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1980     Front Cover (1980)    No author information available Summary: Not available         Table of Contents (1980)    No author information available Summary: Not available         Conference Information (1980)    No author information available Summary: Not available         Editor's comments (1980)    S. Lorant Summary: Not available         Chairman's comments (1980)    W. Keller Summary: Not available         One, two, three--Zero resistance! In defence applications    G. Gamota Summary: I am really delighted to have the opportunity meet with you here today and address the 1980 Applied Superconductivity Conference. It is always good to away from Washington, but to attend a conference "Land of Enchantment" on something as close to my heart professionally as superconductivity, is truly a great treat.         Superconducting magnets for toroidal fusion reactors    P. Haubenreich Summary: Fusion reactors will soon be employing superconducting magnets to confine plasma in which deuterium and tritium (D-T) are fused to produce usable energy. At present there is one small confinement experiment with superconducting toroidal field (TF) coils: Tokamak 7 (T-7), in the USSR, which operates at 4 T. By 1983, six different 2.5 X 3.5-m D-shaped coils from six manufacturers in four countries will be assembled in a toroidal array in the Large Coil Test Facility (LCTF) at Oak Ridge National Laboratory (ORNL) for testing at fields up to 8 T. Soon afterwards ELMO Bumpy Torus (EBT-P) will begin operation at Oak Ridge with superconducting TF coils. At the same time there will be tokamaks with superconducting TF coils 2 to 3 m in diameter in the USSR and France. Toroidal field strength in these machines will range from 6-9 T. NbTi and Nb/sub 3/Sn, bath cooling and forced flow, cryostable and metastable - various designs are being tried in this period when this new application of superconductivity is growing and maturing.         Test of a model coil of "Tore Supra"    R. Aymar, G. Claudet, F. Disdier, J. Hamelin, P. Libeyre, C. Mayaux, C. Meuris, J. Parain and A. Torossian Summary: Inside the qualifying test programme, supporting the "Tore Supra" Tokamak design, a reduced scale model of coil was fabricated by an industrial firm and fully tested. This model coil is provided with the same features as those retained for the complete magnet and is built according to the same design; in particular the Nb-Ti mixed matrix monolithic conductor is cooled by a pressurized superfluid helium bath, supplied from a model of the envisaged complete cryogenic system. Three main objectives have been assigned to this test: operation of the cryogenic system, stability of the superconductor winding under high mechanical stresses, mainly shear, and simulation of coil quench conditions. For this purpose, the model coil (outside bore 0.8 m) is located inside a 4 T magnet, an hydraulic jack applies a 1 MN force along a coil diameter. Operation of the model coil has been found highly stable, under the conditions of applied field and forces, a coil transition can be induced by an electrical heater only when the superfluid bath temperature is close to T/spl lambda/. The 1.8 K cryogenic system provides a useful calorimetric measure of total losses induced inside the winding; its operation has been quite simple and reliable, permitting a sure extrapolation to a much larger size.         Pulsed field loss characteristics of the Japanese test coil for the large coil task    H. Tsuji, K. Okuno, Y. Takahashi, T. Ando, S. Shimamoto and T. Ogasawara Summary: This paper describes some results of an analytical calculation and the measurements of a pulsed field loss on the Japanese LCT conductor. The conductor, whose aspect ratio is around 2.5, is wound edge wise to reduce the pulsed field loss. The Japanese LCT coil, with the conductor thus designed, was evaluated to have a pulsed field loss of about 19W. This includes the loss of the helium vessel under the normal LCT test with a pulsed field of 0 to 0.14T. In addition, the loss measurement has been carried out up to 25 T/s. Measured results on the relation between the loss of a single strand and that of a whole strand pack well supports the validity of the loss analysis which includes a newly arranged set of analytical equations.         Pulsed magnetic field losses of two 15000 A test superconductors designed for the swiss fusion research LCT coil    K. Kwasnitza, I. Horvath and P. Bruzzone Summary: Pulsed magnetic field losses have been investigated on two different NbTi superconductors designed for direct cooling with supercritical He and for I/sub tr/= 15000 A. The loss measurements were performed with perpendicular and parallel pulsed field components. The influence of the dc field component on the pulsed field hysteresis losses was measured up to 7 Tesla.         Further investigations of the upper critical field and the high field critical current density in Nb-Ti and its alloys    D. Hawksworth and D. Larbalestier Summary: The work described in this report was undertaken, within the context of the 12 Tesla program, to investigate the possibility of increasing the upper critical field, Hc/sub 2/, of Nb-Ti through alloying additions. A preliminary report has previously been given by us. In the first part of this paper we report further measurements of Hc/sub 2/in the Nb-Ti-Ta and Nb-Ti-Hf systems. Whilst we find only small enhacements of /spl sim/0.3 Tesla in /spl mu//sub o/Hc/sub 2/(4.2K) compared to binary Nb-Ti, at 2K there is a wide composition range in the Nb-Ti-Ta system where /spl mu//sub o/Hc/sub 2/(2K) exceeds 15 Tesla, reaching a maximum of 15.5 Tesla. This represents an enhancements of 1.3 Tesla over unalloyed Nb-Ti. By comparison alloys in the Nb-Ti-Hf system show a maximum enhancement in /spl mu//sub o/Hc/sub 2/(2K) of only 0.3 Tesla. The reasons both for the enhancements in Hc/sub 2/and for the differences in behavior systems shown by alloys containing Ta and Hf are briefly discussed. In part II we discuss common features in the behavior of the high field critical current density, J/sub c/, of four commercial Nb-Ti composites and upon the basis of this behavior predict the enhancements in the high field J/sub c/to be expected from using Nb-Ti-Ta and its alloys.         The use of NbTiTa as a high field superconducting alloy    H. Segal, T. De Winter, Z. Stekly and K. Hemachalam Summary: NbTi-based alloys containing 8% and 25% tantalum have been studied for use at fields around 12 tesla and at temperatures between 2 K and 3 K. These materials have significantly higher current densities at reduced temperatures than other NbTi-based alloys. Using the results of these studies, a 10,000 A, nominal 12 tesla conductor has been designed and is presently being fabricated for use in a test coil for the Lawrence Livermore Laboratory HFTF. The alloy selected for that conductor is Nb-43% Ti-25% Ta.         Stability analysis of NbTi-Ta- based high field conductor cooled by pool boiling below 4 K    W. Chen, J. Alcorn, Y.-H. Hsu and J. Purcell Summary: Stability analysis has been performed for cabled NbTi-Ta-based superconductors intended for the high field (12 T) toroidal field coils for a large scale tokamak device such as ETF. Ternary NbTi-Ta was selected as the superconductor because of its superior critical current density at high field as compared to the binary alloy NbTi. The operating temperature was chosen to be 2.5 K or below to optimize the performance of the superconductor. A cabled conductor was selected to minimize the pulsed field losses. The conductor is cooled by pool boiling in a subcooled (/spl sim/ 2.5 K, 0.25 atm) bath, or in a superfluid helium (He-II) bath (/spl sim/ 1.8 K, 0.02 atm). The analysis was based on numerically simulating the evolution of a normal zone in the conductor. Appropriate superconductor properties and heat transfer characteristics were utilized in the simulation. In the case of subcooled bath, the low bath temperature reduces both the peak nucleate boiling flux (PNBF) and the minimum film boiling flux (MFBF). In the case of He II bath, the heat transfer characteristic is determined by the cooling channel size, bath pressure and the Kapitza resistance. Results indicated that in both cases of cooling the NbTi-Ta-based conductor can be designed to satisfy the commonly followed stability performance criterion for such large coils. In particular, He II cooling was found to offer significant enhancement in the stability performance of the conductor. The implications of the results are discussed.         Superconducting properties of Ti-Nb-Hf alloys    H. Wada, K. Tachikawa and T. Kato Summary: To achieve improvements in superconducting properties of the Ti-Nb superconductor, effects of ternary additions of Hf have been extensively studied on 42 Ti-Nb-Hf alloys with compositions of 25 - 65at%Nb, 0- 15at%Hf and the balance Ti. Critical temperatures are found to depend upon Hf addition and aging temperature. In as-rolled Ti-40at%Nb-3at%Hf alloy the critical temperature is raised by about 0.3K over Ti- 40at%Nb alloy. Aging at 800/spl deg/C can raise critical temperatures of high Hf alloys by 0.6 - 1.8K. The upper critical field at 4.2K of as-rolled Ti-40at%Nb-3at%Hf reaches 11.7 tesla, a value higher by 0.4 tesla than that of Ti-40at%Nb. High field critical current densities are also improved by the 3at%Hf addition. 2 step aging treatment is found effective in enhancing critical current densities of high Hf alloys. No degradation in fabricability is caused by a few at% Hf additions.         Microstructure superconducting property relationships in a fermilab Nb-46.5w/o Ti filamentary superconducting composite    A. West and D. Larbalestier Summary: A transmission electron microscopy study has been performed on a production Fermilab Energy Saver composite from an intermediate stage in the manufacturing process. Studies of the dynamics of sub-band growth and /spl alpha/-Ti precipitation show that sub-band growth is quite rapid and occurs to a significant extent before /spl alpha/-Ti precipitation starts. Following analysis at intermediate size, the behavior of heat-treated samples was compared to that of samples drawn to final size without heat-treatment. Heat-treated samples were found to have smaller final sub-band diameters, in spite of the initial increase caused by heat-treatment and their critical current densities were also greater. The microstructural evidence points to the crucial role played by /spl alpha/-Ti precipitation in developing high J/sub c/values in this Nb46.5w/oTi alloy.         Lap joint resistance and intrinsic critical current measurements on a NbTi superconducting wire    L. Goodrich and J. Ekin Summary: The lap joint resistance between two Cu:Nb-Ti wires (rectangular cross section, 0.53 X 0.68 mm) was measured at 4 K as a function of current, magnetic field and joint area (0.5 to 7 mm/sup 2/). A simple model, using the magnetoresistance and current dependence, allowed the Joint interface resistance and the current transfer resistance to be separated. The critical current of the wire was also measured adjacent to the Joint. These critical current data were compared with data taken on the control sample (no lap joint). From these comparisons operational checks were deduced for an intrinsic measurement of the critical current adjacent to a joint. The operational checks were on the reversibility of the V-I curves and on their current ramp-rate dependence. When these operational checks were applied to the critical current data of all the joints tested, the results agreed to /spl plusmn/2%.         Development of critical current measurement standards    H. Segal, Z. Stekly and T.A. de Winter Summary: This paper deals with the development of criteria for critical current measurements. The two tasks investigated were: (1) the determination of critical current of short samples as a function of transition criterion, and (2) analysis of current transfer from sample holder to sample. Critical currents were measured using the equivalent resistivity criterion with sensitivities ranging from 10/sup -7//spl Omega/-cm to 10/sup -12//spl Omega/-cm and using the electric field criterion with sensitivities of 1 mV/cm to 100 nV/cm. Current transfer measurements were performed on monolithic conductors with critical currents greater than 1,000 amps. The results of the program are that no single measurement standard and no single test holder are suitable for all types of critical current measurements, and that sample holders must be designed with sufficiently large copper current contacts in order to minimize current transfer effects.         Quench properties of high current superconductors    M. Garber and W. Sampson Summary: A technique has been developed which allows the simultaneous determination of most of the important parameters of a high current superconductor. The critical current, propagation velocity, normal state resistivity, magnetoresistance, and enthalpy are determined as a function of current and applied field. The measurements are made on non-inductive samples which simulate conditions in full scale magnets. For wide, braided conductors the propagation velocity was found to vary approximately quadratically with current in the 2 to 5 kA region. A number of conductors have been tested including some Nb/sup 3/Sn braids which have critical currents in excess of 10 kA at 5 T, 4.2K.         Static and dynamic properties of short, narrow, variable-thickness microbridges    M. Feuer and D. Prober Summary: The electrical properties, including the Josephson-effect response to microwave radiation, have been studied for extremely small, high-resistance microbridges of Pb-In alloy and unalloyed In, with dimensions ranging from 300/spl Aring/ to 2000/spl Aring/. The I/sub c/R product of In and Pb-In microbridges decreases smoothly as the bridge cross section is reduced, approaching the Ginzburg-Landau limit of 0.64 mV/K for the smallest bridges. The voltage range of microwave response and the temperature range of hysteresis-free operation both increase (improve) as the bridge is made narrower, in agreement with Joule heating theory. For example, an 8 ohm Pb/sub 0.9/In/sub 0.1/bridge with all dimensions /spl les/500 /spl Aring/ has a maximum step voltage of V/sub max/ = 1.5 mV and a nonhysteretic temperature range of /spl Delta/T/sub no hyst/ = 1.2 K. Bridges of unalloyed In can show still better response due to a longer coherence length, and nonhysteretic operation over the full temperature range below T/sub c/is possible.         Josephson effects in Nb/sub 3/Sn microbridges    T. Lee and C. Falco Summary: We have studied Josephson effects in long narrow Nb/sub 3/Sn microbridges at temperatures up to 17 K. These microbridges are formed by photolithographic techniques and subsequently subjected to controlled electrical discharges to modify the intrinsic T/sub c/of the bridge region. The bridges exhibit 10 GHz micro wave steps in their I-V characteristics whose amplitudes are in excellent agreement with the Resistively Shunted Junction (RSJ) model. I-V characteristics (with and without microwaves) can be fit assuming an effective temperature approximately 15 K above the bath temperature. We have also investigated in detail structures in the I-V characteristics in the absence of microwaves. We show experimentally that phase-slip centers are induced at weak superconducting positions along the bridge when the S-N boundary of an expanding hot spot reaches within a thermal healing distance. The critical current of the phase-slip center thus formed exhibits a temperature dependence (1-T/T/sub c/)/sup 1/2/instead of the usual mean field result (1-T/T/sub c/)/sup 3/2/.         Transient response of superconducting Pb microbridges irradiated by picosecond laser pulses and its potential applications    C. Chi, M. Loy, D. Cronemeyer and M. Thewalt Summary: We have observed voltage pulses having half-widths of less than 500ps generated by constant-current-biased superconducting Pb variable thickness microbridges driven normal by short (3-5ps) light pulses. This represents a first step in the effort to generate even shorter pulses, which according to our analysis of the Rothwarf-Taylor equations should be possible. The ultimate width should be equal to the phonon pair-breaking time, which for materials such as Nb can be as short as a few picoseconds. In addition to monitoring the voltage pulses directly, we have used a novel adoption of the optical autocorrelation technique having a time resolution limited only by the laser pulse width. It is pointed out that even shorter voltage pulses, and therefore greater potential for device applications, can be achieved by direct injection of quasiparticles.         Microwave power spectra of variable thickness sub-micron bridges    D. Schwartz, P. Mankiewich, A. Jain and J. Lukens Summary: The frequency variation of the radiated power and linewidth of variable thickness bridges from 2 to 18 GHz is reported. A new, simple technique for fabricating these bridges using electron beam lithography is described. The measured power is found to be in unexpectedly good agreement with that calculated using the resistively shunted junction model. The linewidth data are in striking disagreement with existing theories.         Coherent arrays of thin-film Josephson microbridges    J. Hansen, P. Lindelof and T. Finnegan Summary: We have investigated two different methods of coupling between the Josephson oscillations in arrays of superconducting microbridges made of Sn and In in order to establish a single free-running coherent state. We report on experiments involving a broadband inductive coupling between pairs of microbridges, each pair constituting a dc-SQUID; and a narrow hand coupling between microbridges via resonant structures in transmission lines consisting of microstrip or slot lines. We discuss the properties of these two ways of long range coupling of Josephson weak links and evaluate their potential for high-frequency applications.         Microwave wideband tunable oscillators using coherent arrays of Josephson junctions    A. Jain, P. Mankiewich, A. Kadin, R. Ono and J. Lukens Summary: Coherent microwave radiation from arrays containing up to 100 indium microbridges has been directly detected. As expected the power scales as N/sup 2/and the linewidth as 1/N for an array containing N junctions. Design criteria and fabrication methods for these arrays are discussed.         New wave phenomena in series Josephson junctions    A. Davidson Summary: The use of electromagnetic waves to obtain coherence between widely spaced Josephson tunnel junctions is explored. A pair of coupled non-linear differential equations is developed for the case of junctions used as series elements in a microstrip transmission line. We use analysis to demonstrate the existence of oscillatory traveling waves, solitary waves, and standing waves on such a transmission line. We report simulations that demonstrate these waves, and an observation of standing waves in a real series array. It appears that substantial power at frequencies above 100 GHz may be obtained from these series arrays.         Microstrip coupling techniques applied to thin-film Josephson junctions at microwave frequencies    O. Soerensen, N. Pedersen, J. Mygind, B. Dueholm, T. Finnegan, J. Hansen and P. Lindelof Summary: Three different schemes for coupling to low impedance Josephson devices have been investigated. They all employ superconducting thin-film microstrip circuit techniques. The schemes are: (i) a quarterwave stepped impedance transformer, (ii) a microstrip resonator, (iii) an adjustable impedance transformer in inverted microstrip. Using single microbridges to probe the performance we found that the most primising scheme in terms of coupling efficiency and useful bandwidth was the adjustable inverted microstrip transformer.         Mutual phase locking in multijunction Josephson arrays    K. Likharev, L. Kuzmin and G. Ovsyannikov Summary: Mutual phase locking of Josephson oscillations in a two-junction cell and multijunction arrays is analysed. The locking is due to ac currents of Josephson frequency /spl omega/, which flow through some special coupling circuit. For the most important case of almost identical junctions, the locking frequency range is shown to be proportional to the imaginary part of the complex conductivity Y(/spl omega/) of the coupling circuit. The power and linewidth of coherent oscillations, as well as the coherence stability with respect to the junction intrinsic noise and parameter spread, have been calculated. The maximum locking range and, hence, the maximum parameter tolerances are shown to take place in the closed-loop-type (ring) structures with long-range junction interactions.         AA-EDF superconducting generator development program    J. Sabrie, G. Ruelle and P. Dubois Summary: AA-EDF collaboration in this field began in 1971. 250 to 3000 MW superconducting generators have been studied. Tests have been performed on parts for machines of more than 1000 MW. A large cryogenic rotor model (outer diameter : 1,06 m, length between bearings : 5 m with superconductor winding) is undergoing initial tests. Concerning a prototype, the existing turbines impose speeds of 3000 rpm; 250 MW power (47 existing turbines) allows rotor diameter characteristic of machines of more than 1 GW, the field winding could be constructed as in the rotor model; an important technical problem is the ambient temperature damper, a serious concern is to obtain a 250 MW power plant for the tests. The required availability and principal modes of operation in a large system - and, above all, resynchronization without quenching led us to the principal technical options : low-loss superconductors, no low temperature damper and supercritical helium.         Superconducting conductor design for a 250 MW superconducting AC generator    J. Maldy, A. Fevrier, P. Dubots, J. Renard, J. Goyer, H. Nithart and J. Duchateau Summary: We have started extensive works for designing the superconducting conductor for 250 MW to 3 GW cryogenic generators. Numerical computations have been developed to calculate the winding temperature rise due to transient electrical and magnetic variations or in case of quenching. Optimized cables made of composites containing 5/spl mu/m to 10/spl mu/m NbTi filaments in mixed matrix and a normal metal wire to detect quenching voltages have been designed and manufactured. Epoxy impregnated coils made with these cables have been tested in dc and pulsed conditions up to 40 T/s.         Model test coil for a 10 MVA superconducting generator field winding    J. Minervini, K. Tepper and J. Smith Jr. Summary: The superconducting field winding of the MIT-DOE 10 MVA experimental generator has been designed using a unique structural concept of fourteen discrete saddle shaped winding modules supported by a series of yokes. Intramodule stresses are minimized by the use of interlayer slip planes. A model coil has been built to develop the fabrication techniques required for construction of the generator field winding. The coil was constructed to the full scale dimensions of one of the field winding modules, but in a solenoidal geometry to fit the test facility. The coil has been tested under simulated operating conditions to prove the viability of the design concept and to measure the electrical and thermal performance of the winding.         The circular form of the linear superconducting machine for marine propulsion    J. Rakels, J. Mahtani and R. Rhodes Summary: The superconducting linear synchronous machine (LSM) has been shown to be a highly efficient means of propulsion for application to advanced ground transport systems. We have shown that it would also appear to have significant advantages in marine engineering, e.g. for the propulsion of large commercial ships, tankers and military vessels, where the basic requirements of high torque at relatively low shaft speeds, together with the ease of reversibility, are readily met. A design utilising the circular form of the LSM as a ship's drive motor has been proposed and the details of a specific form of the LSM, namely the linear commutator machine (LCM) are discussed. The many advantages of this type of heteropolar machine are listed and compared with the superconducting homopolar motors which have been developed for ship propulsion. In particular, its flexibility in design, the built-in redundancy factors, hence reliability, together with other design details of the cryogenic magnets and the armature winding are described.         Axial transfers tube heat leak of rotating superconducting machines: Fluid contribution    Y. Kim, C. Chuang and T. Frederking Summary: Experiments have been conducted to measure the heat leak of a transfer tube assembly (rotating cylinder/stationary cylinder) in the fluid - filled gap at the low temperature end in axial direction. The angular frequency was varied up to 300 rad/s. Fluid He/sup 4/, pressurized above its thermodynamic critical pressure was used to eliminate two - phase conditions. Zero net mass flow was established. The variation of the heat leak Q/sub L/with the gap width s was found to be(d \log Q_{L} / d \log s) = 1.2 \pm 0.2.         Losses in Nb/Ti multifilamentary composite when exposed to transverse alternating and rotating fields    C. Pang, A. Campbell and P. McLaren Summary: Experimental and theoretical studies have been made of losses in Nb/Ti multifilamentary composite exposed to transverse alternating and rotating fields. Analytical expressions for eddy current losses inside the copper matrix can be found. As for hysteresis losses, an analytical expression can only be obtained in low and high field limits. Numerical calculations have been made to determine hysteresis losses and magnetisation in the Nb/Ti filaments for intermediate fields. These calculations are based on an iterative computer solution for the flux and current profiles in the Nb/Ti filaments. Simple polynomials are fitted to these calculations and theoretical results are compared with experimental results obtained using calorimetric techniques.         