: Investigations of a.c. losses and stability of a mixed-matrix NbTi multifilamentary conductor are presented. Fine filament size of 1.0 /spl mu/m and a tight twist of 5.5 times the wire diameter 0.2 mm result in a time constant of the eddy current of 0.024 msec at 1.0 T. If this conductor is used in superconducting armature windings of rotating machines or in a.c. magnets, generating a maximum field of 1.0 T, economical benefits are expected at operation frequencies below 20 Hz.         Selffield losses and selffield stability of superconducting wires with low conductivity matrix material    J. de Reuver, J. Mulders and L. van de Klundert Summary: The influence of the normal material in a superconducting wire on the selffield losses has been investigated. The results show that the contribution of the normal material is considerable in the case of a highly conductive material like Cu. Measurements on wires with CuNi-material show no significant contribution of the normal material to the losses. In the latter case, however, special attention should be paid to stability. Measurements show that the obtainable maximum current under a.c. conditions obeys the adiabatic stability criterion rather well. The dependence of the maximum current amplitude on the critical current density and the diameter of the wire has been obtained. Wires with Al cores inside the NbTi filaments for better stabilization have also been investigated regarding maximum current and selffield losses.         Reduction of A.C. losses by decrease of the surface barrier    M. LeBlanc and J. Lorrain Summary: We report on an extensive computational investigation of the effect of the surface barrier on hysteresis losses. These model calculations reveal that the losses can be substantially diminished by lowering the height of the surface barrier. The calculations were carried out for planar (ribbon) and for cylindrical (wire) geometry with the applied magnetic field directed along the surface(s) of the sample and swept between (i) 0 and H/sub max/. (half-wave cycle) and (ii) /spl plusmn/H/sub max/(full-wave cycle). We examined the behavior for amplitudes below and above that required for full penetration of the flux disturbance to the center of the specimen. We have explored the phenomena for two extremal types of bulk pinning, namely the Bean-London (J/sub c/= /spl alpha//sub 1/) and the Kim-Anderson (J/sub c/= /spl alpha//sub 0//B) approximations. We have, for simplicity, assumed that the barrier height is field independent and either symmetric (opposing flux entry and exit equally) or asymmetric (opposing flux entry only).         Extending an internally cooled superconducting magnet to higher fields    J. Lue and J. Miller Summary: An internally cooled superconducting (ICS) magnet was built and tested earlier at Oak Ridge National Laboratory (ORNL), and its stability margin as a function of operating fields was measured at an ambient helium temperature of 4.2 K. In the experiment reported here, we retested this magnet with lower bulk helium temperatures. The stability margins of the magnet as a function of temperature were measured. The results demonstrate clearly the flexibility offered by an ICS magnet: The stability margin can be improved substantially or the field output can be extended without sacrificing the stability margin simply by feeding the magnet with lower temperature helium. The analysis made in a previous paper on extended field operation of an ICS magnet is thus confirmed.         Conductor design for superfluid Helium II    J. Parmer Summary: This paper derives some design formulas and charts for a high-field (12 Tesla) application using Nb43Ti25Ta alloy superconductor. This material is selected because of its large critical current (J/sub c/= 71,000 A/cm/sup 2/) at 12 Tesla and 1.8K. Its ductility is beneficial to manufacturing processes and accommodating of the operating condition under stress. A coil packing factor of 70% and an insulation void fraction of 35% are assumed. These are nominal values which, after analysis, leave adequate turn-to-turn space for insulation bearing area, Helium II volume, and voltage standoff. The stabilizer is oxygen-free, high-purity copper in the full-hard condition, /spl rho/ = 7.17x10/sup -8/ohm.cm, wherein the magnetoresistivity at 12 Tesla accounts for 69% of the total. Basing a trial conductor on these assumptions will produce a design very close to optimum. Further refinement would be an iterative process whereby one checks the design against all constraints using the fundamental engineering formulas and makes parametric adjustments as necessary.         Heat transfer and stability characteristics of cable bundles in He I and subcooled He II    A. Khalil, K. Stocker and S. Van Sciver Summary: Results from two experiments aimed at understanding the stability of cabled composite superconductors are reported. The first is a heat transfer study of stainless steel tubular bundles. The peak heat flux from these test sections is investigated as a function of number of bundle tubes and gap between each tube. Experiments are performed in both He I at 4.2 K and subcooled He II at approximately 2 K. Results indicate that the peak heat flux is supressed substantially as the gap between tubes is reduced. With zero gap the surface averaged heat flux is only about 20% of that achieved with large gaps roughly equivalent to an open bath. The second experiment consists of a stability measurement on a bundled composite conductor. The test section is made up of a 66.3 cm length of a 7 wire bundle. The six outer wires are copper-NbTi composites while the core is an insulated resistance wire. Normalization of the conductor, either achieved by exceeding I/sub c/or by pulsing the heater, is detected by voltage taps across the inductively wound test section. Stability measurements made in both He I and He II are correlated with the heat transfer results in the first experiment.         Experimental study of the stability of a superconductor cooled by a limited volume of superfluid Helium    C. Meuris Summary: Stability experiments have been carried out to confirm the validity of a theoretical model which provides us with the conditions of stability of a superconductor cooled by a confined volume of superfluid helium at atmospheric pressure, and subjected to short duration high energy disturbances affecting a large length of conductor. The conductor is quenched by a high power (typically 10 W/cm/sup 2/per unit of cooled surface area) injected in a short time (540 /spl mu/s) by the discharge of a capacitor bank. Experimental results suggest that transient phase transitions occur at the interface conductor-helium during the heat exchange. Dynamic studies of the superconductor and superfluid states are performed. A good agreement is found between the theoretical analysis and the experimental results which allows to give a useful relationship among the maximum current density, the disturbance energy, the cooling channel configuration, and the bath temperature.         Microstructural features of coevaporated Nb/sub 3/Ge films    D. Yin, W. Schauer and F. Wuchner Summary: The microstructure of coevaporated Nb/sub 3/Ge films was studied by means of transmission electron microscopy (TEM). Large area inspection of this material with reproducible high T/sub c/shows two kinds of grains sized about 200 /spl Aring/ and 1000 /spl Aring/ in diameter, respectively, with an overall average size of 600 to 800 /spl Aring/. Images of various lattice defects could be seen, especially a large amount of low angle boundaries with different types of characteristic moire patterns. Two states of the Nb/sub 2/Ge/sub 3/phase have been revealed by dark field imaging: a lamellar and a granular structure. - Some high resolution structure images of Nb/sub 3/Ge are shown.         Critical current of Nb/sub 3/Sn practical superconductors in high magnetic field    Zhou Lian Summary: The critical currents of Nb/sub 3/Sn practical superconductors were measured in high magnetic fields up to 22 T at 4.2 K. The conductors investigated were MF Nb/sub 3/Sn wire, CVD-Nb/sub 3/Sn tape and diffusion processed Nb/sub 3/Sn tape. The measurements show that the conductors have excellent superconducting properties. The multifilamentary Nb/sub 3/Sn wire possesses a higher overall current density Jc/sup ov/(Nb/sub 3/Sn + bronze), especially in high fields above 12T. Its Jc/sup ov/, for example, is 2.4x10/sup 4/A/cm/sup 2/at 15T. The CVD-Nb/sub 3/Sn tape displays a higher Jc in the fields up to 12T, while the diffusion processed Nb/sub 3/Sn tape has an excellent Jc(Nb/sub 3/Sn) in high field. Their Jc(Nb/sub 3/Sn) ,for instance, are 4.0x10/sup 5/A/cm/sup 2/(at 11T) for CVD-Nb/sub 3/Sn and 1.7x10/sup 5/A/cm/sup 2/(at 15T) for diffusion processed Nb/sub 3/Sn tape, respectively. The upper critical field Bc2 are determined extrapolately by using Kramer's scaling law for flux pinning. A discussion is presented respect of the results of measurement and the upper critical field.         NbTi superconducting composite with high critical current density    Li Cheng-ren, Wu Xiao-zu and Zhou Nong Summary: In order to make NbTi50/Cu superconducting composite obtain high critical current density, we have studied carefully the melting method for NbTi50 alloy and the effect of cold work and heat treatment on critical current density. The results show that the ingots obtained through vacuum arc and a vacuum skull furnace melting can be used to fabricate NbTi superconducting composite with high critical current density. Cold work and heat treatment are the important factors which effect the critical current density of NbTi50/Cu superconducting composite. The restarts show that intermediate ageing treatments have improved the critical current density of NbTiSO/Cu composite. If a sample is treated intermediately for several times before final ageing, the Jc of the sample is much higher than that of the final aged sample of the same ageing time. As the intermediate ageing number is increased, the value of Jc (5T,4.2K) increased. It increased rapidly especially at the second and the third ageing. When the cold work between ageing treatments is increased, the value of Jc (5T, 4.2K) increased markedly. The heavier the cold work between ageing treatments is, the higher the Jc (5T, 4.2K) will be. Final deformation has further improved the critical current density of NbTi50/Cu composite in our range of experiment, Jc (5T, 4.2K) increased rapidly for the samples aged at 350/spl deg/C and 385/spl deg/C when the final deformation increased. The value of Jc (5T, 4.2K) comes up to 3.4x10/sup 5/A/cm/sup 2/for the sample of the final deformation 90% after the last ageing at 385/spl deg/C. In order to make NbTi50/Cu superconducting composite obtain high critical current density, cold work and heat treatment must be regulated and coordinated appropriately. We have chosen suitable heat treatment and cold work so that the highest critical current density has reached 3.9-4.14x10/sup 5/A/cm/sup 2/(5T, 4.2K) for the optimum NbTi50/Cu multifilamentary composite.         Geophysical applications of SQUIDS    J. Clarke Summary: Present and potential geophysical applications of Superconducting Quantum Interference Devices (SQUIDs) include remote reference magnetotellurics, controlled-source electromagnetic sounding, airborne gradiometry, gravity gradiometers, rock magnetism, paleomagnetism, piezomagnetism, tectonomagnetism, the location of hydrofractures for hot dry rock geothermal energy and enhanced oil and gas recovery, the detection of internal ocean waves, and underwater magnetotellurics.         An integrated DC SQUID cascade    A. Davidson Summary: An integrated tunnel junction dc SQUID cascade has been built and some of its operating characteristics measured. It is shown for the first time that good modulation can be achieved with a remote termination for the tunnel junction shunts. Response time of one of the SQUID's in the cascade was measured to be better than 5 nanoseconds. Maintenance of this high speed is an advantage of the cascade arrangement over other schemes for matching and reading-out dc tunnel junction SQUID's. True cascade operation was not obtained, due to coupling of Josephson oscillations from the first Stage of the cascade to the second.         Improved multi-loop DC SQUID    P. Carelli and V. Foglietti Summary: We report on an improved version of a multiloop thin film dc-SQUID. The new design features thirty-two parallel loops, a loop area of 400 X 400 /spl mu/m, a total inductance of 20pH, and a coupling constant of 0.5 between the SQUID and the thin film input coil. Particular care was taken to decrease the capacitance shunting the main inductance. A novel "chessboard" design was used for this purpose. Preliminary results in a flux locked loop configuration give a coupled energy sensitivity of 900h at 1KHz with very low l/f noise.         Double transformer coupling to a very low noise SQUID    B. Muhlfelder, W. Johnson and M. Cromar Summary: We demonstrate a new way to couple efficiently to a low-inductance, low-noise SQUID. We have built and tested a planar dc SQUID with an integral matching transformer. The measured coupling agrees with our calculations. We demonstrate that this configuration can efficiently couple a 1 /spl mu/H signal source to a 16 pH SQUID loop. We have also built an uncoupled SQUID of this design that has an energy sensitivity, referred to the SQUID inductor, of 1.3x10/sup -32/J/Hz = 20 h over a flux range of about 0.15 /spl phi//sub 0/.         High-T/sub c/SNS dc SQUIDs produced by electron beam lithography    M. Dilorio, A. de Lozanne and M. Beasley Summary: We have utilized electron beam lithography to fabricate dc SQUIDs incorporating Nb/sub 3/Ge/Cu/Nb/sub 3/Ge step-edge microbridges. The primary advantage of this process, over conventional lithography, is to decrease the width of the microbridges and hence increase their normal resistance. The microbridges produced typically have normal resistances between 0.1-1.0 /spl Omega/, and we have investigated the behavior of the resistance as the width is scaled down. The dc SQUIDs operate without hysteresis over a wide temperature range and exhibit substantial critical current modulation in the presence of a magnetic field, from which we estimate the inductance of the SQUIDs to be about 13 pH. These devices should possess extremely low self-heating effects by virtue of the two-dimensional geometry of the banks made possible by the use of a novel ion beam etching technique. Preliminary noise measurements indicate an intrinsic energy sensitivity as low as 3 h at 2.2 K.         Experiment of 10-T, 60-cm-bore Nb/sub 3/Sn test module coil (TMC-1) for the cluster test program    T. Ando, S. Shimamoto, T. Hiyama, H. Tsuji, Y. Takahashi, M. Nishi, K. Yoshida, E. Tada, K. Okuno, K. Koizumi, T. Kato, H. Nakajima, L. Dresner, F. Iida, Y. Sanada, M. Shimada, O. Takahashi and K. Yasukochi Summary: A 60-cm-bore coil wound with a reacted multifilamentary Nb/sub 3/Sn conductor, named as TMC-1, was constructed. A magnetic field of 10.2 T was successfully generated at a current of 6,056 A with a back-up field of 3.3 T from the cluster test coil. The total stored energy was 39 MJ. The strain of the Nb/sub 3/Sn conductor was 0.67 % including a bending strain of 0.54 % during winding. Moreover, a 30-cm-length normal zone, nucleated by heater-input technique in the innermost turn, was recovered to superconducting state at 10 T. This means that a heat flux of conductor cooling surface is more than 1.08 W/cm/sup 2/. For the manual dump with a decay time of 14 second(B=0.48 T/sec.), the TMC-1 was stable without any damage. The TMC-1, which is pool-cooled at 4.2 K, is constructed as a step of the development of high field toroidal coil in a tokamak fusion machine. From thease results, it is demonstrated that multifilamentary Nb/sub 3/Sn conductor is applicable to large-current and large-size coil.         Status of the Swiss LCT-coil    J. Zichy, I. Horvath, B. Jakob, C. Marinucci, G. Vecsey, P. Weymuth, J. Zellweger, H. Benz, Th. Hilpert, K. Kwasnitza, R. Maix, H. Marti, G. Meyer, J. Rauch and A. Segessemann Summary: The Swiss coil is a forced flow coil cooled by supercritical helium. Following, a brief review of the design considerations, some of its specific features, and the progress in fabrication are described. Next a discussion of both the instrumentation and the cryogenic characteristics of the coil are presented.         Development of a forced-cooling D-shaped superconducting coil by supercritical helium    Y. Wachi, A. Miura, T. Hamajima, T. Uchida, M. Yamaguchi, H. Ohguma, S. Murase, H. Shiraki and T. Fujioka Summary: A D-shaped 12 Tesla superconducting coil with forced cooling Nb/sub 3/Sn superconductor is developed. Cryogenic stability and conduit stress analyses, result of winding test of copper dummy coil, add cooing system for the test coil are presented.         A superconducting toroidal magnet with quasi-force-free configuration    Bi Yanfang and Yan Luguang Summary: A quasi-force-free toroidal magnet has been designed and constructed with 1.8kg, 0.5mm in diameter multifilamentary twisted NbTi composite wire. The magnet major radius is 13.7cm and minor radius is 1.17cm. During test the magnet reached 279A critical current, 6.4T peak field and 14.4kJ stored energy, the superconductor current density is 4x10/sup 5/A/cm/sup 2/. This is corresponding to the magnet "short-sample" performance, when the angle between current and field is near 17/spl deg/. The test result demonstrated clearly the advantage of superconducting force-free magnet and the correctness of the design method.         Comparative evaluation of existing concepts for a 10 tesla FED toroidal field coil    W. Chen, J. Alcorn and J. Purcell Summary: The existing design concept options for FED toroidal field coils have been studied and evaluated by General Atomic Company as part of the FED/INTOR Critical Magnetic Issues effort for 1982. The various design concepts studied are: (1) forced flow cooled NbTi cabled conductor, (2) He-II bath cooled NbTi cabled conductor, and (3) He-I bath cooled Nb/sub 3/Sn-NbTi hybrid with cabled conductor. These design concepts are evaluated based upon their relative merits, including technological maturity, operational reliability, overall reactor compatability, maintainability, and cost. An important aspect of this study was the normalization of each design concept to meet similar operational requirements. The critical issues in the TF coil design, including the structural role of the helium vessel, quench protection, accommodation of neutronic and eddy current heating, credible fault criteria, and the possibility of prototype coil demonstration are discussed. The consequences and implications of extending the peak field in the range from 8 to 10 tesla was also studied.         Cryogenic system for Superconducting Tokamak    S. Shimamoto, T. Ando, T. Hiyama, H. Tsuji, E. Tada, Y. Takahashi, K. Yoshida, K. Koizumi, T. Kato, H. Nakajima, O. Takahashi and Y. Sanada Summary: The purpose of this paper is to give an overall view of the superconducting coil system and to describe the details of the helium cryogenic system for Superconducting Tokamak Test Assembly (STTA) which is a medium-size superconducting tokamak and designed on the basis of tentative parameters chosen through the design work at the Japan Atomic Energy Research Institute (JAERI). The STTA is composed of the superconducting toroidal field (TF) coils which have similar configurations to those of a test coil for the Large Coil Task (LCT), the superconducting poloidal field (PF) coils whose diameter is 2-10 m, and other facilities required for the power generation. The capacity of the helium cryogenic system for the STTA is specified to be 3,000 liters of liquefaction per hour or 12 KW of refrigeration at 4.4 K, reliable for more than 6,000 hours, and high energy efficiency more than 1/500. The cryogenic system can cool the STTA with cooling weight of 1,000 tons down to 4 K in 10 days, and absorb the heat load of 5,000 W and 1,500 1/h at 4.4 K. In addition, the cryogenic system is designed to be able to produce and supply 650-g/s, 4.5-K, and 1.0-MPa supercritical helium to the TF and PF coils. This system is expected as a unit of the cryogenic system for Fusion Experimental Reactor (FER) after JT-60.         Experimental investigation of the dynamic stability of pulse superconducting magnets    S. Han, C. Zhang, Z. Feng, K. Luo, K. Li, Z. Gao, S. Song and H. Huang Summary: The article is concered with the development of pulse superconducting conductors and magnets, some problems about dynamic stable tests for the composite conductors and magnets are summarized. The tested magnets are solenoids and dipoles with bore of 10 cm and 15 cm. According to those test results, the training effect, degredation, quench process and excitation rate are discussed.         A 25 kA, 2T, 78 kJ, 52 litre superconducting test coil. Strength calculations and construction    H. ten Kate, A. Holtslag, J. Knoben, H. Steffens and L. van de Klundert Summary: Within the scope of our research program for a 25 kA superconducting rectifier, we have built a 25 kA s.c. coil being a single layer solenoid with a bore of 0.45 meter and a volume of 52 litre. The starting point for the design was to avoid any metallic structural material. This unique coil consists of 26 turns of a Rutherford cable in one layer covered at the outside with 6 millimeter glassfibre reinforced epoxy, in order to lower the azimuthal and axial stresses in the conductor to acceptable values. The coil has been vacuum impregnated with a glassfilling factor of 0.529. The paper describes the strength calculations and the construction details. A theoretical analysis of the mechanical behaviour of the glassfibre-epoxy-conductor lamination is given.         Further tests of the Argonne 3.3-MJ pulsed superconducting coil and its nonmetallic cryostat    S. Kim, C. Krieger and D. McGhee Summary: A split-pair superconducting coil of the Pulsed Cable Test Facility (PCTF) at Argonne National Laboratory (ANL) has been successfully tested both in dc and pulsing modes. At a peak operating current of 11 kA, the peak magnetic field and stored energy of the coil are 6.5 T and 3.3 MJ, respectively. In the pulsing test, the coil was charged to 10.55 kA in 1.0 s and discharged to zero in 1.6 s. The ac losses of the coil in this mode were 7.5 kJ/pulse. The coil is composed of two solenoids each with 22 layers and 9.14 turns per layer. The cable for the coil consists of 24, 19-strand NbTi subcables. The nonmetallic cryostat of the PCTF consists of two fiberglass reinforced polyester resin vessels. Developmental high current conductors can be tested under the PCTF pulsing magnetic fields in a form of pancake coils or as a short sample for the studies of pulsing effects.         Experimental study of power system stabilization by superconducting magnetic energy storage    T. Shintomi, M. Masuda, T. Ishikawa, S. Akita, T. Tanaka and H. Kaminosono Summary: Superconductive Magnetic Energy Storage (SMES) is one of the effective measures to suppress system instabilities in electric power networks because of its fast response at exchanging electric power. Two types of experiments, dynamic and transient, have been performed to suppress instabilities by using an SMES unit on a model power system. The test system has a 60 kVA synchronous generator, a double-circuit transmission line connected to an infinite bus, and an SMES unit with an SCR converter. They simulate a salient pole synchronous generator of 600 MVA and a transmission line of 275 kV with 380 km in length. The SMES unit whose maximum stored energy is 100 kJ can exchange energy matched with the model system. The SMES unit could effectively suppress these instabilities by exchanging energy.         Constant tension winding in a single layer rippled solenoids    B. Nilsson and Y. Eyssa Summary: The forces on a rippled single layer coil are exactly calculated. The ripple shape is changed in a series of iterations to arrive at constant tension zero bending shape. Analytical expressions and numerical methods are included.         A wide bore superconducting magnet for the Nicolet GC/MS system    Y. Huang and R. Gummer Summary: Nicolet Instrument Corporation (NIC) is engaging in manufacturing high resolution Fourier transform mass spectrometer (FT-MS). The instrument called for a wide bore superconducting magnet to trap sample ions so as to generate cyclotron motion. The critical requirements consisted of 20 cm warm bore, 2 teslas central field, high field homogeneity in large volume, high field stability, high magnet reliability, simple charging/discharging procedures, low liquid helium and nitrogen boil-off rates and long liquids holding time. This paper presents the magnet design considerations, magnet construction experience and magnet test results.         Error field generation of solenoid magnets    J. Saunders Summary: Many applications for large solenoids and solenoidal arrays depend on the high precision of the axial field profile. In cases where requirements of /spl utri/B/B for nonaxial fields are on the order of 10/sup -4/, the actual winding techniques of the solenoid need to be considered. Whereas an ideal solenoid consisting of current loops would generate no radial fields along the axis, in reality, the actual current-carrying conductors must follow spiral or helical paths. A straightforward method for determining the radial error fields generated by coils wound with actual techniques employed in magnet fabrication has been developed. The method devised uses a computer code which models a magnet by sending a single, current-carrying filament along the same path taken by the conductor during coil winding. Helical and spiral paths are simulated using small, straight-line current segments. This technique, whose results are presented in this paper, was used to predict radial field errors for the Elmo Bumpy Torus-Proof of Principle magnet. These results include effects due to various winding methods, not only spiral/helical and layer-to-layer transitions, but also the effects caused by worst-case tolerance conditions both from the conductor and the winding form (bobbin). Contributions made by extraneous circuitry (e.g., overhead buswork and incoming leads) are also mentioned.         Superconducting magnets for gyrotron tubes    Y. Hsu, J. Purcell and R. Prater Summary: Six superconducting magnet systems have been designed and built for gyrotron tubes furnished by Varian. The systems are being installed on the General Atomic Doublet III Tokamak Fusion Device for radio frequency heating. They will initially operate at 60 GHz requiring a 2.5 T field, but the magnets can be operated to 5 T for possible upgrade to 120 GHz. Key design features include high precision coil winding, high precision coil positioning (concentric with bore), low helium boil-off rate, and a one week operating time without refilling. A low operating current of 7 A for 60 GHz operation was selected for reducing the heat leak through the power leads. Aluminum tape and superinsulation are utilized to decrease the radiation heat leak. The overall dimensional constraint makes it difficult to keep the helium boil-off rate very low. Two systems have been operated with 60 GHz gyrotron tubes. The tubes have been brought up to full power and the performance of the magnet is satisfactory. The average liquid helium boil-off rate is 0.4 l/hr, i.e., liquid helium will last for six days without refilling. The liquid nitrogen cooled thermal shield must be refilled every three days. The detailed design, construction, and testing results are presented.         Manufacture of the hollow supercritical He cooled conductor for the ECN/Sultan project    W. Franken, A. deVries, H. terBeeke, M. Brieko, B. Strauss, S. Torrey and T. De Winter Summary: This paper describes the manufacturing process for the conductor used in the ECN contribution to the Sultan project. This conductor which is cooled by forced flow supercritical helium is composed of a 16 strand Rutherford Cable continuously soldered to a rectangular copper tube. The requirements of the magnet design criteria on the choice of materials and manufacturing methods is discussed. In particular the final manufacturing method of joining the conductors by a "continuous casting" process is described in detail.         Design & manufacture of the superconductor for the MHD magnet for the university of Tennessee space institute    R. Randall, W. Larson, J. Wong and S. Wang Summary: This conductor design was developed through the joint efforts of the designer and the manufacturer. It fulfilled the magnet designer's requirements and was easily amenable to standard manufacturing techniques. This conductor could be easily graded depending on the field variation in the magnet. Three different grades were used in this magnet. The design will also permit the manufacture of larger, higher current conductors for future magnets without introducing major new process development. The conductor consists of a cable soldered into a slot in a copper backing strip. The same wire (at different diameters) was used for all three grades of conductor. Details of conductor design are reviewed and the manufacturing process is described.         Experimental parameter study of subsize Nb/sub 3/Sn cable-in-conduit conductors    M. Steeves and M. Hoenig Summary: An experimental study of the influence of design parameters on the short sample critical current of Nb/sub 3/Sn cable-in-conduit conductors at 4.2 K is presented. These internally cooled and cabled superconductors (ICCS) are subsized versions of the conductor used in both the Westinghouse Large Coil and 12 Tesla Programs. Parameters investigated are cable compaction, conduit material, twist pitch and activation time and temperature. The results indicate that mechanical coupling between the conduit and cable has a strong effect on the residual strain of the Nb/sub 3/Sn and hence its superconducting properties.         Lap joint resistance of Nb/sub 3/Sn cable terminations for the ICCS-HFTF 12 tesla coil program    M. Steeves and M. Hoenig Summary: Lap joint resistance as a function of current and magnetic field has been measured across 12 Tesla Coil conductor cable terminations. The terminations were at the ends of a 2.2 m Nb/sub 3/Sn hairpin of internally cooled and cabled superconductor (ICCS), and were soft soldered to NbTi bus bars. The resulting lap joints were each 15 cm long with a contact area of 19.8 cm/sup 2/. The maximum measured lap joint voltage drop was 75 /spl mu/V at 21 kA and 4.2 K, with the cable center at zero magnetic field. This represents an upper bound on all measured voltage drops, including those with the cable center at 10 and 12 T, and corresponds to a maximum heat flux of 0.01 w/ cm/sup 2/to pool boiling helium. The results imply that the 12 Tesla Coil, with four lap joints, would dissipate less than 7 watts in the steady-state at 21 kA. The zero field results and results at cross fields of 10 and 12 T are discussed. Manufacturing and experimental parameters relevant to this study are also considered.         The forced cooled Nb/sub 3/Sn superconductor and its magnet    K. Agatsuma, K. Kaiho, K. Koyama, O. Kohno, Y. Ikeno and N. Sadakata Summary: The coil is a 0.6 m outer diameter solenoid, made up of eight double pancakes which will be tested in a forced cooled test facility that has been already constructed. The hollow conductor consists of a couple of Nb/sub 3/Sn flattened cable in the center, a couple of Oxygen Free Copper stabilizer and the outside welded sheath. Some features of this conductor are as follows; the cooling mechanism by forced cooled supercritical helium and the high current capacity. The experimental results of this conductor and its magnet will be presented in this paper.         Development of a 30-kA cable-in-conduit conductor for pulsed poloidal coils    Y. Takahashi, L. Dresner, H. Tsuji, E. Tada, K. Okuno, T. Kato, M. Nishi, Y. Sanada, F. Iida, T. Ando, S. Shimamoto and K. Yasukochi Summary: This paper describes designed parameters of a 30-kA cable-in-conduit conductor (JF-30), and the test results of stability margin measured by using a triplex in a conduit. Cross sectional size of JF-30 is 35mm X 35mm and 567 NbTi-Cu-CuNi strands are in a stainless steel conduit whose thickness is 2 mm. Void fraction is 33 % and the designed stability margin is 270 mJ/cc at 5 atm and 7 T. Stability test by a triplex showed a favorable margin, a few hundreds of mJ at 7 T even without helium flow. In addition, the stability was strongly increased when helium flow up to 0.2 g/s was applied. At around 3 atm, we found that the stability margin was mere than 2 J/cc which exceeded the present heater capacity. This resulted in an extension of current range, in which the sample is stable, up to 150 to 200 % when compared to the case without helium flow.         Boiling helium heat transfer characteristics in narrow cooling channel    M. Nishi, T. Ando, T. Hiyama, T. Kato and S. Shimamoto Summary: For design of a stable superconducting magnet with pool cooling method, the size of the cooling channel is one of the important factors to determine its overall current density. We measured the steady state boiling helium heat transfer characteristics in a 600 mm long vertical cooling channel. The result shows that heat transfer characteristics in film boiling region do not become worse so far as the channel is not extremely narrow and rather becomes better adding some amount of bubbles in the channel, whereas that in nucleate boiling region becomes worse monotoneously and rapidly as the thickness of the channel decreases. From these results, it proves to be much better to choose the superconductor whose critical temperature is high to get the high current density stable magnets and also proves to be able to design stable pool-boiling magnets as large as toroidal coils for Tokamak machines of the next generation.         Installation, checkout and operation of the largest, uniform field, superconducting solenoid magnet    K. King Summary: TRW's experience in installing, checking out and operating a large superconducting magnet system is described. The magnet is a solenoid 8 meters long, with 1 meter clear bore and 2 Tesla uniform field. It is a central element in a facility designed to support development of the Plasma Separation Process, an advanced technique for uranium enrichment. The emphasis in this paper is on comparisons between expected versus actual behavior and on useful lessons learned. Subjects covered are: system installation and checkout; cooldown; influence of "nonmagnetic" materials on field uniformity; addition of a room temperature trim coil; and problems involving refrigeration capacity and oil contamination in the coldbox.         Internally cooled cable superconductor (ICCS) for TF and PF coils of FED    V. Srivastava, J. Lue and M. Lubell Summary: Internally Cooled Cable Superconductor (ICCS) concepts developed for TF and PF coils of FED are described. These concepts represent one of the options for FED, and other conductor concepts are still being explored, i.e., no decision has been made for the conductor concepts to be utilized for FED. The TF coil conductor design is based on an ICCS successfully used in a small test magnet at ORNL. The conductor consists of triplets of NbTi strands loosely packed in a stainless steel conduit similar to the Westinghouse LCP coil. The operating current for the conductor is 25.5 kA at 10 T and 3.1 K. The conductor is co-wound with a stainless steel C-shaped channel to provide a direct load path to the coil case for the accumulated magnetic loads in the winding. The strand diameter in the conducter is optimized to reduce the eddy current losses. The nuclear heating in the winding is the most dominant heat load. In order to remove these heat loads due to nuclear heating and ac losses in the winding, it is necessary to lower the inlet temperature of helium to 2.2 K. The conductor has a thermal capacity of /spl sim/200 mJ/cc, which provides a comfortable stability margin under the operating conditions. The PF conductor is similar to the TF conductor, but it is modified to meet the requirements of the PF coils. For this conductor, the superconducting filament diameter has been reduced and cupro-nickel barrier is provided between adjacent filaments for reducing the hyteresis and coupling ac losses, respectively, under relatively higher pulsed fields. The conductor is designed to carry 21.3 kA at 8 T and 4.5 K.         Investigation of the properties of PbMo/sub 6/S/sub 8/powder processed wires    B. Seeber, C. Rossel, O. Fischer and W. Glaetzle Summary: We report on recent improvements of the fabrication of PbMo/sub 6/S/sub 8/wires by a powder-metallurgical-technique based on a molybdenum matrix. Using industrial methods for hot drawing of molybdenum we successfully produced Mo-PbMo/sub 6/S/sub 8/wires of 0.3 mm diameter and typical lengths of a hundred meters. After proper annealing the critical temperature measured by an inductive method reaches 13.7 K which corresponds of the T/sub c/of the starting powder. Critical current densities in this type of wire are still insufficient for application but recent investigations in hot pressed bulk PbMo/sub 6/S/sub 8/show that values above 10/sup 8/Am/sup -2/at 14 T and 4.2 K may be obtained. Preliminary tests on PbMo/sub 6/S/sub 8/wires doped with Ga yield an increase of J/sub c/up to one order of magnitude in comparison to an undoped wire.         CVD processing of carbon fiber superconductors    M. Dietrich, C. Dustmann, F. Schmaderer and G. Wahl Summary: NbC/sub 1-y/N/sub y/superconductors are possible candidates for high magnetic field applications because of the high B/sub c2/> 25 T. The deposition of NbC/sub 1-y/N/sub y/on carbon fiber bundles with more than 1000 fibers using a two stage chemical vapor deposition process: NbCl/sub 2/+ 5/2 H/sub 2/350 - 1000/spl deg/C, N/sub 2/Nb + 5 HCl; Nb + (1-y) CH/sub 4/+ yNH/sub 3/1100/spl deg/C NbC/sub 1-y/N/sub y/has been investigated. The deposition process is carried out at total pressures 0.1 mbar < P/sub tot/< 1000 mbar and is supported by a rf-gas discharge and an ultrasonic field. The influence of the deposition parameters on the grain structure and on the superconducting properties are investigated. It is found that at low pressures the grain size decreases with increasing Nb deposition temperature in contrast to earlier experiments at atmospheric pressure. The following high temperature carbonitriding process causes a slight coarsening of the grains (< /spl sim/ 10%). The main parameters, which influence the microstructure are discussed. The superconducting properties of NbC/sub 1-y/N/sub y/deposited without the gas discharge are measured. The critical temperature T/sub c/was in the range of 15 K < T/sub c/< 17 K. The following maximum critical currents were measured at 4.2 K: j/sub c/(O T) = 10/sup 6/Acm/sup -2/j/sub c/(13 T) = 10/sup 4/Acm/sup -2/. The extrapolated maximum critical magnetic field was B/sub c2/= 21 T at 4.2 K.         Superconducting properties of V/sub 2/(Hf,Zr) laves phase multifilamentary wires    T. Kurodo, K. Inoue, H. Wada and K. Tachikawa Summary: Fabrication method, superconducting properties and strain effects of V/sub 2/(Hf,Zr) Laves phase multifilamentary wires have been investigated. Wires containing 1634 V/sub 2/(Hf,Zr) filaments were fabricated by the composite process. The dependence of superconducting properties on compositions, heat treatment conditions and measuring temperatures was examined. Superconducting transition temperatures, T/sub c/, of about 9.7K, upper critical fields, /spl mu/,H/sub c2/, exceeding 21T and critical current densities, J/sub c/, of about 1x10/sup 5/A/cm/sup 2/at 13T and 4.2K were obtained. Overall J/sub c/of the 1634-filament wire was about 1x10/sup 4/A/cm/sup 2/at 14T and 4.2K. At 12.5T J/sub c/was increased by a factor of three when temperature was reduced from 4.2K to 1.8K. /spl mu/,H/sub c2/estimated on the basis of J/sub c/versus magnetic induction curves at different strain levels was found to be independent of intrinsic strains up to 0.9%.         Nb/sub 3/(Al.Ge) superconductors prepared by hot-substrate liquid-quenching and subsequent annealing    K. Togano, H. Kumakura, T. Takeuchi and K. Tachikawa Summary: The A15 Nb/sub 3/(Al.Ge) and Nb/sub 3/Al superconductors with high critical current density J/sub c/have been successfully prepared by the liquid-quenching on a hot-substrate and subsequent annealing. The hot-substrate liquid quenching has a higher cooling rate than that of the conventional liquid-quenching techniques and facilitates the formation of completely supersaturated bcc solid solution of Nb/sub 3/(Al/sub 1-x/Ge/sub x/) up to x=0.3. The quenched materials are then transformed to the A15 structure by annealing above 750/spl deg/C. Following the transformation, the critical temperature T/sub c/rises above 18 K, exact values depending on the composition and the heat treatment condition. The A15 phase converted from the bcc phase has an extremely small grain size of hundreds of angstroms, resulting in a high J/sub c/in high magnetic fields. The J/sub c/of the Nb/sub 3/(Al.Ge) is higher than that of the Nb/sub 3/Al probably due to the smaller grain size. J/sub c/of 3.5x10/sup 5/A/cm/sup 2/at 4.2 K and 16 T has been achieved in the Nb/sub 3/(Al/sub 0.8/Ge/sub 0.2/sample annealed at 850/spl deg/C for 7 hr, which is much higher than the highest value measured in the V/sub 3/Ga superconductors. It is demonstrated that this technique of hot-substmate liquid-quenching process is potentially useful for tape conductor fabrication, because the scaling-up is straightforward and the thin copper substrate which strongly adheres to the A15 layer can serve directly as a stabilizing material.         Properties of NbN films crystallized from the amorphous state    J. Gavaler, J. Greggi, R. Wilmer and J. Ekin Summary: Cubic Bl structure NbN was prepared by annealing amorphous Nb-N films made by sputtering niobium in an argon-nitrogen atmosphere onto low temperature (\siml 350\degC) substrates. Crystallized films on sapphire substrates have equiaxed grains while films on niobium are columnar. Grain sizes vary from 12.5 nm to > 100 nm. The highest superconducting critical properties measured in these films are: T/sub c/= 16K, J/sub c/(4.2K, zero field) = 8x10/sup 5/A/cm/sup 2/, and B/sub c2/(1.3K) = 28T. Data on the effect of uniaxial tensile strain on J/sub c/show that there is no measurable elastic (reversible) strain effect. Irreversible J/sub c/degradation begins at an intrinsic tensile strain of 1.3% in the best case.         A study of superconductivity in the (Hf/sub 0.5-x/Ta/sub x/Zr/sub 0.5/)V/sub 2/H/sub y/C15 system    Chen Lin-fu, Zhou Li, Yin Dao-le, Ruan Jing-hui, Chen Gui-Ying and Chen Zhi-xu Summary: A study of superconductivity in the C15 system (Hf/sub 0.5-x/Ta/sub x/Zr/sub 0.5/)V/sub 2/H/sub y/indicates that both the relationship between T/sub c/and y and the influence of hydrogen on the T/sub c/differ from those in the Pd-H system. The results of thermal neutron inelastic scattering show that acoustic phonons are important factors in the variation of T/sub c/. An evaluation of the distribution of hydrogen atoms in different interstices for small and large concentrations was made with the help of the theory developed by Jacob and Miedema. It seems that the superconducting transition temperature is enhanced when hydrogen atoms occupy mostly the 2Zr-2V interstices. A possible explanation of this effect is proposed.         Theory of current-direction dependence of normal-zone propagation velocity in multifilamentary composite conductors    J. Clem and R. Bartlett Summary: We develop a theory for the current-direction dependence of the normal-zone propagation velocity observed in multifilamentary composite superconductors. Normal-zone propagation is known to be driven primarily by Joule heating in both the normal zone and the current-sharing zone, which lies between the normal (T>T/sub c/) and superconducting (I         Effect of current sharing on the stability of transposed superconductors subject to rapid heat pulses    G. Reiter Summary: A network model of a cabled superconductor that effectively incorporates the crossover resistance and the resistance between parallel strands has been used to obtain equations describing the motion of the currents in a cabled conductor when a region goes normal. These have been solved numerically, in conjunction with the heat flow equations appropriate to a fast pulse of heat applied at the edge of the conductor and the additional stability due to current sharing evaluated. I find that the crossover conductance is much less effective than the parallel conductance in enhancing stability. A current diffusion constant can be defined in terms of an effective resistance and an effective inductance for the cable. Current sharing is only significant in enhancing stability when this diffusion constant exceeds the thermal diffusion constant.         Enthalpy improved dielectric insulation for NbTi    W. Lawless, C. Clark and R. Arenz Summary: Two new dielectric insulation systems applicable to NbTi are described. Both systems incorporate significant enthalpy stabilization in that the volumetric specific heats of the dielectrics are equivalent to, or much larger than, that of Pb below 10K. For one of the systems, the thermal conductivity at 5K approaches that of commercial Cu. Both coating systems can be applied to NbTi without the use of a fugitive binder: One system can be hot-extruded directly on the wire, and the other system can be dip-coated with a room-temperature cure. Both coating systems withstand demanding bend tests. For 0.13-mm thick coatings, the thermal time constants at 5K are 0.24 /spl mu/s and 2.5 ms; the corresponding enthalpies per unit volume at 6K (relative to 4.2K) are 50.5 and 54.6 mJ/cm/sup 3/At 8K; the enthalpies are 179 and 311 mJ/cm/sup 3/respectively. The thermal properties of both systems are unaffected by intense magnetic fields.         Low frequency AC losses in multifilamentary superconductors up to 15 tesla    T. Orlando, A. Zieba, C. Braun, B. Schwartz, S. Foner and W. McDonald Summary: Low frequency (1 Hz) ac losses were measured in a variety of A15 superconducting wires having different fiber geometries. Field modulations of /spl les/ 1 tesla were superimposed on a fixed background field up to 15 tesla. Losses were measured for Nb/sub 3/Sn in continuous fiber, modified jelly-roll, In Situ, and powder metallurgy processed materials, and for Nb/sub 3/Al powder metallurgy processed materials. The results are compared with dc magnetization measurements. The losses are purely hysteretic at these low frequencies, scale with J/sub c/(above /spl sim/ 3 tesla), and are reduced substantially by twisting for all the materials. The lowest losses are observed for the Nb/sub 3/Al wires.         Stability of internally cooled superconductors in the temperature range 1.8 to 4.2 K    J. Lottin and J. Miller Summary: The stability of an Internally Cooled Superconductor (ICS) has been investigated experimentally at temperatures including both the HeI and HeII range. A NbTi/Cu cable was enclosed in a thin wall, tubular, stainless steel sheath for containment of the cooling helium, supported inside a vacuum chamber for complete isolation from external cooling sources, and positioned in the bore of a superconducting magnet that provided fields at the conductor of up to 8 T. The cable was subjected to well defined, sudden heat inputs by superimposing a high current pulse directly on the steady state transport current. Results are reported and compared to previous ICS stability data at 4.2 K and to predictions of performances at lower temperatures.         Mechanical disturbances in Rutherford-type and braid conductors    O. Tsukamoto and Y. Iwasa Summary: The effects of mechanical disturbances on the performance of Rutherford-type and braided superconductors are presented. A set of simulated stability experiments on these two types of conductor has revealed that the Rutherford-type conductor is much less sensitive to mechanical disturbances than the braid, agreeing with the performance records of high-current density dipole magnets wound with these two types of conductors.         Measurements of current noise in DC SQUIDS    J. Martinis and J. Clarke Summary: The current noise circulating around the loop of a tunnel junction dc SQUID has been measured as a function of applied flux. The flux noise generated by this current was coupled via a superconducting transformer to a second dc SQUID that was used to measure the noise in a null-balancing configuration. The voltage noise across the SQUID was also measured, using a cooled LC-resonant circuit, and the correlation between the voltage and current noises was determined. The measured values of the noises are in good agreement with values obtained from an analog simulator.         Investigation of 1/f noise in tunnel junction DC SQUIDS    R. Koch, J. Clarke, J. Martinis, W. Goubau, C. Pegrum and D. Harlingen Summary: We describe two methods of measuring the 1/f noise in a dc SQUID. One is sensitive only to 1/f noise in the critical currents of the junctions, and the other is sensitive only to 1/f flux noise that is not associated with critical current fluctuations. From measurements on a planar thin-film dc SQUID incorporating Josephson tunnel junctions we conclude that the predominant source of 1/f noise is not noise in the crititcal currents, but rather an apparent flux noise of unknown origin.         Conductance fluctuations and low frequency noise in Josephson junctions    C. Rogers and R. Buhrman Summary: We report low frequency noise measurements for small unshunted and shunted Nb-PbBi tunnel junctions and dc SQUIDS. We found that noise voltage spectral density varies as 1/f/sup /spl alpha//, 0.9 /spl les/ /spl alpha/ /spl les/ 1.1for all bias currents, scales accurately as V/sup 2/at high voltage levels, and depends linearly on temperature. The results show that the low frequency noise is due to fluctuations in the tunneling conductance. These fluctuations are tentatively attributed to time variations in the occupation of defect states in the barrier.         Analysis of strong inductive coupling on SQUID systems    C. Tesche Summary: A technique for the analysis of complex superconducting circuits containing one or more current biased inductively coupled Josephson junction interferometers is described. The equations of motion for the system are shown to separate into a set of non-linear junction equations relating the voltage drops across the junctions to the currents passing through the junctions, and a set of linear equations expressing the quantization of the fluxoid around the superconducting loops and the corresponding linear circuit equations for the normal loops. In many cases, the linear equations can be integrated, resulting in an effective elimination of the normal circuit loops from the problem. The circuit is thus reduced to that of an equivalent set of coupled SQUIDs whose device parameters are a function of the original circuit parameters and the inductive coupling strengths. The dc SQUID tuned linear amplifier is analyzed to display the method. As a result of this analysis, the optimal noise temperature of a tuned SQUID amplifier is derived as a function of the current and voltage noise spectral densities, S/sub v/and S/sub J/, and forward transfer function, V/sub /spl phi//. The results obtained demonstrate that the behavior of the SQUID cannot be isolated from that of the rest of the circuit in the manner assumed in previous analyses. The existence of a quantum noise limit on the noise temperature of any phase preserving linear amplifier is used to infer that the noise figures must satisfy the constraint[(S_{v}/2LV_{\phi}^{2})(LS_{j}/2)-S_{vj}^{2}]^{1/2}>\hbarThe behavior of several simple circuits containing a pair of inductively coupled current biased interferometers is discussed to display the extension of the method to circuits containing more than one interferometer.         Preliminary tests of a newly developed superconducting gravity gradiometer    M. Moody, H. Chan and H. Paik Summary: We have recently completed a series of tests on a newly developed superconducting gravity gradiometer consisting of two 400 g niobium proof masses separated by a distance of 15 cm. The resonance frequency of the proof mass suspension systems is 25 Hz. The sensitivity of this gradiometer obtained during these tests was 1 to 2 Eotvos Hz/sup -1/2/(1 Eotvos = 10/sup -9/s/sup -2/ /spl equiv/ E) below 1Hz, and 0.2 E Hz/sup -1/2/between 15 and 20 Hz. Using this gradiometer, a prototype experiment has been performed to demonstrate a new source-independent null test of the inverse square law of gravitation. The result, assuming a potential of the form\phi(r) = -(GM/r) [1 + \alpha \exp(-\mur)], is /spl alpha/ = + 0.024 /spl plusmn/ 0.036 at /spl mu//sup -1/= 1m.         Chaos in Josephson circuits    R. Kautz Summary: Chaotic behavior in Josephson circuits is reviewed using the rf-driven junction as an example. Topics include the effect of chaos on the IV characteristic, the period doubling route to chaos, and power spectra for the chaotic state. Liapunov exponents and the fractal geometry of strange attractors are also discussed.         Superconductive convolver    S. Reible, A. Anderson, P. Wright, R. Withers and R. Ralston Summary: Concepts for realizing superconductive convolvers capable of processing analog signals having bandwidths up to 10 GHz have been developed and are being implemented. A preliminary convolver structure with 19 taps and a 14-ns interaction length has recently been demonstrated. This device employs a superconductive transmission line as a low-loss delay element and superconductive tunnel junctions as nonlinear mixing elements. The niobium delay line provides the relative shifting of signal and reference waveforms, niobium/niobium-oxide/lead mixers with proximity taps provide local multiplication of the two waveforms, and a short output transmission line provides coherent summation of the local products. The principles of device operation, design tradeoffs and experimental results will be presented. Convolvers can provide the essential programmable matched-filter component for extremely wide-bandwidth spread-spectrum communication systems. It appears feasible to produce a convolver with an interaction time of about 100 ns and signal processing gains of up to 1000. This superconductive analog device offers the potential of providing a real-time programmable signal processing function with the digital equivalent of about 10/sup 12/operations/sec.         Superconductive tapped delay lines for microwave analog signal processing    R. Withers, A. Anderson, P. Wright and S. Reible Summary: Passive superconducting tapped delay lines have been fabricated for use as matched filters for multigigahertz bandwidth analog signal processing. Specifically, linear frequency-modulated dispersive delay lines, also known as chirp filters, having a bandwidth of 2.6 GHz centered at 4 GHz and a dispersion time of 35 ns have been constructed. The stripline structure consists of a 4000-/spl Aring/-thick patterned niobium film sandwiched between 5-cm-diameter, 125-/spl mu/m-thick sapphire wafers. Two parallel striplines, each 1.6-m long, are wound in a spiral pattern. The taps are backward-wave couplers formed by bringing the two lines into and out of proximity at specified locations. Pulse expansion and compression have been demonstrated with these devices and are in close agreement with a new theoretical model for this class of signal processors.         Substrates for superconductive analog signal processing devices    A. Anderson, R. Withers, S. Reible and R. Ralston Summary: Superconductive analog devices are being developed which utilize long electromagnetic delay lines, typically 2 to 50 m long on a single planar substrate Criteria for the choice of substrates for these devices are established. Desirable characteristics are low dielectric loss, low dispersion, high dielectric constant, dielectric isotropy and compatibility with fine-line lithography of robust superconductive films such as niobium. A number of different substrates have been examined including crystalline and vitreous quartz, sapphire of various orientations, alumina, calcium fluoride, and silicon. Silicon is shown to be an excellent substrate for most envisioned devices. Experimental results indicate that a 100-m long line with a total loss of 8 dB at 5 GHz is feasible. A technique to allow the use of a 25-/spl mu/m-thick, 5-cm-diameter silicon substrate to realize an 18-m-long niobibm line is discussed.         Microwave mixing and direct detection using SIS and SIS' quasiparticle tunnel junctions    A. Smith, W. McGrath, P. Richards, R. Harris, F. Lloyd, D. Prober and P. Santhanam Summary: Quasiparticle mixers have shown strong quantum effects, conversion gain, and noise levels approaching the quantum limit, but only in tunnel junctions with very low sub-gap "leakage" conductance. It has been suggested that SIS' tunnel junctions, made from two different conductors with unequal gaps, will function as high gain mixers since the dynamic conductance below the gap is negative. We report results of the first SIS' mixing and direct detection experiments. At 36 GHz, a conversion efficiency of -4 dB with a noise temperature of 33 K (SSB) has been obtained. A novel gain mechanism for SIS' direct detectors is predicted. A direct detector responsivity of 250 A/W was measured. We compare our results to quantum theory models. In addition, we demonstrate quasiparticle harmonic mixing of a 36 GHz signal with an 18 GHz local oscillator in tin SIS junctions. Harmonic mixers can have important advantages at high microwave frequencies where insufficient local oscillator power is available.         SIS mixer analysis using a scale model    M. Feldman, S. Pan, A. Kerr and A. Davidson Summary: In this paper measurements on a 115 GHz SIS mixer are shown to be in good quantitative agreement with the predictions of the quantum theory of mixing. A 40 X scale model of the mixer block was used to determine the experimental embedding impedances.         Photon-assisted tunneling and AC Josephson effect at 246 and 604 GHz in small-area superconducting tunnel junctions    W. Danchi, F. Habbal and M. Tinkham Summary: We report the first observations of photon-assisted quasiparticle tunneling and AC Josephson effect in superconducting tunnel junctions irradiated with far-infrared (FIR) radiation. Radiation at 246 GHz (/spl lambda/=1.22 mm) and 604 GHz (496 /spl mu/m) from an optically-pumped FIR laser source was used. Tin-tin oxide-lead junctions of /spl sim/1 (/spl mu/m)/sup 2/area were fabricated on crystal quartz substrates with integral planar dipole antennas of resonant length at the frequency of the incident radiation. The observed photon-assisted tunneling features are in excellent agreement with the Tien-Gordon theory, and the inferred responsivity approaches the quantum limit at low temperatures for photon energies less than the gap. At 604 GHz, with a 176 ohm junction, we have seen 7 Josephson steps, comparable to point contact performance. The variation of the step widths with laser power is found to agree quite well with both the RSJ model and the Werthamer theory. For low resistance junctions (e.g. 16 ohms), we find the Josephson steps to be flat and to agree well with the shape predicted by the RSJ model without noise rounding, while noise rounding is very evident with the higher resistance junctions. In all cases, the step shape is in reasonable agreement with the theory of P. A. Lee, using a noise temperature of 10-20K with an appropriate small junction capacitance.         Cryosampler interface    P. Moskowitz, S. Faris and A. Davidson Summary: A package that permits the electrical coupling of a cryosampling system with a high temperature device has been constructed and tested. The Faris sampling system has demonstrated 5 ps time resolution and 10 /spl mu/V sensitivity. The interface couples the sampler at 4.2 K to a higher temperature region, with minimal heat transfer, by means of low inductance contacts to a high quality 50 ohm thin-film transmission line. Initial time domain reflectometry tests using the sampler have been carried out over a range from liquid helium temperature to 210 K. Five reflections have been observed of a step initiated and detected by the sampler at the low temperature end and traversing a 14 cm path to the high temperature end and back, No more than 20 ps was added to the pulse risetime for one roundtrip and signals on the order of 100 /spl mu/V were detected, We expect to improve this performance and to use the system for experiments on superconductors, gallium arsenide, and semiconductor devices.         Vertical Silicon membranes for super-Schottky diodes    N. Raley, Y. Sugiyama and T. Duzer Summary: We have fabricated vertical silicon membranes in (110) silicon for use in the fabrication of super-Schottky diodes (SSD). Noncritical electron-beam lithography and the anisotropic etching properties of KOH-water solutions are utilized to make vertical membranes typically of 1 /spl mu/m height and 100 nm thickness. Various device configurations are possible utilizing angleevaporation techniques. Current-voltage and derivative measurements of fabricated SSD’s indicate S values close to full theoretical value at 4.2 K and full energy gap of the lead superconductive electrode. At frequencies of 90 GHz or greater, the responsivities of these SSD’s should attain the quantum-limited value at temperatures near 1 K. Parasitic-loss calculations indicate approximateiy 3 dB loss for the present SSD’s operating as video detectors at 90 GHz; this loss can be reduced to < 0.2 dB with a modification of the device structure so that series resistance is negligible. The devices are suitable for matching to waveguide as device impedances can be varied from about 30/spl Omega/ to 1000/spl Omega/, depending on diode area and structure.         Superconductor-sapphire cavity for an all-cryogenic SCSO    D. Strayer, G. Dick and E. Tward Summary: To develop a superconducting cavity stabilized oscillator (SCSO) as a frequency standard, we are studying the properties of cavities consisting of a single crystal of sapphire surrounded by a superconducting film. Measurements of quality factors of spherical and cylindrical samples of sapphire are reported. Loss values less than 2x10/sup -9/have been measured at a temperature of 1.45K. A design for an all-cryogenic SCSO is described, with particular emphasis on the cavity requirements. We conclude that such a design would allow greatly enhanced stability of operation due substantially to the thermal and physical properties of the sapphire substrate. Cavity Q requirements are relatively modest, with better than 10/sup -16/frequency stability predicted for a Q of 10/sup 8/.         Advances in imaging technology: Nuclear magnetic resonance    L. Kaufman, L. Crooks, P. Davis and A. Margulis Summary: We find ourselves in a paradoxical milieu, where increasing standards of safety, convenience, comfort and health while an overlapping segment is suspicious of or hostile to the technology capable of better serving these demands or needs. NMR imaging is one such technology, hailed on one hand as a breakthrough and on the other as a further financial burden on the health system or as a source of unknown hazards. As is usual with this kind, of uninformed evaluation, neither of these assessments is correct . As we shall see below, NMR imaging is a potentially useful technology that is intimately coupled to superconductivity in an application that possibly is the first time that the general public comes into contact with this phenomenon. substantial segments of the population demand         Overview of the development of superconducting synchronous generators    J. Smith Jr. Summary: Superconducting synchronous generators are being developed world wide. Early results established the feasibility of these machines and showed that the best configuration is a rotating superconducting field inside a normally conducting armature in the stator. Extensive analytical development is providing a sound basis for the design of superconducting AC machines. Recent experimental results have demonstrated power density improvements over that of conventional generators. The designs developed by different groups are significantly different in the following areas: Rotor shielding and rotor structure; field coil support and construction; superconductor design; helium system design; and armature configuration. The development strategies of the groups have different emphases on basic engineering, development of components, and construction of prototypes. The major deficiencies of the programs are no full-load or full-fault testing.         Technical overview of the French program    J. Sabrie and J. Goyer Summary: Launched in 1972, the objective of the program is the development of cryoalternators adapted to the electrical systems for the end of the twentieth century. The principal criteria retained for utilizer overall cost optimization are availability, efficiency and construction costs. The cryogenic design has been validated by the construction and testing of a rotor model (diameter 1.06 m; 12 t of which 4t at 5 K, 5000 A, 3000 rpm). Electricite de France and Alsthom Atlantique are considering the costs and means for the industrial putting into operation of 250 MW cryoalternator in an existing coal-fired power plant.         Technical overview of Japanese superconducting generator development program    H. Fujino Summary: Japanese activities on development of superconducting generator are reviewed with a brief historical description. Japanese development program has demonstrated the technical feasibility of superconducting machine by construction and operation of model machines. The experiences in manufacturing and operating such machines have been accumulated to have sufficient potential for realization of practical superconducting generators. At present, although a definite next program is not clear, there is a trend advancing the development of practical superconducting generators.         