Optimal design of superconducting turbogenerators via polyparametric sensitivity analysis    E. Chiricozzi and M. Ciaffi Summary: In this paper the dynamic behaviour of a superconducting turbogenerator is simulated by means of the Park's non-linear mathematical model in the state-space form so as to analyze the influence of the machine parameters simultaneous variations upon its dynamic behaviour via polyparametric sensitivity analysis approach. The computer program worked out by the authors is used to simulate a 2,000 MVA, three-phase, two-pole superconducting turbogenerator as well as to generate its parametric sensitivity functions. The machine model is subjected to a step input simulating a sudden three-phase short circuit occurring at the unit terminals. Its response is observed in the time domain simultaneously with the sensitivity functions, so as to determine the influence of each parameter variations on the dynamic behaviour of the simulated system. Investigation is here confined to the machine resistive parameters and only the ones which largely affect the machine dynamic response will be considered. The values of these ones are selected which achieve the most suitable machine dynamic response. Moreover a polyparametric sensitivity vector is derived from the parametric sensitivity functions in order to investigate the mutual influence of the parameter variations in their chosen ranges.         Control problems in a superconducting turbogenerator    A. Bellini, G. Figalli and G. Veca Summary: The paper takes into consideration the possibility to employ the classical methods of the optimal control theory for the design of a rotor regulator useful for superconducting turbine generators. To this aim, at first a simple dynamic model of this kind of generators is shown and a method for the determination of its parameters is mentioned. Then an observer, able to give the not measurable state variables, is obtained. Finally the goodness of the observer operation is checked by simulation, taking into account the design data of a two-pole, 1500 MVA turbogenerator.         Flux pump excited brushless alternator    A. Ferendeci, O. Mawardi, M. Melfi and H. Laquer Summary: Experimental measurements obtained for a novel brushless superconducting alternator that makes use of a flux pump of the rotating spot type are presented. The flux pump, used to provide the excitation current of the field coils incorporates several features of a machine studied theoretically and reported in an earlier paper. The flux pumping is achieved with six electromagnets having pole pieces of special configurations to yield high efficiency and rapid pumping rates. The maximum design values for the current in the pump is 1,300 amps. and for the rotational speed, 500 rpm. Sensors installed on the generator yield information on the spatial and temporal behavior of the magnetic field in the flux spot and on the operational characteristics of the pump. The preliminary observations are compared with the theoretical predictions.         Construction and properties of a 1-m long Nb/sub 3/Ge-based AC superconducting power transmission cable    J. Thompson, M. Maley, L. Newkirk, F. Valencia, R. Carlson and G. Morgan Summary: We have constructed a prototype 1-m long, coaxial ac superconducting power transmission cable utilizing Nb/sub 3/Ge-clad tapes, Tapes up to 20-m long were produced by pulling 25-/spl mu/m thick by 0.64-cm wide copper substrates through a continuous coating chemical vapor deposition reactor. Nb/sub 3/Ge layer thicknesses in the range 3-5 /spl mu/m were deposited on both surfaces and around the edges of the substrate. A total of 50 m of Nb/sub 3/Ge-coated tapes was incorporated in this cable, with all tapes exhibiting critical current densities J/sub c/@ 14 K /spl geq/ 1.8 x 10/sup 6/ A/cm/sup 2/. The cable was fabricated after the BNL double-helix design. Losses measured in the cable were found to be high, /spl sim/ 1 mW/cm/sup 2/at 500 rms A/cm, and comparable to losses in similar 1-m Nb/sub 3/Sn-based cables. We believe that these high losses are not a result of material dependent properties.         First field trials of a superconducting power cable within the power grid of a public utility    P. Klaudy, I. Gerhold, A. Beck, P. Rohner, E. Scheffler and G. Ziemek Summary: The first tests of a superconducting power cable within the power grid of a public utility were conducted at the Steweag power plant in Arnstein, Austria, in 1979. The cable (conceived by Klaudy [1],[2] and manufactured by ATF and Kabelmetal) is 50 m long and consists of seven concentric, longitudinally welded corrugated tubes using the "Wellmantel" technology. The fully flexible cable was shipped on a reel by conventional rail and road transportation means. It was easily installed by technicians familiar with conventional cable laying methods. No problem developed during the evacuation and cooling by liquid helium to about 6.5 K. The shield was cooled by liquid nitrogen to about 77 K. The cable was designed for 110 kV and 1.6 kA. Although transmitting the entire available power output of the station, the full rating of the cable was not attained during the tests. The conductor for these first trials was made of copper-stabilized niobium. The tests were concluded without any problems and all components performed in accordance with their design expectations under actual field conditions.         An improved 60 Hz superconducting power transmission cable    G. Morgan, F. Schauer and R. Thomas Summary: The third in a series of 10 m, Nb/sub 3/Sn cables for ac power transmission has been installed in a horizontal, refrigerated cryostat. Like the two previous ones, this coaxial cable has its ends rigidly fixed so that it cannot contract axially on cooldown, and has two layers of superconducting helices and two layers of high purity aluminum helices for stabilization in each conductor. It differs from the previous one in having thicker electrical insulation (7.4 mm vs 3.6 mm), in having increased contact resistance between the superconducting layers to reduce ac loss, and in being driven by an external supply through horizontal, coaxial, vapor-cooled current leads. This is the final short cable prior to construction late this year of a 100 m cable which will be tested with high voltage and high current simultaneously. Results of current tests are presented, including ac loss at various temperatures and recovery from thermally induced quenches.         Current test of a DC superconducting power transmission line    F. Edeskuty, R. Bartlett and J. Dean Summary: A test of a prototype dc superconducting electric power transmission line (dc SPTL) has been performed at 5 kA and 12 K. A supercritical helium refrigeration system was used to cool the test system which included a cable with a hollow central core so that the go and return refrigerant streams could countercurrently cool the inner and outer surfaces of the cable. Multifilamentary Nb/sub 3/Sn superconducting wire was developed for the dc SPTL application and extensively tested to establish the optimum fabrication techniques and the expected response of the wire to cabling, operating, and installation stresses.         Typical problems of the correction magnets for fermilab energy saver    D. Ciazynski and P. Mantsch Summary: We have worked on the fabrication, the tests and the improvments of the correction magnets. We will give her some specific results obtained on these magnets, the main characteristics of which are to work in an external magneric field which is generally higher than their own field and to be able to work with different senses of the current which is rather unusual for pulsed superconducting magnets.         Isabelle dipole and quadrupole coil configurations    P. Dahl and H. Hahn Summary: The coil configurations of the ISABELLE dipole and quadrupole magnets have been reviewed and a number of improvements were suggested for incorporation into the final design. The coil designs are basically single layer multiple block approximations to cosine current distributions, wound from a high aspect ratio non-keystoned braided conductor. The blocks are separated by knife-edge wedges to maximize the quench propagation velocity. The current density variation is obtained by an appropriate distribution of the spacer turns and, to a lesser degree, by the wedge locations. The use of inert turns is necessary to minimize the peak field enhancement both in the ends and in the two dimensional section. Schemes for deriving turns distributions yielding harmonic coefficients satisfying the stringent ISABELLE tolerances on field uniformity, while allowing for simplicity in winding and taking into account quench propagation considerations, will be discussed, as well as our approach to the coil end configuration.         Beam heating studies on an early model ISA superconducting cosine /spl theta/ magnet    G. Bozoki, G. Bunce, G. Danby, H. Foelsche, J. Jackson, A. Prodell, A. Soukas, A. Stevens, R. Stoehr and J. Weisenbloom Summary: Superconducting magnets for accelerators can be accidentally quenched by heat resulting from beam losses in the magnet. The threshold for such quenches is determined by the time structure of the beam loss and by details of the magnet application, construction and cooling. A 4.25 m long superconducting cosine /spl theta/ dipole magnet, MARK VI, constructed during the research and development phase of the ISABELLE Project at BNL was installed in the 28.5 GeV/c primary proton beam line from the AGS. By energizing the magnet, the proton beam could be deflected into the magnet. The beam intensity required to quench the magnet was observed for different beam sizes and at several values of magnet current up to 2400 A or approximately 70% of the highest magnet operating current. The maximum current was limited by the gas-cooled power lead flow available using pool-boiling helium rather than single phase forced-flow helium at 5 atm for which the magnet system was designed. Details of the experimental setup including the magnet and cryogenic system, the beam-monitoring equipment and instrumentation are described. The measurements are discussed and compared with beam heating measurements made on another superconducting magnet and interpreted using the Cascade Simulation Program, CASIM.         A high gradient quadrupole magnet for a polarized beam facility    R. Smith, J. Hoffman, S. Kim, K. Mataya, R. Niemann and L. Turner Summary: A prototype quadrupole magnet with 2.8 m effective length is under design and construction for use in a polarized beam transport system at Fermi National Accelerator Laboratory. The operating gradient required is 50 T/m and the higher multipole error fields must not exceed a few parts in one thousand over a 10 cm diameter bore. For cryogenic efficiency the magnet will operate at 1000 amperes and a cold iron yoke will provide complete field shielding.         A six tesla analyzing magnet for heavy-ion beam transport    R. Smith, L. Bollinger, J. Erskine, L. Genens and J. Hoffman Summary: A superconducting analyzer magnet for particle beam deflection has been designed and is being fabricated for use at the Argonne Tandem-Linac Accelerator System (ATLAS). This six tesla magnet will provide 45/spl deg/ of deflection for the heavy-ion beams from the ATLAS tandem electrostatic accelerator and together with its twin will replace the existing conventional 90/spl deg/ analyzer magnet which will become inadequate when ATLAS is completed.         Design, fabrication and testing of superconducting solenoid systems for high energy beam applications    K. Hwang and R. Camille Summary: Two superconducting solenoid systems have been designed, built and tested by Magnetic Corporation of America (MCA) for Los Alamos Scientific Laboratory (LASL). One solenoid system which is being used at the Meson Physics Division has a central field of 3.5 T, coil length of 91.4 cm and a horizontal room temperature warm bore of 10 cm. Another system being used at the Applied Photo Chemistry Division has a central field of 3 T, coil length 91.4 and a room temperature warm bore of 14.6 cm. The stored energy of each coil is in excess of 100 kJ. Each system provides a unique extra heavy-duty low heat loss magnet support system. The design criteria, fabrication experience and test results of the coil and cryostats are presented.         Superconducting compensator magnets to be used with the HRS spectrometer at the SLAC PEP facility    L. Hyman, J. Sheppard and R. Smith Summary: The first of a pair of identical superconducting compensator solenoids required for the High Resolution Spectrometer Facility (HRS) at the Stanford e+ e- Colliding Beam Storage Ring Accelerator (PEP) has been tested. The magnet provides a 2.0 T field in a room temperature bore 19.0 cm in diameter. The magnet winding length is 1.65 m and a cold iron yoke reduces the fringe fields 30 cm outside the cryostat to less than 10 gauss. The pool-boiling helium cryostat with liquid nitrogen cooled thermal radiation shield will be supplied with cryogens from the Spectrometer Facility refrigeration system.         Independent current control in the coupled superconducting coils of a heavy-ion cyclotron magnet    H. Schneider and C. Hoffmann Summary: A heavy ion energy booster cyclotron for a Tandem Van de Graaff is currently under construction at the Chalk River Nuclear Laboratories. The magnet, consisting of a 170 tonne iron yoke, 1.4 m diameter iron poles, and a pair of 3 MA-turn superconducting coils has been built and tested to an average midplane induction of 5 T. The coils, fitted around the poles above and below the midplane, are split electrically into an inner and outer pair. Independent current settings in each pair provides coarse adjustment of the radial profile of the field to allow an energy and ion acceleration range from 50 MeV/u lithium to 10 MeV/u uranium. The coils, which represent a variable inductive load, (inductances decrease by roughly a factor 20 as the iron saturates) are energized by a dual 8 V, 2500 A power supply with automatic voltage/current crossover. A special feedback circuit prevents induced reverse currents that would produce undesirable reverse radial stresses in the coils. Long term current and field stabilities of better than 1x10/sup -5//h have been achieved.         Superconducting magnet system for a 750 GeV MUON spectrometer    S. Wipf Summary: A spectrometer to measure deep inelastic muon scattering needs a uniform magnetic field, in an unobstructed space of 0.8 X 0.8 X 60 m, of 2 T vertical and transverse to the long direction. Outside the field space is an iron shield used for identifying and counting of muons, for reduction of stray flux, for improving field homogeneity and also for entainment of magnetic forces. The magnet is composed of 6 m long units. Each unit is assembled by stacking 44 largely identical subunits. Each subunit is wound as a flat pancake on a window frame 1.7 X 6 m and bent into the required saddle shape. Cooling is by circulating two-phase helium through copper pipes attached to the subunits; heat transport within windings is through solid contact. Operating current, at 2 kA, is below the full stability limit. Half the magnetic forces are contained by cold tension struts connecting the two sides of the coil at top and bottom, the other half by supports between the center of the windings and the warm iron shield.         A large superconducting dipole magnet for the heavy ion spectrometer system (HISS)    R. Wolgast, V. Fletcher, A. Kennedy and Y. Kajiyama Summary: The magnet is the central element of the spectrometer system, where it will be used to momentum-analyze secondary heavy-ion fragments at relativistic energies. High bending power and large acceptance apertures are necessary for simultaneous multiple fragment measurements. Free access over large angles to the magnetic volume is necessary to accommodate a variety of experiments and particle detection systems. The magnet has pole tips two meters in diameter, a one meter gap, and a maximum central field of three tesla. The coils are designed to be cryostable, with a helical winding pattern. A window-frame steel yoke limits the stray field and augments the central field. In terms of its magnetic energy of 55 MJ it will be one of the twelve or so largest magnets in the world. Unusual engineering features of the magnet are the large magnetic forces (one million kg) between the coils at liquid helium temperature and the yoke at room temperature, and the large diameter (7 m) hydraulic cylinder base to provide rotation for the magnet. The magnet will be installed at the BEVALAC heavy-ion facility at Lawrence Berkeley Laboratory.         The superconducting chicago cyclotron magnet--An old magnet with a new pair of energy efficient coils    E. Leung, R. Kephart, R. Fast and J. Heim Summary: Significant electrical power can be saved by replacing existing water-cooled copper coils with superconducting ones. This paper describes a DOE-Fermilab energy conservation project in which a pair of superconducting tori 5.25 m in diameter have been constructed to replace the copper coils, built in 1949, of the 170-inch Chicago Cyclotron, now in use at Fermilab as an analysis magnet. The superconducting magnet, with a stored energy of 32.5 MJ, was fabricated in-house at Fermilab. Engineering concepts, design and optimization of the coil, support structure and cryogenic system are described. In particular, the major support, a composite column capable of a collapse load of 1.33x10/sup 6/N and an expected heat leak of 120 mW will be described in detail. Practical problems encountered during the construction phase are discussed and test results presented.         Mechanical study on the Japanese test coil for the large coil task    K. Yoshida, E. Tada, K. Koizumi, T. Hiyama and S. Shimamoto Summary: Mechanical study for the Japanese test coil for the Large Coil Task will be profitable for the construction of a superconducting tokamak coil system. For high rigidity of coil in the radial direction, high strength 304L stainless steel and full hard high strength copper stabilizer were chosen for the test coil. In the structural analysis of the test coil, unclear factors of the interaction mechanism between the winding and the helium vessel was excluded in order to design the test coil for the worst case condition. A mechanical verification test on the 304L stainless steel and the conductor were carried out. 304L stainless steel test results indicated that it is possible to level up design criterion. A test of the 0.2% yield strength of the full size conductor was 15% higher than the value used for the previous design.         Elastic buckling of superconducting Yin-Yang magnets for fusion    F. Moon and K. Hara Summary: A small superconducting model of yin-yang coils for the Mirror Fusion Test Facility has exhibited a magnetoelastic buckling instability. The 1:22 model, wound with 150 turns of niobium titanium wire and potted in epoxy, can carry up to 30 10/sup 3/Amp-turns. Rotational motion of the magnets is observed to increase as the current approaches a critical value, while the torsional natural frequency is observed to decrease with current. A prediction of the buckling current based on a theoretical model is found to be higher than the measured values. The phenomenon is similar to that observed for tokamak toroidal field magnets. Structural design implications for Yin-Yang magnets are discussed.         A superconducting magneto-hydromechanical separator    C. Li, J. Xu, J. Zhang, D. Yin, Z. Wang, S. Fan, F. Hao and Y. Zhu Summary: A prototype superconducting magneto-hydromechanical separator has been worked out. Test with a diamond-like type of oremixture (empholite-quartz-barite) confirmed the design prediction. Both static and dynamical separations are realized satisfactorily. This apparatus is also able to serve for other applications, where a sufficiently large high-field volume free for manual operating must be required.         AC losses, flux jumps and quench behavior of copper-clad NbTi superconducting wire under coil simulation conditions    J. Chikaba, F. Irie, M. Takeo, T. Matsushita, T. Ezaki, K. Luders, G. Klipping and U. Ruppert Summary: AC losses, flux jumps and quench behaviour of copper-clad single core wires of Nb-50%Ti are investigated under coil simulation conditions. At a frequency of 27 Hz an ac magnetic field and an inphase ac current up to 0.525 T and 99 A, respectively, are applied. The temperature is varied between 4.2 and 1.9 K. Measurements for several ratios of current field and external field are reported. It results, that ac losses and flux jump values are determined only by the effective surface field and the temperature. The quench behaviour is different. Obviously, it is independent of the occurance of flux jumps and influenced by the heat transfer conditions.         Thermal magnetoresistance of copper matrix in compound superconductors, a new measuring method    W. Nick and C. Schmidt Summary: A technique is described which allows the surement of thermal conductivity of technical superconductors with little experimental effort to an accuracy of about 10 %. Results of thermal magnetoresistance of copper show that electrical and thermal conductivity follow the same field dependence. A simple analytical expression for the thermal conductivity of copper as function of residual resistivity ratio, magnetic field and temperature is given. In another experiment the thermal conductivity of an "in situ" Nb/Cu composite wire, a basic material for Nb3Sn conductors, was measured.         On the theory of normal zone propagation in superconductors    A. Gurevich and R. Mints Summary: This paper contains a study of properties of stable normal (N) regions of finite size - resistive domains (R.D.), in superconductors (S) with transport current I. It is demonstrated that in homogeneous superconductors R.D. are moving due to thermoelectric effect (Thomson heat) while the rate of R.D., v/sub d/, for different materials ranges from 1 to 10/sup 2/cm/s. It is also shown that the thermoelectric effect leads to asymmetry in the rate of the NS boundary /spl utri/ v relative to the direction of I, with /spl Delta/v /spl sim/ v/sub d/. The conditions for localizing R.D. in an inhomogeneous superconductor have been obtained, as well as the I-V characterictics of a sample with R.D. Hysteresis effects are discussed associated with the localization of R.D and the thermoelectric effect.         Thermal, electrical and magnetic behaviour of a superconducting winding    A. Fevrier and J. Renard Summary: We have developed a digital computation of the time dependences of losses and of the temperature in a composite, and in a flat braided cable, submitted to any space and time-variations of the magnetic induction and to any time-variations of current and of cooling conditions. Experimental and calculated losses, in the case of a composite submitted to a rotating magnetic induction, are in good agreement within about 5 % to 10 %. This digital computation have also been used to design an optimum flat braided cable for the rotor of a 250 MW superconducting A.C. generator which may undergo a cleared short circuit followed by a fault elimination without quenching. Time variations of the ratio of the current to the critical one, of the temperature and of the losses in the cable during the fault are presented.         Critical state stability and training phenomenon    I. Maksimov and R. Mints Summary: The critical state stability in hard and composite superconductors has been studied under conditions of plastic yield of the material. There has been found the criterion of critical state stability with respect to the jointly developing magnetic flux jump and plastic strain jerk. Based on the obtained results, the authors have offered an interpretation of the training phenomenon in superconductors.         Losses in composite superconductors at high amplitudes and rates of field variation    V. Zenkevitch, A. Romanyuk and V. Zheltov Summary: Differential equations have been obtained which enable one, with the aid of numerical calculation, to find the magnetic field dependence of the magnetic moment of screening currents in a composite superconductor and then calculate transient losses. Results are presented by calculating the losses upon single field sweeps according to the linear and exponential laws and upon triangular and harmonic periodic signals. The calculation results are in good agreement with experimental data obtained.         In situ formed multifilamentary composites part I: Coupling mechanisms, stress effects and flux pinning mechanisms    J. Bevk, M. Tinkham, F. Habbal, C. Lobb and J. Harbison Summary: Recent developments on in situ formed multifilamentary composites are reviewed and their superconducting and mechanical properties discussed in terms of the underlying physical mechanisms. The evidence is presented for a strong size dependence of the strengthening, flux-pinning and coupling mechanisms and, in turn, the composite normal-state and superconducting transport properties. The importance of the composite microstructure and micro-geometry is illustrated with data on Cu-Nb, Cu-Nb/sub 3/Sn and Cu-V/sub 3/Ga conductors. In particular densely spaced interfaces are shown to interact effectively with both matrix crystal dislocations and flux-line lattice, resulting in strongly anisotropic material properties. The importance of the proximity-effect coupling is discussed for Nb/sub 3/Sn-based composites below the microstructural percolation threshold where the self-field critical current densities (normalized to the filament volume fraction) reached values of 1.4x10/sup 7/A/cm/sup 2/. At high fields, the performance of Cu-V/sub 3/Ga in situ composites is significantly better than that of Cu-Nb/sub 3/Sn conductors, with typical normalized values of J/sub c/of 1.4x10/sup 7/A/cm/sup 2/at 18 Tesla and 4.2 K. Possible use of Cu-Nb in situ composites in high-field magnet design is also discussed in view of their remarkable strength (up to 2.9 GPa at 77 K) and high normal-state conductivity.         