Technical overview of the German program to develop superconducting AC generators    L. Intichar and D. Lambrecht Summary: At the Technical University of Munich, a superconducting 320kVA generator has been taken into operation for experimental purposes. KWU and Siemens are running an extensive program to develop superconducting (SC) generators of commercial size. This development program is described in detail, and reports are given about the experimental work on three major components, namely the superconducting field winding, the cryogenic cooling system and the helium transfer equipment         High efficiency and low consumption material electrical generators    I. Glebov and V. Shaktarin Summary: In conjunction with energy shortages and rising fuel and material prices, the development of high efficiency and low consumption material electrical generators will play an important role in the efforts to maintain economic standards for any country. The need for increased efficiency should be considered with improved availability and reliability, that is essential to guarantee the maximum usage of efficient equipment. This report covers superconductive generators which have been designed and developed in the USSR during the last few years.         Flux pinning in high-current-density superconductors    H. Freyhardt Summary: A major application of superconducting wire material is the generation of magnetic fields - often in large volumes - with particular strength, homogeneiry and field gradients.         alpha/-Ti precipitates in high current density multifilamentary Niobium Titanium composites    A. West and D. Larbalestier Summary: Transmission electron microscopy has been used to characterize the microstructure of a Fermilab composite at various sizes, as well as a variety of commercial composites in their as-delivered, final size state. A much more diverse range of precipitate morphologies than had been previously envisaged was seen. High Jc composites were, however, seen to have a similar morphology of walls of plate like /spl alpha/-Ti in a fine subband structure. The precipitate size ranged from about 0.5 to 200 times the coherence length.         1.8 K test of binary and ternary superconducting conductors    M. Wake, T. Shintomi, M. Kobayashi, K. Tsuchiya, H. Hirabayashi, H. Wada, K. Inoue, K. Itoh, K. Tachikawa, K. Ishibashi and A. McInturff Summary: A series of short sample tests have been carried out on Nb-Ti-based binary and ternary alloy conductors. It turns out that the current carrying capacities at high fields of both binary and ternary alloys can be remarkably improved over those previously reported by heavy cold-working after heat treatment. It should be emphasized that the superconducting performance of these ternary alloy conductors manufactured in industrial scale are fairly reliable and that the best results are obtained with Nb-Ti-Ta ternary alloys. Results are shown also on long samples and large kiloampere cables.         Development of high current Nb/sub 3/Sn multifilament superconducting material following the ECN powder method    A. van Wees, P. Hoogendam and H. Veringa Summary: A number of different types of multifilament superconducting wires containing Nb/sub 3/Sn following the powder method have been made in lengths of about 500 meters. The formation of the superconducting Nb/sub 3/Sn layer is based upon the reaction between NbSn/sub 2/powder and the niobium tube which contains this powder. By a careful control of the composition of the wire, the powder core and the wire drawing procedures, it is now possible to make a composite with very good superconducting properties. High current densities can be achieved after a heat treatment at a temperature between 675 and 700/spl deg/C during 50 to 100 hours. The analysis of the kinetics of the growth of the A-15 layers and the wire drawing characteristics has led to the conclusion that the overall current density can still be further increased to values as high as 3x10/sup 8/Am/sup -2/at 14 tesla. The dynamic stability is not seriously affected by this optimization since the copper to superconducting ratio is 5.2 to 1. In this paper the composition, the manufacturing procedures and the main superconducting properties will be described. We will further outline our plans for further production of this kind of material on a larger scale.         Ultrafine fiber in situ Cu-Nb-Sn produced by high temperature gradient solidification    R. Roberge, H. LeHuy and S. Foner Summary: The high temperature gradient solidification (HTGS) technique to obtain a random dispersion of the niobium in the copper matrix is described. The equipment has been modified to accept larger and available graphite tubes. Examples of microstructure control are given and versatility of the technique is illustrated by the addition of iron to the Cu-Nb starting coaxial rod. Following solidification, the iron dispersion was analyzed using EDX, Auger and atomic absorption. The iron is mainly in the niobium dendrites but does not degrade the overall J/sub c/= 10/sup 4/A/cm/sup 2/at 16 tesla.         The influence of coarsening treatments upon properties of in situ Nb/sub 3/Sn-Cu superconducting wire    J. Verhoeven, E. Gibson, F. Laabs, J. Ostenson and D. Finnemore Summary: A controlled coarsening step is shown to offer a technique for greatly extending the range of wire reductions possible in the manufacture of in situ Nb/sub 3/Sn-Cu superconducting wire. Experiments have been carried out in which Cu-30 wt % Nb in situ Nb/sub 3/Sn-Cu wires have been prepared employing a coarsening anneal at 750 and 1000/spl deg/C prior to final reduction to wire size. Results show that coarsening treatments may be utilized to achieve optimum control of filament sizes in order to maximize J/sub c/. Values of J/sub c/equivalent to those of uncoarsened wires are obtained and information is presented on contact welding of Nb/sub 3/Sn filaments in in situ wires.         Scaleup of powder metallurgy processed Nb-Al multifilamentary wire    C. Thieme, H. Zhang, J. Otubo, S. Pourrahimi, B. Schwartz and S. Foner Summary: Powder metallurgy processed Nb-Al superconductIng wires were fabricated from billets up to 45 mm o.d. with nominal areal reduction ratios, R, up to 2x10/sup 5/, Nb powder sizes from 40 to 300 /spl mu/m from various sources, Al powder sizes from 9 to 75 /spl mu/m, Al concentrations from 3 to 25 wt % Al and with a wide range of heat treatments. All the compacts used tap density powder in a Cu tube and swaging and/or rod rolling and subsequent wire drawing. Both single strand and bundled wires were made. Overall critical current densities, J/sub c/, of 2x10/sup 4/A/cm/sup 2/at 14 T and 10/sup 4/A/cm/sup 2/at 16 T were achieved for 6 to 8 wt % Al in Nb.         The quantum-non-demolition measurement of energy using Josephson junction    V. Braginsky and S. Viatchanin Summary: We discuss the schemes of quantum-non-demolition measurement of energy in quantum oscillator (the number of quanta remains wchanged after the measurement), using quadratic nonlinearity of Josephson junction. Numarical estimates for real scheme demonstrate that error of quanta number measurement may be about unity. Possible use of nonlinear low temperature virtual ferroelectric Kfa/spl O/ in similar quantum-non-demolition scheme is also discussed.         Quantum noise in SQUIDs    V. Danilov, K. Likharev and A. Zorin Summary: The sensitivity limitations due to thermal, quantum and shot noise are calculated for dc and ac SQUIDs. Two approximations are used for the Josephson junctions: i. RSJ model with the equilibrium source of thermal-and-quantum fluctuations and ii. microscopic theory of the tunnel junctions with small capacitance (the latter theory takes into account the shot noise as well). The ultimate "output" sensitivity /spl epsiv/_{V}=<\delta\Phi\min{x}\max{2}>/2L\Deltaf is shown to be substantially less than the Planck's constant h, for the both types of SQUIDs. This result does not contradict to the uncertainty principle, because the "total" sensitivity /spl epsiv/=(/spl epsiv/_{V}/spl epsiv/_{I}-/spl epsiv/min{IV}\max{2})^{1/2} rather than /spl epsiv/_{V} is an adequate figure of merit of SQUID as a linear amplifier. The total sensitivity is shown to be, in fact, limited by the quantum fluctuations, /spl epsiv/>h/2. These fluctuations originate in the shunting resistances of the dc SQUID, while in the ac SQUID they are due to quantum noise of the following stage of amplification. Nevertheless, even the total sensitivity /spl epsiv/ can be made less than h/2, if the "degenerate" type of SQUID is used, being sensitive to the only one of the quadrature components of the input signal.         Quantum effects and RF-SQUID sensitivity    I. Dmitrenko, V. Khlus, G. Tsoi and V. Shnyrkov Summary: Fine structure of V/sub RF/vs I/sub RF/dependence of the rf SQUID in the hysteretic mode is investigated experimentally at temperatures from 0.5 to 4.2 K. A suggestion is made that for high resistance point contacts of small capacitance the SQUID sensitivity may be limited by quantum processes for temperatures high enough (T/spl sime/K). To explain the experimental results macroscopic quantum tunneling and zero-point fluctuations are considered as relevant mechanisms.         Limit characteristics of the dc SQUIDS using unshunted Josephson tunnel junctions    O. Snigirev Summary: A limit energy sensitivity is found for dc SQUIDS using unshunted Josephson tunnel junctions. Expressions are derived for the signal transfer function and for the voltage noise spectrum density in these devices. An analytical expression for the phase as a function of time has also been found in switching from zero to the voltage state process. The comparison is performed between these devices and usual dc SQUIDS using shunted Josephson tunnel junctions.         Ultimate sensitivity of the dc SQUIDs using unshunted Josephson tunnel junctions    O. Snigirev Summary: An analitical theory of dc SQUIDs using unshunted Josephson tunnel junctions is developed. An expression for the phase as a function of time has been found for the process of switching from zero-voltage state to gap-voltage state. Expressions are derived for the signal transfer function and for the voltage noise spectrum density in the SQUID. An ultimate sensitivity limit is found, and the comparison is performed between these devices and usual dc SQUIDs using shunted Josephson tunnel junctions.         Calculation, fabrication and investigation of thin-film Josephson interferometers    I. Voitovich, Ju. Kolesnik, A. Polishchuk and V. Sosnitsky Summary: The calculation of n-junction SQUID characteristics is simplified and other methods of calculation of SQUID are proposed. The effectiveness of SQUID self-shielding is shown. The magnetometer which is made on such nonshunted SQUIDs has flux resolution 3x10/sup -3//spl phi//sub 0/x Hz/sup -1/2/. A process for SQUID fabrication is based on the use of Nb-NbO/sub x/-Pb(Bi) Josephson junction with Rj/R/sub N/ /spl ges/ 18, Nb ground plane, Al/sub 2/O/sub 3/insulated films, ion cleaning. Tunnel spectroscopy studies have indicated the correlation between oxide composition and oxidation temperature.         Shunted DC SQUIDs with Nb-NbOx-Pb technology    J. Garnier, J. Villegier, D. Duret and A. Regent Summary: Planar dc SQUIDs have been made and tested. They consist of a 5mm X 5mm square with a 30/spl mu/m to 100/spl mu/m hole, the junctions being near the center of the device. The loop inductance is in the range of 100- 200 pH. The technology uses Nb/NbOx/Pb overlapped junctions and Ta shunt resistors. Coupling is discussed ; we show that the input coupling constant k cannot be obtained by direct measurements and an efficiency constant r = I/sub 1//nI/sub i/, is introduced where n is the number of turns of the input coil, I/sub i/the input current and I/sub 1/the induced current in the SQUID loop. An experimental efficiency of about 50% has been obtained.         Input impedance of the RF SQUID in high frequency regime    S. Tinchev Summary: A simple method is developed for analysis of the RF SQUID in regime, where the bias frequency /spl omega/ is comparable to the natural R/L frequency of the SQUID ring. The input impedance of the RF SQUID is calculated for various values of the parameters q = /spl omega/ L/R/spl les /spl les/ /spl pi//4, signal frequency and detuning of the rf bias frequency from tank circuit resonant frequency. It is shown, that both the input resistance and the input inductance may be positive or negative. Measurement of the real part of the input impedance of a hysteretic RF SQUID are described. The experimental data are in qualitative agreement with the prediction of the theory.         The mutual locking of Josephson microbridges caused by the penetration of the longitudinal electric field into the superconductor    L. Amatuni, V. Gubankov, A. Zaitsev and G. Ovsyannikov Summary: The interaction of the series-connected Josephson microbridges caused by the longitudinal electric field penetration into the superconducting thin-films was investigated theoretically and experimentally. It was shown that the interaction of microbridges nonmonotonously depends on the array's parameters (the voltage, the distances between microbridges, the temperature) that is caused by the quasiwave character of the variable field propagation in the superconductor. The transition of one of the series connected microbridges into resistance state and its excitation of the electric field delays the transition of the second one into the resistance state, i.e. increases the tolerance of the microbridges critical currents really observed. The peculiarities of the mutual locking and current-voltage characteristics (IVC) of the bridges array associated with the penetration of the longitudinal electric field were analyzed.         Short weak links for 115 GHz mixers    H. Ohta, T. Matsui, T. Igarashi, S. Kodaira, Y. Yamada and Y. Takahashi Summary: It has been proved that the current phase relation of a 'short' weak link in the 'dirty' limit at absolute zero Kelvin is expressed in a Fourier series asI = \frac{\pi\Delta}{2eR} \Sigma\min{n=1}\max{\infin} \frac{(-1)^{n+1}}{n^{2}-\frac{1}{4}} \sin n\psi. We have realized 'short' weak links with a three-dimensionnal geometrical structure. Fabrication techniques of the 'short' weak links have been disclosed. We have made 115 GHz Josephson-effect mixers of the 'short' weak links.         Mixing efficiency of SIS junctions    T. Sollner and S. Powell Summary: To evaluate new SIS technologies as low noise mixers we have investigated theoretically the frequency down-conversion efficiency of SIS junctions with IV curves which closely resemble experimentally observed curves. Leakage current and IV curve "sharpness" of the current rise at eV = /spl Delta//sub 1/ + /spl Delta//sub 2/ are included as parameters. We have applied a 3-port version of the quantum mixing theory to study the importance of these parameters on conversion efficiency. The results suggest that the leakage conductance should be less than 10% of the normal conductance, that the voltage width of the current rise should be less than 10% of the gap voltage, and that the optimum frequency of operation is near 10% of the gap frequency, eV/sub gap/ /h.         Nonlinear response of tunnel-type Josephson junctions at submillimeter-wave frequencies    S. Morita, S. Takaki, S. Imai, Y. Takeuti and N. Mikoshiba Summary: We have fabricated tunnel-type Josephson junctions with very small junction area by pressing the tip of a sharpened Nb wire onto a thinly oxidized Sn film, and studied their submillimeter-wave responses. It turns out that the junctions have a very high cutoff frequency, and are suitable for the investigation of the response to the submillimeter waves with the frequency higher than 1 THz. From the frequency and laser-power dependence of the Shapiro step, it is found that the tunnel-type junction shows much larger higher-order steps, and accordingly has much stronger nonlinearity than the bridge-type junction in the submillimeter-wave region. The large enhancement of the steps due to the Riedel singularity is also observed in the tunnel-type junction. In addition to the Shapiro steps, photon-assisted tunneling steps are observed clearly, reflecting the large and sharp gap structure in the dc IV curves of the tunnel-type junctions.         Incoherent radiation spectroscopy based on AC Josephson effect    Yu. Divin, O. Polyanski and A. Shul'man Summary: The new type of spectroscopy making use of ac Josephson effect is described. In contrast to the earlier proposals of Josephson effect based spectroscopic methods the new one is applicable to electromagnetic radiation with continuous spectrum.         The magnetic coupling between the microwave and the tunnel junction on the microstripline    G. Cui, X. Meng and K. Shao Summary: This paper reports a series of controlled experiments which is carried out on the microstripline. The results of the experiments showed, when the resonant Josephson tunnel junction was placed there, where the magnetic field on the stripline was stronger, the coupling was better. Thus the point of view of the magnetic coupling is further proved.         Quantum noise in Josephson-junction parametric amplifiers    L. Kuzmin, K. Likharev, V. Migulin and A. Zorin Summary: Crossover between thermal and quantum noise in the externally-pumped Josephson-junction parametric amplifiers is theoretically followed. Two different approaches are used for the analysis : i. Josephson junction is replaced with its RSJ model with the equilibrium source of fluctuations; ii. microscopic theory of the tunnel junctions is used, which takes into account not only thermal and quantum but also shot noise. Because of inconvenience of the noise temperature T/sub n/for the amplifier sensitivity characterization in the quantum limit, we express our results in terms of the figure /spl theta//sub n/which is essentially the amplifier output noise energy, reduced to its input (in the classical limit,/spl Theta//sub N/=k/sub B/T/sub N/. For the nondegenerate amplifier, the minimum value of /spl theta//sub n/. equals h/spl omega//2 and is due to quantum noise (zero-point oscillations) in the idle-frequency resonator of the amplifier. For the degenerate amplifier, sensitive to only one quadrature component of the input signal, /spl theta//sub n/can be made much less than the above "quantum limit" even at operation temperatures much higher than h/spl omega//k/sub B/, if the Josephson junction characteristic frequency /spl omega//sub c/is high enough,h/spl omega//sub c//spl gsim//sub B/T. Our analysis of the experimental situatlon shows that the values /spl Theta//sub N < h//spl omega//2can be achieved using two-dimensional arrays of a large number (N/spl sime/100) single-tunnel-junction interferometers with low inductances, inductively coupled to a microwave cavity.         SQUID parametric amplifier    A. Silver, R. Sandell, J. Hurrell and D. Pridmore-Brown Summary: The single junction SQUID was previously shown by analysis and simulation to be an attractive candidate for a parametric amplifier. Further calculations of the noise and saturation behavior of the nearly degenerate parametric amplifier have now been performed by numerical simulation. These simulations clearly show that the amplifier noise temperature will be approximately the device temperature T/sub 0/, and that the amplifier will be completely saturated in the presence of white noise characteristic of 30T/sub 0/. Signal saturation of the amplifier also occurs for an output power 10/sup -2/ F/sub o//spl phi//sub o/ /sup 2/ /2L, strongly limiting the dynamic range, However, a coherent array of N single junction SQUIDs is shown to have a signal saturation level increased by N relative to a single SQUID, with no increase in noise temperature, resulting in an N-fold improvement in dynamic range.         SQUID voltage-controlled-oscillator    A. Silver, R. Sandell and J. Wilcox Summary: We have investigated the SQUID as a voltage-controlled source of microwaves. The low impedance "resistive" SQUID can be a relatively high power (/spl sim/ nW), tunable, and monochromatic source for both on-chip and off-chip applications. Studies of the time-dependent junction phase and the available power spectra as they vary with such device parameters as loaded Q and the SQUID-/spl beta/= 2/spl pi/Li/sub c///spl phi//sub o/establish design rules for a well-behaved oscillator. For a VCO /spl beta/Q<2; for /spl beta/ Q/spl ges/ degenerate parametric subharmonic oscillations and chaotic instabilities are observed. Power increase is suggested by the use of voltage-clamped dc SQUIDs and arrays.         Dynamics of Josephson tunnel junctions with a finite-width Riedel peak    A. Zorin, K. Likharev and S. Turovets Summary: The basic properties of high-current-density Josephson tunnel junctions are calculated from the microscopic theory taking into account a finite width 2/spl delta/ of the Riedel peak. The calculated I-V curves for the finite values of the normalized capacitance /spl beta//sub c/, the Riedel peak halfwidth /spl delta/, and the parameter /spl alpha/ of pair current suppression are in good agreement with published experimental results for the high-current-density tunnel junctions Pb(In)-oxide-Pb. The hysteresis parameter I/sub R//I/sub c/calculated from the microscopic theory as a function of the normalized capacitance /spl beta//sub c/is compared with the dependence following from the RSJ and the RSJN models. In addition, the low-frequency spectral density S/sub v/(0) of the voltage fluctuations across the junction is numerically found and compared with that following from the simple shot-noise model.         Chaotic and stochastic phenomena in superconducting quantum interferometers    V. Kornev and V. Semenov Summary: Complex chaotic and stochastic phenomena in single-junction and double-junction superconducting quantum interferometers are studied with the help of specially designed high-speed analog circuit. In Contrast with the earlier versions of the Josephson junction analogs, the digital integrated circuits with the voltage-controlled time delay have been used as the basic elements of the circuit, which has enabled us to extend its frequency range up to 1OO KHz. Of the phenomena studied with the analog, two are discussed in detail: i. For the single-junction interferometer under the periodic external drive the region of parameters is found, where the device exhibits complex and chaotic behavior and thus cannot be used in parametric amplifiers and ac SQUIDs. The boundary of the chaotic behavior region is found to be very close to that predicted from a very simple criterion, ii. For the double-junction interferometer, we have measured the probability of the establishing the basic ("0-th") static state as a result of a slow decrease of the bias current, as a function of the interferometer parameters. The region is determined where the probability is very close to unity, and the interferometer can be used as an NDRO memory cell.         Chaos in Josephson tunnel junctions    V. Gubankov, K. Konstantinyan, V. Koshelets and G. Ovsyannikov Summary: Experimental data have been obtained confirming the theoretical assumption of chaos existence in superconducting tunnel junctions (STJ) with hysteretic I-V curve (IVC) in the presence of the external microwave radiation for zero bias current. The dynamic of the chaos formation was investigated and the chaos intensity was estimated. Observation of chaotic oscillations for bias current smaller than the critical current are reported and discussed.         Possibility of superconducting exciton laser    M. Sugahara Summary: It is shown that spatial higher-harmonic component of electron-electron attractive interaction brings about condensed excitonic state in nonequilibrium superconductor with quasiparticle injection. Photon emission at the transition of an exciton to Cooper-pair state is possible in the region perturbed by injection. Experiments are shown which seem to support the appearance of excitonic level and the generation of coherent emission of electromagnetic waves in injected superconductor.         Transient response of tin microstrips to supercritical current pulses    D. Butler, T. Hsiang and G. Mourou Summary: We have measured the transient response of tin microstrips to short current pulses whose amplitude exceeded the dc critical current I/sub c/of the sample. The current pulses were generated by an electro-optic switching technique. The voltage across the microstrip was measured indirectly by integrating the sample into a transmission line and measuring the transmission characteristics. For a fixed pulse duration, no voltage was measured until a threshold I/sub c1/(>I/sub c/) was reached. Above I/sub c1/, the voltage developed at a delay time of /spl tau//sub d/. When current amplitude exceeded a second threshold I/sub c2/, the voltage onset occurred with no observable delay. These results were partially explained by existing theories that employed TDGL calculations.         Design and performance of integrated DC SQUID gradiometers    V. de Waal, G. van Nieuwenhuyzen and T. Klapwijk Summary: Integration of thin film gradiometers with a dc superconducting quantum interference device (SQUID) is described. A parallel first-order gradiometer has been realized with an overall size of 17 mm X 12 mm and a sensitivity of typically 3x10/sup -12/Tm/sup -1/Hz/sup -1/2/. An intrinsic balance of 300 ppm is easily achieved. Its usefulness for measuring biomagnetic signals is shown. A novel design for a second order gradiometer consisting of eight second order loops in parallel is presented. The design is based on a sensitivity of 3x10/sup -10/Tm/sup -2/Hz/sup -1/2/with a size of 17mm X 17mm and a SQUID inductance of 1nH.         Full-power trials of the Brookhaven superconducting power transmission system    E. Forsyth and G. Morgan Summary: The power transmission test facility at Brookhaven consists of a 700 W supercritical helium cooling system, cable enclosure about 100 m long, four cable terminations, electrical excitation equipment and control and monitoring instrumentation. The cryogenic system was tested extensively prior to installation of two cables in late 1981. Each cable is terminated at each end so that full-power electrical trials are possible with the simultaneous application of voltage and current. The operating characteristics with the cable carrying 4,100 A (60 Hz) at 80 kV to ground are presented; this corresponds to a rated power of 330 MVA per cable. The full engineering evaluation of the system is estimated to take about 30 weeks of running, it is unlikely to be completed in 1983.         Practical conclusions from field trials of a superconducting cable    P. Klaudy and J. Gerhold Summary: Field trials of a Fully Flexible Superconducting Cable (60 kV/1000 A, design Klaudy-Kabelmetal) including the necessary potheads were performed successfully in a real grid for the first time in the world during the years 1977-1980 at Arnstein (Austria). The cable met all electrotechnical and cryotechnical field and test conditions. Encouraged by this success and based on the experiences gained in Arnstein as well as on further theoretical and practical investigations, the authors propose a simplified version of the Fully Flexible Arnstein cable with an improved new superinsulation saving the nitrogen cooling stage. The proposed cable is based on the corrugated tube principle (Wellmantel-technique of Kabelmetal) and offers an economically competitive and technically superior construction compared to presently favoured watercooled cables in the power range of 1 GW or even lower. This power rating is of interest already today for the electricity supply in densely populated areas and industrial centers. Fully Flexible Superconducting Cables have the following essential advantages over other superconducting and conventional cables: 1. The cable can be fabricated in great lengths (a couple of hundred meters) at low cost with well proven methods and equipment. 2. They can be reeled, shipped, and laid like any conventional cable in individual sections. 3. They require no sophisticated expansion elements as the thermal length changes occuring during cooling cycles of the cables are compensated for thanks the elasticity of the corrugated tubes. 4. They guarantee high operational safety since only a small number of splices and joints are necessary for connecting the individual sections of the cables. 5. They offer a high lifetime compared to conventional cables. 6. They are especially suited for the transmission of base load power at power ratings down to 1 GW and at voltages of 100 - 140 kV. 7. Being superconducting cables, they offer the possibility of perfect electromagnetic shielding towards their environment. Shield currents cause practically no losses. 8. The cables require surprisingly small trench widths - an advantage which can not be achieved with any type of normal conducting cables. Consequently Fully Flexible Superconducting Cables of the corrugated tube design will be of importance in connection with electrical high power transmission in future.         The results of work carried out in the USSR on creation of superconducting and cryoresistive cables for electric power lines    G. Meshchanov, I. Peshkov and G. Svalov Summary: The paper presents test results for simulated flexible cryoconducting (CCC) and superconducting cables (SCC) designed and manufactured in VNIIKP.         Status report on the forced flow high field test facility SULTAN    I. Horvath, G. Vecsey, P. Weymuth, J. Zellweger, E. Balsamo, G. Pasotti, M. Ricci, N. Sacchetti, M. Spadoni, J. Elen and W. Franken Summary: The construction of the Test Facility SULTAN - a common action of three European laboratories: ENEA (I-Frascati), ECN (NL-Petten) and SIN (CH-Villigen) is near completion. In this paper the status of the contributions of the different partners is described: (a) The SIN part of the facility, the cryogenic system the current leads, the power supplies and the data acquisition system has been put into operation. Results of these tests are presented. (b) The background field will be generated by two concentric solenoids. The ENEA contribution is concerned with the realization of the outer solenoid. This coil, which has been recently completed, will provide a 6 T field in the useful region, the remaining 2 T being supplied by the coaxial ECN insert coil. Details of the design, winding technique, hydraulic circuitry as well as instrumentation of both coils will be given and discussed. In addition the future upgrading to 12 T is outlined.         An Al-stabilized Nb/sub 3/Sn pulse coil    F. Irie, K. Yamafuji, M. Takeo and F. Sumiyoshi Summary: A pulse coil has been designed and manufactured that generates a pulse field of 1T/0.1sec in a high bias field (/spl sim/12T). The coil is to be used for the measurements on superconducting conductors. It is wound by an Al-stabilized multifilamentary Nb/sub 3/Sn conductor on a FRP bobbin, and consists of two concentric coils arranged to reduce leak field in the outer bias coils. The coil was shown to be stable in repeated pulse operations. Its loss was measured and discussed.         Transient stability in high field dipoles    D. Baynham Summary: Two types of 10T dipoles are currently being considered for the next generation of particle accelerators, NbTi conductors at 1.8K or Nb/sub 3/Sn conductors at 4.2K. A theoretical analysis of conductor transient stability for these two modes of operation is presented. The aim is to ascertain the construction mode with the maximum stability and performance prospects.         Quench transients in internally cooled conductors    C. Walters, M. Wilson, J. Ross and M. Liddle Summary: A 70 Kg superconducting coil using an internally cooled cabled conductor has been made and tested in order to verify computer-predicted phenomena such as occur during quenching. A satisfactory correlation between the theoretical predictions and the experimental results was obtained in respect of the pressures generated during a quench; these were much lower than predicted by simple theory. Resistive voltage, temperature, and propagation velocity were monitored at two current levels (5 kA and 7.5 kA) and in general were similar to the computed results. The coil was energized to 10.5 kA without training, this current exceeded the short sample characteristic of the conductor.         Safety and stability of superconducting magnets for fusion using internally cooled conductors    L. Turner and R. Ryne Summary: Vincent Arp's computer code for the stability analysis of internally cooled conductors (ICC) has been combined with ANL's TASS code to create the code SSICC for the analysis of the safety and stability of ICC. The code has been tested against the ICC experiments of Lue, Miller, and Dresner, and applied to the FED TF coil conductor.         Detailed analysis of the quench characteristics of the Swiss LCT coil    C. Marinucci, P. Weymuth and G. Vecsey Summary: Because of the relevant impact on the design and on the safety factor of the coil components, an accurate analysis of the quench characteristics of the Swiss LCT coil system was performed. Helium pressure, temperature and flow rate in the forced-flow cooled TUCO conductor and in the other components of the coil system have been calculated using a code developed at SIN. The effect of several parameters and different operating conditions have been investigated.         The source, origin and propagation of quenches measured in superconducting dipole magnets    S. Caspi and W. Hassenzahl Summary: Transitions from the superconducting to normal state at 4.4 and 1.8 K in several model accelerator dipoles were recorded by a fast data acquisition system. The resistive voltage rise in the conductor during the transitions is used to determine accurately the location of the quench source in the magnets and to estimate the axial and turn-to-turn quench velocities. The quench velocity, temperature evolution and energy deposition in the coil were calculated using the program QUENCH and are in reasonable agreement with the data. In the two dipole magnets studied, the transitions almost always occurred in the regions of highest field. In one coil the high field region is in the straight section because the field in this region is enhanced by iron support rings. In the other magnet the high field region is at the end, in the innermost turn of the first layer. Some quenches were preceded by large voltage spikes that can be ascribed to conductor motion. Other quenches do not appear to be associated with any large energy release. Acoustic emission (AE) was monitored during the tests and AE bursts were observed simultaneous with the initial voltage spike. An increased AE signal continued as the quench progressed.         Doubler system quench detection threshold    K. Koepke, P. Martin and M. Kuchnir Summary: The experimental study leading to the determination of the sensitivity needed for protecting the Fermilab Doubler from damage during quenches is presented. The quench voltage thresholds involved were obtained from measurements made on Doubler cable of resistance X temperature and voltage X time during quenches under several currents and from data collected during operation of the Doubler Quench Protection System as implemented in the B-12 string of 20 magnets. At 4kA, a quench voltage threshold in excess of 5.0V will limit the peak Doubler cable temperature to 452K for quenches originating in the magnet coils whereas a threshold of 0.5V is required for quenches originating outside of coils.         Protection of high current density superconducting magnets    D. Ciazynski Summary: Theoretical studies of the protection of a high current density magnet (J/sub average/= 540 A/mm/sup 2/at B = 6.5T and T = 4.2 K) have shown that following a quench, a fast removal of the stored energy from the magnet is needed in order to limit the maximum temperature rise in the winding to below 150K. A protection system using a superconducting switch as a current breaker and a secondary copper winding for the extraction of the stored energy was developed, This system enabled us to obtain a short reaction time and a fast current decrease without overvoltage across the magnet. The theoretical study of the protection, the analysis of the characteristics of the switch and the secondary winding and their effects on the behaviour of the protection system are discussed. Results of tests of the superconducting switch with a NbTi dipole and tests of the complete system with a Nb/sub 3/Sn dipole are presented.         Diagnosis and analysis of an electrical short in a superconducting magnet    Y. Iwasa, M. Leupold, R. Weggel, J. Hale and J. Williams Summary: A case study of an electrical short that occurred in a large superconducting coil is presented.         Critical current, stability and AC-loss measurement on the Euratom LCT conductor    C. Schmidt Summary: An integral test of the LCT cable conductor was performed in a test facility where a short-circuited loop of conductor was placed in an external 5 T field. The transport current was induced in the loop by variation of the external field. Measured I/sub c/values agree with single-strand measurements. Stability measurements were performed using an inductive heater. The instantaneous point source energy inducing a quench can be fitted by the empirical expression E /spl prop/ I/sup -3/ B/sup -2/. In a separate experiment the ac-losses of the cable were measured and found to be a factor of 6 - 10 higher than expected from theoretical calculations, due to low resistance contacts between strands. The conductor is, however, still within the LCT specifications.         Design and manufacture of the conductor for the Swiss LCT coil    H. Benz, B. Jakob, F. Konig, K. Kwasnitza, R. Maix, H. Marti and G. Meyer Summary: The design and manufacture of the cabled and soldered conductor for the Swiss LCT coil is described.         Development and testing of a 50 kA, pulsed superconducting cable    J. Wollan, W. Hamilton, J. DeClerc and B. Zeitlin Summary: Prototype cables for 7.5 T, pulsed field application in tokamak poloidal field coils have been designed, fabricated, and evaluated. Successful fabrication of a 10 m superconducting sample represents the largest superconducting cable ever made. Details of the fabrication, the problems expected and encountered, and the solutions to those problems are discussed. Results of stability measurements on the superconducting prototype also are presented.         Critical current measurements on superconducting cables    M. Garber, W. Sampson and M. Tannenbaum Summary: In this paper we describe the essential features of short sample measurements on high current superconducting cables. The purpose of such measurements is threefold: to provide a basis of comparison for assessing magnet performance, to provide Quality Assurance data on purchased materials, and to evaluate metallurgical R & D aimed at understanding and improving conductor perf0rmance.         Structural behavior of cable superconductors    H. Becker and P. Marston Summary: The structural properties of cable superconductor coils, for particle accelerators such as the Tevatron and the CBA (Colliding Beam Accelerator), depend upon direction of loading. For compression perpendicular to the "flat faces" of the conductor, the coils exhibit nonlinear, inelastic and time dependent behavior. The same is true for "inplane" compression loading perpendicular to the conductor edges. In the lengthwise direction, the coils display tension and compression stress-strain curves typical of structural metals. The loading of primary concern is compression perpendicular to the conductor faces since deformations in that direction can have a major influence on magnetic field quality. However, the coil behavior under that condition is uncertain because of the nonlinear stress-strain curve complicated by creep and relaxation at the stress levels induced by preloading and Lorentz forces. Furthermore, the stiffness of the loading fixture appears to influence the data as shown by results from tests run under different conditions at Berkeley, Brookhaven and MIT. The paper displays test data on stress-strain curves for all three loading directions. Results are presented for RT, 77 K and 4 K behavior. Data of various investigators are compared. The applicability of a relatively simple power law between stress and strain is depicted.         Mechanical properties of Nb/sub 3/Sn stranded superconducting potted cable windings    S. Caspi, R. Meuser and R. Wolgast Summary: The electromagnetic stresses in projected designs of high-field magnet coils sometimes exceed the yield points or creep strengths of the presently used coil winding materials. This is especially true of react-after-winding Nb/sub 3/Sn coils, plastic insulating materials, and the crossed strands of twisted cable. This report presents compression stress-strain curves of stranded and twisted flat cable coil winding specimens for reacted and epoxy-impregnated Nb/sub 3/Sn coils, at 300 K and 80 K. The lateral and longitudinal strains of one specimen were measured along with the direct compressive stress-strain, at 300 K. A similar specimen was compressed to 40 MPa (6 kpsi) at room temperature and then to 145 MPa (20 kpsi) at 80 K. Plastic flow occurred up the maximum stress. Stress cycles subsequent to maximum stress were elastic. Some specimens were mounted in a rigid enclosure to simulate hydrostatic containment of the magnet coil. Pure annealed Cu was tested at 300 K, and pure epoxy was tested at 300 and 80 K. In addition the thermal contractions from 300 to 80 K were measured.         Development of a forced-cooled Nb/sub 3/Sn bundle conductor    N. Aoki, M. Ichihara, E. Suzuki, H. Shiraki and S. Murase Summary: Forced flow cable conductors using Nb/sub 3/Sn superconductors have been developed. In manufacturing the cable-in-conduit type conductors, some problems are considered. Initial phase of investigations of these problems have been carried out. Some results of the investigations are discussed and described in this paper. Using a roll-forming method, the reliable manufacture of the long length cable-in-conduit type conductors has been achieved. By forming the Cu/sub 2/O+ Cu/sup 2/S film on the surface of strands, there was no adhesion between strands after the heat treatment at high temperature for a long time. Both Nb/sub 3/Sn superconductors by the bronze process and the tube method have achieved a critical current density in the non copper area of more than 400A/mm/sup 2/at 12T, 4.2K.         Evaluation of the scattering in critical current and Niobium-Titanium volume fraction along a length of conductor    P. Genevey, J. Le Bars, A. Sagniez and B. Turck Summary: The knowledge of critical current at any point of a length of a conductor has always been a wish for a coil designer. It is now possible to contemplate this matter without running the whole length at helium bath temperature. From the local resistance per metre of composite measured at room temperature it is possible to derive the cross sectional area of the Niobium-Titanium. We show from samples taken along lengths of different conductors that the cross sectional areas derived from weighing the Niobium-Titanium and from the resistance per metre measurements are in very good agreement and that the current density is constant along a given length. As a result the critical current can be estimated from three measurements: critical current, weight of the Niobium-Titanium in a sample taken at one end and the measurement on line of the resistance per metre.         A control line for the qualification of large quantities of superconducting wires    J. Le Bars and B. Turck Summary: The fabrication of the coils for the toroidal field of Tore Supra has now been ordered. The first lengths of conductors are expected in February 1983. A special line has been developed, in order to control at room temperature the overall production of the 320 kms of conductor in a continuous process. Special attention is drawn on the shape, the mechanical integrity and homogeneity of the conductor. The geometrical sizes are measured by two special devices. One uses Hall probes moving in the bore of permanent magnets, the other explores the outer surfaces with diamonds attached to electric sensors. The resistance of each meter of conductor can be directly related to the local amount of Niobium-Titanium, and provides a very good information on the homogeneity of the composite. A device developed by the CEA using induced eddy currents is able to detect very local changes in the amount of copper, and the presence of voids, bad bonding, inclusions and surface defects.         Microstructure related superconducting and mechanical properties of some Nb-Ti alloys with additions of Ta and Zr    H. Khan Summary: Effect of the substitution of Ta and Zr in different metallurgical states on the micro-structure, lattice structure, superconductivity as well as the mechanical properties like room temperature Vicker's hardness, tensile strength and ductility of bcc-/spl beta/Ti phase alloys: Nb/sub 0.5/Ti/sub 0.5/, Nb/sub 0.40/Ti/sub 0.45/Ta/sub 0.15/and Nb/sub 0.40/Ti/sub 0.45/Ta/sub 0.075/Zr/sub 0.075/is investigated. Optical, SEM and EDX investigations show the alloys to be of homogeneous bcc-/spl beta/Ti phase with no segregation of Ta or Zr at the grain boundaries upon annealing. The room temperature Vicker's hardness and tensile strength increase upon addition of Ta and Zr whereas the ductility decreases and these parameters also depend upon the metallurgical of the samples. Among the ternary and quarternary alloys the highest values of Vicker's hardness: 261 kg/mm/sup 2/; tensile strength: 694 N/mm/sup 2/and ductility: 11 are observed for the Nb/sub 0.40/Ti/sub 0.45/Ta/sub 0.075/Zr/sub 0.075/(1100/spl deg/C; 30 h). The T/sub c/value decreases upon addition of Ta and Zr and also depends on the metallurgical state. The highest T/sub c/and the slope, dH/sub c2//dT|T=T/sub c/values are observed for the as cast cold rolled alloys: Nb/sub 0.40/Ti/sub 0.45/Ta/sub 0.15/(T/sub c/= 9.02 K; 2.14 T/K); Nb/sub 0.40/Ti/sub 0.45/Ta/sub 0.075/Zr/sub 0.075/(T/sub c/= 8.88 K; 4.28 T/K). The critical magnetic field values of Ginzburg-Landau and Maki as well as the Maki parameter are determined which also depend strongly on the metallurgical state. The alloy of composition Nb/sub 0.40/Ti/sub 0.45/Ta/sub 0.075/Zr/sub 0.075/(as cast; cold rolled) shows the presence of highest spin-orbit scattering for the compensation of paramagnetic limitation.         Compositional inhomogeneities in Nb-Ti and its alloys    A. West, W. Warnes, D. Moffat and D. Larbalestier Summary: Results are presented showing that commercially produced Nb-Ti and Nb-Ti-Ta can have extensive chemical inhomogeneities, of order 10 wt.%. These chemical inhomogeneities are associated with significant sub-structure irregularities and, in one case, with filament sausaging and poor J/sub c/performance. Homogenization of such alloys is discussed. Some recent ingots have been much more homogeneous than those first studied and it is concluded that purchase of chemically homogeneous materials is preferred for high J/sub c/composites.         Empirical scaling formulas for critical current and critical field for commercial NbTi    M. Lubell Summary: Short sample 4.2 K experimental facilities are plentiful, but equipment for measurements of current as functions of temperature and field is scarce. An analysis has been made of published data comprising at least six manufacturers and spanning a range of critical current density at 4.2 K, 8 T of 50 to 108 kA/cm/sup 2/, and linear equations have been found to fit the data over a wide range of field B and temperature T. For a constant temperature of 4.2 K, the following expression holds for B in the range of 3 to 10 T: j/sub c/(B, T = 4.2 K) = j/sub o/[1 - 0.096B], where [B/sub c2/(4.2 K)]/sup -1/= 0.096 with a standard deviation of 3% for ten samples. The constant j/sub o/can be determined for any sample from a single point measurement at a convenient field. For a constant field of 8 T, the following expression holds for T in the range of 2 to 5.5 K: j/sub c/(B = 8 T, T) = j'/sub o/[1 - 0.177T], where [T/sub c/(8 T)]/sup -1/= 0.177 with a standard deviation of less than 1%. Linear equations have also been obtained for higher fields and lower temperatures. The critical field vs temperature is B/sub c2/(T) = B/sub c2/(0) [1 - (T/T/sub c/(0))/sup n/], where B/sub c2/(0) = 14.5 T, T/sub c/(0) = 9.2 K, and n = 1.7 (not 2, which is used in theoretical derivations). For more accurate critical temperature calculations above 10 T, this equation can be used with the modification B/sub c2/(0) = 14.8 T. No one simple power law for the upper critical field holds over the whole temperature range.         Mechanical and electrical properties of high current density NbTi conductor    S. Hong, E. Adam, E. Gregory, W. Marancik and F. Roemer Summary: Tensile properties of copper matrix NbTi superconductors have been measured and correlated with actual critical current densities. The effects of high tensile strength on conductor fabrication is discussed for various conductor configurations and filament distributions.         Aluminum stabilized multifilamentary NbTi conductor    J. Royet, J. Scudiere and R. Schwall Summary: It has long been recognized that high purity aluminum offers several potential advantages in the stabilization of superconductors. Specifically, aluminum is commercially available with a residual resistance ratio (RRR) in excess of 2500 compared to a maximum of approximately 200 for copper. The magnetoresistance of aluminum also saturates rather quickly such that the specific resistivity of RRR 2500 aluminum is approximately 1/20 that of RRR 200 copper at 12 T. Aluminum also offers well recognized weight and radiation transparency advantages. Previous attempts to fabricate commercially viable aluminum stabilized conductors have, however, been unsuccessful because of the great disparity in the metal forming properties of NbTi and aluminum. This disparity of flow stresses has led to the use of higher resistivity aluminum alloys as conductor matrices. These conductors have met with marginal success. The present approach involves applying aluminum stabilizer to a completely fabricated and optimized NbTi/copper composite. The challenge is, of course, achieving complete metallurgical bonding and uniform cross section. Through the use of an orthogonal extrusion process whereby aluminum is solid state bonded to a cleaned copper conductor we have successfully clad a wide range of superconductors with high purity aluminum. Moreover, with proper control of the cladding process an aluminum resistivity ratio over 2500 has been preserved in the finished conductor with no degradation of the NbTi critical current properties.         Submicron filament multistrand powder metallurgy processed Cu-Nb-Sn wire    J. Otubo, S. Pourrahimi, C. Thieme, H. Zhang, B. Schwartz and S. Foner Summary: Submicron size ultrafine Cu-Nb-Sn superconducting wire has been fabricated by the powder metallurgy process simulating large scale industrial fabrication using the bundling technique. Starting copper and niobium powders ranged from 250 to 500 /spl mu/m. Both external and tin core processed wires were fabricated with overall current densities of J/sub c/ /spl sim/2-3 /spl times/ 10/sup 4/ A/cm/sup 2/at 14 T, demonstrating that both particle size and billet can be scaled up to large scale fabrication.         Tin core processing of powder metallurgy Cu-Nb-Sn    H. Zhang, S. Pourrahimi, J. Otubo, C. Thieme, B. Schwartz and S. Foner Summary: Powder metallurgy processed CuNbSn superconducting wires were fabricated using different internal tin core geometries. Variations of the process included: 1) a single central tin core surrounded by a multifilamentary composite or by a multistran powder composite, and 2) bundled multistrand compacts, each containing a tin core. External Ta or Nb barriers were also incorporated in the wire. Nominal areal reductions of 10/sup 4/to 10/sup 6/were used. Overall critical current densities of 3x10/sup 4/A/cm/sup 2/at 14 tesla were achieved.         Growth kinetics and characterization of superconducting properties of multifilament materials made by the ECN powder method    H. Veringa, P. Hoogendam and A. Wees Summary: Analysis of the growth of the niobium-tin phases during heat treatment of multifilament material containing niobium tube and NbSn/sub 2/powder has revealed that the occurrence of an Nb/sub 6/Sn/sub 2/intermediate phase has a great influence on the superconducting properties of the final A-15 phase. It is found that a very high J/sub c/combined with high T/sub c/and B/sub c2/values can be obtained. On the other hand, the homogeneity of the structure in both radial and axial direction and the current carrying capacity of the A-15 layer is strongly dictated by the heat treatment temperature and the composition of the original powder core. From this study an improved filament composition is found which now guarantees excellent and well controllable superconducting properties. Further experimental work to find the dependence of the overall current density on the powder core size is underway. This should eventually give a tool for further improvement. Also the determination of the critical current degradation under application of mechanical strain and bending is proceeding. Provisional results are given in this paper.         Irradiation effects for in situ Nb/sub 3/Sn-Cu composite conductors    J. Ostenson, D. Finnemore, J. Verhoeven, E. Gibson and C. Snead Jr. Summary: A series of high performance in situ Nb/sub 3/Sn-Cu conductors have been studied to determine the detrimental effects of neutron irradiation on the upper critical field, the transition temperature and the critical current. For fluences up to 1x10/sup 18/n/cm/sup 2/, there is essentially no degradation of any of the superconducting properties. At 7x10/sup 18/n/cm/sup 2/, however, T/sub c/has dropped to 13 K and at 10/sup 19/neutrons n/cm/sup 2/T/sub c/has dropped to 9 K. The ratio of H/sub c2//T/sub c/is essentially constant at 1.0 T/K for fluences out to 1.3x10/sup 19/n/cm/sup 2/. The volume pinning force goes as (1-b)/sup 2/for all samples indicating that shear in the flux line lattice controls J/sub c/even for samples with T/sub c/as low as 6 K.         Equilibrium and propagation of the resistive-normal zone in AC superconducting composites    V. Altov, E. Blagov, N. Kulysov, Yu. Lvovsky and V. Sytchev Summary: Equilibrium thermal cycles of ac conductors with a current sharing between a superconductor and a substrate are treated. During the propagation process a possibility of the coexistence of the superconducting and resistive zones or resistive and normal zones along the conductor is revealed. A possibility of the zone propagation process at the currents above the critical one is stated.         Improved Nb-Si-Nb SNAP devices    H. Kroger, L. Smith, D. Jillie and J. Thaxter Summary: We have compared the tunneling characteristics of Nb-Si-Nb junctions whose amorphous silicon barriers have been sputtered in pure Ar with those sputtered Ar-H/sub 2/plasmas as well as in various combinations. We observe lower subgap currents with composite barriers which comprise a central region which is hydrogenated but which is sandwiched between two thin unhydrogenated layers. The improved tunneling characteristics may be associated with the lower density of localized states in the hydrogenated silicon.         Uniformity and stability of Nb-aSi-Nb "SNAP" Josephson tunnel junctions    L. Smith, H. Kroger and D. Jillie Summary: We have examined the suitability of Nb-aSi-Nb tunnel junctions, patterned by the selective niobium anodization process (SNAP), for large scale integrated circuit applications. Using sputtered SiO/sub 2/as the SNAP anodization mask, the device area closely reproduces the mask area, with undercut < 50 nm, and no detectable perimeter effects. The critical current density increases with the radial distance from the center of the Si target, due to the quadratic decrease in the thickness of the sputtered Si barrier: at a distance of 1 cm, this increase is /spl sim/ 10%. Arrays of 12/spl mu/m X 12 /spl mu/m junctions have been fabricated with standard deviations of the critical current of /spl sim/ 1%. These arrays have been thermally cycled between room temperature and 4.2 K over 600 times without change. Junctions can be annealed at 175/spl deg/C for extended periods of time to increase the current density by up to /spl sim/ 50% with no deterioration in junction quality.         Preparation and properties of Nb Josephson junctions with thin Al layers    M. Gurvitch, M. Washington, H. Huggins and J. Rowell Summary: Josephson tunnel junctions of the types Nb/Al-oxide-Nb and Nb/Al-oxide-Al/Nb, where Al represents thin (/spl sim/50/spl Aring/) films of Al, were prepared by D.C. magnetron sputtering. The tunnel barrier was formed by in-situ thermal oxidation. Individual junctions were defined using photolithography coupled with the plasma etching technique. Junctions with critical current density up to 1300 A/cm/sup 2/and V/sub m/= i/sub c/R(2mV) between 15mV and 47mV at 4.2K were obtained.         XPS and tunneling study of air-oxidized overlayer structures of Nb with thin Mg, Y and Er    J. Kwo, G. Wertheim, M. Gurvitch and D. Buchanan Summary: Guided by the criteria of strong oxygen affinity and strong tendency toward surface segregation over Nb, artificial tunnel barriers of thin Mg(10-65 /spl Aring/), and Y(4-30 /spl Aring/) overlayers on Nb were investigated. Very high-quality tunnel junctions of the types Nb/Mg-oxide/Pb/sub 0.9/Bi/sub 0.1/and Nb/Y-oxide/Pb/sub 0.9/Bi/sub 0.1/were obtained, particularly in the latter case, with /spl utri//sub Nb/of 1.57 meV and excess conduction at 2 mV to be 1.4x10/sup -3/of that at 4 mV. As characterized by the XPS technique, Mg and Y overlayers as thin as 10 /spl Aring/ are sufficient to protect the underlying Nb film from oxidation. The Mg-oxide and Y-oxide formed on the surface by air oxidation are mainly hydrated. The rapid loss of metallic Mg and Y near the surface can be accounted for by the grain boundary diffusion mechanism previously invoked to explain results on Nb/Al overlayers. The Nb spectrum of the Nb/30 /spl Aring/ Y sample shows remarkably clean, metallic Nb feature, very comparable to that obtained on a Nb foil in-situ scrape-cleaned in ultrahigh vacuum. Artificial barriers formed by oxidation of thin rare-earth metal layers Er(5.1-20.4/spl Aring/) were also attempted. Good-quality tunnel junctions of the type Nb/Er-oxide/Pb/sub 0.9/Bi/sub 0.1/were made, but inferior to those made with Al, Mg, and Y overlayers. XPS shows clearly that the surface oxide consists of both Er-oxide and Nb-oxide.         On resonant tunneling in Nb-Nb/sub 2/O/sub 5/-diodes    J. Halbritter Summary: In Nb/sub 2/O/sub 2/adjacent (/spl les/ 5 nm) to a metal, the hybridization of localized electrons with conduction electrons yields interface states, which exist up to the Fermi energy E/sub F/of the metal. These interface states can be classified in 2 groups: -Localized electrons between 1 and 5 nm in front of Nb have a long decay life time into the metal, so that exchange processes via these interface states are obstructed and show a correlation (image potential) energy /spl utri/U/sup x/> 5 meV. -Adjacent to the metal (< 1 nm) exchange processes without /spl utri/U/sup x/are possible. Thus an electric field is already shielded in front of the metal and such interface states are weakly superconducting. These interface states yield a resonant tunnel current which cannot be fitted by direct barrier tunneling and which is exponentially enhanced over direct tunneling, yielding: -A strong, symmetric increase of the tunnel current, above 10-40 meV (giant zero bias anomaly: GZBA). -Josephson and leakage currents and smearing out of structures in the tunnel current at voltages between 0 and 20 meV.         Characterization of Nb/Nb oxide structures in Josephson tunnel junctions    S. Raider, R. Johnson, T. Kuan, R. Drake and R. Pollak Summary: The subgap conductance of Nb, Nb oxide/Pb-alloy Josephson tunnel junctions was found to strongly depend on the rf plasma processing used to form the Nb oxide tunnel barrier. We have therefore studied the Nb/Nb oxide structures after rf plasma processing using x-ray photoelectron spectroscopy (XPS) and transmission electron microscropy (TEM) data. A crystalline Nb-C-O layer was formed as a transition region between the polycrystalline Nb base electrode and the Nb/sub 2/O/sub 2/tunnel barrier. The thickness of this transition region is sensitive to the rf plasma cleaning conditions prior to the tunnel barrier formation. An unexpected relation between junction electrical properties and the Nb/Nb oxide structure exists. The lowest subgap conductances are those obtained for tunnel junctions with transition regions about 30/spl Aring/ thick. An abrupt interface between Nb and Nb/sub 2/O/sub 2/leads to junctions with high subgap conductances.         Electrical characterization of Nb/Nb oxide/PbAuIn Josephson tunnel junctions    W. Gallagher, S. Raider and R. Drake Summary: We have studied the low temperature electrical characteristics of high quality, high current density (/spl sim/500 A/cm/sup 2/) Nb-Nb oxide-PbAuIn Josephson junctions with the aims of understanding the deviations of these characteristics from the ideal and of correlating the deviations with information about the physical characteristics of the barrier region of the junction. We find we can understand the knee structure at the sum gap in terms of a proximity effect with a normal metal-like NbO/sub x/C/sub y/transition layer. Excess currents in the subgap region in the highest quality junctions are mostly consistent with a multiparticle tunneling picture. In the lower quality junctions, the excess subgap currents appear to be due to tunneling between the superconducting Pb alloy and some low energy states in the Nb electrode. We are unable to distinguish between several possible sources of such states.         Process characterization of Josephson packaging technology    R. Wang Summary: Process characterization is an essential step in the development of circuit chips and package parts for the Josephson technology. In our laboratory various test vehicles were designed with test sites to explore new designs and processes, to provide in-process and end-of-process evaluations of fabrication runs as well as to serve as powerful diagnostic tools. This article describes some of the process characterizations used in the package for the first system level test vehicle in the Josephson technology. The types of electrical characterizations, the full vertical structures, requirements of package parts and major process steps are discussed. Results from wiring, contacts, and insulation sites are used to illustrate the nature of this work and will benefit the development of a prototype machine in suggesting areas that require special attention.         Comparison of temperature cycling stability of Pb-alloy Josephson junctions with various counter electrode materials    J. Gates and S. Pei Summary: The stability of Pb-alloy Josephson junctions upon repeated temperature cycling between 300 K and 6 K has been investigated. Various size cross type junctions were fabricated with PbInAu base electrodes and PbAu, PbBi or PbSb counter electrodes. The Pb alloy electrodes were deposited on room temperature substrates by either sequential deposition or evaporation to completion of predetermined alloys. The films were patterned by a lift-off stencil and the tunneling barriers were formed using dc slow discharge in oxygen. The junctions were then passivated with sequentially deposited layers of Ge and SiO and annealed at 80/spl deg/C for various periods of time. The critical current stability and the junction failure due to shorts as a function of temperature cycling are compared for junctions with different counter electrodes. In the most favorable case, 40 /spl mu/m square junctions have been thermally cycled for over 6000 times and no failures were observed among a population of more than 1000 junctions.         Trimming the critical current of Josephson junctions    S. Pei, T. Fulton, L. Dunkleberger and R. Keane Summary: We have demonstrated the feasibility of trimming the critical current of Josephson tunnel junctions by doping the lead alloy counter electrodes. The critical current may be changed by more than a factor of six, while retaining the quality of the current-voltage characteristics and the critical current uniformity. For junctions with PbSb counter electrodes doped with less than 0.2 nm of Sn, the increase of critical current is stable after proper annealing and depends linearly on the dosage. For dosages heavier than 0.25 nm, the increase of critical current saturates at /spl sim/ 500%. These changes may be explained by the conversion of some oxide at the interface between the counter electrode and the tunneling barrier to the oxide of the dopant. The modification of the height and thickness of the tunneling barrier changes the critical current of the junction.         