In-situ formed multifilamentary composites part II: AC losses    A. Braginski and G. Wagner Summary: AC losses determined by ac and dc magnetization and calorimetric techniques in a wide variety of twisted and untwisted in-situ composites are discussed. In all conductors studied so far the full penetration hysteresis losses are much larger than would be expected based on the filament size. The effect of twist and the anisotropy of magnetization as a function of the superconductor volume fraction has been used to characterize the transverse coupling between filaments which gives rise to the increased loss. Eddy current losses have been observed by electronic wattmeter and calorimeter techniques and are found to be small.         Magnetization of in situ multifilamentary superconducting Nb/sub 3/Sn-Cu composites    S. Shen and J. Verhoeven Summary: Magnetic properties are reported for in situ superconducting Nb/sub 3/Sn composites that have exhibited attractive electrical properties and superior mechanical characteristics. Magnetization measurements were conducted up to 4 T at 4.2 K on a variety of samples of different sizes and twist pitches, and the results are presented in absolute M-H curves and losses per cycle. It is observed that the magnetization of such composites is generally proportional to the size of the wire (/spl sim/0.25 to 0.51 mm) rather than the fiber size (/spl sim/10/sup -7/m), which indicates a strong coupling effect among Nb/sub 3/Sn fibers.         Preparation of in-situ Nb/sub 3/Sn-Cu wire by consumable arc melting    J. Verhoeven, F. Schmidt, E. Gibson, J. Sue, J. Ostenson and D. Finnemore Summary: Procedures have been developed for casting 10 cm diameter Cu-Nb ingots and for fabricating these castings into Nb/sub 3/Sn-Cu in-situ wire. Operating conditions which produce consumable arc cast ingots homogeneous to 1.5 wt % Nb are presented along with analyses of macro-segregation, carbon pickup and Nb dendrite size. Carbon impurity level is found to be an important parameter which controls the critical current.         Use of in situ wire in small magnets    D. Finnemore, J. Ostenson, J. Verhoeven, E. Gibson and R. Schwall Summary: A number of small solenoids have been wound from Nb/sub 3/Sn-Cu in situ wire in order to determine the suitability of these compositions for magnet construction. Magnets were wound after the wire was reacted and it was found that bending strains as large as 2% at the outer surfaee of the wire can be used with no degradation of the critical current. Calorimetric measurements of the ac losses indicate full penetration of the magnetic field into the wire above 8 Tesla. In addition it is found that losses are proportional to frequency as would be expected if the losses were hysteretic. Both the core method and an external diffusion method can be used satisfactorily for the fabrication of long lengths of wire.         Production of Nb/sub 3/Sn by the in-situ process    C. Spencer, E. Adam, E. Gregory, W. Marancik and C. Rosen Summary: Using CuNb alloys cast at Airco and at Ames Laboratory, processes have been developed for drawing commercially useable lengths of wire and for electroplating the strands with high purity tin. Tensile strengths exceeding 1378 MPa have been observed during the cold drawing operations. Critical current densities were measured in fields of 1.0 to 10 Tesla. J/sub c/values taken at 8 Tesla, for example are 812 A/mm/sup 2/for 20% Nb 0.15 mm diameter wire, and 997 A/mm/sup 2/for 30% Nb 0.30 mm diameter wire.         The effects of additives to the Cu-Nb melt on the high field properties of in situ multifilamentary Nb/sub 3/Sn wires    H. LeHuy, R. Roberge, J. Fihey, G. Rupp and S. Foner Summary: In Situ multifilamentary superconducting Cu-30 wt % Nb wires have been produced with small admixtures of Al, Zn, Be or Ta. The resulting 0.25 mm diameter wires have been processed with an external plating of Sn, diffused and reacted. The measured high field J/sub c/values are compared to Cu-30 wt % Nb-Sn without additives, and correlated with measured values of T/sub c/, the fraction of Nb transformed to Nb/sub 3/Sn, residual tin concentration in the matrix, and reaction time and temperature. Compared to Cu-30 wt % Nb wires without additives, the critical currents of those containing additives are comparable if the prestress is removed.         Origin of the improved resistance to strain of in situ Nb/sub 3/Sn multifilamentary composites    J. Lanteigne, R. Roberge, H. LeHuy, J. Fihey and S. Foner Summary: For in situ or ultra-fine multifilamentary Cu-Nb-Sn, the J/sub c/maximum versus strain varies from strain values of /spl sim/0.6 - 0.7% for the smallest interfilament spacing to 0.2 - 0.3% for the largest interfilament spacing. Finite element analysis is used to calculate the residual stress (and strain) components from the thermal contraction and to obtain the stress-strain curves following uniaxial loading. The influence of the superconducting volume fraction and the plasticity of the matrix are included in the analysis. One of the most important features is the net reduction of the residual tensile stress on the matrix which occurs when the configuration is changed from a monofilament to multifilament.         V/sub 3/Ga micro-composites conductors: Preparation and superconducting properties    R. Bormann and H. Freyhardt Summary: The powder metallurgical preparation of Nb/sub 3/Sn microcomposite wires is considered to represent an attractive alternative to the conventional processing of Nb/sub 3/Sn multicore conductors. In this contribution the analogous preparation of V/sub 3/Ga microcomposites is described in detail. The method is based on the hot extrusion of Cu-V powder mixtures and a subsequent cold deformation without intermediate anneals, whereby the V particles are drawn into 100 - 500 nm thick fibres. After Ga charging, the V/sub 3/Ga phase forms during a reaction treatment at temperatures between 550 and 600/spl deg/C. For Cu-30 wt.% V + Ga overall critical current densities J/sub c/(at 4.2 K) reach values of 4x10/sup 8/A/m/sup 2/at 16 T, with an (extrapolated) upper critical field of 23 T. They lie well above those obtained for Nb/sub 3/Sn micro-composites, in particular in the high field region.         Fabrication of multifilamentary Nb-Al by a powder metallurgy process    R. Akihama, R. Murphy and S. Foner Summary: Fabrication of multifilamentary Nb-Al superconducting wires with high overall critical current densities at high fields is discussed. Powder metallurgy processed materials have been made with low reaction temperatures and with J/sub c/> 10/sup 4/A/cm/sup 2/at 14 T. The effects of variations of Nb and Al powder size, composition, reduction ratio, reaction temperature, and reaction time on J/sub c/vs appiied field are presented. All the Nb-Al materials show good strain tolerance at high J/sub c/and high field. The results also show that scaleup is promising.         Microstructure and properties of A15 superconductors formed by direct precipitation    M. Hong, D. Deitderich, I. Wu and J. Morris Summary: Superconducting materials were made by quenching supersaturated solutions of V-Ga and Nb-Al, deforming the quenched specimens, and then precipitating the A15 phase by aging at intermediate temperature. The critical current characteristics of the product materials depend both on the inherent properties of the A15 phase, which presumably reflect its composition, and on the details of the precipitation process, which determine the grain size, continuity, and volume fraction of the A15. These features of the precipitation process differ qualitatively between V-Ga and Nb-Al. They are described and used to interpret the critical current characteristics.         Process test chip for Josephson integrated circuits    S. Klepner Summary: Process test chips are fabricated along with chips containing experimental circuits in our laboratory in order to aid in forming a data base to characterize the technology. All the test sites are placed on a 6.35mm X 6.35mm chip with two distinct final wiring patterns. Wafers containing two chips of both types are processed along with the other substrates. Testing is done at the end of the run. Sites containing repetitive elements are populated at 1-10% of LSI density.         Specific capacitance of Josephson tunnel junctions    J. Magerlein Summary: The specific capacitance of several types of Josephson tunnel junctions has been measured by observing resonances in lightly-damped 2-junction interferometers. The capacitance was calculated using the resonance voltage, obtained by analyzing steps in the I-V characteristics, and the interferometer inductance, which was measured directly by the injection of a control current. Using this technique, the specific capacitance C/sub s/was determined for tunnel junctions with Pb-In-Au alloy base electrodes and Pb-Bi counterelectrodes, as well as for junctions made on Nb films with Pb-In-Au counterelectrodes. In both cases, barriers were produced by rf plasma oxidation. Junctions with Josephson current densities j/sub 1/between 200 and 5000 A/cm/sup 2/were investigated. It was found that 1/C/sub s/decreased with log j/sub 1/, and that at j/sub 1/= 1000 A/cm/sup 2/, C/sub s/was 4.2 /spl plusmn/0.3 /spl mu/F/cm/sup 2/for the Pb-alloy junctions and 13.4 /spl plusmn/1 /spl mu/F/cm/sup 2/for the Nb junctions. These results are discussed in relation to available data on oxide thickness and dielectric constant.         A new lead alloy for Josephson junctions    C. Fu and T. Van Duzer Summary: We have investigated a new ternary superconducting alloy applicable to Josephson junction circuit fabrication. The alloy is composed of lead, chromium, and gold. The energy gap of the alloy, based on derivative measurements on tunneling junctions, is approximately 2.64 meV at 4.2 K and the superconducting transition temperature is 7.6 K. Tunneling-junction characteristics based on this new alloy show very low subgap leakage and are suitable for logic and mixing applications. The alloy is strongly corrosion-resistant and adheres well to silicon and glass substrates.         Submicron tunnel junctions    L. Jackel, E. Hu, R. Howard, L. Fetter and D. Tennant Summary: We have fabricated a variety of small-area, superconducting tunnel junctions and simple superconducting interferometer circuits using novel e-beam and optical lithographic techniques. These Pb-oxide-Pb(In) tunnel junctions are made using self-aligning processes which involve multiple oblique evaporations through suspended liftoff stencils formed in two-layer resist systems. Oxide barriers are grown in situ immediately after evaporation of base electrode films. Junction areas range from 10/sup -9/cm/sup 2/(optically patterned) to about 10/sup -10/cm/sup 2/(e-beam patterned). Current densities as high as 2x10/sup 6/A/cm/sup 2/have been attained. The high current-density junctions show only small hysteresis at 4K and are completely non-hysteretic at higher temperatures. These junctions have been used to make low-hysteresis interferometers with a current gain of 3. A positive feedback scheme is described which provides sharper switching characteristics in non-latching interferometers.         Nb/Nb oxide/Pb-alloy Josephson tunnel junctions    S. Raider and R. Drake Summary: A procedure is described for fabricating thin film Nb/Nb oxide/Pb-alloy Josephson tunnel junctions that satisfies the principal requirements for integrated circuit design and fabrication. A deposited Nb film, evaporated from an e-gun heated source, was patterned by chemical etching to form a base electrode. A junction was completed by plasma etching and plasma oxidizing the Nb junction area to form a tunnel barrier and by depositing a Pb alloy counterelectrode. Josephson tunnel junctions with Nb/Nb oxide/Pb-Au-In structures were prepared with low excess subgap currents in the current-voltage (I-V) curve and with reproducible and stable I-V characteristics. Variations in junction current density from run-run were /spl plusmn/ 15%. Seven 3-junction interferomeeters out of a population of 50,000 were shorted (99.99% yield) for causes not immediately attributable to photoresist-related defects. No changes in Josephson current were detected after thermal cycling 17,000 interferometers 1,800 X between room temperature and 4.2/spl deg/K, after storing them for 2 years at 5/spl deg/C, or after annealing 5,000 interferometers for 4.5 hours at 70/spl deg/C.         Reactive ion etching in the fabrication of niobium tunnel junctions    S. Reible Summary: A niobium-based tunnel-junction technology has been developed for analog signal-processing applications. Devices of interest would integrate superconductive transmission lines and superconductor/insulator/superconductor (SIS) mixers. Reactive ion etching of niobium patterns with linewidths of 1 /spl mu/m or less has been investigated with regard to the composition of gases, chamber pressure and power levels. These studies were made on RF-sputtered niobium films having critical-transition temperatures above 9/spl deg/K. Junction area is defined by reactively ion etching insulating films of silicon monoxide to resolutions of 0.3/spl mu/m or better. A niobium-oxide tunnel barrier is grown by RF-plasma oxidation. Proper control of the technology has allowed the achievement of critical current densities which are uniform to 10% or better over the silicon substrate. Junction V-I characteristics show low leakage currents with critical current densities to 2x10/sup 4/A/cm/sup 2/. Lead is employed for counter-electrodes and indium-gold (or aluminum) for circuit resistors. The robustness and stability of niobium-based junctions is essential in applications which normally require extreme dependability and long standby times.         Submicron niobium tunnel junctions with reactive ion beam oxidation    A. Kleinsasser, B. Hunt, A. Callegari, C. Rogers, R. Tiberio and R. Buhrman Summary: Niobium-lead alloy tunnel junctions have been fabricated using a new reactive ion beam oxidation technique and an edge geometry. Critical current densities exceeding 10/sup 8/ amp/cm/sup 2/, areas as small as a few times 10/sup -10/ca/sup 2/, and excellent I-V characteristics have been achieved. The fabrication and behavior of such devices is described.         Semimetal-barrier quasi-planar Josephson junction    H. Ohta Summary: Niobium-based bismuth-barrier Josephson junctions have been made whose geometrical structure is almost planar. The amplitudes of their zero-voltage currents and microwave-induced constant-voltage current-steps are periodically modulated by applied microwave radiation. Voltage current curves of the junctions have similar energy gap structures to those of point contact Josephson junctions. The value of the parameter S, defined as the ratio of the differential resistance just above the gap to that just below the gap, is about 2.0. The junctions have a barrier length of less than 100 nm, a very low capacitance and a life of several months even at room temperature. A quasi-planar Josephson junction has been turned out a hybrid of other kinds of Josephson junctions.         Fabrication of NbN/Pb Josephson tunnel junctions with a novel integration method    S. Kosaka, F. Shinoki, S. Takada and H. Hayakawa Summary: We have developed a new integration method for Josephson tunnel junctions based on high Tc superconducting compound materials such as NbN. In this method, a sputtered ZnO film has been employed as a resist mask which can be used in high substrate temperatures during the film deposition. It has been found that fine patterns of the refractory superconducting film can be obtained by this method and the patterning processes have no interference with other integration processes. We have applied this method to patterning base electrode of NbN and formed high quality NbN-oxide-Pb Josephson tunnel junctions by using an rf plasma oxidation. The fabricated junctions have been found to have a relatively large gap ( /spl sim/ 4.0 mV ) and low current leak in the subgap region, and to be quite stable for thermal cyclings and storage. We have also fabricated quantum interference memory devices by integrating these junctions and the operation has been successfully demonstrated.         Superconductive tunneling into Nb/sub 3/Sn with barriers formed by RF oxidation    L. Houck and J. Nordman Summary: Thin film tunnel junctions were fabricated using rf oxidation of sputtered Nb/sub 3/Sn films and subsequent evaporation of Pb. Very little control of junction impedance could be obtained from variation of the rf voltage or the partial pressure of oxygen. Small Josephson currents and high leakage in the quasi-particle characteristics were observed. Using an approximate proximity effect density-of-states model it appears that a damaged surface layer causes a reduced energy gap with a value somewhat dependent on the oxidation process. Two types of characteristics were observed and can be explained by the existence of two metallic phases in some of the films.         Superconductivity of Ta-Zr films produced by co-sputtering    E. Spencer and J. Rowell Summary: Using the phase spread deposition technique, thin films of Ta/sub 1-x/Zr/sub x/have been prepared over a wide range of composition. We find a maximum superconducting transition temperature of 8 K, but only over a narrow range of deposition temperatures. Tunnel junctions form reliably at all Zr concentrations. X-ray analysis indicates that the bcc Ta phase extends to much higher Zr content than expected from the bulk phase diagram.         V/sub 3/Si-SiO/sub x/-Mo/sub 3/Re/sub 2/superconducting tunnel junctions    Y. Tarutani, K. Yamada and U. Kawabe Summary: The possibility of obtaining sandwich-type Josephson junctions that can be operated at temperatures higher than 10 K is examined. A high-T/sub c/superconductor which can be deposited at substrate temperatures below room temperature is found, and the tunnel junctions are fabricated, therewith. Tunnel junctions are made by using the high-T/sub c/superconductors V/sub 3/Si and Mo/sub 3/Re/sub 2/for the base electrode and counterelectrode, respectively. These films are prepared by a co-evaporation technique. Oxide-barrier formation is performed by oxidizing a Si thin film 2 to 3 nm thick which is deposited before exposing the V/sub 3/Si film surface to air. The superconducting onset temperature of the V/sub 3/Si thin film is 16 K. The Mo-Re thin film has a metastable A-15 type phase in the Re concentration range of 25 to 50 at.%. The T/sub c/of the Mo/sub 3/Re/sub 2/thin films deposited on the room temperature substrate is 10-11 K. However, the T/sub c/value decreases as the substrate temperature is lowered with a background gas pressure of about 10/sup -4/Pa. In fabricating the V/sub 3/Si-SiO/sub x/-Mo/sub 3/Re/sub 2/junctions, the Mo/sub 3/Re/sub 2/thin film is deposited with the substrate at lower than room temperature. Superconducting characteristics are observed in the current-voltage curve of the junction.         Magnetic energy storage    J. Rogers Summary: Magnetic energy storage has become the foundation for near time and longer range electric utility applications and for current induction in the plasma of fusion devices. The fusion program embraces low loss superconductor strand development with integration into cables capable of carrying 50 kA in pulsed mode at high fields. This evolvement has been paralleled with pulsed energy storage coil development and testing from tens of kJ at low fields to a 20 MJ prototype tokamak induction coil at 7.5 T. Energy transfer times have ranged from 0.7 ms to several seconds. Electric utility magnetic storage for prospective application is for diurnal load leveling with massive systems to store 10 GWh at 1.8 K in a dewar structure suported on bedrock underground. An immediate utility application is a 30 MJ system to be used to damp power oscillations on the Bonneville Power Administration electric transmission lines. An off-shoot of this last work is a new program for electric utility VAR control with the potential for use to suppress subsynchronous resonance. Pulsed magnetic energy storage is not a widely developed technology. Current work is done almost exclusively in Japan and the United States. This paper does not cover past work or completed studies but presents work in progress, work planned, and recently completed unusual work.         An evaluation of superconducting magnetic energy storage    B. Winer and J. Nicol Summary: A Superconducting Magnetic Energy Storage (SMES) system will accept and regenerate ac electrical energy very efficiently. It can therefore compete economically with alternative advanced storage technologies if (1) the unit's cost and efficiency are within the presently expected ranges; and (2) the unit is sized so as to perform the same task as the alternatives and no more. Present conceptual SMES designs are unlikely to meet the electric utilities' needs for reliability, maintainability and system protection; and the environmental impact of the magnetic field may be large. Consequently, the uncertainties associated with the costs of an acceptable SMES system are large. Their reduction should be the principal goal of future component and system research.         Superconductive energy storage for diurnal use by electric utilities    R. Boom Summary: A summary report of a five-year study of superconductive energy storage for electric utility systems is presented, Conceptual designs over that period have all been for one layer solenoids of aluminum-NbTi composite conductors cooled to 1.8 K in superfluid helium, The solenoids are mounted underground in bedrock in one or more tunnels. The two preferred designs in 1980 are: a 15 tunnel solenoid arranged in a circular pattern and a large radius single tunnel solenoid. The electrical energy storage efficiency in all cases is 95 to 96%.         A superconducting magnet for Stanford University    J. Parmer, G. Magnuson, R. Jones, W. Taylor, S. Peck and J. Waszczak Summary: The Department of Energy is currenty developing three MHD magnet concepts for application to baseload coal power generation technology. One concept is a rectangular saddle magnet having nonmetallic substructure for conductor support. This magnet is to be installed at DoE'S Component Development & Integration Facility at Fhtte, Montana, Another is a circular saddle magnet in which the radial Lorentz forces are contained by interlayer bands which take the place of a superstructure. This technique was used for the U-25 magnet currently in operation in Moscow. A larger version is being developed for the Coal-Fired Flow Facility (CFFF) at the University of Tennessee Space Institute. The third concept is the Stanford Superconducting Magnet (SSM), a circular saddle magnet having a metallic substructure to support the conductors. It will be a part of the MHD research facility at Stanford University. The specific metallic substructure described in this paper was designed in 1979. This design is being modified during 1980 to incorporate features of the CASK concept into the substructure design. The producibility features of CASK are prototypical of baseload-size magnets, The revised design will be reported in a forthcoming paper. Two major advantages of using a substructure to support the conductors are (1) conductor movement within the winding is controlled which, in turn, limits frictional heating of the conductor, and (2) the substructure reacts a substantid portion of the magnetically induced loads. Energy dissipation and voltage protection in metallic subplates is discussed. An analysis of the eddy current in the,substructure during a rapid quench has shown that the dissipation is only 2.5% of the total 93 MJ stored in the winding. Quench voltages have required the use of coil-to-subplate shorting resistors within the winding to reduce subplate stray capacitance effects and to limit ground fault currents. One unexpected benefit of eddy current has been discovered. During seismic event or MHD channel-induced vibration of the winding, eddy currents induced in the vacuum vessel provide substantial damping for the control of resonant amplitude, The damping magnitude is360 J/cycle for a Stanford-sized magnet.         The design of a tapered bore superconducting MHD magnet system    Z. Stekly, R. Pillsbury, W. Punchard and S. Mushnick Summary: This paper presents the design and system characteristics of a superconducting MHD magnet system presently being fabricated at the Magnetic Corporation of America for the United States Air Force Aero-Propulsion Laboratory at Wright-Patterson Air Force Base. The magnet is designed to produce a magnetic field on axis that tapers from 4 T to 2.75 T over an active field length of 1.04 m. The warm bore has a minimum ID of .29 m at the inlet and .53 m at the outlet. The magnet windings, structure, and helium vessel are 1.77 m long and have a maximum diameter of 1.22 m. This cold mass will weigh approximately 2,727 kg (6,000 pounds). The room temperature vessel is 2.62 m long, has a 1.7 m outside diameter, and will weigh 818 kg (1,800 pounds). A 24-strand Rutherford cable with both a Kapton and B-stage epoxy/glass wrap is wound onto a cold bore tube in the shape of an annular saddle with arched end turns. The windings are separated by internal structure used to transmit the Lorentz body forces to the external or superstructure.         