Device applications of reactive ion beam sputter deposited superconducting thin films    A. Hebard and R. Eick Summary: The technique of Reactive Ion Beam Sputter Deposition has been used in the preparation of metal oxide thin-film composites which have a promising potential for superconducting device applications. We have investigated the correlation between film deposition parameters such as reactive gas (oxygen) partial pressure, substrate temperature, target composition etc., with the film microstructure and superconducting properties. The resulting granular and amorphous films are extremely stable with respect to repeated temperature cycling. We have demonstrated the use of these materials as base electrodes in Josephson tunnel junctions and as weak-link Josephson switches. The extremely smooth surface topography of the films also implies low flux-pinning thresholds which should be useful in fluxoid memory and logic devices.         All refractory Josephson tunnel junctions fabricated by reactive ion etching    A. Shoji, S. Kosaka, F. Shinoki, M. Aoyagi and H. Hayakawa Summary: We have developed a novel process for fabricating all refractory Josephson tunnel junctions whose base and counter electrodes are composed of (Nb-NbN) double-layered films. In this process, tunnel junctions have been isolated using a reactive ion etching from a junction sandwich which had been formed on an entire silicon wafer, and also the reactive ion etching has been used for patterning electrodes and insulation layers in devices. Fabricated junctions have yielded good tunneling characteristics with excellent uniformity and reproducibility. The maximum critical current density was widely changed from 300 A/cm/sup 2/to 8 kA/cm/sup 2/. All refractory single flux quantum(SFQ) memory cells in a 32 X 32 arrangement have been integrated with a 2.5 /spl mu/m minimum linewidth on a chip using this process, and an SFQ cell in the memory array has been successfully operated. The maximum deviation of critical currents in the memory array was measured to be /spl plusmn/6.5%.         High quality niobium nitride-niobium Josephson tunnel junctions    E. Cukauskas, M. Nisenoff, D. Jillie, H. Kroger and L. Smith Summary: Niobium nitride-niobium Josephson tunnel junctions with sputtered amorphous silicon barriers (NbN-/spl alpha/Si-Nb) have been prepared using processing that is fully compatible with integrated circuit fabrication. These junctions are of suitable quality and uniformity for digital circuit and S-I-S detector applications. At 4.2K, the product of the critical current and normal resistance is 1.8 mV; the subgap resistance is /spl ges/14 times the normal resistance; and the sum of the electrode gaps is /spl sim/3.8 mV -- in good agreement with the expected value. The current density can be controlled from /spl sim/10 amp/cm/sup 2/to >500 amp/cm/sup 2/by varying the thickness of the /spl alpha/Si barrier. The processing steps required to achieve these results will be described and their effect on the physics of the tunneling process will be discussed.         Application of SQUID sensors to the investigation of neural activity in the human brain    S. Williamson and L. Kaufman Summary: The unique capabilities of superconducting magnetic field sensors have made the study of weak magnetic fields associated with neural activity in the brain a significant area of research in the laboratory and clinic. To illustrate these applications of superconductivity we give examples of the kinds of results that can be obtained by studying cortical and subcortical sources.         Domestic test result of the Japanese LCT coil    S. Shimamoto, T. Ando, T. Hiyama, H. Tsuji, Y. Takahashi, E. Tada, M. Nishi, K. Yoshida, K. Okuno, K. Koizumi, T. Kato, H. Nakajima, O. Takahashi, M. Shimada, Y. Sanada, F. Iida and K. Yasukochi Summary: Japan Atomic Energy Research Institute (JAERI) has been preparing one D shape superconducting coil for the Large Coil Task. This paper describes mainly the results on domestic test which has been successfully carried out with a single test condition in JAERI this year. The main results, which were obtained during the test, are cool-down and warm-up characteristics, superconducting recovery characteristics, discharge characteristics, strain and displacement measurements, and heat load measurements. Before describing the results, the Japanese coil design parameters and the Superconducting Engineering Test Facility for the domestic test are shown in this paper.         Magnets for the mirror fusion test facility: Testing of the first yin-yang and the design and development of other magnets    T. Kozman, S. Wang, Y. Chang, E. Dalder, C. Hanson, R. Hinkle, J. Myall, C. Montoya, E. Owen, R. Palasek, D. Shimer and J. VanSant Summary: Completed in May 1981, the first yin-yang magnet for the tandem Mirror Fusion Test Facility (MFTF-B) at Lawrence Livermere National Laboratory (LLNL) was successfully tested in February 1982 to its full design field (7.68 T) and current (5775 A). Since that time, the entire magnet array has been reconfigured-- from the original A-cell to an axicell design. The MFTF-B magnet array now contains a total of 26 large superconducting coils: 2 sets of yin-yang pairs, 2 sets of transition magnets (each containing two coils), 2 sets of axicell magnets (each containing three coils), and 12 central-cell solenoids. This paper chronicles recent magnet history--from the testing of the initial yin-yang set, through the design of the axicell configuration, to the planned development of the system.         Conceptual design of a superconducting magnet for a 200 MW/sub e/MHD engineering test facility    P. Marston, A. Hatch, R. Thome and A. Dawson Summary: A 6 T superconducting magnet system conceptual design has been completed for the U.S. Department of Energy's 200 MW/sub e/Engineering Test Facility. The 1000 tonne magnet will be built of two grades of pool-cooled NbTi cable superconductor supported in 26 layers of stacked epoxy-plastic plates which form each 60/spl deg/ rectangular saddle coil half. Each coil half will be enclosed in a stainless steel vessel which contains the liquid helium that cools the coils and provides some structural support against the electromagnetic forces. The main force containment structure, external to the LHe vessels and located in the vacuum chamber, is designed for maximal access to structural and coil containment vessel welds for purposes of routine inspection. An LN/sub 2/-cooled thermal radiation shield is situated between the force containment structure and the outer vacuum vessel. Fiberglass-epoxy low-heat-leak struts position and hold the cold mass in place in the vacuum vessel and also withstand gravity, seismic and magnetic interaction loading. The magnet system, warm bore liner and roll-aside mechanism provided for channel changeout will be discussed as well as such interfacing considerations as fringe field effects on personnel and control instrumentation.         The design approach and innovations for the largest, uniform field, superconducting solenoid magnet    G. Danninger, D. Lieurance and D. Walker Summary: Design, development, manufacture, and acceptance testing of the Preprototype Magnet System (PMS) was undertaken in April 1978 under contract with the TRW Energy Systems Group as sponsored by DOE for Advanced Isotope Separation System Development. The PMS began operation in September 1981. The principal design requirement was to provide a uniform magnetic field of 20,000 gauss /spl plusmn/0.1% for a 5-meter-long by 0.75-meter-diameter test region. The paper presents the magnet design, manufacturing and in-process test approach taken to meet this requirement. This includes the development of equipment and techniques for ensuring winding integrity and the method of achieving field uniformity during manufacture. Design innovations for coil cryostat components are also presented. These include 1) the cold mass support strut, which was redesigned from a previously proven configuration due to manufacturing scaling problems, 2) the thermal shield, which was simplified from the previous full-flow configuration, 3) the layer-to-layer insulation configuration, which must provide for sufficient LHe circulation, and 4) the coil overbanding configuration, which prevents conductor movement when the coil is energized.         3000 horsepower superconductive field acyclic motor    R. Marshall Summary: A 3000 hp acyclic motor was assembled and tested utilizing superconducting field coils. The magnet assembly is designed as a quadrupole magnet, utilizing a multifilamentary niobium titanium superconductor. Each magnet coil is 18 inches in diameter and 10 inches long, and operates at rated current of 200 amperes, providing 5.8 tesla in the bore of the coils in the motor configuration. The average winding current density is 10,600 A/cm/sup 2/. The acyclic motor is of a drum-type design with liquid metal current collectors, and is designed to model full-scale machinery for ship propulsion applications. Laboratory test data verified the electrical and electromagnetic design to be within three percent of the calculated values.         Design concepts for a mechanically refrigerated 13 K superconducting magnet system    M. Hoenig Summary: The construction of small superconducting magnets operating in the 12 to 14 K temperature range without use of supplemental cryogenic fluids is of interest for a number of applications. This requirement can be satisfied for peak fields of up to 3.3 T using Nb/sub 3/Sn superconductor and cooling by means of a close-coupled two stage refrigerator. In order to reduce lead losses, the current must be minimized. Conduction-cooled leads, heat stationed at 14, 70 and 300 K have been designed. Operating at 40 A, they impose 5 and 1 W heat loads (respectively) on the first and second stages of the CTI- 1020 refrigerator capable of absorbing 30 and 2.5 W (respectively) at the 70 and 13 K heat stations. The refrigerator is a relatively inexpensive "off-the-shelf" item.         Experimental characterization of the flux-line lattice in superconducting V/sub 3/Si    D. Christen, H. Kerchner, J. Narayan, Y. Chang, B. Larson and S. Sekula Summary: Several microscopic properties of the flux-line lattice (FLL) in three separate single crystals of V/sub 3/Si have been investigated by means of small-angle neutron diffraction. These low-field FLL characterizations have been correlated with the following material and superconducting properties: (A) The real crystal symmetry parallel to the applied magnetic field; (B) The micro-structure as determined by TEM; (C) Magnetic irreversibilities in the mixed state; (D) Reversible flux-line motion in ac response; (E) Martensitic structural transformation observed by X-ray diffraction. The three samples, V/sub 3/Si-MP3, -MP4, and -MP5 possessed different defect structures, and this was manifested foremost in the FLL perfection. At low field (B<0.2 T) and T=4.85 K, only MP3, which is free of second-phase precipitates, showed a highly resolved FLL. Sample MP5 contains a low density of small (200 /spl Aring/) coherent precipitates, and revealed well-defined FLL Bragg peaks for B/spl gsim/ 0-.5T, but a highly mosaic, nearly polycrystalline FLL at lower fields. Sample MP4 contained large (500-1000 /spl Aring/) incoherent precipitates, and showed only a polycrystalline FLL at low field. In both MP3 and MP5, distinct anisotropic correlations were observed between the FLL morphology and the real-crystal direction along the applied field. The FLL perfection was strongly dependent on the growth history. The peak width history dependence for two different scattering geometries can be qualitatively modeled by proposed flux-pinning mechanisms. Quantitative comparisons with critical current measurements, however, are not totally reconcilable.         Theoretical studies of point defects and diffusion in Nb/sub 3/Sn    D. Welch, G. Dienes, O. Lazareth and R. Hatcher Summary: The structure and energetics of several simple point defects in A15 Nb/sub 3/Sn were investigated by means of computer simulations based on a pair-potential model of cohesion. The properties of vacancies on both the Nb and Sn sublattices, as well as those of simple antisite defects, were examined, and estimates were made of the energetics of several types of atom-vacancy exchange ("jump") processes. The results show an unusual structure for the vacancy on the Nb sublattice: the vacancy is "split" between two adjacent sites along the Nb chain with an atom midway between them. We find the Sn vacancy (on the Sn sublattice) to be metastable; this vacancy will "decompose" by an activated process into a more stable configuration consisting of a Nb atom on a Sn site adjacent to a split Nb-sublattice vacancy. We find that the lowest energy grouping of defects compatible with maintaining sublattice sites in the proper three-to-one ratio is the antisite defect pair; the lowest energy grouping which contains vacancies is found to consist of Nb-sublattice vacancies and Nb-on-Sn-sublattice antisite defects in the ratio of four of the former to one of the latter (quintuple defects). Our results also suggest that bulk Sn diffusion is slower than Nb diffusion; this is consistent with the belief that rapid Sn diffusion during Nb/sub 3/Sn layer growth does not occur by bulk but by grain-boundary diffusion.         Effect of interstitial hydrogen on Young's modulus and the martensitic transformation of Nb/sub 3/Sn    H. LeHuy, J. Bussiere and B. Berry Summary: The effects of interstitial hydrogen on the elastic softening, the martensitic transformation and the critical temperature of Nb/sub 3/Sn were studied. Using internal friction as a diagnostic tool, it was found that the martensitic transformation temperature is decreased with hydrogen and completely suppressed for /spl sim/ 0.6 at %H. For these small hydrogen additions, the onset critical temperature is increased to /spl sim/ 18.4K. For higher concentrations of hydrogen, Tc decreases as previously reported and softening of Young's modulus is almost entirely suppressed.         Effect of hydrogen content on the superconducting behaviour of commercial Nb/sub 3/Sn wires    F. Matacotta, C. Ferdeghini, M. Ferretti and G. Bruzzone Summary: Nb/sub 3/Sn commercial wires (diameter 0.5 mm, 3700 filaments) have been hydrogen doped at various concentrations and the superconducting properties of these wires have been correlated to the hydrogen content x in Nb/sub 3/SnH/sub x/. Here the results are presented which regard critical temperature and overall critical current density for applied fields from 9 T to 12 T at 4.2K and 6K for hydrogen content up to x = 0.310. The critical temperature trend shows a slight maximum at x /spl sime/ 0.02, after which it decays abruptly. Also the critical overall current density at same hydrogen concentration is higher than that of unhydrogenated samples at 4.2 K and is comparable or better at 6 K. The resulting dJ/sub ov//dB shows a good behaviour in the studied field range.         J-B-T-/spl epsiv/ interaction and strain limits in A15, B1, and C15 crystal structure superconductors    J. Ekin Summary: Experimental evidence is presented which indicates, that the elastic strain effect on the critical current of high-field compound superconductors correlates strongly with the type of superconductor crystal structure. Large strain effects are observed in all practical A15 superconductors examined to date, including Nb/sub 3/Sn, Nb-Hf/Sn-Ga, Nb/sub 3/Ge, Nb/sub 3/Al, and V/sub 3/Ga. Strain is observed to have no measurable effect, however, on either the critical current or the critical field of superconductors having the B1 crystal structure [NbN] or the C15 crystal structure [V/sub 2/(Hf, Zr)]. Strain limits placed on the mechanical design of superconducting devices are evaluated as a function of magnetic field for several A15 superconductors (Nb/sub 3/Sn, Nb-Hf/Cu-Sn-Ga, and V/sub 3/Ga) and compared with the strain limits imposed by B1 and C15 superconductors. It is shown that the latter materials have mechanical design advantage in applications where the superconductor is subjected to strain in excess of 0.2% (either compressive or tensile).         The critical current density of filamentary Nb/sub 3/Sn as a function of temperature and magnetic field    P. Hudson, F. Yin and H. Jones Summary: We have built and developed an apparatus which permits the reliable evaluation of J/sub c/(B,T) for helically wound samples of superconductor. This apparatus is used in conjunction with The Oxford Hybrid Magnet which achieves a maximum field of 15.5T. The temperature range over which measurements can be made is 2 to 30K. Results on filamentary NbTi have already been published. We present here results of a highly detailed characterisation of an Nb/sub 3/Sn filamentary conductor produced by the post-winding, high-temperature reaction of a Cu-Sn bronze - Nb composite which contains high purity copper florets and was developed at A.E.R.E. at Harwell. J/sub c/has been measured as a function of temperature, in 0.5K increments, from 2K to 18K, at field levels ranging from 0T to 15T in 0.5T increments. We present also an empirical fit to the data. This was made possible by the near linear behaviour of the function over much of the range of practical interest. We believe these results could be of great interest to the designers of superconducting machines and devices.         Thirteen tesla magnet constructed with MJR wire    M. Siddall, W. McDonald and K. Efferson Summary: We have constructed an insert booster superconducting magnet of 20 mm clear bore and outside diamener of 100 mm and height 130 mm, wound and reacted from the Teledyne patented foraminous layered foil (jelly roll) wire fabricated by low cost, non-rebundled reduction to wire. This magnet was placed inside the 101 mm bore of a NbTi wound solenoid which was operated at 8.5 Tesla. The total field achieved was 13.0 Tesla with no training quench observed; although training was initially observed when the magnet was first tested alone up to 4.6 Tesla at American Magnets, Inc. (AMI). The magnet winding techniques utilize Airco's fiberglass type wire insulation, an AMI proprietary cement, argon atmosphere 700/spl deg/C for 100 hour reaction, followed by a post-reaction potting impregnation. The MJR wire lot used (M22) was short sample tested and the Ln (J/sub c/) -vs-H line intersected the insert magnet operating curve at 13.5 Tesla. The wire lot used has a 34 volume % copper external sheath for quench protection. The wire was fabricated with 15.4 volume % niobium and bronze/niobium ratio of 3.0 with 13.% Sn bronze.         Distributed tin Nb/sub 3/Sn superconductor    W. Marancik, E. Adam, E. Gregory and M. Suenaga Summary: A unique conductor configuration has been developed. The tin is distributed internally as the core of a cable. The cable is then sheathed in copper on a continuous tube mill to produce long lengths of finished product. Process and product data will be presented.         Multifilamentary Nb-Nb/sub 3/Sn composite by liquid infiltration method: Superconducting, metallurgical, and mechanical properties    M. Hong, G. Hull, J. Holthuis, W. Hassenzahl and J. Ekin Summary: A rapid solid-liquid reaction mechanism has been used to form A15 Nb/sub 3/Sn in the liquid-infiltration processed Nb-Sn wire. Small, equiaxed A15 grains across the fine reacted filaments of 0.2-1.0 /spl mu/m thickness were revealed with the transmission electron microscopy studies. A uniform Sn concentration near the stoichiometry was found in the A15 region. High inductive T/sub c/'s of 17.9K with sharp transition widths (<0.3K) and excellent overall J/sub c/'s of 10/sup 4/A/cm/sup 2/at 19T and 4.2K were achieved. Mechanical properties of the reacted wire are no worse than those of typical commercial bronze-process Nb/sub 3/Sn conductors, and /spl epsiv//sub irrev/is slightly higher.         On the mechanical properties of Sn-core processed Nb/sub 3/Sn filamentary composites    S. Cogan, J. Klein, S. Kwon, H. Landis and R. Rose Summary: We have investigated the mechanical properties of a Sn-core processed Nb/sub 3/Sn filamentary superconductor. The observed strain dependence of the critical current density was as expected for more conventionally processed composites with similar niobium contents and filament diameters. Low cycle fatigue measurements revealed some shakedown behavior which diminished rapidly at higher stresses.         Fabrication of 20 KA, 12 Tesla conductor using external Bronze process MF Nb/sub 3/Sn    R. Schwall and G. Ozeryansky Summary: A MF Nb/sub 3/Sn cabled condcutor with a design critical current in excess of 20 KA has been delivered to the Oak Ridge National Laboratory for stability test in the CWTX Facility. The 5.2 cm X 1.1 cm conductor, an adaptation of a 12 Tesla ETF design by Walker, et al is a 7 X 7 X 3 X 16 cable. The seven strand primary cables incorporate two 0.3 mm diameter external bronze process MF Nb/sub 3/Sn strands and five barrier protected stabilizer strands. Critical current density in the active strands is approximately 5x10/sup 4/A/cm/sup 2/at 12 Tesla, 4.2 K.         Metallurgical and superconducting properties of multifilamentary V/sub 3/ Ga wires    D. Howe, T. Francavilla and D. Gubser Summary: Multifilamentary V/sub 3/Ga wires containing small additions of yttrium have been produced commercially for the Naval Research Laboratory by Airco Superconductors Inc. These conductors containing 55 and 3025 filaments were metallurgically processed through a combination of hot extrusion and wire drawing. The yttrium additions were found to soften the vanadium alloy and consequently enhance the size reductions necessary to produce the wire without detrimental effects to previously achieved growth rates and critical current properties.         Magnetic properties of pure and surface treated Vanadium    F. De Schutter, Y. Bruynseraede and A. Gilabert Summary: The very high surface pinning present in superconductors strongly hinders the analysis of fission fragment irradiation experiments which produce heavy damage in a surface layer of approximately 10 /spl mu/m. In order to decrease this pinning effect, different treatments such as coating with a normal metal or oxygen diffusion can be used. In this paper we show that oxygen doping lowers the critical temperature T/sub c/of Vanadium and surface oxidation reduces drastically the irreversibility of magnetization curves. We show that the dependence of T/sub c/on the oxygen concentration combined with the measurement of the oxygen concentration gradient (obeying Fick's diffusion law) can explain our magnetic permeability data.         The use of critical current measurements for the development of technological superconductors    A. Van den Bosch, J. Cornelis and F. Biermans Summary: The development of superconductors of technological interest is studied in our institute. The quality of the products is controlled in an apparatus for measuring critical currents up to 1000 A at 4.3 K in magnetic fields up to 13 tesla. The "short sample" is a one meter long wire in the form of a helix. A shunt limits the power generated in the cryostat at the quench. A data acquisition system, with digital voltmeters of 0.1/spl mu/V sensitivity, is adapted to the apparatus. The data are transferred to the main computer of the institute for further processing. The reliability of the apparatus has been checked measuring critical currents of commercial superconductors, the agreement with the producer's data being good. The apparatus is used to optimize the thermal treatments of home made niobium-tin superconductors. The power supply and the data acquisition system were also used for the study of small superconductive coils which were wound with commercial niobium-titanium multifilament wire. One of these coils generates fields up to 8 tesla.         Filament breakage in Bronze process Nb/sub 3/Sn superconductors    D. Holmes Summary: Wire breakage during fabrication of bronze process Nb/sub 3/Sn conductors has been linked to individual broken filaments within the wire. The wire breaks produce a cup and cone fracture with the tip of the cone centered on an enlarged filament rather than on the center of the wire. Samples of two different types of wire were sectioned longitudinally or cross-sectionally and examined for occurrence of irregular filaments. Enlarged and broken filaments were found and their occurrence analyzed. The enlarged heads of broken filaments are significantly harder than the matrix or the surrounding, undisturbed filaments. Broken filaments were found most frequently among filaments at the edges of filament groups near the center of the wire. Data on enlarged filament size distribution, hardness, and distribution within the wire are presented in the paper.         Fabrication of Nb/sub 3/Ge/Si(SiO/sub x/)/Pb Josephson tunneling junction    H. Ihara, Y. Kimura, H. Okumura and S. Gonda Summary: The Josephson junction of Nb/sub 3/Ge was fabricated by using a Si(SiO/sub x/) thin film as the tunnel barrier and Pb as a counter electrode. The thickness of the Si barrier is 2 nm, and the junction size is 0.5 X 0.5 mm/sup 2/. The critical current of the junction was 8 /spl sim/ 12 Acm/sup -2/. the normal-state tunneling resistance was 30 /spl sim/ 60 /spl mu/ /spl Omega/ cm/sub 2/. The onset voltage of gap was 5.2 mV. The Shapiro step mode and the Fiske step mode were observed in a well-defined shape. The dependence of maximum dc-Josephson current upon external magnetic field gives the penetration depth of Nb/sub 3/Ge of 130 nm. The dependence of the resonance voltage upon external magnetic field gives the dielectric constant 8.7 of the Si(SiO/sub x/) barrier.         Process characterization of Niobium based Josephson integrated circuits    J. Villegier, M. Goniche, M. Levis, P. Renard, M. Vabre and J. Veler Summary: Process test chips for Josephson integrated Circuits including refractory metal resistors have been achieved and tested with Niobium based technology made in LETI. Tantalum resistors are lying above niobium base electrode. Such a configuration gives compact logic circuits and very good mechanical bahaviours. An entire 14 layers technology including Nb-Nb/sub 2/O/sub 2/- Pb(In) tunnel junctions, control lines and contact pads is being achieved and described. Arrays of 100 interferometers cells, superconductive contacts in series, and other chips for measuring capacitance of junctions and insulators, penetration depths in superconductive materials, resistors are fabricated on sapphire, wafers and tested. Such devices yield a good stability upon thermal cycling and storage at room temperature.         Investigation of high rate magnetron sputtering of niobium films for Josephson integrated circuits    J. Villegier and J. Veler Summary: High rate Dc-magnetron sputtering of 30 nm niobium thin films is shown to be a very good technique to achieve reproducible and stable ground plane, tunnel junctions electrodes, control lines and even resistors for Josepson Integrated Circuits. Pure niobium films have low residual resistivity (/spl rho//sub 10/k /spl sime/ 2/spl mu/ /spl Omega/cm), low stresses, and are no longer in the "dirty limit". High quality ratio (R/sub J//R/sub N/ /spl sime/ 20 at 4 K). Josephson Junctions were performed with niobium base electrode. Critical temperatures either below 4.2K used for resistors or between 4.2K and 16K can be controlled accurately by reactive magnetron sputtering in an argon-nitrogen plasma. Homogeneous low critical temperature can be also selectively obtained by liquid cathodization or by RF plasma post-treatments on a pure niobium film through a photoresist mask. Nb, Nb(N), Nb(O) and Nb (H) films are studied by TEM and X ray diffraction. The critical temperature change obtained can be explained by lattice BCC structure dilatation or distorsion and by impurities inclusion.         Properties of NbN/Pb Josephson tunnel junctions    R. van Dover and D. Bacon Summary: Tunnel junctions made with NbN base electrodes and Pb counterelectrodes are investigated and characterized in terms of their potential for high-performance digital Josephson circuits. The NbN is deposited by dc magnetron reactive sputtering onto substrates which are held near room temperature (T/sub s/ < 90°C) to assure compatibility with conventional photoresist liftoff; the process results in films with a T/sub c/ of 14.2K and an energy gap parameter /spl tri//subNbN/ = 2.4meV. Tunnel junctions are formed by ion         NbN/sub x/-NbO/sub y/-PbIn/sub z/Josephson junctions with R.F. oxidised tunneling barriers    M. Deen and E. Thompson Summary: We report the fabrication of high quality Josephson tunnel junctions made by the r.f. sputter-deposition method. The characteristics of these junctions were determined at 4.2/spl deg/K as a function of the following fabrication parameters: the substrate temperature, the sputtering power during base electrode deposition, and the r.f. oxidation time for the barrier. We have obtained critical current densities from 90 to 800 Amperes/cm/sup 2/which depended exponentially on the barrier formation time, a gap energy of 3.3meV, and hysteretic current-voltage characteristics. Thermal cycling of a few junctions resulted in small changes in the current-voltage curves. Auger Electron Spectroscopy and ESCA of the films show that x=1.02, z=0.25, and that the niobium oxide is a mixture of Nb/sub 2/O/sub 2/and the lower oxides, NbO and NbO/sub 2/, that are present at the oxide-base electrode interface.         A novel technique for preparation of tunnel junction barriers using electrochemical anodization    R. Simon, P. Chaikin and S. Wolf Summary: A novel method has been developed for preparing both Josephson and single particle tunnel junctions. This technique has been extensively applied to Sn-Sn/sub x/O/sub y/- metal films where the tin oxide barrier is formed on the surface of a freshly evaporated Sn film by electrochemical anodization. By varying the anodization parameters, the junction resistances can be controlled over more than three orders of magnitude: i.e., from less than 10/sup -4/ohm-cm/sup 2/to 0.1 ohm-cm/sup 2/. In each instance, high quality junctions with nearly ideal IV characteristics and low leakage currents have been produced. Low resistance Josephson junctions have been fabricated whose critical currents scale with junction resistance and modulate with applied magnetic field in the familiar Fraunhofer-like diffraction pattern. Sn-Sn/sub x/O/sub y/Ag-Pb proximity effect samples with the oxide barriers prepared as described above have been used to study magnetic penetration in the Ag layer. We hope to extend this technique to prepare junctions using base electrode superconductors like NbN which then will have considerable technological significance.         Ion-beam-deposited films for refractory-metal tunnel junctions    S. Ruggiero, D. Face and D. Prober Summary: We report on the application of a Kaufman ion source to the deposition of Nb and Ta thin films. We find that high quality Nb films (T/sub c/= 9.1 K) can be produced by this technique under tolerant deposition conditions. In addition, substantial, systematic improvement in the I-V characteristics of Nb tunnel junctions has been realized by depositing, in situ, thin (/spl ges/10/spl Aring/) Ta layers on the Nb film surface.         Planar interferometers with two Nb-NbO/sub x/PbIn Josephson junctions    A. Cucolo and G. Paterno Summary: Two different kinds of planar interferometers with two Nb-NbOx-PbIn junctions have been fabricated. The effects of a magnetic field coupled both to the loop and to the junctions have been investigated. A comparison of the experimental results with the theory is reported.         Microwave properties of superconducting tunnel structures based on refractory materials    V. Gubankov, K. Konstantinyan, V. Koshelets, G. Ovsyannikov and A. Vystavkin Summary: The electrophysics and microwave properties of Niobium oxide-barrier tunnel junctions with critical current densities up to 10/sup 5/A/cm/sup 2/were studied. Millimeter wave mixing using strong nonlinearity of quasi-particle tunnelling curve is described. Nonhysteretic Josephson junctions obtained by the low inductance resistive shunting of the tunnel structures were investigated in the large frequency band. The frequency range where these junctions obey the resistively shunted junction model was determined. The shunted tunnel junctions have been shown to be suitable for various applications which require stable enough Josephson junctions with nonhysteretic I-V curve (IVC).         Microstructures of lead alloy Josephson junction electrode materials: PbInAu and PbSb    S. Pei, S. Nakahara, H. Schreiber and J. Gates Summary: The microstructures of PbInAu and PbSb films similar to those used as electrodes for Josephson junctions were investigated. These films were deposited mainly by evaporation to completion of alloys. The depth profiles of various elements in these alloy films were determined by a combination of sputter etching and Auger electron spectroscopy. The surface morphologies and microstuctures were examined by scanning and transmission electron microscopies respectively. X-ray energy spectroscopy and transmission electron diffraction techniques were used to identify different crystalline phases. No apparent difference was found in the morphologies or microstructures of PbInAu films deposited on substrates with or without a thin layer of oxidized chromium film. The result suggests that the improved cyclability of the PbInAu film deposited on an oxidized chromiun layer may be due to the increased adhesion of the film composite to the substrate. For the PbSb films, antimony was found to segregate and form Sb-rich grains dispersed between Pb-rich grains. We believe that the better thermal cyclability of PbSb films is largely due to this dispersion hardening process.         