ETF magnet design alternatives for the national MHD program    P. Marston, R. Thome, A. Dawson, E. Bobrov and A. Hatch Summary: The national MHD program of the U.S. Department of Energy will require an Engineering Test Facility as the next significant step following operation of the Montana Component Development and Integration Facility. Toward that end the MHD Magnet Technology group at FBNML is evaluating five superconducting magnet design concepts. The facility rated at 200 MWe, will require a magnet with an on-axis field of 6T, an inlet bore area of /spl sim/2m/sup 2/and an outlet bore area of /spl sim/4m/sup 2/. The magnet will store /spl sim/6 /spl times/ 10/sup 9/. The designs under evaluation include a straightforward rectangular saddle coil set which is a scale-up of the CDIF magnet, a circular saddle design which is a scale-up of the Coal Fired Flow Facility magnet, a "Cask" design using staves and corper blocks as the principal support structure, an advanced design using internally-cooled, cabled superconductor to minimize substructure and eliminate the need for a helium vessel and, finally, a modular design that involves six coils with individual helium vessels and an integrated structure. Each of these designs is being considered in terms of operating characteristics, fabricability, transportability and cost. The characteristics of each design will be described and relative advantages summarized.         Conductor qualification tests for the 30-MJ Bonneville Power Administration SMES coil    R. Schermer, H. Boenig, M. Henke, R. Turner and R. Schramm Summary: The 30-MJ energy storage coil for the Bonneville Power Administration requires a low-loss, cryostable conductor that is able to carry 4.9 kA in a field of 2.8 T and will maintain its properties over 10/sup 8/partial discharge cycles. The multi-level cable which satisfies these requirements has been extensively tested at various stages in its development and in its final form. Tests have been performed to determine the effect of manufacturing options on ac losses, low temperature electrical resistivity, stability, and fatigue resistance of the insulated conductor. This paper will concentrate on the stability and fatigue tests which have not previously been reported.         Characterization of Nb/sub 3/Sn diffusion layer material    J. Evetts, J. Cave, R. Somekh, J. Stanton and A. Campbell Summary: An analysis is given of the fundamental limitations of different techniques for characterizing the superconducting properties of A15 compound layers prepared by solid state diffusion From a bronze matrix. Theoretical and experimental results are presented for inductive measuremenns of the local variation of the critical temperature, T/sub c/, together with preliminary specific heat measurements. Finally a discussion is given of the problem of making similar measurements for the critical current, J/sub c/, and upper critical field, B/sub c2/.         The effect of strain on the martensitic phase transition in superconducting Nb/sub 3/Sn    R. Hoard, R. Scanlan, G. Smith and C. Farrell Summary: The connection between the cubic-to-tetragonal martensitic phase transformation and the phenomenon of superconductivity in A15 compounds is being investigated. The degradation of the critical parameters, such as T/sub c/, H/sub c2/, and J/sub c/, with mechanical straining is of particular interest. Since martensitic transitions are also known to be strain sensitive, perhaps the structural change is directly responsible for the reduction in superconducting properties. We performed low-temperature x-ray diffraction experiments on Nb/sub 3/Sn ribbons (with the bronze layers etched off) mounted on copper and indium sample stages. The cryostat we used is unique in that it has a vacuum mechanical insert which allows the superconductor to be placed under both compressive and tensile strains while at low temperatures. Preliminary results indicate that the martensitic phase transition temperature, T/sub m/, increases with compressive strains. Other effects of strain on tetragonal phase production are also discussed.         The role of disorder in maximizing the upper critical field in the Nb-Sn system    T. Orlando, J. Alexander, S. Bending, J. Kwo, S. Poon, R. Hammond, M. Beasley, E. McNiff Jr. and S. Foner Summary: We have measured the transition temperature T/sub c/, upper critical field H/sub c2/(T) and the resistivity above T/sub c/, /spl rho/T/sub c/, for thin films of electron beam co-evaporated Nb-Sn which were deposited as Nb/sub 3/Sn at various substrate temperatures, or off-stoichiometry, or with tertiary additions of Al or Zr. The T/sub c/and H/sub c2/correlate with the resistivity, no matter how the materials were made. A maximum H/sub c2/(0) of about 300 kOe occurs when /spl rho/T/sub c//spl sim/ 30 /spl mu//spl Omega/-cm and the corresponding T/sub c//spl sim/ 16 K; also H/sub c2/shows no sign of Pauli limiting.         Upper critical field in multifilamentary Nb/sub 3/Sn conductors    G. Rupp, E. McNiff and S. Foner Summary: The critical current of bronze processed multifilamentary Nb/sub 3/Sn conductors was measured at 4.2 K up to 23 T. The flux pinning theory of Kramer does not fit the results at flux densities higher than about 18 T. The critical field B*/sub c2/extrapolated from data below 18 T is smaller than the field B/sub c2/at which superconductivity is completely suppressed. From independent measurements of the temperature dependence of B/sub c2/on the same samples (using very small current) B/sub c2/at 4.2 K can be calculated by applying the GLAG theory. A nonvanishing resistivity at fields close to B/sub c2/is evidence of inhomogeneities which considerably broaden the transition.         Improvement of Nb/sub 3/Sn high field critical current by a two-stage reaction    W. Schauer and W. Schelb Summary: The grain structure of a commercial multifilamentary Nb/sub 3/Sn wire has been investigated as a function of reaction temperature, T/sub R/, and time, t/sub R/. Results allow a quantitative description of grain growth. Based on the dependence of critical current, Nb/sub 3/Sn area and grain size on the heat treatment conditions a two-stage reaction process is proposed to improve the critical current carrying capacity in magnetic fields greater than 10 Tesla. The first reaction converts the major part of the Nb to fine grained Nb/sub 3/Sn at low T/sub R/. Subsequent high temperature (T/sub R/ /spl simeq/800/spl deg/C) heat treatment for a short time (t/sub R//spl leq/1 h) increases both T/sub c/and B/sub c2/due to composition approaching stoichiometry (or a higher degree of order) without detrimental grain growth. First experimental results show a remarkable improvement in the high field critical current for this two stage-reaction process.         Properties of microfilamentary superconducting composites produced by a modified external diffusion method    J. Klein, S. Cogan, G. Warshaw, N. Dudziak and R. Rose Summary: Nb/sub 3/Sn-based bronze matrix superconducting composites have been produced with micron-sized and submicronsized superconducting fibres by the external diffusion process, with precautions taken as recently recommended to suppress Kirkendall porosity. Such composites were found to carry overall critical current densities at 4.2/spl deg/ K in excess of 2x10/sup 4/a/cm/sup 2/at 15.4 T and over 10/sup 5/a/cm/sup 2/at 12 T; strains ca. 2% and stresses in the 500-1000 MPa range were sustained without degradation. It is seen that the finer fibres sustain higher intrinsic strains before degradation of J/sub c/; and a method is demonstrated for the control of internal residual stresses by thermomechanical processing. The latter permits appropriate trade offs of fatigue life and zero-strain J/sub c/.         On the suppression of Kirkendall porosity in multifilamentary superconducting composites    J. Klein, G. Warshaw, N. Dudziak, S. Cogan and R. Rose Summary: The effect of hydrostatic pressure during reaction heat treatment on Kirkendall porosity in Nb/sub 3/Sn multifilamentary composites is examined. Above a critical pressure which is a function of wire size, void formation is suppressed, and at higher pressures voids already present may be healed. The critical pressure is relatively low, 300-500 psi for 0.010" wire, for external diffusion.         Studies on the composite processed Nb-Hf/Cu-Sn-Ga high-field superconductors    H. Sekine, T. Takeuchi and K. Tachikawa Summary: The effect of hafnium addition to the niobium core, and that of gallium addition to the matrix, on the superconducting properties of the composite processed Nb/sub 3/Sn have been studied. The stress effects on the Nb-Hf/Cu-Sn-Ga composites, and the effects of external diffusion of gallium into the Nb-Hf/Cu-Sn composites have been also studied. The composites consisting of pure niobium, Nb-2Hf and Nb-5Hf cores, and Cu-7Sn, Cu- 5Sn-4Ga and Cu-3Sn-9Ga matrices were fabricated into single-core tapes and 19-core wires. The growth rate of the Nb/sub 3/Sn layer is greatly increased by the hafnium addition to the core. The hafnium addition to the core as well as the gallium addition to the matrix increases T/sub c/by 0.4-0.5 K and H/sub c2/(4.2k) by 2.0-4.0 T. The simultaneous addition of hafnium to the core and gallium to the matrix increases T/sub c/by 0.6-0.9 K and H/sub c2/(4.2K) by 6.0- 7.0 T. J/sub c/'s of over 1x10/sup 5/A/cm/sup 2/were obtained at 18 T for the 19-core Nb-5Hf/Cu-5Sn-4Ga and Nb-5Hf/Cu-3Sn-9Ga wires reacted at 700/spl deg/-750/spl deg/C for 50-100 hr. The Nb-5Hf/ Cu-5Sn-4Ga composites showed appreciably improved strain dependence of I/sub c/compared with the Nb/Cu-7Sn composites. Eirr, the strain where the irreversible degradation occurs in I/sub c/, is increased by the addition of hafnium to the core and gallium to the matrix. The Eirr increases with the volume fraction of the unreacted niobium core. The external diffusion of gallium into the Nb-Hf/Cu-Sn composites enhances the Nb/sub 3/Sn layer growth and improves the J/sub c/of Nb/sub 3/Sn. The most appropriate amount of external gallium addition is about 5 at.%.         DC SQUIDs 1980: The state of the art    M. Ketchen Summary: The four primary areas of concern in the development of high performance dc SQUIDs are white noise, 1/f noise, readout schemes, and coupling. For an optimized dc SQUID the intrinsic energy sensitivity in the white noise region is given by /spl epsiv//sub w/=/spl gamma//sub 1/hk/sub B/T(eI/sub 0/R)/sup -1/+/spl gamma//sub 2/h, where I/sub o/is the critical current per junction and R is the shunt resistance per junction. /spl gamma//sub 1/, which multiplies the thermal noise contribution, and /spl gamma//sub 2/, which multiplies the shot noise/zero point fluctuation contribution, are numerical factors of order unity. Values of /spl epsiv//sub w/approaching h have recently been measured for several members of a new generation of low noise dc SQUIDs. The intrinsic energy sensitivity in the 1/f noise region, /spl epsiv//sub f/, is predicted to scale as (I/sub 0/R)/sup 2/for tunnel junctions. This may impose significant low frequency limitations on SQUIDs with very low values of /spl gamma//sub w/. Readout schemes for high sensitivity dc SQUIDs will require further development. At the moment primarily small signal amplifier readout schemes are being used to evaluate the new generation of low noise SQUIDs. Planar thin-film coupling schemes are about to have a big impact on dc SQUID design. Such schemes can achieve tight coupling between SQUID and input coil. and can be implemented using the same fabrication techniques that produce SQUIDs with low values of /spl epsiv//sub w/.         Ultra low noise Nb DC SQUIDs    R. Voss, R. Laibowitz, A. Broers, S. Raider, C. Knoedler and J. Viggiano Summary: Electron-beam lithography has been used to produce ultra low noise Nb dc SQUIDs (Superconducting QUantum Interference Devices) with Josephson elements consisting of either small area tunnel junctions or very narrow variable thickness bridges (nanobridges). Detailed voltage noise and transfer function measurements have been made as a function of temperature and flux and current bias. These measurements allow a computation of the intrinsic energy resolution /spl epsiv/ vs bias parameters as well as comparison with models of intrinsic SQUID noise. The best /spl epsiv/ obtained was of order Planck's constant h. Moreover, the detailed characteristics of the SQUID voltage noise are in agreement with a small signal analysis that depends only on the current noise in each of the Josephson elements and measurable parameters.         Planar coupling scheme for ultra low noise DC SQUIDs    J. Jaycox and M. Ketchen Summary: We have devised and tested a planar coupling scheme in which the technology used to produce ultra low noise tunnel junction dc SQUIDs is employed to achieve tight coupling between the SQUID loop and and the input coil. In our scheme the planar, ungroundplaned, inductive loop of the dc SQUID acts as the wide single turn primary of a thin-film transformer. The input coil consists of a multiple-turn secondary in the form of a spiral stripline fabricated directly above the primary. The two tunnel junctions are located at the outside edge of the SQUID loop. A low inductance stripline structure connects the junctions to the region of high current flow in the SQUID loop. We have evaluated this coupling scheme experimentally in SQUIDs with 10-turn, 19-turn, 50-turn, and 100-turn input coils. All have mutual inductances per turn of approximately 80 pH, in good agreement with numerical calculations. Detailed measurements on the 50-turn SQUID gave a mutual inductance M of 3.8 nH, an input coil inductance L/sub i/of 190 nH, a SQUID self inductance of L of 89 pH, and a coupling constant k/sup 2/= M/sup 2//L/sub i/L of 0.86. The 100- turn version is estimated to have similar coupling performance with an input coil inductance of approximately 0.8 /spl mu/H.         Toroidal DC SQUIDs with point-contact junctions    H. Paik, R. Mathews and M. Castellano Summary: The well-developed technique of a toroidal point-contact rf SQUID has been extended to a dc SQUID. Two point-contacts are made on the symmetry axis of the toroid. A large Nb cavity containing a signal coil is connected to the junctions via a narrow gap. Such geometry allows good coupling of the SQUID to a high-inductance signal coil without increasing the effective SQUID inductance at the Josephson frequency. It is expected that both the shot-noise-limit performance and a high signal coupling will be achieved in this SQUID. We discuss the status of design and the result of preliminary test of the device.         Noise properties of thin film granular weak link SQUIDs    E. Cukauskas and M. Nisenoff Summary: A study of the magnetic flux noise in thin film NbN SQUIDS with variable thickness weak links has been initiated using the fractional step rise parameter, a , to characterize the noise. A series of devices have been fabricated and measured which exhibit Kurkijarvi magnetic flux noise, each over a restricted temperature range below their T . The T ' s for the devices ranged from below 5K to as (high as 15.7K. The variable thickness weak links are nominally 1 micrometer in length, between 50 microaeters to submicrometer in width and less than 10 MI. in thickness. For these thicknesses, the weak link region is granular ("inhomogeneous") in nature and the temperature dependence of the critical current obeys either the Josephson or the mean field theories depending on the strength of the intergranular coupling. The deduced magnetic flux noise obeys Kurki-jarvi theory for critical current values greater than 2@ /L but lessthanapproximately 61p /L for most deGices tested. The dependence of the 'measured magnetic flux noise on the degree of granularity of the weak link and the temperature dependence of the critical current is discussed.         Parametric properties of SQUID lattice arrays    A. Silver, D. Pridmore-Brown, R. Sandell and J. Hurrell Summary: Josephson junctions incorporated into microcircuit SQUIDs have many uses including digital logic and memory, parametric amplification, signal generation, and analog to digital conversion. Combining SQUIDs into coherent arrays can preserve these functions and add great flexibility in selecting power and impedance. We have investigated such general properties of the SQUID lattice array as the mode structure, dispersion relations, and stability. In particular, one unique antisymmetric mode is shown to precisely reproduce the performance of a single rf SQUID, with increased power and impedance. The application of this mode to parametric amplification has been demonstrated analytically and numerically, projecting a useful low noise amplifier with a gain of 10dB at 16% bandwidth.         Development and testing of high field, high current density solenoids and magnets, wound with stabilized filamentary Nb/sub 3/-Sn cable and reacted after winding    A. Asner, Ch. Becquet, D. Hagedorn, Ch. Niqueletto and W. Thomi Summary: First, the successful development and testing of a 2.6 cm inner diameter, high field and high current density solenoid, wound with a Cu-stabilized, fine filamentary Nb/sub 3/-Sn cable, and reacted after winding, is described. At an overall current density in the winding of 352 A/mm/sup 2/ corresponding to a current density of 565 A/mm/sup 2/in the non-insulated cable, a maximum field of B/sub m/= 8.8 T had been obtained without any training. Based on this very positive result, a 0.9 m-long, 10 cm-warm bore, beam line quadrupole magnet, wound with the same cable, is actually being assembled. The nominal parameters are : field gradient 74 T/m, maximum field in the winding B/sub m/= 7.4 T at an overall current density in the winding of 300 A/mm/sup 2. The very specific technological and design aspects of this magnet, related to the "wind and react" technique, such as the conductor insulation, coil winding technique, execution of connections etc, will be discussed. Actually, the four coils for the quadrupole magnet have been manufactured and the assembly of the magnet started. We expect to perform the first tests early next year.         Room temperature harmonic analysis of superconducting energy saver quadrupoles    H. Fisk, R. Peters and R. Raja Summary: The multipole structure of Fermilab Energy Saver quadrupoles is obtained from low current, room temperature measurements using a rotational Morgan coil and lock-in amplifier. Multipole data are presented for the first forty Tevatron quadrupoles.         The effects of potting on training and quench propagation in a large stored energy superconducting dipole coil    B. Cox, P. Garbincius, J. Guerra, P. Mazur, J. Satti and E. Tilles Summary: A superconducting racetrack dipole coil was constructed to compare directly training and quench behavior in potted and non-potted coils. The stored energy of this coil was 175 KJoules at the conductor's short sample limit of 238 Amp with a peak field in the coil of 7.6 Tesla. The outward magnetic forces were restrained by rows of tie rods between side plates. Comparisons of training behavior were made for both steel and aluminum tie rods. Helium flow was provided by channels in the fiberglass cable tape allowing one-quarter of the conductor surface direct access to the helium supply. After training the coil to 90% of short sample limit, the tie rods were relaxed and the entire coil was vacuum impregnated with a standard clear magnet epoxy. After potting, the previous tie rod preloads were re-established. This resulted in a shallower training curve, and required retraining after thermal cycling. The unpotted coil showed no evidence of internal quench propagation below 80% of short sample, whereas the potted coil exhibited good quench propagation and energy dissipation at all currents, simplifying protection strategies.         Nb/sub 3/Sn dipole magnet by wind and react process    K. Ishibashi, M. Koizumi, K. Hosoyama, M. Kobayashi and T. Horigami Summary: An attempt was made to fabricate a Nb/sub 3/Sn dipole magnet by adopting "wind and react process" where nonreacted Nb/sub 3/Sn conductors were heat-treated after wound into coils. The fabricated magnet showed a performance of 88% of its critical current. Detailed fabrication techniques and experiences obtained from this attempt are reported. The effect of bending of nonreacted Nb/sub 3/Sn conductor on critical current is also described.         Quench behavior of a superconducting accelerator magnet    A. McInturff, W. Sampson, M. Garber and P. Dahl Summary: Data are presented on the minimum energy required to cause quenches to propagate in an accelerator dipole magnet. The amount of stored energy dissipated into the magnet was measured as a function of dipole excitation current. This in turn determines the maximum coil temperature reached in a given magnet. Quench velocities in the longitudinal direction of the conductor were as high as 11m/sec. The azimuthal velocities or turn to turn velocities were found to be a function of the number of fiberglass layers of insulation that the quench had to cross and were on the order of a few tens of centimeters/sec. The field shape of a given magnet was found to be unchanged for more than 100 quenches. The coil to coil connection and inter-coil splice resistances were found to be less than a nano-ohm and therefore of little consequence in the cryogenic load considerations. No definitive answers were found on how to decrease the rate of training (130 Gauss/Quench average) required from 4.0T to 5.1T.         Protection for low current superconducting coils wound with insulated strand cable    J. Satti Summary: The insulated strand cable concept for winding of low current superconducting coil leads to an ideal quench protection by induction coupling. A superconducting secondary loop was made within a cable of an 6.2 Henry dipole coil. When quenching occurred, current was induced in the secondary strand above the critical value. The normal strand quenched the whole cable due to good thermal contact. The secondary loop works as a heater turned on as the wire becomes normal throughout the coil. With a well spread quench, the energy dissipation density is decreased thus preventing local burnout. The mechanism is possible because of close coupling that is present in the insulated cable as in bifilar wLndind. For the coil tested a 12 strand cable was used, thus a favorable 11 to 1 turn ratio was obtained for the primary to secondary. The superconductor in the secondary had a lower resistance until the critical current was achieved. A theoretical explanation is described for a simplified circuit. Test on the dipole coil with four individual shells showed that the one shell protected with the induced coupling heater always had a more rapid reduction of current.         Quench detector for large pulsed coils and quench analysis for the LASL/Westinghouse 20 MJ coil    M. Hennessy, A. Heintz and P. Eckels Summary: A unique detection scheme has been devised for possible use in the test of the 20 MJ Induction Heating Coil. This scheme allows the sensing of plus or minus voltages less than 320 millivolts resistive in magnitude in coils which will have inductive voltage components as high as /spl plusmn/2.5 kVolts. The network which achieves this sensitivity is stable to less than 12.8 ppm. The method adopted involves the bucking out of the inductive voltage with two secondary co-wound flux sensing coils tapped at locations adjacent to voltage taps in the main superconducting coil. The detection scheme is recommended especially if large ripple or control voltages exist subsequent to the coil pulse. The most severe credible event which might quench the coil and/or damage the winding is exposure of the operating coil to gaseous cooling through lack of proper liquid level control. The detection scheme described will protect the coil against this and other abnormal conditions that could conceivably damage the coil.         Mechanical and helium cooling factors in dipole magnet training    S. Caspi, W. Gilbert, W. Hassenzahl, G. Lambertson, R. Meuser, J. Rechen, R. Schafer and R. Warren Summary: An investigation of the roles of prestress, friction and cooling in the alleviation of the problem of training in superconducting dipole magnets is undertaken. An analysis of the Lorentz force and its influence on variously pre-stressed coils is presented. Mechanical tests have been made on typical coil materials. Material characteristics are used in the calculation of the coil pre-stress level attained in several magnets. The training behavior of these magnets is shown to depend on the coil pre-stress level attained, although the prediction is more pessimistic than the actual performance. Finally, the strongly beneficial influence of enhanced heat removal in superfuid helium-II is demonstrated.         Direct optimization of the winding process for superconducting solenoid magnets (linear programming approach)    E. Bobrov and J. Williams Summary: In order to reduce conductor motion during the charging of anadiabatically stable superconducting magnet, tension is applied to the conductor during the winding process. However, excessive winding tension may cause circumferential compression sufficient to buckle the innermost conductor layers. This can be minimized by a method of winding optimization based on linear programming. Such a method is discussed in this paper. It eliminates excessive circumferential compressive stresses in the innermost conductors of a solenoid magnet, at the same time keeping the cumulative radial and circumferential stresses in the winding within acceptable limits.         Reclosing on superconducting systems    G. Donaldson Summary: A comparison is drawn between the existing practice of reclosing following fault conditions on electric power transmission lines and proposed reclosing on superconducting systems. It has been found that on power lines there is a high probability of any particular fault being of a transient nature. A reclosure attempt is likely to be successful and the operation of the system suffers little disturbance. The conditions for applying reclosing principles to large superconducting systems are discussed. Tests in which reclosing is attempted on a small superconducting coil are described.         Observation on the elimination of explicit quenching in a superconducting magnet by a controlled external local shunt    C. Li, J. Xu, K. Xion and D. Yin Summary: An advancing quenching zone with normal conductor length about 10M in a superconducting magnet can be eliminated by a controlled external local shunt. This effect was observed in a 6CM bore diameter NbTi magnet with over all current density 10/sup 4//CM/sup 2/and a copper-to-superconductor ratio 2. A general qualitative analysis is given.         A computer circuit analysis investigation into stray subplate capacitance effects during the discharge of an MHD magnet    G. Magnuson and E. Woods Summary: A computer model has been constructed to evaluate the contribution of stray subplate capacitance to the generation of overvoltage transients to the anticipated value of the emergency discharge voltage levels. The model includes voltage tap location and effects of adding resistors between the subplate and the magnet conductor. Order-of-magnitude approximations were used to obtain values for capacitances, resistances, and inductances. The first two subplates of fifteen were modeled, together with the circuit breaker, dump resistor, and power supply. The model consisted of 26 resistive elements, 19 inductive elements, and 22 capacitance elements. Results show no overvoltage transients were generated during discharge. In addition, there were no local channel bundle overvoltages, although the bundle did generate damped oscillations at approximately 500 kHz, for approximately 20 microseconds. The addition of a current-limiting resistor between each subplate (ground) and the magnet conductor, has beneficial effects on oscillations observed in the channel bundles and across the voltage taps, in that oscillation damping is increased with the resistor added.         Considerations of a large force balanced magnetic energy storage system    Y. Eyssa and R. Boom Summary: We show in this paper that any generalized toroid-dipole force balancing system will require a minimum unidirectionally stressed structure equal to the minimum amount required by the virial theorem. The analytical proof is general and independent of configuration, current distribution, and the fraction of energy stored in the poloidal and toroidal fields.         Safety of superconducting magnets for fusion: Thermal analysis of large cryostable magnets    L. Turner Summary: A thermal analysis program has been developed to study the response of a cryostable fusion magnet to abnormal conditions such as a localized heat input, overcurrent, or uncooled length of conductor. It performs a heat balance on each element. Variation of parameters with temperature, pressure, and magnetic field are incorporated. The program has been applied to a conductor with magnetic field variation along its length, carrying a high current as might occur in one toroidal field toil when a neighboring coil discharges rapidly. It is found that a stable normal region can develop, with possibly serious consequences.         Experimental test and evaluation of the Nb/sub 3/Sn joint and header region for the westinghouse LCP coil    R. Blaugher, M. Janocko, P. Eckels, A. Patterson, J. Buttyan and E. Shestak Summary: The Westinghouse LCP coil utilizes a supercritical helium forced-flow Nb/sub 3/Sn cable enclosed in a stainless steel sheath. The helium flow to the conductor is supplied by a header system mounted on the top surface of the magnet. Each header also encloses the electrical joint between two lengths of cable. The superconducting stability of the joint area is essential under all current and field operating conditions. Experimental and analytical evaluation of the joint, header, and adjacent conductor has been performed to verify the helium flow distribution, pressure drop, and conductor and joint stability. This paper reviews the header and joint design and observed performance under forced-flow cooling and field conditions similar to those for the actual coil operation. The results showed a much higher than expected joint resistance which exceeded the design specification by an order of magnitude. Nevertheless, the joint and adjacent superconductor remained stable (at /spl sim/13.5 kA) at a mass flow rate of /spl sim/ 1.0 gm/sec which is one-half of the design inlet condition. These results and the required flow rates are discussed in terms of a forced cooled minimum propagating zone (MPZ). The observed hydraulic performance for the header region basically followed earlier flow measurements on forced cooled cables.         Variations in the characteristics of the superconducting wire used for the ISR superconducting high-luminosity insertion    J. Billan, J. Rinn and R. Wolf Summary: A total of 30.000 meters of NbTi solid multifilamentary superconductor, l/sub c/ /spl sim/ 2500 A at 6 T, was tested. For each stretch of wire received, measurements were made to check if the wire met the specifications. The specification and the measuring set-up are described. Systematic measurements of the critical currents, Cu : SC ratio, Ti content and wire size are discussed. A strong variation in the critical current could be correlated to a strong variation in the Ti content.         Techniques for quality assurance, critical-current and stability measurements for CDIF conductor    J. Maguire, R. Thome and Y. Iwasa Summary: This paper described methods developed to produce quality control measurements for conductor being procured for the CDIF superconducting magnet. The CDIF magnet, under construction by General Electric Company, will be upon its completion, installed at the Department of Energy's MHD Component Development and Intergration Facility (CDIF) at Butte, Montana.         An alternative winding technique for the production of A15 magnets    K.-J. Best and B. Rothe Summary: A new winding technique is proposed for the production of magnets from A15 filamentary wire. It is characterized by the application of ceramics as filling material during the winding process. Thus disturbing carbon bridges between neighboured turns or adjacent layers can easily be avoided. Furthermore after the turns are fixed they keep their positions during the reaction heat treatment and with the magnet in operation. First results are reported from a small laboratory coil which in the meantime did run for appr. 300 working hrs. without any disturbing event.         Evaluation of a cryostable low-loss conductor for pulsed field applications    J. Wollan, M. Walker, B. Zeitlin, D. Pollock and S. Shen Summary: A cryostable, low loss conductor as the basic strand in a 50 kA cable for a 20 MJ prototype, tokamak induction heating coil has been developed, fabricated, and evaluated. The conductor has a copper matrix multifilamentary NbTi core surrounded by a CuNi ring and stabilizing copper segmented by radial CuNi fins. Pulsed loss measurements have been made up to 2.2 T and for decay times from 0.7 to 278 ms. Measurements made on samples with various twists and portions etched away have allowed accurate evaluation of the loss components. Stability measurements were also made on insulated and uninsulated single strands and on sub-cables. Measured recovery heat flux for the bare strand is about 0.3 W/cm/sup 2/; however, the application of a 0.0005 in. layer of Omega insulation increases the value to about 0.5 W/cm/sup 2/.         LCP heater thermal performance test results and unique test techniques    R. Bailey and E. Christensen Summary: The Large Coil Program (LCP) magnet requires integral heaters capable of normalizing conductor half-turns to simulate energy deposition. During a series of tests to determine the cryogenic thermal performance of our LCP conductor, we evaluated the relative thermal performance of two prototype heater installation methods which were tested using a unique heater power control circuit. The prototype heaters were installed in two LCP conductors which were part of a 15-conductor test array used during the conductor thermal performance testing. Results are given comparing the thermal performance of the two heaters, one installed with indium foil and the other "soldered" with Woods metal. The performance of the Woods metal installation agreed closely to the finite element model predicted conductor thermal response to fast, high-power heater pulses, both in maximum temperature rise and time characteristics of the rise and recovery. The sluggish thermal response of the conductor with the cold-welded indium ribbon-secured heater demonstrated that intimate thermal coupling of the heater elements to the conductor is mandatory. The heater control circuitry is described which was developed in support of this test and provided transient heater power durations down to 5 msec and at power inputs up to 3000 watts. A brief description also is given of the transient and steady-state data acquisition systems used as well as the interface between the heater control circuitry and the remote computer used to control the transient testing.         The superconductor test facility sultan    J. Elen, W. Franken, I. Horvath, G. Pasotti, M. Ricci, J. Roeterdink, N. Sacchetti, M. Spadoni, C. Spoorenberg, G. Vecsey and P. Weymuth Summary: Independent of the different tokamak scenario's (ETF, TNS, INTOR, etc.) the common need in the mid eighties for reliable operation of large scale high-field (10-12 10-12 T) superconducting magnets can clearly be identified. For the development of large scale conductor and for the evaluation of design criteria a collaboration between CNEN, Italy, ECN, The Netherlands and SIN, Switzerland has been established with the main objective to construct a large European test facility, called SULTAN. The construction of the facility will be realized in two phases. Description of the design for the first phase with an eight Tesla background field of one meter bore is given. Experimental feasibilities, including cooling flexibility, instrumentation and power supplies are shortly reviewed. Progress of components and facility construction is described. The second phase extension to higher field application is outlined.         Construction and operation of the cluster test facility    S. Shimamoto, T. Ando, T. Hiyama, H. Tsuji, E. Tada, M. Nishi, K. Yoshida, K. Okuno, K. Koizumi, Y. Takahashi, T. Kato, K. Oka, Y. Ibaraki, Y. Sanada and K. Yasukochi Summary: The 20MJ superconducting cluster test facility, which has been under construction for the last two years at Japan Atomic Energy Research Institute (JAERI), was successfully operated in August 1980. Operating design values were achieved without any premature quenching. The fabrication and operation of the facility was the first experience with a superconducting toroidal coil in Japan. The succesful operation of the facility system makes it possible to test a 10T Nb/sub 3/Sn magnet as a Test Module Coil which will be placed in the facility next year. This paper outlines briefly the facility system and describes mainly thermal results and stress results.         The MHD component test facility at the Francis Bitter National Magnet Laboratory    Y. Iwasa, R. Thome, M. Leupold, J. Maguire, A. Montgomery, M. Olmstead, A. Rabasco, M. Sinclair, D. Sliski and J. Thompson Summary: This paper describes the MHD Component Test Facility at the Francis Bitter National Magnet Laboratory and the first set of experiements scheduled in the Facility.         Development of a Pulsed Cable Test Facility for superconducting ohmic heating coils    S. Kim, R. Smith, R. Kustom, W. Praeg and C. Krieger Summary: This paper describes a Pulsed Cable Test Facility (PCTF) under development at Argonne National Laboratory (ANL). Its essential part is a pulsed superconducting split coil. The inner and outer diameters of the coil will be 45.1 cm and 88.3 cm, respectively, with an adjustable gap between the two halves of the coil. At a peak current of 11 kA, the coil will store an energy of 3.5 MJ and produce a magnetic field of 6.4 T. Using a 7MW pulsed (2.9 MW rms) power supply, the PCTF coil will produce field change of 6 T/s. With the addition of a solid state switch to the system, dB/dt values of up to 24 T/s can be obtained. Pancake coils, wound with developmental cables, will be placed in the adjustable gap of the PCTF coil and be tested at up to 50 kA furnished by a separate power supply. The PCTF cryogenic facilities include a non-metallic cryostat and a helium liquefier.         0.5 MJ superconducting pulse magnet for energy storage    Y. Murakami, T. Okada, J. Yamamoto, Y. Inuishi, A. Mitsuishi and M. Nishimura Summary: Laboratory for Applied Superconductivity was started in FY 1980 in Osaka University. The main objectives of laboratory are to develop the basics of the technology of superconducting magnet; superconducting material, control system, and energy application of superconducting magnet such as energy storage. The system of pulsed superconducting coil is the main facility of the laboratory. The specifications of the magnet are; I.D.: 30 cm, O.D.: 49 cm, Height: 25.5 cm, Stored energy: 515 KJ, Central field: 5T, dB/dt: 5 /spl sim/ 7 T/s.         Background field coils for the high field test facility    J. Zbasnik, D. Cornish, R. Scanlan, A. Jewell, R. Leber, A. Rosdahl and M. Chaplin Summary: The High Field Test Facility (HFTF), presently under construction at LLNL, is a set of superconducting coils that will be used to test 1-m-o.d. coils of prototype conductors for fusion magnets in fields up to 12 T. The facility consists of two concentric sets of coils; the outer set is a stack of Nb-Ti solenoids, and the inner set is a pair of solenoids made of cryogenically-stabilized, multifilamentary Nb/sub 3/Sn superconductor, developed for use in mirror-fusion magnets. The HFTF system is designed to be parted along the midplane to allow high-field conductors, under development for Tokamak fusion machines, to be inserted and tested. The background field coils were wound pancake-fashion, with cold-welded joints at both the inner and outer diameters. Turn-to-turn insulation was fabricated at LLNL from epoxy-fiberglass strip. The coils were assembled and tested in our 2-m-diam cryostat to verify their operation.         Construction of a model magnet for shielded pulsed energy storage    T. Shintomi, M. Masuda, Y. Eyssa and R. Boom Summary: The first model magnet system of the shielded pulsed superconductive energy storage was designed and constructed to test the shielding effect. The capacity is 200 kJ. The superconductive coil was designed as a usual dc magnet. The rated current was decided as 1,350 A not to be large heat leak through power leads. The shield coil was divided into 12 blocks which were wound in a solenoid type. These blocks were distributed in optimum distribution not to generate magnetic field on the superconductive coil. This enables the construction of such small scaled shield coil. The system is designed to be able to generate energy of 250 kJ in the duty factor of 0.2 %. The field was measured and well agreed with the calculated one.         Application of superconducting coils to reactive power control in electric power systems    H. Boenig and W. Hassenzahl Summary: A novel type of static thyristor-controlled reactive power compensator, called SAVAR, consisting of a multipulse Graetz bridge controlled in a variable free wheeling mode and connected to a superconducting coil is described. Each thyristor of the Graetz bridge is fired twice during a cycle in a cyclic order that results in a constant average coil current which flows through the line during part of a cycle and free wheels through the bridge during the rest of the cycle. By varying the fraction of a cycle during which the coil current is free wheeling, the line current can be varied continuously between a minimum and maximum limit according to the required reactive current demand. The control algorithm for the variable free wheeling mode of the bridge and the methods to produce a low loss superconducting coil subjected to high voltage harmonics are described. Experimental results of a prototype unit with an existing non-optimized superconducting coil are given, providing the proof-of-principle of the SAVAR system. Preliminary cost and performance data for a 40 MVAR SAVAR reference design are compared with those obtained from a conventional static reactive power compensator.         Design of the BPA superconducting 30 MJ energy storage coil    E. Hoffmann, J. Alcorn, W. Chen, Y.-H. Hsu, J. Purcell and R. Schermer Summary: The design of a superconducting magnetic energy storage coil is presented. The purpose of this coil is to stabilize low frequency power oscillations in long high voltage ac power lines. The practical application for this specific coil will be the installation in the Pacific intertie between Washington State and Los Angeles, California. The guiding principles of the design are performance, fabrication economy and reliability.         Identification of control system of superconducting magnet    Y. Murakami, M. Nishimura, T. Shintomi and M. Masuda Summary: The dynamics of superconducting inductor - thyristor converter (I-C) unit for SMES have been studied through input/output relations. The input gate signal of random waveform given to thyristor converter and the response waveforms of currents and voltages of the I-C unit are sampled and memoried to form an input/output (I/O) sequence. An I/O sequence is identified by a multi-input/multi-output discrete time system (MI/MO DTS), that is, the dynamics of I-C unit is described. The dynamics of an I-C unit composed of 12 phase thyristor power converter and 100 KJ superconducting magnet have been identified by this method. The simulated outputs by the derived MI/MO DTS have closely fitted to the measured waveforms, and the optimal control system can be designed based on the MI/MO DTS. The three dimensional MI/MO DTS present a good approximation to the measured waveforms. One of the equivalent circuits is a parallel connection of R-L-C. The ac loss have been estimated from the parameters of the equivalent circuit. The simulated waveforms of equivalent circuit have closely fitted to the measured waveforms and show the method is useful for the estimation of ac loss.         Construction program for a large superconducting MHD magnet system at the coal-fired flow facility    S.-T. Wang, L. Genens, J. Gonczy, H. Ludwig, M. Lieberg, E. Kraft, D. Gacek, Y.-C. Huang and C.-J. Chen Summary: The Argonne National Laboratory has designed and is constructing a 6 T large aperture superconducting MHD magnet for use in the Coal-Fired Flow Facility (CFFF) at the University of Tennessee Space Institute (UTSI) at Tullahoma, Tennessee. The magnet system consists of the superconducting magnet, a magnet power supply, an integrated instrumentation for operation, control and protection, and a complete cryogenic facility including a CTI Model 2800 helium refrigerator/ liquefier with two compressors, helium gas handling system and a 7500 liter liquid helium dewar. The complete system will be tested at Argonne, IL in 1981. This paper first briefly reviews the magnet design. Second, the coil fabrication programs are described in detail.         Development of long continuous Nb/sub 3/Ge tape conductors with high current density at elevated temperature and field    M. Maley, L. Newkirk, J. Thompson and F. Valencia Summary: Superconductors based on Nb/sub 3/Ge have been fabricated by the chemical vapor deposition (CVD) process in continuous lengths up to 20 m. This material exhibits a transition temperature T/sub c/ > 21.0K and a self field critical current density J/sub c/ /spl ges/ 2.5 /spl times/ 10/sup 6/ A/cm/sup 2/@ 14 K and offers the possibility of high current operation at temperatures > 14.0 K. Values of J/sub c/measured in high magnetic fields exceed 8 /spl times/ 10/sup 4/ A/cm/sup 2/at 18T @ 4 K. The material development program that resulted in reproducing the excellent short sample superconducting properties on long continuous lengths of tape is described. The tapes consist of 3-6 /spl mu/m of Nb/sub 3/Ge coated completely around 0.64-cm-wide, 25-/spl mu/m-thick substrates of Cu, Ni, or Cu-clad stainless steel. More than 150 m of this tape has been fabricated for use in winding a 1-m prototype transmission cable. AC-loss measurements on short samples of the long tapes show complete shielding of the substrate and losses which are acceptably low for power transmission applications.         High T/sub c/phases in the Nb-Si, Nb-Ge, and the Nb-Ge-Si ternary systems    E. Haase and O. Meyer Summary: In the course of a systematic investigation of the Nb-Ge-Si binary and ternary systems we have found, apart from the A15-phase, two new high T/sub c/phases. The first one, observed in the Nb-Si system, in the range of 8-13 at% Si, is cubic with a lattice parameter a/sub 0/falling from 5.195 to 5.186 /spl Aring/, with T/sub c/values of 9.5 to 17.7 K, respectively. Our analysis of a sample prepared by Dew-Hughes and Linse shows the existence of the Nb/sub 7/Si phase with a T/sub c/of 17.7 K. The primitive cubic x-ray line pattern and the lattice parameter indicate some relation with the A15 phase; however, the line intensities and residual resistance ratios are distinctly different. The second high T/sub c/phase, which we first found around the Nb/sub 2/Ge composition, is a tetragonal phase with lattice parameters of about a/sub 0/=10.175 and C/sub o/=5.151 /spl Aring/. It is similar to the D8/sub m/type, but with line intensities distinctly different. Its resistive T/sub c/is about 18 K. The highest resitive T/sub c/'s of up to 19.5 K were found for compositions near Nb/sub 2/Ge/sub .7/Si/sub .3/. These samples showed no detectable presence of the A15-phase. Either the above tetragonal phase or a small superconducting fraction of the hexagonal C40 phase could be the cause of the observed T/sub c/.         Epitaxial growth of A15 Nb/sub 3/Si    R. Feldman, R. Hammond and T. Geballe Summary: Films of niobium-rich Nb/sub 3/Si have been grown epitaxially on polycrystalline, A15 Nb/sub 3/Ir using electron beam evaporation. The use of epitaxy has allowed formation of A15 Nb/sub 3/Si under deposition conditions in which it normally would not form. The Nb/sub 3/Si has been made niobium-rich in order to match lattice parameters with the Nb/sub 3/Ir. Some samples have then been brought toward stoichiometry by gradually lowering the evaporation rate of the Nb. The use of this compositional grading technique has been found to enhance the T/sub c/'s relative to the epitaxial films by in some cases more than 6 K. T/sub c/onsets, measured resistively, have been found up to 13.2 K. The effects of varying the thickness of the graded layer have been studied, and T/sub c/'s have been found to continue to increase after the graded layer has been brought to 25 at. % Si.         Comparison of T/sub c/'s and phase relationships of Nb/sub 3/Ge films deposited on A15 Nb/sub 2/Ir and Al/sub 2/O/sub 3/substrates    C. Umbach, L. Toth, E. Dahlberg and A. Goldman Summary: Nb-Ge films containing approximately 25 at% Ge were simultaneously d.c. sputtered on both sapphire and A15 Nb/sub 3/Ir substrates. The films were analyzed using Auger electron spectroscopy, X-ray diffraction, and low temperature resistance measurements. X-ray diffraction data showed that the films deposited on A15 Nb/sub 3/Ir remained single phase up to a higher concentration of Ge than those deposited on sapphire. Superconducting transition temperatures of films deposited on A15 Nb/sub 3/Ir were almost always lower than those of films deposited on sapphire under identical conditions. Annealing at 750/spl deg/C decreased T/sub c/'s for films deposited on Al/sub 2/O/sub 3/, while it increased T/sub c/'s for those deposited on A15 Nb/sub 3/Ir substrates. Under optimum conditions, T/sub c/onsets greater than 20 K were obtained for both as-deposited and annealed Nb-Ge films sputtered on Nb/sub 3/Ir substrates.         Homogeneity investigations of superconducting transition of Nb/sub 3/Ge films    C. Gunkel, B. David and C. Heiden Summary: Superconducting transition curves of Nb/sub 3/Ge films prepared by cosputtering or by chemical vapor deposition on sapphire substrates were determined using voltage probes on the sample of variable distance between the contacts. Noticeable reduction of transition width /spl utri/T with decreasing voltage probe separation is found, /spl utri/T-values determined from the slope at the midpoint of transition of the order of 0.2 K resulting for contact separations below 1 mm, with transition temperatures T/sub c/(midpoint) up to 22.3 K. No dependence between T/sub c/and /spl utri/T was observed, however there exists a noticeable correlation between T/sub c/-values of adjacent sample regions. A very similar spatial correlation is found for the residual resistivity ratio RRR. Locally determined RRR- and T/sub c/-values exhibit for a given specimen qualitively a similar correlation as reported by Testardi et al.         Metallurgy and superconductivity in Nb-Al    J. Jorda, R. Flukiger, A. Junod and J. Muller Summary: The formation of the Nb/sub 3/Al A15 phase under equilibrium conditions is studied on bulk, homogenized samples. Due to compositional effects, T/sub c/of samples annealed during long periods at temperatures below 900/spl deg/C is found to be close to 12 K. It follows that the high T/sub c/values (15-16 K) observed on multifilamentary Nb/sub 3/Al wires reacted at these temperatures cannot be interpreted on the basis of the equilibrium phase diagram.         Critical currents at high fields in NB/sub 3/AL multifilamentary wires    D. Dew-Hughes Summary: Short sample critical currents have been measured on wires of Nb/sub 3/Al in fields up to 21 tesla. The wires consisted of 7 or 19 filaments of niobium-aluminium foil "jelly rolls" in a copper matrix. They were reacted at temperatures between 750/spl deg/C and 950/spl deg/C to form Nb/sub 3/Al. Critical temperatures were measured inductively and showed transitions with three stages whose onsets were at /spl sim/15K, 10-13K and /spl sim/9.2K. Critical currents measured at low fields reproduced the high values previously reported for this material. Measurements were made at the Francis Bitter National Magnet Laboratory in high fields up to 21 tesla. The magnetic field variation of the critical Lorentz force, J/sub c/B, could be fitted to the Kramer relation, b/sup 1/2 /(1-b)/sup 2/, for most samples. The bulk Bc/sub 2/, believed to correspond to the intermediate temperature transition was in the range 10-17 tesla. In addition there was a high field tail with Bc/sub 2/from 17-21 tesla, related to high (/spl sim/15K) transition onset temperature. These results are discussed in terms of the Nb-Al phase diagram.         