Characterization of Pb/sub 3/Bi alloy surfaces by Auger spectroscopy and ion sputtering    G. Allie, E. Blanc, R. Chicault and C. Lauroz Summary: The surfaces of Pb/sub 3/Bi films obtained through evaporation on silicon substrates are analysed by using Auger Electron Spectroscopy and ion sputtering. These films reveal a strong gradient of concentration in the vicinity of the surface. In particular, the topmost layers almost exclusively contain lead, and it is only after the removal of 200 or 300 layers that the composition reaches a constant value.         Josephson tunnel junctions with monomolecular barriers    G. Larkins, E. Thompson, M. Deen, C. Burkhart and J. Lando Summary: We report here the fabrication of Josephson junction tunnel diodes in which the barrier has been deposited using the Langmuir-Blodgett technique. Diodes have been fabricated using lead-indium alloys and niobium nitride for the electrodes. The barrier was vinyl stearate polymerized by Co/sup 60//spl gamma/ radiation just prior to depositing the counter electrode. We have obtained critical current densities from 100-820 amps/cm/sup 2/at 4.2/spl deg/K, and we have observed hysteretic behavior. Preliminary measurements of the dependence of the critical current on the applied magnetic field have also been made.         Tunneling characteristics of Pb-CdS-Pb light-sensitive Josephson junctions    F. Andreozzi, A. Barone, R. Cristiano, M. Russo and G. Peluso Summary: Experimental results concerning Pb-CdS-Pb light-sensitive Josephson junctions are reported. Current-voltage and conductance-voltage characteristics are analyzed in terms of an equivalent rectangular average barrier model. The tunneling barrier characteristic parameters are calculated both in the junction high and low resistance state (before and after illumination).         Non-mean-field behavior and T/sub c/enhancement in granular microbridges    B. Dwir and G. Deutscher Summary: New measurements of critical current I/sub c/in granular Al microbridges are presented. They show, near the critical temperature T/sub c/, a departure from the mean-field behavior (linear dependence of I/sub c//sup 2/3/on T). Enhancement of I/sub c/by microwaves is simultaneously observed, up to T/sub c/. The results point out to a T/sub c/enhancement (by /spl sim/ 10 mK). A numerical model, which depicts the shape of the I/sub c//sup 2/3/(T) curve, is presented. The model also explains the co-existence of microwave enhancement, and can account for non-linear I/sub c//sup 2/3/(T) curves measured by others.         RF characteristics of Nb vertical type microbridges    K. Gamo, H. Ichinoki and S. Namba Summary: We have been fabricating Nb microbridges with a novel vertical structure and measuring their basic characteristics. The bridges have a three dimensional structure which connects two Nb planes separated by a thin insulating film (SiO/sub 2/or Si/sub 3/N/sub 4/) through a small pinhole in the insulator. With this structure, self heating effect can be much reduced because of the three dimensional structure and it is easy to have a short bridge with a small cross sectional area. Bridges fabricated have a dimension of 50-300 nm in length, 100-200 nm in pinhole diameter and 150-400 nm in Nb film thickness. We have measured temperature dependence of critical current and rf response under an irradiation at 9.55 GHz. Current steps were observed up to a voltage higher than 1.2mV on 1-V curves for a 50nm long bridge. This indicates that a self heating effect is much reduced by the three dimensional structure.         Fabrication and electromagnetic properties of planar variable-thickness S-N-S microbridges    O. Liengme, P. Lerch, W. Liu and P. Martinoli Summary: A fully optical version of the oblique evaporation technique through undercut photoresist stencils developed by Dolan is used to fabricate planar variable-thickness S-N-S microbridges. An experimental study of the static and dynamic behaviour of Pb-Cu-Pb devices is reported. I/sub c/R/sub n/-products are found in good agreement with the Likharev theory and its modifications. In the shortest microbridges we find I/sub c/R/sub n/- values of the order of the limiting value 2/spl utri//sub pb/(O)/e. The I-V curves show hysteresis only at the lowest temperatures of our experiments and exhibit sharp quantum steps when the samples are exposed to microwave radiation.         Investigation of the gap edge density of states at oxidized Niobium surfaces by RF measurements    A. Philipp and J. Halbritter Summary: Investigations of superconducting Nb cavities yield temperature and frequency dependences of the surface resistance, which deviate from the predictions of the BCS-theory for homogeneous Nb and strongly depend on the oxidation of the Nb surface. Increasing oxidation leads to an increase of the slope of the frequency dependence R /spl prop/ f/sup /spl alpha// from /spl alpha/=1.55 to /spl alpha/=1.86 and to a decrease of the reduced energy gap /spl utri/(O)/kT/sub c/from 1.92 to 1.76. The frequency dependence can be explained by a smeared out BCS density of states (DOS). The apparent width of the smearing increases with oxidation from 2/spl epsiv//spl utri/(O)=0.05 meV to 0.19 meV. The energy gap reduction can partly be explained by smeared out DOS. In addition, the reduction of the energy gap by dissolved oxygen and the formation of oxygen clusters have to be taken into account. The rf results of differently oxidized cavities show a linear correlation between energy gap and width of the smearing of the DOS. Extrapolation to zero smearing yields an undistorted energy gap /spl utri/(O)/kT/sub c/=1.975, which agrees well with the best result /spl utri/(O) = 1.56 meV from tunneling investigations of polycristalline Nb.         RF surface resistance of high-T/sub c/superconducting A15 thin films    L. Allen, M. Beasley, R. Hammond and J. Turneaure Summary: A calorimetric apparatus for measuring the surface resistance of thin film superconductors has been developed and applied to the study of high-T/sub c/A15 materials. The apparatus is capable of measurement at 8.6 GHz over a temperature range of 1.5-20K. The samples were deposited using electron-beam co-evaporation on sapphire substrates. The effective magnetic loss tangent of the sapphire substrates has been observed to have a value as low as 4.2x10/sup -8/. Surface resistance data are presented for the A15's Nb/sub 3/Sn and V/sub 3/Si and for the elements Nb and Sn. Structure in the surface resistance of A15's indicate material inhomogeneities that have been linked to temperature variations during deposition. Use of an improved style of substrate holder has greatly reduced this structure.         Josephson junction fluxon oscillators of in-line geometry    S. Erne, A. Ferrigno and R. Parmentier Summary: Resonant fluxon propagation on an in-line geometry Josephson tunnel junction of length 5/spl lambda//sub J/having a McCumber /spl beta//sub c/=5/spl pi/ is studied by numerical integration of the circuit equations of a 50-section RSJ-type model. Dc current-voltage characteristics and microwave emission spectra are calculated and shown to be qualitatively similar to, although quantitatively somewhat different from, corresponding results for an overlap geometry junction.         Microwave radiation from long in-line Josephson tunnel junctions    S. Erne, A. Ferrigno, T. Finnegan and B. Savo Summary: The frequency and power of the microwave radiation detected from long in-line Josephson tunnel junctions when dc biased on low order singularities or self-induced steps have been measured as a function of bias current and externally applied magnetic field. The preliminary experimental results reported here show that the magnetic tuning of the emitted radiation may be considerably greater than that obtained in similar junctions of overlap geometry.         RF driven long Josephson junctions    M. Cirillo, G. Costabile, S. Pace and B. Savo Summary: An analysis of the behavior of zero-field resonances in long Josephson tunnel junctions under the influence of RF fields is performed. The measurements lead to establish some criteria under which fluxon oscillations are stable. The stability is investigated mainly via the relation between the amplitude of the current singularities and an external magnetic field. We find that the junction is able to support the fluxon's steady motion almost as long as the amplitude of the RF signal does not disrupt the d.c. Josephson current.         Effect of external magnetic field on fluxon dynamics and current voltage characteristics of long Josephson junctions    M. Radparvar and J. Nordman Summary: The presence of zero field steps (ZFS) on the volt-ampere characteristics of long Josephson junctions has been generally accepted as a manifestation of fluxon propagation. Each step represents an equal number of fluxons and antifluxons resonating in the junction in a period fixed by the junction length. However, extra steps have been experimentally observed which appear to correspond to non-integral numbers of fluxons traversing the junction in one period. We use a computer simulation of the sine-Gordon equation and a separate mechanical model to demonstrate that it is feasible to maintain a different number of fluxons and antifluxons in the junction within one period. With the appropriate choice of asymmetric boundary conditions corresponding to an applied magnetic field, one end of the junction, upon arrival of an antifluxon, may release one or more extra fluxons, while the opposite end is capable of absorbing these extra fluxons. Thus, the number of fluxons passing through a given point in the junction is not equal to the number of antifluxons passing the same point within a period. If the difference between the number of fluxons and antifluxons is an odd number, steps in addition to ZFS appear on the volt-ampere characteristic. We demonstrate that a variety of complex step behavior in magnetic fields can be explained by using the concept of creation and annihilation of fluxons at the boundaries.         A D.C. biased, microwave operating SQUID    M. Cirillo, S. Pace and B. Savo Summary: A device with two long overlap hysteretic Josephson tunnel junctions in parallel is analyzed by a mechanical analog. Two identical junctions incorporated in a superconducting ring in a suitable geometrical configuration behave as a single junction. A magnetic flux threading the ring introduces a phase discontinuity in the center of the junction. On the analog the introduction of the discontinuity gives rise to significant changes in the kink's oscillation frequency.         Observation of vortex structures in Josephson junctions by laser scanning    J. Lhota, M. Scheuermann, P. Kuo and J. Chen Summary: By scanning a focused laser beam (diameter /spl sim/20 /spl mu/m and < 1 mW) on Josephson tunnel junctions we observed variations in the zero-voltage current as a function of beam position. We believe that the laser beam at the appropriate power levels serves as a direct probe of the current distribution in the junction. Two types of factors contribute to the non-uniformity of the current distribution. The first is related to the intrinsic non-uniformity of the junction and the second is due to external parameters such as applied magnetic field and temperature. Using this technique, we have directly observed the formation of vortices in a junction in a magnetic field.         Magnetic field distribution in large two-dimensional Josephson junctions    S. Vasenko, K. Likharev and V. Semenov Summary: Asymptotic approach to the theory of large (a >> /spl lambda/sub J/) two-dimensional Josephson junction is developed. As a result, the usual dc sine-Gordon equation for the rapidly changing Josephson phase difference /spl phi/ is reduced to the much more simple hydrodynamic-type equationsdiv\{A(k)\rightarrow{k}\} = 0, curl /spl rarr/k = 0, for the slowly changing wave vector /spl rarr/k (A is a simple function of k). The reduced equations are applied for analysis of a square-shaped Josephson junction and are solved using the rigorous boundary conditions. The obtained dependence of the junction critical current on the applied magnetic field is discussed and compared with the recent experimental data.         Josephson current in proximity junction    V. Kresin Summary: The thickness and temperature dependence of the maximum dc Josephson current in the presence of proximity system is investigated. The method of thermodynamic Green's function is applied. The effect of strong coupling is taken into account.         Superconducting generator field winding design for high fault tolerance    M. Ashkin, P. Eckels, C. Flick, J. Parker Jr. and A. Patterson Summary: Development of rotating electrical machines with superconfiction field winding is proceeding at numerous sites worldwide. The primary emphasis is on large turbine generators for application to power systems.         A.A-EDF cryogenerator development program tests of the superconducting rotor model coil in steady state and in transient conditions    J. Duchateau, A. Fevrier and P. Denis Summary: The superconducting winding of the model rotor has been tested in rotation at different speeds. Junctions and current leads have been studied in steady state (up to rated current 5000 A), the hottest point of the winding being 6.2 K. This has been possible thanks to a minicomputer which enables to monitor several temperature sensors in the critical parts of the windings. The thermal behaviour of the coil has been tested during fast phenomena such as quenches (training) and pulses of current up to 25000 A/s thanks to a magnetic tape associated to the minicomputer.         The basic test on the 20 KVA superconducting synchronous generator    T. Okada, T. Nitta, T. Shintani, I. Muta, T. Ishigohka and H. Fujino Summary: An experimental superconducting synchronous generator (3-phase, 4-pole, 20kVA, 220V, vertical shaft type) has been manufactured and some fundamental experiments including an on-line test has been performed. On the other hand, a three dimensional theoretical analysis for the calculation of magnetic field distributions and the determination of machine parameters was carried out. Good agreement between the measured and the calculated values is confirmed.         Design and manufacture of a large superconducting homopolar motor (and status of superconducting A.C. generator)    A. Appleton Summary: This paper describes the design and manufacture of a large superconducting motor which, in the present time of financial restraints, is continuing at least to the point of having a completed cryostat with its superconducting winding operating with a dedicated helium refrigeration plant. Comments are also made on the superconducting a.c. generator project, although a final decision on the rating of a prototype and the approval of the funding has not yet been made, the selected rating is expected to be between 200 MW and 6OO MW.         Fault current limiter using a superconducting coil    H. Boenig and D. Paice Summary: A novel circuit, consisting of solid-state diodes and a biased superconducting coil, for limiting the fault currents in three phase ac systems is presented. A modification of the basic circuit results in a solid-state ac breaker with current limiting features. The operating characteristics of the fault current limiter and the ac breaker are analyzed. An optimization procedure for sizing the superconducting coil is derived.         Superconducting fault current limiter and inductor design    J. Rogers, H. Boenig, P. Chowdhuri, R. Schermer, J. Wollan and D. Weldon Summary: A superconducting fault current limiter (SFCL) that uses a biased superconducting inductor in a diode or thyristor bridge circuit was analyzed for transmission systems in 69, 138, and 230 rms kV utility transmission systems. The limiter was evaluated for costs with all components--superconducting coil, diode and/or SCR power electronics, high voltage insulation, high voltage bushings and vapor cooled leads, dewar, and refrigerator--included. A design was undertaken for the superconducting cable and coils for both diode and SCR 69 kV limiter circuits.         Status report of the three phase 25 kA, 1.5 kW thermally switched superconducting rectifier, transformer and switches    H.t. Kate, A. Holtslag, J. Knoben, H. Steffens and L. Klundert Summary: A 25 kA, 1.5 kW superconducting rectifier system has been developed. This rectifier system working like an a.c.-d.c, converter with a primary current of 35 A at 0.1Hz, will energize a 25 kA coil with an average power of 5.4 MJ/hr and a proposed energy efficiency of at least 96%. Such a highly efficient device might work instead of a 'normal' rectifier and a pair of 25 kA current leads with its energy loss of at least 2 W/kA. The 25 kA current step-up transformer has been tested succesfully concerning its maximum current (26.4 kA) and a.c. losses (2 W at 25 kA and 0.1Hz). A conductor for the 25 kA switches has been manufactured and processed into the switching system. Their construction is described.         Characteristics of superconducting magnetic energy storage (SMES) energized by a high-voltage SCR converter    H. Kaminosono, T. Tanaka, T. Ishikawa and S. Akita Summary: A small-scale Superconducting Magnetic Energy Storage(SMES) unit was constructed using small magnets and a high-voltage converter, and the characteristics of this unit were examined. The high output voltage of the converter makes it possible for even a small magnet to charge and discharge large power. Moreover, converter control provides adequate protection during quenching. AC and DC filters can be eliminated from the converter system, and ripple voltage does not harm the superconducting magnet. These features demonstrated the potential of an SMES unit as a power system stabilizer and a peak load power supply.         High voltage superconducting switch for power application    O. Mawardi, A. Gattozzi and A. Ferendeci Summary: This paper reports the development of a novel interrupter which meets the requirements of a high voltage direct current (HVDC) power switch and at the same time doubles as a current limiter. The basic concept of the interrupter makes use of a fast superconducting, high capacity (SHIC) switch that carries the full load current while in the superconducting state and reverts to the normal resistive state when triggered. Typical design parameters are examined for the case of a HVDC transmission line handling 2.5KA at 150KVDC. The result is a power switch with superior performance and smaller size than the ones reported to date.         Characteristics of a 200 kJ shielded superconductive coil for pulsed energy storage    T. Shintomi and M. Masuda Summary: The first model of the shielded pulse superconductive energy storage was constructed and tested. The model which has the stored energy of 200 kJ is composed of a superconductive coil made by a commercially available monolithic wire and a shield coil by a copper cable. The shield coil is divided into 12 blocks which are distributed appropriately arround the superconductive coil. The accuracy of the shield coil distribution was confirmed by measuring the leakage magnetic field on the superconductive coil. The experiment of the pulse operation has been performed to test the effectiveness of the shield coil. The results shows that the pulse current in the superconductive coil could be suppressed and the good performance of this method was confirmed.         Intermediate superconductive magnetic energy storage    M. Masuda, H. Fujino, M. Iwamoto, M. Murakami, T. Shintomi and K. Ueda Summary: In the past decade, the superconducting magnetic energy storage (SMES) for application to peak shaving in utility has been investigated in a manner to construct the huge superconducting coil in bed rock.         Superconducting magnetic energy storage for BPA transmission line stabilization    J. Rogers, M. Barron, H. Boenig, A. Criscuolo, J. Dean and R. Schermer Summary: The Bonneville Power Administration (BPA) operates the electrical transmission system that joins the Pacific Northwest with southern California. A 30 MJ (8.4 kWh) Superconducting Magnetic Energy Storage (SMES) unit with a 10 MW converter is being installed at the Tacoma Substation to provide system damping for low frequency oscillations of 0.35 Hz. The integrated system status is described and reviewed. Components included in the system are the superconducting coil, seismically mounted in an epoxy fiberglass nonconducting dewar; a helium refrigerator; a heat rejection subsystem; a high pressure gas recovery subsystem; a liquid nitrogen trailer; the converter with power transformers and switchgear; and a computer system for remote microwave link operation of the SMES unit.         A 100 kWh energy storage coil for space application    Y. Eyssa, R. Boom, G. McIntosh and Q. Li Summary: The design of a 100 kWh superconductive storage unit for space application is the subject of this paper. High current densities in NbTi-copper composites, adiabatic stability and advanced construction techniques with Kevlar/epoxy tensile supports are used for a /spl beta/ = 0.3 solenoid cooled to 1.8 K at 10 T. The best weight efficiencies are 26.4 Wh/kg and 21.2 Wh/kg for current densities of 5 and 2.5x10/sub 8/B A/m/sub 2/respectively.         Discussion of acoustic emission of a superconducting solenoid    M. Pappe Summary: To improve the understanding of acoustic emission data from superconducting magnets some factors affecting the sensitivity of the test arrangement will be discussed. The mechanical conditioning of a superconducting solenoid and its relation to the temperature reached before cooldown will be shown by means of assessment of the acoustic emission event rate.         Acoustic emission data from the MFTF magnets    J. Lore, N. Tamada, O. Tsukamoto, J. Horvath and Y. Iwasa Summary: An acoustic emission (AE) technique for monitoring mechanical disturbances in large superconducting magnets was applied during testing of the MFTF yin-yang coils. A signal processing method was developed to locate sources of AE in the magnet and distinguish the type of activity. The method was then used to provide information on conductor motion activity and structural integrity of the magnet.         Short circuit detection in the winding and operation of superconducting magnets    P. Walstrom Summary: When a superconducting magnet with a shorted turn or turns is rapidly discharged, the changing magnetic flux can drive large currents through the short. These currents can lead to local temperature rises, melting of the conductor and failure of insulation, and finally to destruction of the magnet. It is, therefore, highly desirable to detect and remove shorts during the manufacture of coils.         Sequential switching of dump resistors and reclosing on a 100-KJ system    G. Donaldson, R. Walsh, L. Ascone and J. Webber Summary: A fault in an electric power system may be cleared if the faulty section is isolated and de-energised. If the section is then re-energized quickly by reclosing the circuit breakers, there is a good chance that the system can become fully operative again. Similarly in a superconducting system it is often possible to reclose successfully after a fault. However the system inevitably stores a large amount of magnetic field energy which must first be reduced. The speed at which stored energy may be transferred or dumped is limited by the voltage which the insulation can withstand safely. Sequential switching of dump resistors can keep the voltage within safe design limits and at the same time reduce the stored energy quickly, resulting in less damage and a greater possibility of reclosing successfully. Following successful reclosing tests on a smaller system, a 100 kJ system has now been investigated for sequential switching of dump resistors, followed by reclosing the power supply breakers. The paper describes a microprocessor controlled system in which the micro-processor is used to detect faults, make decisions and initiate appropriate switching action.         Internal voltage distribution in magnet systems    M. Hilal Summary: Magnet systems with large stored magnetic energy are under consideration for applications such as magnetic confinement, MSF power generation and energy strorage. Magnet protection is a prime concern in the design of these magners and has to be carefully considered.         Superconducting windings with parallel connected sections    V. Andrianov, M. Parizh and S. Kopylov Summary: A theoretical treatment of superconducting magnets with parallel connected sections has been performed. The method and results of calculation and optimization of magnet geometric and electromagnetic parameters is described. It is shown that by selecting the dimensions of sections with due regard for the superconductor critical current dependence on the magnetic field the conductor consumption can be markedly reduced. Main regularities of the quenching process in a sectioned winding are found. It is shown that segmentation improves the reliability of winding, especially in the case when the normal zone is localized in one section of the magnet. Criteria of segmented magnet reliability based on the parameters of constituent modules are found.         The characterization of superconducting materials - conflicts and correlations    J. Evetts Summary: A superconducting material can be said to be characterized when sufficient of its properties have been measured for its response to be predicted under any conceivable experimental constraints. A reasonable and straightforward proposition at first sight, but not one that stands up to close inspection. The experimental constraints constitute a moving target, because of increasing demands made on materials and because our conception of possible experimental situations is expanding. Furthermore there are problems in deciding which properties constitute a sufficient set for the description of a material, particularly when the material is inhomogeneous or has one dimension smaller than the characteristic length associated with some material property. The problems and pitfalls in making superconducting measurements on inhomogeneous superconducting materials will be reviewed by reference to recent work on A15 and Nb-Ti conductors. The breadth of information available in comparative studies of inductive transitions and various types of resistive transition will be assessed. The problem of the critical current criterion and its relation to a time dependent voltage-current characteristic will be discussed as will also the measurement and definition of the upper critical field in inhomogeneous superconductors.         Cracking and layer growth in Nb/sub 3/Sn Bronze route material    J. Cave and C. Weir Summary: A sensitive AC technique has been used to investigate T/sub c/and layer growth in Nb/sub 3/Sn diffusion layer material. This method and the more frequently used resistive T/sub c/measurement have been used in conjunction to examine several pertinent topics in diffusion layer growth. Firstly, it has been shown that the 37% volume expansion that occurs when Nb/sub 3/Sn is formed can be accommodated without cracks forming. Secondly, by deliberately deforming the layer the effects of cracks have been investigated; the inductive and resistive methods being sensitive to cracks along and across the layer respectively. Thirdly, by deconvoluting the increase in amplitude of the inductive signal with annealing time (t) the layer thickness (/spl delta/) of Nb/sub 3/Sn in a standard multifilamentary wire can be plotted; for IMI All Bronze (3000 X 5/spl mu/m filaments) at 750/spl deg/C /spl delta//spl sim/ t/sup 0.25/.         Manufacture and evaluation of Nb/sub 3/Sn conductors fabricated by the MJR method    W. McDonald, C. Curtis, R. Scanlan, D. Larbalestier, K. Marken and D. Smathers Summary: The bronze matrix/niobium filament process has become established as a commercially viable method for producing multifilamentary Nb/sub 3/Sn superconductors. This paper describes a new method, the Modified Jelly-Roll (MJR) approach, which can produce a structure similar to that in a conventionally fabricated multifilamentary Nb/sub 3/Sn conductor. This approach utilizes alternate sheets of niobium expanded metal and bronze, which are rolled into a "jelly-roll" configuration and then extruded. During extrusion and subsequent drawing, the junctures in the niobium are elongated and the material develops a filamentary structure. This method may offer significant advantages in terms of reduced fabrication time and cost over the conventional approach. Results of a manufacturing development program will be presented in which two lengths of conductor were made to High-Field Test Facility conductor specifications. In addition, critical current and transition temperature measurements of the sub-elements used to construct the HFTF-type lengths will be reported.         Properties of Nb/sub 3/Sn discrete filamentary wires by a new reliable process    K. Yoshizaki, M. Wakata, F. Fujiwara, M. Imaizumi, O. Taguchi and Y. Hashimoto Summary: We have developed a new process to improve drawbacks of In Situ technique and powder metallurgical processing. Chopped composite wires were employed instead of Nb dispersed Cu matrix ingots or Nb and Cu powders, and then the tin source for internal diffusion was prepared in the matrix. The wire by the new process had very well workability through the process, because Nb filaments were very ductile compared with filaments from powders. And the filament size control which was required for large scale production, was possible. By the critical current measurement, a 0.29 mm wire had critical current density of 4x10/sup 4/A/cm/sup 2/at 9 T, and the critical current density was increased about three times by the reduction of the wire size from 0.5 to 0.29 mm. Although the present value of the critical current density are not optimized, the higher critical current density will be promised by increasing tin content and reduction ratio.         Nb/sub 3/Sn superconducting cables processed by internal tin diffusion    K. Yoshizaki, O. Taguchi, F. Fujiwara, M. Imaizumi, M. Wakata, Y. Hashimoto, K. Wakamoto, T. Yamada and T. Satow Summary: Modified fabrication techniques of the internal tin diffusion process and optimization of the reaction condition are discussed. By this process, the large-scale production of practical multifilamentary Nb/sub 3/Sn conductors has been able to be performed very easily and reliably. The critical current density without stabilizing Cu was achieved 460 A/mm/sup 2/at 12 T, 4.2 K. Furthermore, the properties of the conductor fabricated from high tin composite are investigated. It was found that there is possibility to fabricate the conductor which has higher critical current density at high fields from high tin composite.         Properties and performance of high current density Sn-core process MF Nb/sub 3/Sn    R. Schwall, G. Ozeryansky, D. Hazelton, S. Cogan and R. Rose Summary: Commercial production quantities of Sn-core-processed MF Nb/sub 3/Sn have recently been manufactured and delivered. The 1.73 mm (0.068") diameter strand contains 721 02, 2 micron filaments and 49% stabilizing copper protected by a diffusion barrier. Critical current density in the filament bronze region can be optimized to exceed 2x10/sup 5/amps/cm/sup 2/at 10 Tesla 4.2 K and 3.7x10/sup 4/amps/ cm/sup 2/at 14 Tesla 4.2 K. Critical current as a function of applied tensile strain has been measured at 14 Tesla 4.2 K on samples of this material drawn to 0.36 mm (0.014") diameter. The peak in the Jc-/spl epsiv/ curve occurs at /spl epsiv/ = 0.28% and Jc = 1.25 Jc/sub o/.         Fabrication of large diameter external-diffusion processed Nb/sub 3/Sn composites    S. Cogan, S. Kwon, J. Klein and R. Rose Summary: Large diameter multifilamentary Nb/sub 3/Sn composites have been fabricated by the external-diffusion process. Consideration of the phase relationship in the CuSn binary system, Sn diffusion kinetics and vacancy diffusion has led to the development of an appropriate Sn homogenization anneal. By correctly annealing the composites Sn flow and Kirkendall porosity may be controlled. The application of bronze electrodeposition has also been investigated and found to significantly reduce annealing times. These concepts have been applied successfully to 0.76 mm (0.030 in) diameter composites which have overall critical currents in excess of 7x10/sup 3/amps/cm/sup 2/at 17 Tesla.         