NbN materials development for practical superconducting devices    R. Kampwirth and K. Gray Summary: Power switches such as a Superconducting Fault Current Limiter require large cross sectional area superconductors with both high critical current density J/sub c/and normal state resistivity /spl rho//sub n/. Large values of J/sub c/and /spl rho//sub n/have been previously reported in small cross sectional area "weak links" of NbN. We report on reactively sputtered NbN films up to 5 /spl mu/m thick and 2.2 cm wide which have /spl rho//sub n/> 200 /spl mu//spl Omega/ cm and a self-field J/sub c/up to 10/sup 6/A/cm/sup 2/. Severe degradation in J/sub c/was observed with increasing film width and for millisecond current pulses. This degradation could be substantially reduced by stabilization with either low /spl rho//sub n/normal metal or the use of a sapphire substrate. The resistivity and critical current dependence both imply Josephson coupled grains and the results will be discussed within that model.         Superconducting properties of reactively sputtered NbCN thin films    T. Francavilla, S. Wolf and E. Skelton Summary: Niobium Carbonitride thin films have been prepared by rf reactive sputtering of niobium in ar argon, reactive-gas (RG) atmosphere where the RG is a mixture of cyanogen and nitrogen. Film composition ranged from Nb/sub 1/C/sub x/N/sub 1-x/(0.03 /spl les/ /spl times/ /spl les/ 0.5) as determined by Auger analysis, the carbon content roughly tracking the cyanogen partial pressure. Composition and substrate temperature were systematically varied and the resultant films studied by measurements of x-ray structure, resistivity, superconducting transition temperature T/sub c/, and critical magnetic fields. We have found systematic preferential orientation of the crystallites in these films depending upon substrate temperature ana RG to argon ratio. Increasing either quantity causes the crystallites to reorient from the         Dimensional effects on current and field properties in NbN films    J. Gavaler, A. Santhanam, A. Braginski, M. Ashkin and M. Janocko Summary: We have investigated dimensional effects, i.e., variations in thickness, width, grain size, and separation between grains, on the current and field properties of NbN films. The films, all of which had T/sub c/'s of /spl sim/ 16K were prepared by reactive sputtering, Self-field current densities measured at 4.2K ranged from /spl sim/ 5 /spl times/ 10/sup 5/ to > 10/sup 7/Amps/cm/sup 2/. Measured upper critical fields at 4.2K varied from < 100 kG to > 220 kG. Extrapolated H/sub c2/'s of over 500 kG were calculated from data taken near T/sub c/. All of these results are correlated with transmission electron microscopy studies. The very highest upper critical fields are attributed to an H/sub c3/arising from a column-void microstructure. In general, we conclude that dimensional effects are a dominant factor in achieving the very high current and field values observed in these films.         Analog measurement applications for high speed Josephson switches    C. Hamilton, F. Lloyd and R. Kautz Summary: This paper reviews high speed analog applications of Josephson switching devices. The design and performance of two different analog sampling circuits is described. A method is proposed for delivering room temperature signals to these samplers with 30 GHz or more of bandwidth. An analog-to-digital converter based on quantum interference comparators is also described. This device has achieved conversion rates of 2x10/sup 9/samples per second.         Characteristics of a counter-electrode coupled logic gate using Josephson junctions    S. Hasuo, H. Suzuki and T. Yamaoka Summary: This paper proposes a new superconducting logic device controlled by input signal currents applied to the counter-electrode of a tunneling junction. This device has no specific control lines unlike the conventional magnetically coupled logic devices. Input signals couple to the junction magnetically by using the counter-electrode instead of the control line. We call this a Counter-electrode Coupled Logic (CCL) gate. The following describes the basic characteristics of the CCL gate.         A four input-and-gate with five asymmetric interferometers    H. Beha, W. Jorger and W. Jutzi Summary: The static and dynamic behavior of a four input-AND-gate for a parallel fan out of three has been simulated. Only asymmetric interferometers with two unequal Josephson junctions as input devices are used instead of interferometers with three junctions in order to save circuit area and to improve performance. The input devises have a characteristic phase /spl lambda/ = 2.1 and a ratio of the maximum Josephson-currents of 3:1. The AND-function of each pair of inputs is performed in a similar manner as described by Klein and Herrell. The AND-function of the two input pairs is realized with a nonlinear injection gate. The number of interferometers used in this AND-gate is reduced by two compared with known proposals. With tolerances of the maximum Josephson currents of /spl plusmn/ 10% and additional tolerances of /spl plusmn/ 9% of the input and supply currents the worst case and average nominal logic delays are about 170 ps and 60 ps.         A soliton device    T. Rajeevakamar Summary: A simple, novel superconducting tunneling device has been investigated experimentally as well as theoretically. The device can be used to perform logic by the steering of Josephson solitons. It may be used as the basis for wide margin, high density, high speed circuits. The concept was demonstrated experimentally through the operation of a chain of 10 devices fabricated with a 5 /spl mu/m Pb-alloy technology.         Measurements of the effects of asymmetry in an on-chip regulated power distribution system using a dual trace Josephson sampling oscilloscope    C. Anderson and M. Ketchen Summary: Josephson latching logic devices can be powered by a bipolar trapezoidal waveform shaped from a incoming ac by a voltage regulator consisting of two or four Josephson junctions in series. For reasons of local power regulation, uniform thermal loading and timing, it is desirable that there be a number or regulators (typically 16-64) distributed over the surface of the chip. These regulators are driven in parallel by a symmetric tree-like distribution network with one or more inputs at the chip periphery. Provided all regulators and their loads are identical, the regulated power waveform will be the same everywhere on the chip. We have used a Josephson sampling oscilloscope to study the effects of asymmetry in a simple power system with two regulators at frequencies up to 500 MHz (representing a 1ns logic cycle time). Initially the nearly identical voltage waveforms across the two regulators are measured with a common time base using high resolution on-chip sampling techniques. The resistive load across one of the regulators is then mechanically changed by a factor of two or three. The subsequently measured waveforms are somewhat different in shape and displaced from each other by approximately 100 ps. This experiment and accompanying simulations help established design limits on acceptable levels of asymmetry in the on-chip power distribution system.         Low-probability punchthrough in Josephson junctions    R. Jewett and T. Van Duzer Summary: Punchthrough in latching Josephson junctions is the apparently random failure to reset to the zero-voltage state when the drive current passes through zero as it changes polarity. This phenomenon has previously been analyzed for probabilities approaching unity. This paper extends the analysis and compares derived expressions with numerical simulations for probabilities as low as 10/sup -7/. A linearized analysis indicates that the presence of noise currents has only a minor effect on punchthrough. This is confirmed by simulation. Design curves are presented, relating device capacitance, resistance, critical current, and clock transition time to punchthrough probability. Preliminary results for interferometers are shown.         Punchthrough in Josephson logic devices    E. Harris and W. Chang Summary: We present here an analysis of punchthrough for simple latching circuits containing Josephson junctions and driven by a trapezoidal AC supply current. Until recently it was thought that in such circuits there should exist a critical transition time for polarity reversal of the supply current above which punchthrough would not occur. Recent work, however, has suggested that there is a punchthrough probability tail which extends beyond the supposed critical transition time. We have developed a simple model for punchthrough in the tail region that is in good agreement with numerical simulations. Our analysis also indicates that the addition of a short dwell time at the zero-crossing of the supply current waveform will greatly reduce the punchthrough probability. A first-pass estimate of the implications of our results for punchthrough in large systems suggests that punchthrough may not be a serious limitation.         Superconducting materials: Ten years do make a difference    R. Hein Summary: Superconduction materials research has evolved into a truly interdisciplinary effor involving chemists, engineers, metallurists and physcists. The experiences of almost three decades of intensive materials research have produced a certain reluctance to the acceptance of any drastic departure from "conventional" wisdom. In light of this perceived state-of-affairs, a brief sojourn into the history of superconduction materials research is felt to be in order; there might just be a message or two for us.         Reliability of large superconducting magnets through design    C. Henning Summary: As superconducting magnet systems grow larger and become the central component of major systems involving fusion, magnetohydrodynamics, and high-energy physics, their reliability must be commensurate with the enormous capital investment in the projects. Although the magnet may represent only 15% of the cost of a large system such as the Mirror Fusion Test Facility, its failure would be catastrophic to the entire investment. Effective quality control during construction is one method of ensuring success. However, if the design is unforgiving, even an inordinate amount of effort expended on quality control may be inadequate. Creative design is the most effective way of ensuring magnet reliability and providing a reasonable limit on the amount of quality control needed. For example, by subjecting the last drawing operation in superconductor manufacture to a stress larger than the magnet design stress, a 100% proof test is achieved; cabled conductors offer mechanical redundancy, as do some methods of conductor joining; ground-plane insulation should be multilayered to prevent arcs, and interturn and interlayer insulation spaced to be compatible with the self-extinguishing of arcs during quench voltages; electrical leads should be thermally protected; and guard vacuum spaces can be incorporated to control helium leaks.         An ETF TF-coil concept employing NbTi alloy, bath cooled with superfluid helium    Y.-H. Hsu, J. Purcell, J. Alcorn and W. Homeyer Summary: Under subcontract to the MIT/FBNML, General Atomic Company has performed a preliminary study to assess the feasibility and engineering considerations of employing NbTi alloy conductor, bath cooled with superfluid helium (He II), in an Engineering Test Facility (ETF) toroidal field (TF) coil. This study indicates that saturated superfluid helium (He II) merits serious consideration as an alternative to the use of He I for high field (11-12 tesla) NbTi alloy TF-coils, which require bath temperatures below 4 K. The primary advantages of He II over reduced temperature (2.5-3 K) He I are two: (1) Due to the extremely high thermal conductivity of He II, almost all of the sub-lambda enthalpy is available to absorb local or transient heat loads. Further, this He II characteristic results in vapor evolution only at the bath surface, thus obviating concerns over vapor locking within the heated centerpost region; and (2) The relatively high surface heat transfer results in substantially improved conductor stability characteristics. As a result, coil protection limits (dump voltage and conductor temperature) become the limiting factors in allowable substrate current density. The disadvantages of He II relative to reduced temperature He I are increased refrigeration power and pumping requirements, and some additional system complexity. This study affords a direct comparison with the He I bath cooled TF-coil concept developed by Team One (GA/MCA) for the DOE 12 Tesla Coil Development Program.         The ORNL/General dynamics/AIRCO design for the DOE 12-tesla magnet program    D. Hackley, G. Kruse and D. Ring Summary: General Dynamics Convair Division has been actively engaged in development of toroidal field superconducting magnet concepts for future tokamak reactor systems. Experience with the Oak Ridge National Laboratory (ORNL) Large Coil Program (LCP) has been instrumental in our study of the toroidal field coil requirements for an engineering test facility (ETF), made up of twelve 6m X 10m-bore size 12-Tesla magnets. Under contract to ORNL, General Dynamics has teamed with Airco to examine the engineering requirements for ETF, with particular emphasis placed on development of a candidate Nb/sub 3/Sn pool boiling 12-Tesla conductor. This paper highlights the results of the General Dynamics-Airco scoping study which produced a simple, reliable, and achievable conductor designed to meet the performance aspects of an ETF-size toroidal field magnet.         Scoping study of a 12T toroidal field coil for the fusion engineering test facility    J. Heinrich, J. Donato, S. Kalsi, C. Linkinhoker, R. Willig, M. Walker, J. Royet and G. Morrow Summary: A scoping study of a 12T TF Coil for ETF has been performed. Major design drivers included: /spl middot/High field (12T) and overall current density (1700 A/cm/sup 2/) /spl middot/Large mechanical forces due to field, current density and coil size(6 X 10m bore) /spl middot/Stability against a 100 mj/cm/sup 3/disturbance deposited over a half turn /spl middot/Ability to survive poloidal field pulses and plasma disruptions without quenching Significant conclusions reached during the study were: /spl middot/Pool boiling cooling of a Nb/sup 3/Sn conductor is preferable to supercritical or superfluid cooling because it leads to a cheaper, more reliable system /spl middot/Distributed structure is required to support the conductor /spl middot/Most of the losses resulting from a plasma disruption are dissipated in the coil case /spl middot/Testing should be performed on the full-size conductor to eliminate the need for extrapolation.         Progress in the ICCS-HFTF 12 tesla coil program    M. Hoenig, M. Steeves, A. Montgomery and M. Olmstead Summary: The U.S. Magnetic Fusion Energy Program requires the development of very large and powerful superconducting toroidal magnets. Combined with optimized reactors, these superconduction coils will provide plasma confinement for the feneration of electricity. This development is being carried out on two parallel fronts.         Status of the GA/MCA 12 tesla coil development program    J. Alcorn, J. Purcell, W. Chen and Y.-H. Hsu Summary: The current status of the Team One effort of the DOE/ OFE/D&T 12 Tesla Coil Development Program is presented. Sub-atmospheric, helium bath cooled, NbTiTa alloy is employed for the test coil, and ETF TF-coil concept. General Atomic is the Team One leader, with Magnetic Corporation of America as industrial subcontractor.         Fabrication techniques and properties of multifilamentary Nb/sub 3/Sn conductors    M. Suenaga, W. Sampson and T. Luhman Summary: Various processing techniques for multifilamentary Nb/sub 3/Sn and V/sub 3/Ga are reviewed. The critical current of commercially produced Nb/sub 3/Sn wires manufactured by both the bronze and external diffusion techniques are compared. Critical currents for in situ and powder processed Nb/sub 3/Sn are also included. New developments which promise improvements in J/sub c/are discussed.         Recent developments on processing and properties of V/sub 3/Ga composite wires    D. Howe, D. Gubser and T. Francavilla Summary: The addition of small amounts of third elements to V-Ga alloy rods have resulted in improvements in ductility. Cerium, yttrium, and titanium additions have been studied. Cerium (0.2atomic%)and yttrium (0.2 atomic%) additions reduced the microhardness from 180 to 160 KG/mm/sup 2/. Lower mlcrohardnesses in alloy rods facilitates the metallurgical processing to small filament diameters used in multifilamentacy V/sub 3/Ga wire. The effects of these alloy additions on V/sub 3/Ga wire formed by the modified bronze technique are presented. Progress is reported on the development of high critical current density V/sub 3/Ga wires using the V-Ga/Cu-Ga modified bronze process.         Strain scaling law for flux pinning in NbTi, Nb/sub 3/Sn, Nb-Hf/Cu-Sn-Ga, V/sub 3/Ga and Nb/sub 3/Ge    J. Ekin Summary: Critical current and flux pinning densities have been determined for a series of practical conductors as a function of uniaxial tensile strain in magnetic fields ranging from 4 T to 19 T. An empirical relation has been found at 4.2 K that accurately describes these data over the entire range of field under both compressive and tensile strain. The pinning force F has been found to obey a scaling law of the form:F = [B*_{c2}(\varepsilon)]^{n} f(b)where f(b) is a function only of the reduced magnetic fieldb \equiv B/B*_{c2}, andB*_{c2}is the strain dependent upper-critical field determined from high-field critical-current measurements. This strain scaling law was found to hold for all superconductors examined thus far, including commercial multifilamentary wire, mono-filamentary conductors, CVD tapes, extremely fine-filament conductors, partially-reacted specimens, and "in-situ" cast conductors. For Nb/sub 3/Sn,n /spl cong/ 1.0, for Nb/sub 3/Sn with Hf and Ga additions,n /spl cong/ 1.2, for V/sub 3/Ga,n /spl cong/ 1.4, for Nb/sub 3/Ge,n /spl cong/ 1.6, and for NbTi,n /spl cong/ 4. The importance of this relationship is that, for these conductors at least, it is possible to measure F at one strain and then immediately be able to predict F (and thus J/sub c/) at other strain levels simply by scaling the results by[B*_{c2}(\varepsilon)]^{n}. The relation between strain scaling and temperature scaling is discussed as it relates to flux pinning theories.         Bend strain tolerances of a Nb/sub 3/Sn conductor proposed for use in the magnetic fusion energy program    T. Luhman, D. Welch and M. Suenaga Summary: Bend strain tolerances were studied on a 2869 filament bronze-processed Nb/sub 3/Sn wire conductor in magnetic fields to 8 T. Relative values of the wire's current transfer length to twist pitch were shown to influence the bend-strain tolerance. Low matrix resistivities, associated with Sn-depleted bronzes following heat-treatments of 48 h at 725/spl deg/C, produce current transfer lengths less than the twist pitch, 10 mm, The resulting bend-strain tolerances, at 10/sup -12/ohm.cm, are improved over those found for shorter heat-treatment times. Results from bend-fatigue experiments were divided into two domains separated by the strain value required to produce compound cracking,\varepsilon\min{f}\max{B}. Applied bending strains less than\varepsilon\min{f}\max{B}were found to increase zero strain critical current values and this increase was independent of the number of fatigue cycles. When applying strains large enough to produce cracking in the compound critical currents decreased from their as-reacted values tending to reach a minimum after several fatigue cycles. Evidence exists for a neutral axis shift during bending and slight differences between tensile and bend strain tolerances are accounted for in terms of such a shift.         Critical properties of multifilamentary Nb/sub 3/Sn between 8 and 14 tesla    P. Sanger, E. Adam, E. Ioriatti and S. Richards Summary: The multifilamentary NB/sub 3/Sn strand used in the Airco/Westinghouse Large Coil Program was studied for possible direct applicability to the 12 Tesla Coil Program. These studies began with an optimization of the reaction heat treatment to improve the critical current at 12 Tesla. Subsequently the critical surface of a strand heat treated under the optimal conditions was mapped out between 8 and 12 Tesla. The results of these studies are described.         Nb/sub 3/Sn conductors for 12 tesla toroidal field coils    M. Walker, D. Damiano, W. Hamilton, R. Wilcox, B. Zeitlin, R. Stuart, J. Heinrich and C. Linkinhoker Summary: Several advanced multifilamentary Nb/sub 3/Sn conductors were examined for various modes of cooling for the 12 Tesla ETF application. Of these, a pancake-wound 15,000 Ampere flat cable of triplets of large strands in a perforated stainless steel channel was selected as the preferred candidate. This cable will be cold-end cryostable in a pool-boiling environment with a maximum heat transfer from the unoccluded strand surface of 0.24 Watts/cm/sub 2/. The construction of the conductor and coil is relatively simple, offering potential economies in quality assurance and production costs.         The effect of heat treatment on practical multifilamentary Nb/sub 3/Sn conductor    Tang Xian-de, Chan De-qin, Li Ming-sheng and Zhu Ding-shi Summary: The effect of heat treatment on the practical copper-stabilized multifilamentary Nb/sub 3/Sn conductor prepared by a "bronze" technique has been investigated. In the temperature range of 650-750/spl deg/C, there is a relation of Y /spl prop/ t/sup n/ between Nb/sub 3/Sn layer thickness (Y) and heat treatment time(t). However, it has been found that the n values in all conductors investigated considerably differ from that reported by M. Suenaga[1] and H. H. Farrell[2]. At 700/spl deg/C, for a conductor with the bronze/Nb ratio of 3.0, the variation of Sn contents in bronze matrix and that of Nb/sub 3/Sn grain size follow the laws of t/sup -0.47/and t/sup 0.20/, respectively. The dependence of J/sub c/(bronze + Nb, same for the following.) of conductor on t is approximately parabolic. The J/sub c/(4.2K, 5T) is 2.8x10/sup 5/A/cm/sup 2/when t=100 hr. For another conductor, J/sub c/(4.2K, 5T) has reached 3.9x10/sup 5/A/cm/sup 2/. We have found that the temperature and time of heat treatment have certain influence on T/sub c/of conductor. A discussion is given to explain the foregoing results.         Computer simulations of the performance of quasiparticle heterodyne mixers    T.-M. Shen and P. Richards Summary: Heterodyne mixers for millimeter wavelengths which have conversion gain and noise comparable to the quantum limit can be made using the non-linearity of the quasi-particle I-V curve of SIS or SIN tunnel junctions. When the voltage range of the non-linearity becomes small compared with h/spl omega//e, classical device theory breaks down and photon assisted tunneling theory must be used to understand mixer performance. In this paper we describe detailed computer simulations of SIS and SIN quasiparticle mixers. Predictions for conversion efficiency and noise are given for both devices as a function of operating frequency, bias voltage, RF source conductance and local oscillator power. A novel type of SIN harmonic mixer is proposed for which gain is also predicted.         Dayem-Martin (SIS tunnel junction) mixers for low noise heterodyne receivers    T. Phillips, D. Woody, G. Dolan, R. Miller and R. Linke Summary: Superconducting thin film tunnel junctions of small area (/spl middot/1 /spl rarr/ 1 /spl mu/m/sup 2/) have properties which make them suitable for high frequency (/spl gsim/100 GHz) heterodyne receivers. Both pair and single quasiparticle tunneling is present in these devices, but it is found that the mixing due to the pair effect is apparently excessively noisy, whereas the single quasiparticle effect has a low noise character which gives hope for near quantum limited performance. The physical effect involved is photon assisted quasiparticle tunneling and was first observed by Dayem and Martin[1]. We have made laboratory tests at 115 and 230 GHz which gave single side band (SSB) mixer noise temperatures of 60 and 300 K respectively. Also we have fabricated a 90-140 GHz receiver for the Caltech Owens Valley Radio Observatory which has an overall receiver noise temperature of about 300 K (SSB).         The antenna-coupled SIS quasiparticle array mixer    S. Rudner, M. Feldman, E. Kollberg and T. Claeson Summary: We report SIS mixing with Pb(In) junction arrays at 73.5 GHz. The array geometry and antenna coupling can be scaled to 300 GHz with existing technology. The measured SSB conversion loss is as good as 2.0/spl plusmn/0.9 dB. This is marginally the best conversion result for a resistive mixer without image rejection yet published and agrees well with the quantum theory of mixing. We examine Josephson effect noise and thereby give a rough upper frequency limit for single-junction SIS mixers.         Observation of subharmonically pumped mixing with gain using SIS junctions    S. Slusky, R. Trambarulo and L. Fetter Summary: We have observed subharmonically pumped, switched mode mixing in superconductor-insulator-superconductor (SIS) junctions. Experiments were performed at signal frequencies of 14.4 and 16.8 GHz using PbIn-oxide-Pb junctions approximately 1 /spl mu/m X 1/2 /spl mu/m The best single sideband power conversion seen was 2.0 /spl plusmn/ 0.5 dB gain. The lowest single sideband mixer temperature measured was 48 /spl plusmn/ 47K. This is the first superconducting mixer to combine the advantages of subharmonic pumping with single sideband gain and low noise.         The millimeter wave super-schottky diode detector    A. Silver, R. Pedersen, M. McColl, R. Dickman and W. Wilson Summary: The superconductor-Schottky (super-Schottky) diode has been extended to millimeter wavelengths by manipulation of the semiconductor interface, and measurements are reported at 31 and 92 GHz. Diodes were formed by pulse electroplating Pb on 2x10/sup 19/cm/sup -3/p-GaAs which was etched wth HCl. A thin Au overplate protects the Pb surface from degradation and extends the lifetime of the diode. The diodes were contacted with cat whiskers and mounted across 1/4 height waveguide. The measured diode noise performance is nearly ideal at both 31 and 92 GHz. At 31 GHz, the reported performance is L/sub c/= 8.6 dB, T/sub mixer/= 10K, NEP = 4.8x10/sup -16/W/Hz/sup 1/2/; at 92 GHz, L/sub c/= 18 dB, 76K < T/sub mixer/< 190K. Therefore this device is a quantum-noise-limited detector at 31 GHz (measured sensitivity of 7 photons) but suffers from excess parasitic losses at 92 GHz. Reducing the loss at 92 GHz will require further engineering of either the semiconductor surface or the contact geometry.         Isabelle--A progress report    H. Hahn Summary: This paper discusses the ISABELLE project, which has the objective of constructing a high-energy proton colliding beam facility at Brookhaven National Laboratory. The major technical features of the intersecting storage accelerators with their projected performance are described. Application of over 1000 superconducting magnets in the two rings represents the salient characteristic of the machine. The status of the entire project, the technical progress made so far, and difficulties encountered are reviewed.         State of the energy doubler    R. Lundy Summary: A number of papers were presented during the 1978 Applied Superconductivity Conference concerning the Energy Doubler, a large scale superconducting accelerator, proposed as a construction project to the Department of Energy by Fermilab but at that time proved. These papers described various aspects of an extensive research and development program on magnet design, production techniques and testing. This report will try to provide an overview of the ments in this area during the last two years. The papers (1-5) from the 1978 Conference and additional papers being presented at this Conference will more complete details.         Two cell doubler systems test    K. Koepke, C. Rode, G. Tool, R. Flora, H. Jostlein, J. Saarivirta and M. Kuchnir Summary: A superconducting magnet system testing area has been constructed above ground at the B12 location of the Fermilab main accelerator which facilitates the testing and development of superconducting magnet systems prior to committing their design to the full scale production Of the Doubler accelerator. The test results and operating experience of this system will be reported.         A superconducting ondulator for synchrotron radiation light    R. Auzolle, J. Perot and C. Bazin Summary: An ondulator to produce synchrotron radiation light has been designed and built at SACLAY for the "LURE" Laboratory at ORSAY (France). A magnet with a very short period was required with a number of periods as high as possible to increase the brightness of the source. For this reason superconducting coils have been used in order to reduce their size. 92 coils have been made for the 23 period ondulator with a wavelength /spl lambda//sub 0/of 40 mm. This light source whose design began in 1978 has been in operation since february 1980 on the "ACO" electron storage ring.         Superconducting magnet for EHS    H. Desportes, R. Duthil, J. Gelebart, C. Leschevin and C. Lesmond Summary: A 55 Mjoules Magnet has been installed and commissioned at CERN for the Rapid Cycling Bubble Chamer of the EHS experiement (European Hybrid Spectrometer). The magnet consists of two separate circular coils, assembled with their axis horizontal into a massive iron structure, and provides a central field of 3T in a useful volume of 1.4, in diameter and 0.82m gap with a complerely azimuthally free acceptance of /spl plusmn/ 18° from the central plane. Special features of the magnet, which is otherwise of a classical pancake-type, bathcooled design, are a relatively high average current density (2500 Amp/cm/sup 2/) and an elaborate support structure required by the particular force configuration within the iron structure.         Eddy currents, dispersion relations, and transient effects in superconducting magnets    R. Shafer Summary: The purpose of this paper is to discuss the effects eddy currents in superconducting magnets. Of primary interest are magnets suitable for accelerator applications, as they must operate under high ramp (dB/dt) conditions, but the effect is important in other applications as well.         Transmission line properties of long strings of superconducting magnets    R. Shafer Summary: The purpose of this paper is to discuss the trical characteristics of a long string of superconducting magnets, such as in a superconductiag storage ring or accelerator. As the magnets have a shunt capacitance to ground as well as a series inductance, travelling waves can propagate along the string, as in a transmission line. As the string is of finite length, standing waves can also exist. In accelerator quality superconducting magnets, considerable effort has devoted to minimizing AC losses, the net result being that the magnet string has a high Q precisely at the frequencies which are important for the standing travelling waves. The magnitude of these effects are estimated, and the solution to be used at Fermilab will be discussed.         Development of superconducting magnets for beam lines and accelerator at KEK    H. Hirabayashi Summary: Recent rapid development of superconducting magnets at KEK is reported. KEK is now constructing a superconducting pion beam line at the 12GeV Proton Synchrotron. A large bore superconducting dipole and a superconducting septum magnet for the beam line have been manufactured and successfully tested. Concurrently KEK is developing big aperture superconducting accelerator magnet of warm iron and warm bore. The first 1m model dipole of coil I.D. 14cm has been assembled and tested. A dipole field of 5.1 Tesla has been obtained in the second cool down test. This is a test dipole for TRISTAN proton ring magnet. Development program of superconducting magnets at KEK is also presented.         Transient stability of high current density superconducting wires    D. Baynham, V. Edwards and M. Wilson Summary: The transient stability of cooled superconductors is described by a theoretical model and the criteria for achieving an order of magnitude improvement in transient stability are delineated. Transient stability measurements on single wire NbTi and Nb/sub 3/Sn samples subjected to 100 /spl mu/sec heat pulses are reported. Samples cooled with a porous metal surface heat exchanger show the order of magnitude improvement in stability predicted by the theoretical model.         Mechanical training of impregnated superconducting solenoids    E. Bobrov, J. Williams, M. Sinclair and Y. Iwasa Summary: Quenching and training in an impregnated superconducting magnet has been identified with mechanical effects in the winding and coil form. Methods for reduction of training are recommended.         Transient heat transfer and recovery behavior of superconductors    C. Schmidt Summary: Transient heat transfer from bare and coated copper surfaces to saturated liquid helium was measured with a time constant of /spl sim/ 5 /spl mu/sec. In another experiment recovery of a superconducting wire after a temperature excursion was studied. The results show a large difference between bare and coated surfaces, latter recover at higher surface heat fluxes. While the recovery time of the coated surface is a smooth function of the temperature excursion, that of the bare surface exhibits a discontinuity, being higher for a small disturbance.         Some experiments on liquid helium heat transfer-characteristics affecting stability of superconducting magnet operation    S. Wipf Summary: Heat transfer from 25 /spl mu/m thick, 6.36 mm wide Nb tape into boiling helium in vertical channels of 1.7x 21 mm cross section was studied. Normal zones were initiated by heaters attached to the tape surface not in contact with the liquid. Two heat transfer effects of possible importance for superconductor stability were observed: 1. Steady normal zones enabling the measurement of localized heat transfer, and 2. Heat transport to neighboring tapes by means of the coolant. 1. Steady normal zones are those that neither grow nor decay; they occur at current densities of 13 to 17 kA/cm/sup 2/, corresponding to heat transfers of 0.45 to 0.8 W/cm/sup 2/for the normal portion of the tape. Fluctuations of the length of the normal zone are < 0.4 mm. Comparison of measured temperature profiles with calculations yields localized heat transfer values. A heat transfer /spl sim/3 times higher than the peak nucleate boiling value of 0.42 W/cm/sup 2/(measured for brass tapes) exists in a 2 mm wide region near the normal to superconducting boundary. It is inferred that this is the region where the gaseous film covering the normal zone terminates and wetting by the boiling liquid begins. 2. In a current range where the normal zones decay again, it is observed that heater pulses (square,1 s long) larger than a critical level (0.7 W) cause normal zones to appear in tapes directly above the heater-induced normal zone, with a delay of the order of 0.1 s. Suggested explanation: The heat from pulse and induced resistive zone vaporizes the limited amount of liquid helium in contact with the zone and, before convection has time to develop, the helium becomes superheated above the critical 6 - 8 K. As it then rises normal zones are created.         Enthalpy stability criterion for magnets cooled with superfluid helium II    S. Van Sciver Summary: A criterion is presented which describes the limits to local heat pulses sustained by a magnet cooled in superfluid helium II. The magnet will remain stable for a length of time defined by the enthalpy of the helium between bath temperature and the maximum superfluid temperature (T/sub /spl lambda//= 2.17K). For a bath temperature of 1.8K, this enthalpy is 300 mJ/cm/sup 3/. For long pulses, the volume of helium that absorbs the heat can be considered to approach the contents of the entire dewar. For short heat pulses, there is a limited region into which the heat diffuses. This diffusion process can be defined using experimental results on transient heat transfer. A model is presented to describe how to generalize the thermal diffusivity in superfluid helium II. Application of this criterion to specific magnet designs is discussed.         Measurement of stability of cabled conductors cooled by He I at reduced temperature, or He II    Y.-H. Hsu, J. Purcell, W. Chen and J. Alcorn Summary: Stability tests of cabled NbTi alloy conductor are underway at the General Atomic High Field Test Facility, in support of the Team One effort of the DOE 12 Tesla Coil Development Program. A background field of up to 10 tesla within a 20 cm bore is provided by a nested pair of 4.2 K bath cooled NbTi coils. An insulated bore insert tube (coldfinger) is provided in order to perform heat pulse/ recovery tests of coiled samples in cooling regimes anticipated for the 1 m O.D. coil to be tested at the LLNL 12 tesla facility during FY 82. Specifically, tests are being performed in the 2.5-3 K He I, and saturated superfluid (He II) regimes. The testing apparatus, procedures, and initial results are presented.         Parametric study of the stability margin of cable-in-conduit superconductors: Theory    L. Dresner Summary: Recently, Lue, Miller, and Dresner reported that the stability margin of cable-in-conduit superconductors is multivalued for certain combinations of transport current, ambient helium pressure, and externally imposed helium flow. There is a limiting transport current below which the stability margin is single-valued and equal to the upper stability margin. The theory of ref. 1 is used here to determine the scaling of the limiting transport current with critical temperature, ambient helium temperature, resistivity of copper, length of the heated zone, duration of the heat pulse, hydraulic diameter of the helium-filled part of the cable, volume fraction of copper in the metal, and volume fraction of metal in the cable. Combined with experimental data, the scaling relation provides a sound basis for design.         Parametric study of the stability margins of cable-in-conduit superconductors: Experiment    J. Lue and J. Miller Summary: In a previous experiment on the stability of cable-in-conduit superconductors, we sometimes observed multivalued stability margins, which we attributed to strong heating-induced transient flows. We proposed a schematic theory from which we derived a scaling relation for the limiting current below which the stability margin is always singlevalued. Measurements at different magnetic fields are used to test the scaling with critical temperature and resistivity. We also examine the scaling with heated length and heat pulse duration. The results of these experiments are given and compared with theory.         Electrical performance of high density probe array for testing Josephson circuit chips    P. Moskowitz Summary: An assembly has been constructed and successfully evaluated for contacting 228-pad Josephson test chips. Miniature spring contacts mate with the 228, 100 /spl mu/m diameter pads arranged on 200 /spl mu/m centers in a double row about the edge of a 6.35 mm chip. Measurements have been made at 4.2K of contact reliability, resistance, self and mutual inductances, and current capacity. Experimental values of electrical characteristics compare well with computer simulations. This probe array is being incorporated into a non-magnetic cryoinsert for Josephson chip testing. The design uses materials such as pyrex, molybdenum, silicon, machineable ceramic, and aluminum to be consistent with a microgauss ambient magnetic field.         Numerical calculation of the inductances of a multi-superconductor transmission line system    W. Chang Summary: A variational numerical method is described in this paper to calculate the inductances of a multi-superconductor transmission line system. We show that the currents in the superconductors are distributed in a way that the sum of the total magnetostatic energy and the total kinetic energy of the system is a minimum. Using this principle, a variational technique is formulated to calculate the current distribution in the conductors and to calculate the inductances of the conductor system, in particular, we subdivide the conductor into small rectangular sub-conductors and assume a uniform trial current in each of the sub-conductor. The total energy of the system is obtained through Green's function and is minimized by applying the Lagrange multiplier technique. Once the current distribution is obtained, the inductances can be obtained easily. The method is implemented numerically and proved to be fast and accurate.         Ion beam induced changes in the oxide composition of PbIn alloy tunnel junction electrodes    A. Hebard, R. Eick and G. Schwartz Summary: A systematic correlation between krypton ion beam cleaning time and critical current density has been observed in Josephson tunnel junctions fabricated from thermally evaporated PbIn alloys which were ion milled prior to room temperature oxidation under water saturated O/sub 2/. The observed effect is strongly nonlinear and is in a direction such that the critical current density increases with increased ion milling. Auger and x-ray photoemission studies have revealed that the ratio of lead oxide to indium oxide also increases with increased milling time. The lead oxide is observed to be spatially concentrated at the oxide/ambient interface rather than being uniformly distributed. Vacuum annealing of the alloy subsequent to ion milling but preceding the oxidation step systematically reduces both the critical current density and the quantity of lead oxide observed in the films. These results have a direct bearing on the technological problem of obtaining uniformity and day-to-day reproducibility of Josephson critical currents.         Nb based Te barrier Josephson junctions    K. Nagata, S. Uehara, A. Matsuda and H. Takayanagi Summary: A study was made on Nb based Josephson junctions with evaporated Te barriers. As the first step, a Nb-Te-Pb configuration was tested. The smooth surfaced Nb electrode enabled the formation of a pinhole free barrier. Supercurrent density was found to be large compared to that for surface oxidized junctions. As the second step, a Nb-Te-Nb structure was tested. Although the junction uniformity was not as good as that of the Nb-Te-Pb junctions, the aging property was drastically improved. Considerations were made on the origin of the remaining aging. The junctions showed excellent response to 50 GHz signals.         Fabrication and properties of very thin proximity Josephson junctions    L. Van den dries, C. Van Haesendonck, Y. Bruynseraede and A. Gilabert Summary: We report on Josephson current measurements in Nb-Nb/sub x/O/sub y/-Cu/Pb tunnel junctions where the Cu/Pb electrode is a very thin proximity sandwich. The Cu and Pb film thicknesses are of the order of 100 /spl Aring/, which is much smaller than the coherence length, so that the superconducting order is uniform across the sandwich and the influence of the Cu-Pb interface barrier can be neglected (Cooper limit). Although the Pb layer is electrically discontinuous, the junctions exhibit current-voltage characteristics and Josephson effects similar to the behaviour of a classical Nb-Nb/sub x/O/sub y/-Pb junction.         The Josephson effect applied to the study of superconducting magnetic alloys    C. Van Haesendonck, L. Van den dries, Y. Bruynseraede and A. Gilabert Summary: The coexistence of superconducting and magnetic order in ternary rare earth compounds (Chevrell phases) is very important for the high field properties of new superconducting materials. By studying /spl underline N/X/S proximity sandwiches, where /spl underline N/X is a normal magnetic alloy and S is a pure superconductor, we can simulate such a ternary alloy in which the amount of superconductivity and magnetism is well defined. The most sensitive method to study the superconducting-magnetic interactions is the Josephson tunneling experiment on those /spl underline N/X/S sandwiches. The interpretation of the proximity effect data is difficult due to the spatial variation of the superconducting order and the existence of a finite barrier between the NX and S films. Both effects can be eliminated if the experiment is performed in the Cooper limit i.e. when the NX and S thicknesses are much smaller than the coherence length /spl xi/. In this paper we report on calculations and first measurements performed on Nb-Nb/sub x/O/sub y/-/spl underline N/X//Pb junctions where NX is the Kondo alloy CuCr or the spin glass AgMn. Even for low impurity concentrations the sandwich becomes highly gapless while the Josephson current can still be used as a sensitive probe for the interaction between superconductivity and magnetism.         A Josephson voltage standard using a series array of 100 junctions    R. Kautz and G. Costabile Summary: Levinsen et al. have suggested that the voltage level of the Josephson-effect voltage standard might be increased by using a series array of highly hysteretic junctions which have rf-induced steps crossing the zero current axis. If the Phase lock condition which yields quantization is stable then biasing the array at zero current insures that the voltage across each junction will be quantized, eliminating the need to individually bias the junctions. Here we describe the design and operation of a 100 junction array fabricated using photolithography. The array produced stable quantized voltages up so 27 mV when operated at 20 GHz.         Current noise effects on the microwave induced steps in current fed Josephson junctions    Y. Braiman, E. Ben-Jacob and Y. Imry Summary: Harmonic and subharmonic microwave induced steps in the I-V characteristics of current fed Josephson junction were found and investigated by numerical and approximate analytical methods, for a purely sinusoidal Josephson current. The dependence of the steps on the various parameters is given and their local stability is discussed. Various types of I-V characteristics are shown. We have introduced thermal noise effects via a Langevin term in the equation of motion. The smaller steps are easily washed out by the thermal noise. The width of the fundamental step was found to be proportional to T/sup x/for the range of parameters which we used, where x /spl gsim/ 1/2.         Fluctuations and the return to the superconducting state in granular microbridges    T. Refai, R. Peters, S. Wolf and F. Rachford Summary: We observe the effect of thermal fluctuations acting on the critical currents of an ultra-thin granular niobium weak-link in the presence of a critical current hysteresis. We find that the these fluctuation induced variations in the dissipative-superconducting transition in this film can be quantitatively explained by a model whereby the non-equilibrium length associated with the dissipative site shrinks exponentially in time while being modulated by thermally activated fluctuations. Since the nonequilibrium region recovers with a characteristic time /spl tau//sub d/, the current at which the transition to the superconducting state occurs and its associated fluctuations are rf frequency dependent. Fitting the data to our model we find the characteristic non-equilibrium site length, L/sub 0/, to be 1900A and /spl tau//sub d/to be 4.0 nsec, both of which are in good agreement with other determinations of these parameters on other niobium samples.         Nonlinear electrical phenomena and microwave detection in superconductor-normal metal contacts    V. Gubankov and N. Margolin Summary: Energy gap peculiarities, excess current and non-monotonic temperature dependence of the first derivative of I-V curve of superconductor-normal metal contacts with immediate conductivity have been observed and investigated experimentally. It was clarified that formation of I-V curve non-linearity and its temperature evolution, in accordance with the microscopic theory 1, was associatted with existence of two mechanisms of charge transfer across S-N interface by quasiparticles: 1) with energy |E| > /spl utri/; 2) with energy |E| > /spl utri/, transferred from the N-in the S-region with conversion in the S-region in Cooper pairs. Investigation of microwave (/spl lambda/ = 8 mm) detection by S-N contacts enabled to observe additional response peak caused by energy gap peculiarity on I-V curve; at the same time the presence of this peculiarity permitted to realize maximum sensitivity ~10/sup 4/ V/W) to small ( ~10/sup -9/) microwave signal.         Observation of fluxon propagation in asymmetrically based long Josephson junctions    M. Radparvar and J. Nordman Summary: We have investigated the volt-ampere characteristics of long Josephson junctions with various geometries. The VI curve of an asymmetrically biased junction has asymmetric structures with respect to the voltage axis. No such asymmetry was observed in devices with symmetrical bias current distribution. The structures are attributed to the propagation and annihilation of vortices. The junction voltage in the flux flow mode increases linearly with external magnetic field when one increases the field beyond the value necessary to have more than one vortex in the junction. The voltage vs applied magnetic field characteristics, from which the characteristic impedance of the transmission line can be obtained, are in good agreement with theoretical work. A separate linear branch in the VI characteristics was observed in a few devices and is attributed to shorts in parallel with the long junction.         Dynamics of the long Josephson junctions    V. Semenov, S. Vasenko and K. Likharev Summary: Static and dynamic properties of long sandwich-type Josephson junctions have been analyzed. These junctions, both rectangular ("uniform") and non-rectangular ("shaped"), can be described by the one-dimensional equation for the phase difference /spl varphi/ (x,t), with the coefficients generally dependent on x. The variation of these coefficients reflects that of effective junction inductance, capacitance, critical current density and injected current density, along the junction length L. If L >> /spl lambda//sub J/, the equation for /spl varphi/ (x,t) can be reduced to a simpler "hydrodynamic-type" equation for the Josephson vortex density. Coefficients of this reduced equation have been found analytically for the limit cases. The static version of the reduced equation has been used for calculating the threshold characteristics of the shaped Josephson junctions, including the amplitude of "side-lobes". The dynamic version of the equation has been used for the description of the I-V curves of the uniform junctions; viscous flux flow, Eck peak and "displaced linear branch" are particularly discussed.         Microwave radiation from long Josephson tunnel junctions    S. Erne and R. Parmentier Summary: Resonant fluxon propagation in long Josephson tunnel junctions gives rise to the emission of microwave radiation from the junction, which may find applications in the local oscillators of an integrated, Josephson microwave receiver system. We have studied the dynamics of such Josephson fluxon oscillators by numerical integration of the circuit equations of multi-section lumped RSJ-type models.         The influence of self-coupling in Josephson junctions on the lower threshold of the I-V characteristic    S. Erne and H. Lubbig Summary: A study of a dc-current biased retarded tunnel junction is presented. The influence of self-coupling on the hysteresis-characteristic is reported for vanishingly small temperature.         