The effect of quantum mechanical uncertainty on punchthrough probability in a Josephson junction    S. Jackson and T. Fulton Summary: Using a quantum mechanical analog of the Stewart-McCumber model of a Josephson junction we have calculated the time evolution of the minimum uncertainty wavepacket for a particle localized near a maximum in a Josephson-like potential. This is used to calculate the punchthrough probability as the probability of finding a particle, initially localized (at t = 0) in the vicinity of the peak of the potential, still within a certain distance of the peak at a time t/sub d/later (wheret_{d}=\frac{2I\min}{|\dot{I}|} - RC). Our main prediction is that there is a tail to the punchthrough probability, but that it is substantially quantum mechanical in origin, since the quantum mechanical spread of the wavepacket describing the particle contributes to the punchthrough probability tail and reduces it, in any given region near the peak of the Josephson potential, from what would be expected classically.         Phase-plane analysis of punchthrough in Josephson tunnel junctions    K. Yoshida, K. Enpuku, F. Irie and T. Nagatsuma Summary: The so-called punchthrough phenomenon in a Josephson tunnel junction is studied analytically with the phase-plane method. The dynamic behavior of the junction in the resetting process is solved analytically, whose solution leads to an expression for the punch-through probability. The obtained expression for the punchthrough probability is capable of quantitative discussion and is applicable to arbitrary waveforms of the gate current. The effect of the thermal noise on the punchthrough probability is also studied analytically. It is shown that the present analytical results agree well with those of computer simulations.         Heating in Nb edge junctions    P. Arnett Summary: Heating in Josephson tunnel junctions fabricated on the edge of a Nb line, and the cooperative heating effects of edge junctions on the same line and on adjacent lines were studied. In one measurement two edge junctions on adjacent parallel lines share a common counter electrode. One junction serves as the heat source and the other as a temperature sensor. The sensor temperature was found to increase linearly with power at the first junction to near the T/sub c/(6.8 K) of the counter electrode. In addition, by varying the distance between edge junctions in several test sites the temperature profile was measured and a thermal healing length of 5 /spl mu/m was determined. In a second geometry two edge junctions share common base and counter electrodes while the width between junctions is varied in different test sites. Critical power levels were measured and again related to a temperature rise. Combining these two results it is predicted that a high current device using multiple edge junctions at a spacing of 2.5 /spl mu/m and a current density of 4000 A/cm/sup 2/would have a temperature rise of 150 mK when powered halfway up the current step at the gap voltage.         Three terminal, non-equilibrium quasiparticle device experiments with submicron tunnel junctions    B. Hunt and R. Buhrman Summary: A multilayer film edge technique has been developed for the fabrication of dual small area tunnel junctions on the aligned edges of two overlapping thin films separated by a thin insulating layer, with a common electrode shared by the two junctions. Using this technique with electron beam lithography, junction areas as small as 3x10/sup -10/A/cm/sup 2/have been produced with separations between the two tunnel barriers of 50-80 nm. Devices of this type have been fabricated with Pb alloy counterelectrodes on Nb edges, using reactive ion beam oxidation to obtain tunnel current densities in the 10/sup 5/A/cm/sup 2/range. The potential of this multijunction configuration as a high speed, three terminal Josephson device with current and power gain has been investigated. In addition, the edge junctions have been employed to probe non-equilibrium phenomena in the common electrode.         Moat-guarded Josephson SQUIDs    S. Bermon and T. Gheewala Summary: We report experimental investigations of a simple structure, called a moat, which significantly reduces the probability of flux-trapping in Josephson SQUIDs. Proper operation of Josephson logic and memory circuits requires that the SQUIDs be free of stray magnetic flux that may become trapped in the superconducting groundplane upon cooling through the critical temperature. The problem is particularly severe for so-called holey SQUIDs which rely on holes in the groundplane to obtain suitably large device inductances. Moats are rectangular channels in the groundplane surrounding the SQUID's which provide preferred sites for trapping flux, thus preventing such flux from coupling to the SQUID. We have measured the effectiveness of moats by monitoring the flux trapped in the moats and comparing it to the flux trapped in the associated SQUID as a function of applied field. The number of flux quanta in the moat is determined by measuring the shift of the threshold curve of a two-junction SQUID coupled to the moat. The data indicates that at fields on the order of a mG, moats reduce the sensitivity of holey SQUIDs to trapped flux by at least several orders of magnitude. As the chips are cooled through T/sub c/, transient magnetic fields are produced in the metallic sample holder parts surrounding the chip by thermal-gradient-induced EMF's. The effects of such magnetic fields on the flux trapping behaviour of the SQUIDs are also reported.         Monte Carlo analysis of Josephson logic devices    D. Heidel Summary: Results of Monte Carlo simulations of the tolerances of Josephson logic devices are presented. The Monte Carlo analysis was carried out for a large number of cases; for each case, the circuit parameters were randomly selected from their assumed statistical distributions. This technique facilitated the handling of complex, non-Gaussian distributions that can exist for the process parameters. These tolerance calculations included the effects of thermal noise, variations in voltage regulation, and power bus disturbs. To reduce computing time, analytical approximations to the threshold curves of the devices were used. Typically, 10,000 to 100,000 cases were analyzed for a given set of assumptions on parameter variations. This size of simulation allows one to estimate, with a high degree of confidence, the tolerance-limited yield of a chip containing 1000 devices. The Monte Carlo analysis, for 10,000 cases, used approximately three minutes of computing time on an IBM 3033.         JAWS-SNAP refractory logic circuits    D. Jillie, L. Smith and H. Kroger Summary: We describe a Josephson integrated circuit technology based on Nb-aSi-Nb tunnel junctions patterned by the selective niobium anodization process (SNAP). This technology also uses Mo resistors, bias-sputtered SiO/sub 2/insulators, and Nb wiring to complete circuits of the direct current-injection variety using only five photolithographic steps. We have fabricated and tested chains of JAWS "OR" gates produced with this process. Proper operation is obtained for supply and offset currents varying by /spl plusmn/ 20% (FANOUT = 1) and /spl plusmn/ 10% (FANOUT = 2). This is in good agreement with calculations.         Ring oscillator experiment using a huffle circuit    N. Kotera, A. Asano, Y. Harada and U. Kawabe Summary: A ring oscillator circuit composed of Josephson junction devices has been designed and tested for the first time. Nine huffle circuits, each of which includes two Josephson junctions of an in-line gate type, are combined to form an inverter ring. The ring oscillator has produced oscillations with 1.8- to 8.2-ns periods using DC power sources. Inverter and flip-flop logic operations are also observed with the single huffle circuit. The operating margins were investigated and found to be reasonable as a result of comparing experimental threshold curves and a theoretical prediction.         Josephson two-bit full adder utilizing wide margin functional gates    Y. Ichimiya, H. Yamada and A. Ishida Summary: A Josephson two-bit full adder circuit with wide margin functional gates has been studied. The adder circuit is comprised of functional exclusive-OR (EXOR) gates for sum operation and majority gates for ripple carry operation. A wide margin EXOR gate was constructed with serial connection of two double-input asymmetrical interferometers (AILs), in which two input lines were coupled to the interferometers with such an arrangement that the input-induced magnetic fluxes electromagnetically cancel each other. For majority gates, gate-to-input coupling should be made uniform for all three inputs. For this purpose, three input lines were laid in parallel on the loop of triple-input planar interferometer, so that one of two outer lines ran along the loop outside the edge but returned along the inside and the other vice versa. By using these functional gates a full adder circuit can be constructed with only three gates/bits. Experimentally, the two-bit parallel adder circuit was fabricated by standard Pb-alloy technology with 5/spl mu/m line width. Two-bit parallel full adder operation was successfully performed. Additionally, operating margin over /spl plusmn/10% for the bias was obtained for each gate.         Transmission of high speed electrical signals in a Josephson package    C. Anderson, M. Klein and M. Ketchen Summary: It is proposed that Josephson circuit chips are housed in a three-dimensional, card-on-board package operated near 4.2K. In this technology logic signals travel on matched, low-loss, superconducting transmission lines and through low resistance but inductive package connectors. In an experiment designed to model closely the electrical environment of this package, the waveform of a Josephson driver signal was measured before and after propagation through a card-to-card path in the package. The measurements were made on-chip using Josephson sampling techniques. The degradation in risetime of a 125ps driver signal was less than 20ps; crosstalk to a parallel path through the package was less than 2%. The inductances of right angle and pluggable micropin connectors were determined using an impedance current split experiment. Measured values of about 100pH and 250pH respectively are in good agreement with numerical calculations.         Operation of a superconducting analog-to-digital converter at short conversion times    R. Kautz and F. Lloyd Summary: The accuracy of a six-bit superconducting analog-to-digital converter has been tested at short conversion times. The accuracy was found to be good for conversion times down to 0.5 ns but significant errors were observed at a conversion time of 0.1 ns. These errors can be understood in terms of unwanted switching events that occur when the mode boundary separating two flux states is crossed rapidly.         Cryogenic wafer prober for Josephson devices    J. Geary and G. Vella-Coleiro Summary: A wafer probing system has been built for the testing of Josephson junction devices at helium temperature. A mechanism moves a probe card from one position to another on a two inch wafer while immersed in liquid helium. The mechanism is actuated by shafts which connect to stepper motors positioned above the helium dewar. A positioning accuracy of /spl plusmn/ 50 /spl mu/ m at the probe tips is achieved. The replaceable probe card is all ceramic and carries 120 rigidly mounted palladium-alloy needles, arranged in signal-ground pairs and positioned in an array which matches the pad design of the particular device under test. Controlled impedance transmission lines are maintained all the way to the wafer's surface. A computer interface is included so that probing of a whole wafer can be conducted under software control. The system is intended for routine testing of Josephson devices in wafer form as well as for testing very large numbers of individual junctions.         Magnetic field and current distributions in a system of superconductor microstrip lines    J. Chilo and C. Monllor Summary: Inductance matrix, current distributions and magnetic field structure for a system of coupled super conductor transmission lines has been calculated by a variational energy method. The influence of the superconducting character, the line geometries and the dielectric thickness on the current and magnetic field distributions have been shown. The coupling between the different lines produces induced currents, superposed on the exciting currents. The real current distribution and the magnetic field at any point determinated by considering this coupling, allow us to optimize the design of superconducting transformers in microstrip technology.         An analysis of fluxons in long Josephson junctions    B. Dueholm, E. Joergensen, O. Levring, R. Monaco, J. Mygind, N. Pedersen and M. Samuelsen Summary: Fluxon propagation in long overlap and inline Josephson junctions is analyzed in the framework of the perturbed sine-Gordon model. The analysis leads to analytical expressions for the zerofield steps, the magnetic field dependence of these, and the line-width of the microwave radiation emitted from the overlap junction. Some of the results are compared to experiments on real junctions.         Fluxoid motion in phase mode Josephson switching system    K. Nakajima, G. Oya and Y. Sawada Summary: We have investigated the possibility of the phase mode operation, i.e. the mode to transfer the fluxoid, not to transfer the voltage pulse, of Josephson switching system by fabricating a resistively coupled D.C. SQUID's array and 4J-loop which are expected to be advantageous in miniaturization by using its large kinetic momentum effect. The threshold characteristics of these superconducting loops and its LI/sub c/dependence agreed with the theoretical predictions. The phase mode logic actions were verified to operate really in a resistively coupled D.C.SQUID's and a coupled D.C. SQUID with a 4J-loop. A computer simulation showed that a resistively coupled SQUID's array acts both on phase mode and voltage mode by changing the circuit parameters, but that the two modes are clearly separated in a parameter space. Finally we have shown a total system configuration of the phase mode operation. For the power loss and the information processing speed, the phase mode was verified to have an advantage over the ordinary voltage mode by two orders of magnitude.         Multi-Josephson junction transmission line    M. Morisue, K. Kuramochi, Z. Shaikh and H. Fukuzawa Summary: This paper reports the phenomena produced in transmission line containing multi-Josephson junctions. The presented model consists of a distributed Josephson line connected by successive inductances and Josephson junctions, and a lossless transmission line. In this paper, a procedure of modeling the multi-Josephson transmission line is introduced and then the phenomena produced in the line is analyzed by use of computer-aided technique. The results of simulation show that the most important effect on switching operation is the mismatched effect of the characteristic impedance to the output load resistance. The relations between the produced phenomena such as oscillation frequency, propagation delay and output voltage, and circuit parameters are illustrated. This analysis shows profitable results for designing the Josephson logic circuit with transmission line.         Punchthrough analysis of Josephson logic circuits    E. Harris and W. Chang Summary: We have developed a simple analytical method for determining punchthrough probabilities of Josephson logic circuits. In this paper we describe the method, apply it to the Current Injection Logic (CIL) family, and compare the results to punchthrough probabilities determined by numerical techniques. The method involves replacing interferometers by point junctions to simplify the equivalent circuit, and then finding approximate solutions to the resulting circuit equations which allow reduction of the circuit punchthrough problem to a point-junction punchthrough problem for which the solution can be calculated from existing theory. Of the circuits in the CIL family, we find that the AND circuits have higher punchthrough probabilities than the OR circuits, and that the 4AND has higher punchthrough probabilities than the 2AND. We predict that in order to reduce the punchthrough probability of the CIL 4AND (designed in 2.5 micrometer Pb-alloy technology) to less than 10/sup -20/, the required transition time of the bipolar AC power supply will be about 750 pS. This is roughly 200 pS more than would be required for the 2OR.         Noise margins for Josephson logic and memory devices    J. Kadlec Summary: Noise which can produce erroneous transitions in Josephson logic devices can be treated in terms of the familiar model for thermal activation of a particle over a potential barrier. Noise curves are calculated which represent the effective threshold curves for a given transition rate; this approach can be applied to the mode-to-mode (superconducting) transitions as well as to the mode-to-voltage state switching. The analysis will be illustrated with the example of a three-junction current injection device. The practical consequences for design of Josephson logic circuits will be indicated.         Macromodeling of Josephson logic circuits    P. Crozat, A. Ouslimani, H. Hafdallah and R. Adde Summary: A scheme for macromodeling superconducting logic circuits is presented which takes into account propagation effects along transmission lines. Simulations performed on a desktop computer illustrate the importance of signal propagation in Josephson circuits. The efficiency of the simulator is compared with ASTEC III on some test circuits.         Time response of small capacitance tunnel junctions and the simulation of fast logic circuits    A. de Lustrac, P. Crozat and R. Adde Summary: A simulation method of small time constant Josephson tunnel junctions is developped. It is based on a first order series expansion of the time dependent Josephson current given by the microscopic BCS theory. The method is well adapted to the switching dynamic of logic gates when the RSJC model lacks of accuracy, has a comparable efficiency both in computer time and memory space. The scaling down of resistively coupled logic gates is presented among the illustrations.         Direct-coupled Josephson logic gate using low /spl Beta//sub c/elements    M. Sugahara and H. Kaneda Summary: It is shown that a circuit with resistively-connected Josephson-junction pair makes an interference performance which may be interpreted as time-domain correspondence of SQUID principle. Some logic application of this device is proposed.         Josephson device with well-defined and low critical points    H. Beha Summary: Two different basic types of switching behavior of Josephson interferometers are possible: a vortex-to-vortex and a vortex-to-voltage transition. Both transition types are separated by the so-called critical points on the threshold curve of the device. For critical points, in general, no analytic expression is available. Therefore, the position of the critical points can only be determined by numerical solutions. In the designs known, the critical points are very sensitlve with respect to parameter variations, which makes LSI design very difficult. In this paper, the design and the experimental results of an asymmetric Josephson interferometer with one well-defined and low critical point are described. This well-defined critical point corresponds to the tip point of the threshold characteristic, which is defined by an analytical expression. The practical consequence for the design of Josephson circuits will be indicated. The dynamic switching behavior of the asymmetric interferometer with respect to the critical points will be discussed extensively in the phase plane, together with the potential energy.         Variable threshold logic with superconducting quantum interferometers    N. Fujimaki, H. Hoko, H. Shibayama, S. Hasuo and T. Yamaoka Summary: This paper proposes a two-junction interferometer called Variable Threshold Logic. It has both magnetically-coupled control-lines and current-injection terminals. The threshold curve of this gate can be shifted by the applied currents. This property enables its use for both OR and AND function with the same structure by only changing the wiring. Operating margins of /spl plusmn/12 % for OR and /spl plusmn/ 29 % for AND are obtained with the optimized device parameters. Any logic circuit can be obtained by Josephson master-slice LSI of this gate with a dual-rail logic system.         Inductance-compensated Josephson current-injection device    S. Kaplan, T. Gheewala and A. Mukherjee Summary: A current-injection device (CID) can be used to perform the AND function in Josephson technology. The sensitivity of the CID operating margins to variations in the critical currents of the Josephson junctions is examined. Further, we present here a novel Compensated Current-Injection Device (CCID) in which Josephson junctions are used not only as switches, but also as inductors. This significantly increases the tolerance of the CCID to systematic variations in Josephson junction critical currents, by maintaining the effective LI/sub o/product invariant. Monte Carlo analyses of the threshold curves of the CID and the CCID under identical sets of assumed process variations show roughly a factor of two improvement for the CCID in the signal current operating window and also in the standard deviation of the device threshold, for cases with an arbitrarily assumed /spl plusmn/ 20% chip-to-chip systematic variations in critical currents. The relative improvement is less if the systematic variation is smaller.         A decoder using Josephson junction    M. Morisue and K. Isaji Summary: A mesh-type decoder employing Josephson junctions is proposed. In this paper we describe two types of the decoder, one of them is constructed by using JTL and the other is CIL. The Josephson junctions in these decoders are directly coupled so as to immediately issue the gate current for the junction in the next stage when a signal is propagated from the previous stage. The principles of the operation are described and the simulations of 3 X 4 matrix decoders, of which each matrix element is denoted by Josephson junction, are illustrated in detail. The main advantages of these decoders are their simple construction and extremely high operating speed.         Lead alloy Josephson junction direct injection logic gates    T. Wang, R. Josephs, P. Young, W. Flannery, B. Stein and J. Sheppard Summary: A new group of high gain, wide margin direct injection Josephson junction logic gates including a three Josephson junction OR (3J/OR) and a four Josephson junction AND (4J/AND) was previously described. In the present work, these gates have been fabricated in an improved lead alloy technology using 5/spl mu/m design rules. The measured threshold curves of the 3J/OR and the 4J/AND are in good agreement with the theoretical predictions despite the fact that current density and sheet resistance of the samples differed from the design values.         Power distribution in a Josephson package environment    P. Arnett Summary: An ac power supply designed to power 8K Josephson logic circuits has been tested in a package environment for the first time. The test was part of an experiment that utilized the essential package components for a Josephson computer. All accessible chip-level power signals had the predicted amplitude variation with frequency over the range 50-400 MHz when normal fabrication tolerances were taken into account. This power supply, with reduced loading to accommodate some lines with unexpectedly low critical currents, was used to power the logic circuits in a path representative of a critical path for a proposed prototype processor. A minimum cycle time of 3.7 ns was achieved.         A pipelined gray code-to-natural binary decoder for use in a Josephson A/D converter    J. Spargo, R. Jewett and T. Van Duzer Summary: A 4-bit A/D conversion system with a sampling rate of up to 5 GHz utilizing Josephson digital technology is being constructed. The system consists of a comparator stage, which utilizes the multiple lobes of Josephson interferometers to achieve 4-bit Gray code encoding of an analog signal with only 4 comparators; a decoding stage, to process the Gray code into natural binary; and an interface stage, to amplify the millivolt level Josephson signals in order to drive room temperature instruments. We report here on the design, construction, and testing of a 2-bit decoder stage. The decoder utilizes alternating latch and logic blocks operating in a pipelined fashion to perform the decoding while maintaining the speed of the input stage. Timing is controlled by a multi-phase overlapping clock. The fabrication technology used is an eight-level Pb alloy process, with 5 /spl mu/m linewidths. Extension to 4 bits is discussed.         8-bit superconducting A/D converter    C. Hamilton and F. Lloyd Summary: The design, fabrication and testing of a superconducting 8-bit converter are presented. Experimental results show essentially monotonic output code at conversion rates of a few megahertz. An algorithm for automatic adjustment and potential problems of higher speed operation are discussed.         Non-destructive read out operation of SFQ memory cells: Simulations and experimental results    G. Matheron and Ph. Migny Summary: Single flux quantum two junction interferometers appear as attractive memory cells for constituting dense and low dissipating arrays. In this paper an investigation of cell parameters leading to Non-Destructive Read Out (NDRO) operation and non volatile storage is presented. Basic requirements are defined, various possible designs are studied through static and dynamic simulations, experimental results for one of them are given. Finally, memory array concepts involving statistical analysis on electrical parameters spreads are proposed.         An experimental memory cell using edge-junction gates    L. Geppert, T. Rajeevakumar, W. Henkels and U. Deutsch Summary: We have fabricated and successfully operated NDRO memory cells designed with Nb edge-junction interferometers. To our knowledge this represents the first experimental circuits operated with edge-junction devices. The design was mapped from a design for lead-alloy devices. The cell occupies an area of 60/spl mu/m X 60/spl mu/m. In conjunction with the memory cell investigation we designed and tested several individual edge-junction gates. These included several geometries of write gates and sense gates (undamped), and several damped gates, which could be used in the peripheral circuitry of a memory. We have found close agreement between our experimental results and the theoretical models, similar to that found previously for planar-junction gates.         The miniaturisation of Josephson interferometer memory cells for nondestructive read out    W. Jutzi and J. Wunsch Summary: A static, nonvolatile interferometer memory cell prototype for nondestructive read out has been implemented with the lead alloy technology and tested successfully. For a Josephson current density of 3.5 kA/cm/sub 2/the implemented cell area is about 3600 /spl mu/m/sup 2/. For a Josephson current density with the niobium lead technology of 125 kA/cm/sup 2/a miniaturisation of cell area to 50 /spl mu/m/sup 2/at 0.8 /spl mu/m minimum line width seems feasible.         Nondestructive memory cell using a two-junction Josephson interferometer    M. Morisue, S. Koike and K. Moritan Summary: This paper presents a novel nondestructive memory cell using a two-junction interferometer. Most of single-flux-quantum memory cells have been the destructive ones, which must rewrite the information for logic "1" after a reading operation. This makes the circuitry of the cell complex. To avoid this disadvantage, a novel self-rewriting technique is introduced by setting a coil between the terminals of the interferometer. The principle of the operation of the cell is described and the simulation for the behaviours of the cell are illustrated in detail. The results of the simulation show that the reliable operation of the cell can be achieved with high operating speed.         Zero-quantum superconducting magnetic shielding apparatus and method    J. Clem Summary: The design of a new superconducting magnetic shield is described, together with a method for achieving a final state in which no magnetic flux quanta are trapped in the shield's central region. The magnetic shield consists basically of a specially designed superconducting cylindrical tube, equipped with electrical and magnetic devices to remove flux quanta trapped during cooldown. An electrical current is applied along the length of the tube to cause mutual annihilation of trapped vortices and antivortices in the tube's central region and thus to remove flux quanta transverse to the cylinder axis. A parallel applied magnetic field then moves an appropriate number of vortices and antivortices from tube-end reservoirs to opposite ends until no longitudinal flux quanta thread the tube. Typical dimensions, various materials requirements, and conditions for successful operation of the magnetic shielding apparatus are discussed.         Josephson analog-to-digital converter using self-gating-AND circuits as comparators    S. Dhong, R. Jewett and T. Van Duzer Summary: This paper describes the comparator stage of a Josephson junction 4-bit A/D converter. It utilizes the periodic nature of SQUID's to make a 4-bit A/DC with only four comparators for parallel conversion. A new design for a symmetrical three-junction SQUID provides identical lobes beyond the four required. The necessary short aperture time is obtained by imbedding the SQUID's in self-gating-AND circuits that detect the input signal only during the rising edge of the clock. A binary resistor divider provides the correct proportions of the input signal to the four comparators. Both computer simulation results and low-frequency test results are presented.         Alpha particle induced switching in Josephson tunnel junctions    R. Magno, R. Shelby, M. Nisenoff, A. Campbell and J. Kidd Summary: Alpha particle irradiation has been observed to cause Josephson tunnel junctions to switch from the zero resistance to the finite resistance state. The results can be interpreted by assuming that a portion of the junction is raised above T/sub c/by the energy lost by the alpha particle as it passes through or near the device. This causes a redistribution of the current to the portion of the device which is still superconducting, and an upset will then occur if the critical current density is exceeded. The data indicates that every alpha particle that can raise a sufficiently large area above T/sub c/will cause an upset. For the Nb-Si-Nb devices studied here, an alpha incident at 90 degrees to the plane of a junction will "normalize" an area of about 1.3 square micrometers if it deposits energy at a rate of 350 keV per micrometer along its track.         100 GHz binary counter using SQUID flip flops    C. Hamilton Summary: A binary counter using bistable dc SQUID's as flip flop circuits is reviewed. Its potential for frequency division in the THz range and for ultra high accuracy A/D conversion are discussed.         Quiteron    S. Faris, S. Raider, W. Gallagher and R. Drake Summary: The QUITERON is the first three terminal superconducting switch possessing true transistor-like characteristics as well as ultra-low switching energy. Its action is based on non-equilibrium superconductivity in the regime of heavy external and self injection of quasiparticles leading to gap suppression. Experimental confirmation of the operating principle is presented, including the demonstration of large signal power gain, high switching speed, as well as other digital and analog transistor-like features.         Examination of superconducting micro-circuits by low-temperature-scanning-electron-microscopy    H. Pavlicek, L. Freytag, R. Huebener and H. Seifert Summary: By scanning a thin-film superconductor with the electron beam in a scanning electron microscope equipped with a low-temperature stage, a two-dimensional voltage image of spatial structures in the sample configuration can be generated. The spatial resolution of this technique has been investigated by monitoring the voltage response of a current-biased superconducting microbridge as a function of the distance between the microbridge and the point of the electron-beam focus. Our results indicate that the electron irradiation can be treated as a local heating effect and that the spatial resolution is dominated by the thermal healing length. By modulating the beam at high frequencies, the thermal healing length is reduced considerably below its low-frequency limit because of the thermal skin effect. It appears that, depending upon the sample parameters, a spatial resolution limit less than 1 /spl mu/m can be obtained for frequencies of the beam modulation in the range 10 - 1000 MHz.         The science of useful superconductors - and beyond    T. Geballe Summary: Improved methods of depositing thin film composites embodying transition metals have opened opportunities for finding out more about transition metal superconductors. Results from many research groups are reviewed. In order to reach higher transition temperatures with A-15 structures it will be necessary to synthesize them as ordered structures with more metastable compositions. An interesting dependence of the critical currents upon resistivity of A-15 superconductors has been found. Some indication of the temperature dependence of phase boundaries at low temperatures is discussed. The bottleneck in tunneling into transition metals due to the lack of well-behaved barriers has been broken. Superconducting tunneling spectroscopy has given new insights into the stability of high transition temperature superconductors with the A-15; an important role of impurity gases such as oxygen has been demonstrated. Composites consisting of very fine-scaled multilayered films can be synthesized and show crossover and other interesting behavior when the period is reduced below 50/spl Aring/.         Characterization of surface defects in niobium microwave cavities    H. Padamsee, J. Tuckmantel and W. Weingarten Summary: Superconducting microwave cavities usually break down at localized regions of enhanced losses. Several such regions have been located during low temperature cavity measurements using a temperature mapping system. The regions are then isolated by cutting the cavities and analyzed under a SEM to determine their size and composition. The breakdown field for such defects is calculated using a mesh program and compared with experiment. The composition of defects gives clues to the origin and suggestions for elimination of defects.         A 145 MHz niobium split-ring resonator for particle velocities from 0.12 to 0.23 c    K. Shepard and G. Zinkann Summary: A niobium split ring resonator has been designed with an optimum particle velocity /spl beta/ = v/c = 0.16. This type of resonator will be used to extend the Argonne superconducting heavy-ion linac. The peak surface electric field in the resonator is 3.9 times the effective accelerating field, a value 20% lower than for previously developed split-ring resonators. A prototype niobium resonator has been completed. Results of performance tests are discussed.         A new chemical polishing procedure for lead-plated copper superconducting accelerating resonators    G. Dick and J. Delayen Summary: A procedure has been developed for polishing the thin electroplated lead coating used in Pb-Cu superconducting resonators which is much more effective than those available previously. Conventional polishing procedures cannot be used because their rapid action is inappropriate to the thin (10/spl mu/) lead layer. A previous procedure, designed for very slow action, rounded sharp edges to a radius of curvature of approximately 1/spl mu/. The new procedure provides nearly complete leveling of crystals 10/spl mu/ in size. Results of tests on a /spl beta/ = 0.10 split loop accelerating resonator designed for the SUNYLAC Heavy Ion Booster will be reported. This resonator shows considerable improvement in performance over the previously tested cavity. On this basis, accelerator operation at an average field of 3 MV/m now seems feasible.         Calibration of the scanning thermometer resistor system for a superconducting accelerating cavity    R. Romijn, W. Weingarten and H. Piel Summary: A calibration measurement for the temperature mapping system in use at CERN for superconducting accelerating cavities immersed in subcooled liquid helium is presented. It allows a study of cavity losses in a quantitative way by relating the temperature increase (/spl utri/T) at the cavity outside wall to the power dissipated at the inside. The calibration set up simulates an isolated lossy region in a superconducting cavity. The influence of the bath temperature and the orientation of the heated surface have been investigated. /spl utri/T is determined by the heat current density Q at the resistor location according to /spl utri/ T = /spl alpha/ Q/sup 3/4/. The proportionality constant /spl alpha/ depends on the particular experimental conditions. The experimental results are compared with heat transfer calculations in subcooled helium. As an application typical loss mechanisms in superconducting cavities are described.         Calculations for breakdown induced by "Large defects" in superconducting niobium cavities    H. Padamsee Summary: A computer program has been written to model thermal magnetic breakdown. It incorporates all the heat production and heat transport factors. The temperature of the defect and vicinity is calculated for increasing rf field levels until the defect grows unstably, determining the breakdown field level. Calculations are performed for a variety of circumstances to explore the relative influence of the various heat production and heat transport factors.         An investigation of thermal transport in superconducting cavities made of high thermal conductivity niobium    K. Krafft Summary: Thermal-magnetic breakdown is the mechanism which ultimately limits field strengths in superconducting cavities whose microwave performance is not affected by multipactoring or field emission. Thermal-magnetic breakdown is thought to arise from localized heating of an isolated lossy area on the cavity surface; at a certain power level the excess heating may cause the temperature near the lassy area to exceed the superconducting critical temperature and lead to cavity breakdown. The objective of this investigation was to investigate systematically the two mechanisms of thermal transport in the cavity-cooling bath system: the thermal conductivity of the metal and heat transport across the metal to liquid helium interface. For this investigation, cavities were prepared with high thermal conductivity Nb; the thermal conductivity of this Nb at 4.2K was over 100 times higher than that of typical reactor grade Nb. To investigate the thermal transport processes, cavity surface temperature profiles were measured with dc heater power applied locally to the surface. The results agreed well with calculated equilibrium surface temperatures when reasonable values for the thermal boundary resistance between superconducting Nb and liquid He I or superfluid He II were used in the calculations. The microwave performance of the Nb cavities at X-band was considerably improved by the use of high thermal conductivity Nb; the high thermal conductivity Nb cavities consistently reached field levels over five times higher than the low thermal conductivity Nb cavities and sustained over 100 times as much dissipated power. These cavities never exhibited breakdown. Theoretical calculations showed that the performance of the low thermal conductivity Nb cavities was limited by the large temperature gradients at defects, whereas the performance of the high thermal conductivity Nb cavities was limited by transport of heat across the Nb-liquid He interface.         Field emission in superconducting RF cavities    U. Klein and J. Turneaure Summary: Broad area rf field emission from superconducting Niobium surfaces was investigated. A specially designed superconducting resonator (reentrant cavity) allows direct measurement of the field emission current. Experiments were performed at four cavity modes between 500 MHz and 3.5 GHz in order to study the frequency dependence of rf field emission. Details for the cavity design, cavity treatment, experimental set-up, and measurement technique are given. Field emission currents in the range 10/sup -15/A to 10/sup -6/A were detected at macroscopic electric surface fields of 10 to 50 MV/m at the emitter. The data were analyzed with the Fowler-Nord-heim theory, modified for rf fields. The microscopic field enhancement factor B was in the range of 40 to 150 for different surface conditions and showed no significant frequency dependence. These observations are in agreement with the predictions of dc field emission, but in contradiction to the not yet understood field emission phenomena in superconducting accelerating cavities. The hypothesis of field emission from hot emitters, probably consisting of dust particles heated by the rf fields, can qualitatively explain this discrepancy. Experimental observations on superconducting accelerating cavities support this model.         C-band superconducting structure for a electron linac    P. Fernandes, V. Lagomarsino, G. Manuzio, R. Parodi and R. Vaccarone Summary: We have built a 5-cell superconducting structure, for the main section (/spl beta/=1) of an e- linear accelerator, forming half cavities, "door-bell" shaped, by deep drawing a 2 mm thick niobium sheet (Kawecki). Running the structure in the /spl pi/ mode, (the accelerating one) accelerating field in excess of 7 MV/m was achieved at a fairly low Q/sub o/value of 3x10/sup 8/. We report a comparison between the results obtained in a single cell cavity of the same shape (B/sub p//spl sim/ 50mT) and that ones previously obtained in the 1mm thick cavities operating at the same frequency (B/sub p/= 105 mT). We introduce a simple model for the heat transfer to He bath which explain the worse behaviour of the low Q/sub o/cavities.         Some aspects of superconducting accelerator design    Z. Farkas and S.St. Lorant Summary: The performance of an accelerator can be characterized by the efficiency with which electrical energy, ac and rf, is converted into accelerating energy, the minimum energy needed to generate a given beam voltage. The current accelerator improvement program at SLAC aims at raising the beam voltage to 50GV which will use 240 klystrons each capable of producing a pulse 5/spl mu/s in length at a peak power of 36MW. The Linear Collider requires 50MW klystrons to achieve 60GV which will raise the concomittant power consumption to 32.3MW. We show that with superconducting elements we can increase the rf and ac conversion efficiencies and achieve the necessary 60GV using only 1/3 of the present power requirements, provided that we exclude CW operation. We will further demonstrate that this increase in efficiency is crucial and highly significant in the design of a proposed 1000GV linear accelerator.         Performance of 1 m long/100 mm bore superconducting dipole prototypes for HERA    G. Horlitz and S. Wolff Summary: Three 1 m long superconducting dipole prototypes with 100 mm inner coil diameter for the proposed HERA electron-proton storage ring have been built and tested. Main design principles are a two layer coil clamped with stainless steel collars inside a cryostat with warm beam tube and surrounded by a warm iron yoke. All prototypes have been tested without yoke and one of them with yoke. The design induction of 4.73 Tesla at 4.6 K has been easily surpassed up to short sample fields with negligible training. The quench behaviour has been investigated between temperatures of 3.8 K and 5.0 K. The field quality has been found well within the specified limits given by the requirements of the storage ring optics. The reproducibility found in this sample of magnets gives great confidence for the production of dipole prototypes of full length.         High field superconducting window-frame beam transport magnets    J. Allinger, A. Carroll, G. Danby, B. DeVito, J. Jackson, W. Leonhardt, A. Prodell and J. Skarita Summary: The window-frame design for high field superconducting beam transport magnets was first applied to two, 2 m long, 4 T modules of an 8/spl deg/ bending magnet which has operated for nine years in the primary proton beam line at the Brookhaven National Laboratory Alternating Gradient Synchrotron (AGS). The design of two 1.5 m long, 7.6 cm cold bore superconducting window-frame magnets, described in this paper, intended for the external proton beam transport system at the AGS incorporated evolutionary changes. These magnets generated a maximum aperture field of 6.8 T with a peak field in the dipole coil of 7.1 T. Measured fields are very accurate and are compared to values calculated using the computer programs LINDA and POISSON. Results of quench propagation studies demonstrate the excellent thermal stability of the magnets. The magnets quench safely without energy extraction at a maximum current density, J = 130 kA/cm/sup 2/in the superconductor, correspoding to J = 57.6 kA/cm/sup 2/overall in the conductor at B = 6.7 T.         2.6 K refrigeration system for CBA magnet testing    J. Bamberger Summary: The superconducting magnets for the accelerator's rings will be cooled by a forced flow supercritical helium system from a central refrigeration plant. The design temperature for these magnets varies from 2.6 K to 3.8 K depending on a magnets location in the ring. This paper describes the forced flow cooling system for testing a prototype magnet near 2.6 K; this lowest temperature being of special interest to evaluate magnet quench protection. The test forced flow cooling system uses a three-stage approach, including an ejector pumped bath, similar to a cycle described previously. The coolant exists at 3.8 K from these first stages and is then cooled further in a 64 cm diameter by 3 m high shielded liquid helium dewar. The supercritical helium gas passes through a submerged copper coil in this bath which is pumped to a pressure of 65 mm absolute by a screw compressor system. Temperatures are measured by thermistors located in the gas stream, and also embedded in the magnet coil.         Correlation of superconductor strand, cable and dipole critical currents in CBA magnets    M. Tannenbaum, M. Garber and W. Sampson Summary: A calibration between vendor critical current data for 0.0268" diameter superconductor strand supplied to Fermilab, and the BNL 10/sup -12//spl Omega/cm critical current specification is presented. Vendor critical current data for over 400 Fermilab type billets are shown, both as supplied by the vendor and converted to BNL units. Predictions of cable critical current are made using the sum of the critical currents of the 23 strands, where all strands from the same half billet are assigned the same critical current. The measured critical current shows excellent correlation to the predicted value and is approximately 14 /spl plusmn/ 2 percent below it. Colliding Beam Accelerator (CBA) full length dipoles reach the conductor critical current limit, essentially without training. Magnet performance is predictable from the measured critical current of a short sample of cable to within 2%.         A safe, low current, high gradient, superconducting quadrupole magnet for high energy physics beam transport    R. Smith, S. Kim, C. Krieger, J. Gonczy, A. Kelly, D. Underwood, E. Wallace, K. Wiggins, P. Garbincius, P. Mazur and R. Stanek Summary: A superconducting quadrupole magnet has been fabricated and tested that generates a gradient of 60 T/m at a peak operating current of 1100 amperes. The cold bore of the magnet is 12.7 cm in diameter and 2.8 m long, and the unwanted field multipoles sum to 4 parts per thousand of the quadrupole field at a bore radius of 5.0 cm. The magnet operates safely without quench protection and peak coil temperatures following quenches deliberately induced at full field do not exceed 50 K. Testing at the design gradient of 50 T/m indicates a beam energy deposition quench threshold of approximately 5 mJ/cm/sup 3/.         Winding design study of superconducting 10 T dipoles for a synchrotron    K. Ishibashi and A. McInturff Summary: A comparative design study was made for windings of a superconducting 10 T dipole magnet, which could be used for a future large accelerator. Calculations were done for different magnet winding design types; given a few simplifying assumptions, their general magnetic and mechanical parameters were obtained. The four shell configuration seemed to show the most promise of all the magnet designs considered for a 10 T small aperture (5 cm) dipole magnet.         Design of an indirectly cooled 3-m diameter superconducting solenoid with external support cylinder for the Fermilab collider detector facility    R. Wands, R. Fast, J. Grimson, R. Kephart, E. Leung, L. Mapalo, R. Yamada, H. Minemura, S. Mori, M. Noguchi, R. Yoshizaki and K. Kondo Summary: A 3-m diameter, 5 m long superconducting thin solenoid with indirect cooling and an external support cylinder has been designed for the Fermilab Collider Detector Facility. An aluminum stabilized Nb-Ti superconductor produced by the extrusion with front tension (EFT) method is used. Radiation length for the solenoid is .831, and absorption length is .186.         Fermilab Tevatron quadrupoles    W. Cooper, H. Fisk, D. Gross, R. Lundy, E. Schmidt and F. Turkot Summary: Details on the design, construction, and performance tests of Energy Saver/Doubler quadrupoles are presented along with recent data from the test of a special high gradient low beta prototype quadrupole.         Construction and test of a synchrotron dipole model using Nb/sub 3/Sn cable    J. Perot Summary: A short dipole magnet for accelerator has been built using Nb/sub 3/Sn cable with the "wind and react" technique. The magnet has a two shell coil configuration similar to the "Doubler" dipole and the designed central field is 6 teslas. Details of the construction are given along with test results. Due to the high current density in the copper the protection of the dipole requires a sophisticated protection system which makes use of a fast superconducting switch associated with a secondary copper dipole for the extraction of part of the magnetic energy.         Development and test of a high current density superconducting saddle magnet SSM-3    Yan Luguang, Yu Yunjia, Ye Zuxian, Jing Bohong and Wang Silian Summary: Following the Stekly's work in the direction of development of lightweight superconducting MHD magnets, a relatively large bore (inner diameter of winding 215mm) saddle magnet SSM-3 has been constructed and tested. The wax-filled magnet achieved 1.525ka critical current, about 4.2T central field and 0.35MJ stored energy, i.e about 82% of " short-sample" performance, at this current the stainless steel bolts on the aluminium girders of the support structure were broken and the winding with its epoxy-fiberglass banding remains undamaged.         Superconducting dipole magnet with cold Iron    S. Han, C. Zhang, Y. Kuang, Z. Feng, K. Luo, S. Song, H. Huang, Z. Gao, K. Li and Y. Chen Summary: The paper presents mainly the design of a Superconducting Dipole With Cold Iron, the parameters selected for the iron shield, the effect of iron shield on field in bore and the results of experiment. The dipole is made of NbTi brald of 29 strands. Each strand has a diameter of 0.3 mm and the smallest ratio of copper to superconductor (1:1). The conductor is wrapped by mylar tape as insulation. The cross section of the conductor is 0.8 X 5.9 mm/sup 2/. This dipole has 10 cm inner diameter, 15.2 cm outer diameter and 46 cm outer diameter of cold iron. It is excited both by direct current and by pulse current. Very little training is observed at full field. After four times of quench, the field normally reached 4.6T at 1190A. The magnet current was about 89% of short sample. The field of dipole with cold iron shield increases in bore by 30% over the field of dipole without iron shield.         A four layer, two inch bore, superconducting dipole magnet    W. Hassenzahl, C. Peters, W. Gilbert, C. Taylor and R. Meuser Summary: Superconductors provide the accelerator designer with unique opportunity to constreuct machines that can achieve high perticale energies and yet have low operating costs. This paper describes the design, facrication and testing of a 4 layer, 50 mm bore superconductng dipole magnet, D-9A. The magnet reached short sample, 5.8T at 4.4K and 8.9T and 1.8K, with little training, and exhibited low losses and low ramp rate sensitivity.         Ramp rate sensitivities of several superconducting dipole magnets operated in He I and superfluid He II    S. Caspi, W. Gilbert and J. Rechen Summary: The quench current of a superconducting dipole magnet decreases from its slow-ramp value as the current ramp-rate is increased, due to heat buildup in the coil winding. This ramp-rate dependence has been measured for several superconducting dipoles in both normal He I and in superfluid He II. The heat generated by changing fields has been measured for several magnets in He II, where particularly sensitive and accurate measurements can be made of any heat input to the essentially isothermal helium bath by its temperature rise. Previously measured values of heat transfer are applied to the data from one magnet to explain its observed behavior. The conclusion is drawn that at a given cycle rate, a superfluid He II-cooled superconducting accelerator can operate closer to the short-sample limit of the magnet's superconductor than can a corresponding He I-cooled machine.         Design of a 10-T superconducting dipole magnet using niobium-tin conductor    C. Taylor, R. Meuser, S. Caspi, W. Gilbert, W. Hassenzahl, C. Peters, R. Schafer and R. Wolgast Summary: In order to minimize the size and cost of conventional facilities -- land, tunneling, shielding, cryogenic and vacuum system -- the dipole magnets for the next generation of particle accelerators must produce as strong a magnetic field as possible. Ten tesla seems to be a reasonable goal, and can be attained by using either niobium-tin conductor a t4.2 K or niobium-titanium at 1.8 K.         Application of an analytical method for the field calculation in superconducting magnets    G. Martinelli and A. Morini Summary: Superconducting magnets are taking on ever-growing importance due to their increasingly prospects of utilization in electrical machines, nuclear fusion, MED conversion and high-energy physics. These magnets are generally composed of cylindrical or saddle coils, while a ferromagnetic shield is generally situated outside them. This paper uses an analytical method for calculating the magnetic field at every point in a superconducting magnet composed of cylindrical or saddle coils. The method takes into account the real lengths and finite thickness of the coils as well as their radial and axial ferromagnetic shields, if present. The values and distribution of the flux density for some superconducting magnets of high dimensions and high magnetic field, composed of cylindrical or saddle coils, are also given. The results obtained with analytical method are compared with those obtained using numerical methods.         Superconducting poloidal coils for the reacting plasma project-test results of a model coil (RPC-I) at a 200 T/sec pulsing rate and design of a new coil (RPC-II)    T. Satow, M. Iwamoto, K. Toyoda, T. Ogasawara, Y. Kubota, T. Makiura, K. Yasukochi, H. Momota, K. Sato, S. Yamada, K. Koyama and T. Onishi Summary: A model pulse coil with a stored energy of 0.45 MJ at 6 T has been built and tested in order to meet the requirements of superconducting poloidal coils of a medium size tokamak of the Reacting Plasma Project. The inner and outer diameters of the coil (RPC-I) are 19.0 and 46.8 cm, respectively, with an axial length of 41.4 cm. The pulsing test was performed by a condenser discharge method with a clamp circuit. By applying a terminal voltage of 7.0 kV, the coil was charged up to 3.84 T in 26 msec and discharged to zero with a time constant of 100 msec. The average and maximum of pulsing rates in charge-up period were 147 T/sec and 231 T/sec, respectively. The associated a.c. loss per pulse was approximately 1 kJ which was only 0.57 % of the energy stored in the coil. These results have shown for the first time the scientific feasibility of superconducting pulse coils with a pulsing rate of about 200 T/sec. As the next step, we are constructing a new coil (RPC-II) with a winding composed of wider helium cooling channels and insulation sheets between layers.         Development and successful testing of the first Nb/sub 3/Sn wound, in situ-reacted, high-field superconducting quadrupole of CERN    A. Asner, C. Becquet, H. Rieder, C. Niqueletto and W. Thomi Summary: Following an extensive development of the "wind and react" technology of high-field and high-current density, Cu-stabilized Nb/sub 3/cables, a sizeable, 1 m long, 9 cm bore, 100 KJ superconducting quadrupole magnet has been built and successfully tested and operated. Specific technological and design aspects of this magnet will be described, such as the simultaneous reaction process and heat treatment of the quartz insulation and solutions to problems of interconnections, the coil manufacture and the assembly of the active part of the magnet given. The quadrupole has been successfully tested and operated. The maximum current of 1.1 kA corresponds to an overall current density over the cross-section of the insulated cable of 3x10/sup 4/A/cm/sub 2/at a maximum field of 8 T (within 0.2 T) and was reached after only 5 quenches. These figures correspond to 93-99% of the critical current densities, measured on cable samples, reacted with each pole winding of the quadrupole. The nominal current of 1 kA was reached without quench and repeatedly maintained for several days. We believe that this new technology and the successful development of the first high-field, Nb/sub 3/Sn-cable-wound quadrupole magnet of CERN open new and exciting possibilities for the development of accelerator and storage ring high-field dipole magnets in the 10 T range with stored energies of 1 MJ per metre of length.         Observations of the effect of pre-reaction on the properties of Nb/sub 3/Sn Bronze composites    D. Smathers, K. Marken, D. Larbalestier and R. Scanlan Summary: The effect of varying the annealing temperature on the degree of pre-reaction of two Nb/sub 3/Sn composites has been investigated. Annealing at 550, rather than 450 C produces noticeably more irregular growth and more uneven Nb/sub 3/Sn layers when final reaction occurs. It is believed that this is due to the effect that pre-existing Nb/sub 3/Sn nuclei have on subsequent Nb/sub 3/Sn growth. In one case the use of four anneals at 550 C, rather than 450 C was found to reduce the J/sub c/by 50%. Results are also presented on some samples of the HFTF conductor. It is concluded that over-annealing of the bronze can be a major cause of reduced J/sub c/in bronze Nb/sub 3/Sn conductors.         Scanning Auger investigation of commercial multifilamentary Nb/sub 3/Sn conductors    D. Smathers, K. Marken, D. Larbalestier and J. Evans Summary: A Physical Electronics 595 Scanning Auger Microprobe was used to study etched filaments and transverse sections of variously reacted commercial bronze matrix multifilamentary Nb/sub 3/Sn conductors. Using beams as fine as 100 nm, tin concentration profiles were observed in polished samples. Differences were noted in the shape of the tin gradient as a function of the location of the reacted filaments within the wires. The tin content of the bronze was also measured between pre-reacted filaments in an unreacted composite and found to be about 1 at.% lower than in the large bronze reservoirs. In a Harwell composite with P-poisoned niobium diffusion barriers, P was detectable in the Nb/sub 3/Sn formed on the barrier but not on the filaments.         Superconducting critical current densities of pure and alloyed (Ti) Nb/sub 3/Sn multifilamentary wires by the expanded-metal process    M. Suenaga, C. Klamut and W. McDonald Summary: The critical current densities J/sub c/(H) at 4.2 K and up to 19 T were measured for a number of pure and alloyed (with Ti) Nb/sub 3/Sn multifilamentary wires which were fabricated by the expanded metal process. The critical current density (including the areas of Nb/sub 3/Sn, the Cu-Sn alloy matrix and the Ta barrier) of the pure Nb/sub 3/Sn wire at 10 T was essentially equal to the value for conventionally processed Nb/sub 3/Sn wires. However, it rapidly decreased with increased magnetic fields. Although the addition of small amounts (/spl sim/0.8 and /spl sim/ 1.6 wt% Ti) to the Nb filaments decreased the values of J/sub c/at 10 T, they did not decrease with the increasing field as rapidly as is the case for the pure Nb/sub 3/Sn. The additions of Ti slightly decreased the amount of tensile strain on the wire required to achieve a maximum in J/sub c/(8 T) when compared to that required for the pure Nb/sub 3/Sn. However, this amount was higher than that for a similar Nb/sub 3/Sn wire which was conventionally processed.         Improvements in current-carrying capacities of Nb/sub 3/Sn composites in high fields through titanium addition to the matrix    H. Sekine, Y. Iijima, K. Itoh, K. Tachikawa, Y. Tanaka and Y. Furuto Summary: Single-core and multifilamentary Nb/sub 3/Sn composites with titanium addition to the matrix have been fabricated. The electron-probe microanalysis indicates that the titanium is more rapidly incorporated into the Nb/sub 3/Sn layer from the matrix than from the core. The titanium addition of less than 1.5 at.% to the matrix does not deteriorate the workability of the Nb/sub 3/Sn composites. The titanium addition to the matrix remarkably increases the growth rate and J/sub c/in high fields of the Nb/sub 3/Sn layer. The optimum amount of titanium addition to the matrix to produce the highest overall J/sub c/at 16 T was found to be about 0.8 at.% for the 160-core Nb/Cu-7at.%Sn-Ti composite wires. The simultaneous titanium addition to the core and to the matrix produces further improvement in J/sub c/in high magnetic fields. An overall J/sub c/of about 2.7x10/sup 4/A/cm/sup 2/at 16 T is obtained for the 370-core Nb-1.5at.%Ti/Cu-8at.%Sn-0.5at.%Ti composite wire reacted at 700/spl deg/C for 200 h.         Optimization of critical currents in composite-processed multifilamentary Nb/sub 3/Sn conductors with Nb-Ti alloy cores    K. Kamata, N. Tada, K. Itoh and K. Tachikawa Summary: Multifilamentary Nb/sub 3/Sn conductors with Nb-(1,2,3, 5at%) Ti alloy cores were successfully fabricated, and the relationships among the amounts of titanium addition to the core, core sizes, heat treatment conditions ,Nb/sub 3/Sn grain structure and the superconducting properties have been studied. The multifilamentary Nb-3Ti/ Cu-7.5Sn conductor shows the highest overall critical current density J/sub c/(overall) at 16 T for all the core sizes of 17 /spl mu/m-diam, 10 /spl mu/m-diam and 7.5 /spl mu/m-diam, after the optimum heat treatment. The optimum heat treatment condition for the multifilamentary Nb-3Ti/Cu-7.5Sn conductor varies slightly with core diameter. The J/sub c/( overall) of multifilamentary Nb-3Ti/Cu-7.5Sn conductor with 10 /spl mu/m-diam 6,289-cores heat treated at 700/spl deg/C for 200 hr exceeds 2.5x10/sup 4/A/cm/sup 2/at 16 T. The amount of residual tin in the Cu-Sn matrix of the multifilamentary Nb-Ti/Cu-7.5Sn conductor after heat treatment decreases with increasing titanium content in the core and decreasing core diameter. The multifilamentary Nb-3Ti/Cu-7.5Sn conductor showed appreciably improved uniaxial strain dependence of critical current I/sub c/at 14.5 T, as compared to that for a typical multifilamentary Nb/sub 3/Sn conductor. The multifilamentary Nb-3Ti/Cu- 7.5Sn conductor developed in this study makes feasible to generate a magnetic field of 16 T.         The influence of magnesium addition to the bronze on the critical current of bronze-processed multifilamentary Nb/sub 3/Sn    I. Wu, D. Dietderich, J. Holthuis, W. Hassenzahl and J. Morris Jr. Summary: Prior work by Tachikawa and coworkers has shown that the addition of magnesium to the bronze matrix prior to the formation of bronze-processed Nb3Sn tape causes a significant increase in the critical superconducting current density at 6.5 tesla, and that this increase is associated with a decrease in the apparent A15 grain size. The present work was undertaken to determine whether a similar improvement in J/sub c/ would follow the addition of Mg to multifilamentary Nb/sub 3/Sn wires and to identify the microstructural and mechanistic sources of any beneficial effects.         Superconducting and mechanical properties of internally steel reinforced Nb/sub 3/Sn wires with Ta or (Ni+Zn) additions    R. Flukiger, E. Drost, W. Goldacker and W. Specking Summary: The effects of internal steel reinforcement of Nb/sub 3/Sn wires on the current carrying capacity are studied. A strong enhancement of the precompression is found with respect to unreinforced Nb/sub 3/Sn wires: critical current density measurements as a function of the applied strain yielded /spl epsiv//sub m/values reaching up to /spl sim/ 1%. The supercondcuting parameters are strongly affected: the upper critical field, B/sub c2/*, is lowered from /spl sim/20 to 16 T with respect to the unreinforced wire, while the ratio J/sub c//J/sub cm/is very low, 0.37 at 10 T and 0.12 at 14 T. The effects of the enhanced precompression on J/sub c/are found to be partly compensated by Ta or (Ni+Zn) additions to Nb/sub 3/Sn.         Author Index (1982)    No author information available Summary: Not available

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