Comparison of the microscopic theory and the RSJ model of Josephson tunneling for calculating the amount of flux entry into a single-junction squid    R. Gayley Summary: Smith and Blackburn and Blackburn et al measured flux entry into single juxtion SQUIDs and found results that disagreed with their calculations, were based on the resistively shunted junction (RSJ) model, Since this model is Known to be very crude, seems worthwhile to see if use of a more accurate theory could remove the discrepancy. Also, this system, or a more complex version of it, holds for use as a high speed computer element, so it is important to understand its behavior in some detail. This paper presents the first study of this SQUID the full BCS theory of superconductivity. The results are quite different from the RSJ model predictions, the disagreement with experiment is made worse.         Frequency dependence of the quality factor of Nb-Nb/sub x/O/sub y/-Pb Josephson tunnel junctions    A. Cucolo, S. Pace, R. Vaglio, V. Lacquaniti and G. Marullo Summary: In the context of Josephson devices optimization for the Italian Voltage Standard manteinance, the frequency dependence of the quality factor (Q) of Nb-Nb/sub x/O/sub y/-Pb tunnel junctions has been carefully measured at various temperatures in the frequency range 10-160 GHz. The Q was determined via the measure of the amplitude of Fiske resonant modes in the junction. The different frequencies were obtained by changing the lenght of the junction after the liquid helium test through a photolitographic process. The results show that for our junctions, for current densities of 1-10 Amp/cm/sup 2/,the only relevant contributions to the Q are the losses associated with the surface impedance of the superconducting films. The data show good agreement with the BCS theory if, as already pointed out by other authors, a small residual term is added to the conductivity.         Microwave impedance measurements of point-contact Josephson weak links    P. Michelson and R. Giffard Summary: We describe measurements of the 10 GHz dynamic impedance of niobium point-contact weak links at 2 K, biased below their critical currents. The measured quantity is /spl Gamma/(/spl omega/), the complex reflection coefficient Of the weak link in parallel with a superconducting cavity resonator terminating a waveguide. Measurements were made at several frequencies close to resonance. In order to interpret the results it is only necessary to assume that the weak link is a two-terminal device consisting of a phase-dependent susceptance in parallel with a phase-dependent conductivity, which is connected to the waveguide through a lossless, phase-independent two-port. The data are consistent with the resistively shunted junction model including a phase-dependent conductance with a negative sign. An important feature of this study was the ability to measure the d.c. IV characteristic simultaneously. The point-contacts investigated had nearly ideal I/sub c/R products, and exhibited reproducibile structure in the differential conductance at the superconducting energy gap voltage.         Frequency conversion of millimeter radiation to X-band with superconducting point contacts    V. D'yakov, V. Gubankov, M. Tarasov and A. Vystavkin Summary: Experimental research directed to making more accurate the existing idea about the Josephson frequency downconverter operation is reported in this paper. The limits when the converter operation qualitatively differs from usual theoretical model are inversigated. The Josephson converter operation peculiarities connected with contact I-V-curve deformation by radiation are considered. It's reported about the performance of the first sample of the F-band jospheson suerheterodyne radiometer. The radiometer passed radiotelescope tests successfully.         Microwave receivers using SQUIDs and Josephson junction arrays    L. Kuzmin, K. Likharev and V. Migulin Summary: Performance of various microwave receiving devices, using the Josephson junctions closed with superconducting loops and/or united in arrays, is discussed. These composite nonlinear elements enable us to eliminate problem of their matching with the signal source, to increase the saturation power and to come close to ultimate limits of the device noise performance. For internally-pumped devices, connection of several junctions in a closed-loop (ring) array turns out to be most effective, with coherent junction self-oscillations. For externally-pumped devices, the use of low-inductance (non-hysteretic) SQUIDs is of the greatest interest, enabling one to avoid the difference in junction dynamics due to parameter random spread.         Broadband RF-coupling to thin-film Josephson and SIS devices    G. Hohenwarter and J. Beyer Summary: The fabrication of a planar fin-line circuit for rf-coupling to Josephson tunnel junctions and SIS devices is reported. E-field coupling is achieved by means of tapered transitions from a rectangular waveguide to a fin-line and from this line to the active device. Its low impedance can be matched by an antipodal fin-line with a fin-separation in the /spl mu/m-range. Circuit parameters have been determined for Nb-Pb-devices mounted in a split Ka-band waveguide. Measurements were performed in the frequency range from 33 GHz and 38 GHz. Mismatches as low as 10 dB have been observed.         Performance limits of the Josephson junction microwave receivers    V. Zavaleev and K. Likharev Summary: The performance limits are found for the Josephson junction microwave receivers: self- and externally-pumped mixers, as well as self-selecting and wideband quadratic detectors. The effect of the signal source impedance upon the Josephson junction properties is considered in two extreme approximations for the junc-, tion matching with the source, the approximations yielding close results. It has become possible to find the device characteristics for the arbitrary values of ratios R/sub E//R/sub n/and F/F/sub c/, where R/sub E/is the reduced source resistance, R/sub n/is the junction normal resistance, F is the signal frequency and F/sub c/is the junction characteristic frequency. The performance factors obtained are optimized and their ultimate limits are found. The relatively poorly-developed devices without external pumping (self-pumped mixer and self-selecting detector) occur to have the best performance limits. Achievement of these limits is possible, however, only if the recently proposed specially-designed multi-junction arrays are used.         Theories of the noise rise in Josephson paramps    M. Feldman and M. Levinsen Summary: A physically very interesting problem is the origin of the gain-proportional noise that distinguishes the zero-voltage Josephson parametric amplifiers. Many radically different theories have been proposed to explain the disturbingly high noise outputs from these devices. Here we collect the known experimental information about the "noise rise", and discuss the various theories in light of the experimental data. We also present some incompletely developed basic ideas which combine aspects of and expand upon the most successful of these theories.         A superconducting tunnel diode oscillator    I. Campisi and W. Hamilton Summary: We have performed some preliminary measurements on a type of tunnel diode oscillator stabilized by two additional cavities. With proper choice of the couplings among cavities and their quality factors, it is possible to tightly lock the oscillator's frequency to a high-Q, superconducting cavity. Although the system is now operating with parameters not yet optimal, we have observed improvements in the stability performance of the three-cavity oscillator over the single-cavity one of a few orders of magnitude.         Microwave properties of thin film NbN SQUIDs with granular weak lines    R. Steiner, A. Flora, B. Deaver Jr. and E. Cukauskas Summary: A series of NbN thin film SQUIDs with transition temperatures ranging from 5 K to /spl sim/14 K are being characterized by microwave measurements at 9.6 GHz. The data are being used to determine the critical current, resistance, and energy sensitivity of each device, to identify features that may be related particularly to the granular nature of the weak links, and to study systematically the variations of the SQUID response with temperature. The devices are nominally 1 /spl mu/m long, 10 nm thick and from 1 /spl mu/m to /spl sim/50 /spl mu/m wide and are fabricated on 1 mm-diameter quartz rods. All have previously been well characterized as SQUIDs at 23 MHz. Detailed results are presented for the first five devices studied.         Resistive squids for thermal measurements    J. Park and A. Vaidya Summary: We describe the results of the first successful measurements of the heat capacity of materials using a 20 MHz resistive SQUID (RSQUID) as a detector of heat current. The method has been tested on samples of Cu and In of mass /spl sim/1 gm. The relative accuracy of these measurements, made between 2 and 7 K, was /spl sim/0.1%, only about twice the uncertainty to be expected if Johnson noise were the only cause of fluctuations. The precautions that had to be taken to achieve this performance in a rather unsophisticated cryostat, and the modifications that will need to be made to it in order to measure the heat capacity of much smaller specimens, will be discussed. Apart from the size of the specimen, the principal factor in determining the accuracy of measurement turns out to be the frequency range /spl delta/f over which the frequency can be allowed to run during a measurement. /spl delta/f is ultimately limited by the frequency of the drive current.         Use of a superconducting instrumentation for biomagnetic measurements performed in a hospital    S. Barbanera, P. Carelli, R. Fenici, R. Leoni, I. Modena and G. Romani Summary: A superconducting instrumentation has been set up to perform biomagnetic measurements for screening analysis in one of Rome hospitals. The magnetic detector is a 2nd derivative gradiometer, which can be balanced against both spatially uniform fields and field gradients. The overall noise level is /spl sim/ 4 /spl times/ 10/sup -14/ T.Hz-1/2 in the frequency range 0.5 /spl divide/ 3000Hz. Main efforts are devoted to the recording of magnetocardio-graphic maps of normal and abnormal subjects while a detailed analysis of some segments of the heart cycle is carried on in subjects previously investigated by means of other techniques. Magnetomyograms of normal and abnormal subjects are detected and studied in the frequency domain. Magnetoencephalographic power spectra of various subjects have been mapped as well. Most remarkable results so far collected are presented. Some of the measurements have been performed in the hospital and some in the laboratory, always without the aid of any shielding.         Operation of an ultrasensitive superconducting accelerometer    W. Oelfke, W. Hamilton and D. Darling Summary: In designing a transducer system for optimum sesitivity one must consider both the properties of the transducer and the input charateristics of the amplifer that is driven by the transducer. There is howerever a type of transducer system, that parametric amplifier transducer, in which the transducer and amplifer are completely coupled into one component.         Some properties of Nb-Nb/sub 2/O/sub 5/-Pb(In) Josephson tunnel junctions for devices applications    J. Villegier and G. Matheron Summary: A detailed investigation of tunneling has been carried out on Nb-Nb/sub 2/O/sub 2/-Pb(In) junctions where the tunnel barrier is made-of Nb/sub 2/O/sub 2/thermal oxide with accurately controlled oxidation parameters. The oxide barrier appears as a n-type semiconductor with two Schottky barriers at the interfaces. The transport of charged oxygen vacancies is supposed to play a fundamental role in the oxidation process. The barrier potential /spl phi/ and the tunnel resistance R have been related to the oxidation parameters. The junctions realized have sizes ranging from 4 to 10/sup 4//spl mu/m/sup 2/, the Josephson current density, dependent on the oxide thickness, is in the 1-10/sup 5/A/cm/sup 2/range. Very low transition times from the superconductive to the normal state have been observed.         Very low noise all-niobium DC SQUIDs    V. de Waal, P. van den Hamer, J. Mooij and T. Klapwijk Summary: All-niobium thin film planar DC SQUIDs have been fabricated, containing submicron tunnel junctions. The fabrication method using photoresist techniques is briefly described. The I/sub c/R product of the SQUIDs is 0.3 mV, the inductance 1 nH. They show no changes after repeated thermal cycling or storage over extended periods. The best intrinsic energy resolution obtained so far in a flux-locked loop configuration is 4 . 10/sup -32/J/Hz. The noise power is an order of magnitude higher than predicted from the simple RSJ model calculation.         A superconducting gyroscope with no moving parts    R. Brady Summary: If a charged cylindrical capacitor is rotated about its axis, the magnitude of the current induced on the inner surface will be a measure of the angular velocity of rotation. In this note we explore the possibility of building such an apparatus with superconducting materials and a SQUID to measure the current. We show that this device is capable of measuring its intrinsic rotation velocity and we consider designs which are sensitive enough to measure the mass of the electron to a high degree of precision or conversely establish a voltage measurement in terms of fundamental constants.         Care and training of superconducting magnets    A. Tollestrup Summary: Superconducting magnets are notorious for the wide gap between the performance that is predicted on paper and that which is achieved for produced magnets. In the early years before multifilamnt conductors becam available, many of the difficulties were associated with flux instabilities. However, the availability of this type of conductor solved this problem, and yet W. P. Smith at RHEL still reported training and degradation in magnets built with such superconductor.         General design aspects of a 300 MVA superconducting generator for utility application    C. Flick, W. McCown and J. Parker Jr. Summary: Development of a 300 MVA electric utility generator with superconducting field winding has been initiated by the Westinghouse Electric Corporation under joint sponsorship with the Electric Power Research Institute. This generator is scheduled to be on line in a U. S. utility by mid-1984 for an extended test and demonstration period. A brief review of the configuration and design features of the 300 MVA machine is given, the emphasis is then shifted to a discussion of the utility environment and its impact on the design of the generator. Specially, system transient events such as faults are covered in terms of their mechanical and thermal consequences for the designer. Finally, the analytical tools and models that are being developed for the present program are discussed.         Superconducting generators: Economics, technical considerations and ancillary technology    J. Bzura, F. Abtahi and L. Stratton Summary: An economic analysis of superconducting generators was performed[1] and compared with analyses by Westinghouse[2] and General Electric[3]. Superconducting generators were compared with conventional generators over a 30-year operating life using three energy sources (nuclear fuel, coal and oil), and including the effects of inflation on fuel and operating costs. The ADL analysis shows that operating cost savings of a 1200 MVA superconducting unit can be approximately 70% of the capital cost of a conventional generator driven by a coal-fired steam turbine. Principal R&D needs for superconducting generators and the limitations of ancillary technology are also discussed.         High-performance superconducting windings for AC generators    T. Laskaris Summary: Superconducting windings are susceptible to mechanical instabilities that degrade their performance. The problem, often referred to as training, results from, wire motion. A technical approach is presented to develop superconducting rotor windings for large generators that are capable of attaining the theoretical maximum current density of the superconductor without training. The winding is assembled from racetrack-shaped, epoxy-impregnated modules, Epoxy impregnation is used to restrict wire motion and frictional heating within the winding. A support structure is shrunk around the winding modules to provide support of the winding against centrifugal and magnetic forces, and restrict sliding movement of the winding relative to the support. Further, a winding interface material is employed to enhance friction so that compression at the winding interface results in frictional forces that are larger than the shear forces. Thus, sliding motion can be prevented. A model superconducting rotor for a 20 MVA generator has been developed according to this technique to simulate the winding electromagnetic loading and interface parameters. The winding was tested statically in a bath of liquid helium. It attained the theoretical maximum current repeatedly without training. The experiments have validated the analytical predictions.         Electricite de France - Alsthom-Atlantique superconducting turbogenerator development program    R. Gillet, J. Goyer, Y. Laumond, A. Marquet and M. Berthet Summary: In this paper, we summarize the studies and tests performed on in progress, intended to solve the technological difficulties peculiar to these machines.         Mechanical and thermal design of the EPRI/Westinghouse 300 MVA superconducting generator    A. Ying, P. Eckels, O. Litz and W. Moore Summary: Westinghouse Electric and the Electric Power Research Institute (EPRI) are engaged in a joint program to develop a 300 MVA generator with a superconducting field winding to demonstrate the increased efficiency, reliability and stability of such units as base load generators. Considerations such as conductor support, transient heating, electrical damping, magnetic shielding and dynamic stability demand creative structural and thermal designs. Unique structural designs are required to support the rotor damper shield and to limit transient torsional loads under fault operation. The rotor cooling system is designed to remove the shielding losses induced by fault operation as well as those encountered during steady state operation. So effective is the cooling system that the winding can undergo resistive transition over a large portion and still recover the superconducting state. The conceptual design of the 300 MVA rotor is reviewed. The structural design and calculated performance of the cooling system during steady state and fault operation are presented. The opportunities presented by new materials and manufacturing technology are summarized. Future developments, and model testing anticipated during the program are reviewed.         A 50 kW homopolar motor with superconducting field windings    A. Arkkio, P. Berglund, J.-T. Eriksson, J. Luomi and M. Savelainen Summary: A short description of the first superconducting motor in Finland is given. The project was completed in two years giving information of the feasibility of superconductivity and liquid metal current collection in motors with application in industry and ship propulsion.         Roughened surface study on japanese test coil for the large coil task    M. Nishi, T. Ando, K. Yoshida, K. Koizumi, S. Shimamoto and K. Yasukochi Summary: The Japanese test coil for the Large Coil Task utilizes a pool cooling method. In order to get better stabilization in the coil, many different roughened surfaces were investigated. Chemically oxidized Thermo-excel-C surface was selected as the cooling surface for the Japanese LCT conductor. The steady state boiling helium heat transfer characteristics of this surface were measured, and even with the coil simulating long narrow cooling channel its equal area heat flux is more than 1.0 W/cm/sup 2/. Stability of the Japanese LCT conductor was analyzed using measured data, and the conductor proved to be sufficiently stable.         Superconductor design and loss analysis for a 20 MJ induction heating coil    M. Walker, J. Declercq, B. Zeitlin, J. Scudiere, M. Ross, M. Janocko, S. Singh, E. Ibrahim, P. Eckels, J. Rogers and J. Wollan Summary: The design of a 50 kAmpere conductor for use in a 20 MJ Induction Heating Coil is described. The conductor is a wide flat cable of 36 subcables, each of which contains six Nb-Ti strands around a stainless steel core strand. It is cryostable, with a pool-boiling, fully-normal equivalent heat transfer from the unoccluded strand surface of 0.26 Watts/cm/sup 2/. A thin, tough polyester amide-imide insulation enhances heat transfer and prevents interstrand coupling. The tightly-twisted strands are configured using Cu-Ni elements to provide low AC losses with Nb-Ti filaments in an all-copper matrix. AC losses are expected to be approximately: (1) 0.3% of 20 MJ for a -7.5 T to 7.5 T one-second 1/2-cosinusoidal bipolar operation in a 20 MJ coil, and (2) for additional reference, 0.1% of 100 MJ for a 1.8 second -8 T to +8 T ramped operation in a 100 MJ coil with a heat transfer of 0.36 Watts/ cm/sup 2/. The design is based on the manufacture and testing of prototype strands and subcables.         Physical, mechanical and electrical properties of MF NbTi superconductors    J. Scudiere, R. Schwall, K. Mortensen, D. Hazelton and B. Zeitlin Summary: This paper is divided into two main sections: First, we describe the significant physical and electrical properties of seven (7) different conductors. The physical and electrical data presented includes photographs of manufactured conductor, conductor size, critical current, critical current density overall copper to superconductor ratio. The second section presents compressive modulus measurements.         Fabrication of the NbTi compacted monolith conductor for Elmo Bumpy Torus (EBT-P) prototype coils    S. Hong, E. Adam, E. Gregory, D. Koop and W. Marancik Summary: Unique 6 T and 8 T 2800 A NbTi monolithic superconductors are being manufactured for the Elmo Bumpy Torus (EBT-P) prototype magnets at Oak Ridge National Laboratory. A novel manufacturing process is employed to fabricate conductors having higher current densities and longer continuous lengths than are achieveable by the usual production technique for large monolithic conductors. The critical currents, residual resistivity ratios and mechanical strengths are reported.         Manufacturing and testing of a forced flow cooled superconductor for Tokamak magnets    H. Krauth, A. Nyilas, H. Hoflich and J. Rudolf Summary: A forced flow cooled NbTi-conductor with a nominal critical current of 15 kA at 8 T has been developped jointly by KfK and Vacuumschmelze. It will be used in the EURATOM coil for the Large Coil Task. The design principles are described and the main parameters are presented. Major part of the paper is devoted to the description of the manufacturing of the conductor and of its constituents. A survey on the testing of the conductor and its components is given.         Constructing, fabricating and forming internally-cooled cabled superconductors    M. Olmstead and M. Hoenig Summary: A designer using an ICCS conductor in building a coil must consider the force required to form his coul and tool accordingly. In winding the ICCS-HFTF (12T) model coul a torque of 1,2000 ft. -lbs. was required to form the conductor. The spring-back forces must also be accounted for. The model coil conductor required a moment oa approximately 310 ft.-lbs. to precent spring-back. The model coil in its fully wound condition will be subjected to heat treatment required for the activation of its NB/sub 3/Sn superconductor.         Summary data from large scale quality control tests on superconducting wire    W. Fowler, M. Kuchnir, R. Flora and R. Remsbottom Summary: The construction of superconducting magnets for the Energy Saver Synchrotron caused the procurement Fermilab of 3x10/sup 7/m of multifiliamentary NbTi wire. This .68 mm diameter wire is composed of /spl sime/2X10/sup 3/ filaments 8/spl mu/ diameter in a copper matrix with 1.8:l copper to superconductor ratio. It is now the most common superconductor wire commercially available. A previous publication describes how lengths of this wire are managed for the manufacture of a 23-wire cable of Rutherford type for final use in the winding of our magnets. Here we present the results of short sample tests done on these wires by the manufacturer for every half billet (-5x10/sup 4/m) and by Fermilab on the cables for every reel to be used in a magnet.         Nb- and Nb/sub 3/Sn-cavities produced by sheet material    N. Krause, B. Hillenbrand, H. Pfister and Y. Uzel Summary: X-band TM/sub 010/cavities have been fabricated from Nb sheets by spinning and welding together. Studies of different surface preparations have shown that smooth surfaces and relatively good RF properties can be obtained by a simple chemical polishing treatment. Also the degradation caused by welding can be overcome by chemical polishing without any heat treatment. On welded TM/sub 010/cavities critical flux densities of more than 70 mT and high-field Q-values of 5.10/sup 9/have been measured. Up to this field level no electron loading was observed. This procedure is very promising for the fabrication of Nb cavities for technical applications as well as of substrates for Nb/sub 3/Sn cavities.         Microwave surface resistance of Nb films    T. Yogi and J. Mercereau Summary: The surface resistance, R/sub s/, of niobium (Nb) films has been experimentally investigated as a function of thickness, preparation technique and substrate material at 8.86 GHz. Nb films were prepared by either sputtering or evaporation in the thickness range Between 0.1 /spl mu/m and 3.0 /spl mu/m on either copper (Cu) or sapphire substrate. R/sub s/was determined using a cylindrical TE/sub 011/mode resonant cavity with one removable end-plate which was utilized as the test substrate. The low field R/sub s/at 4.2 K is lower than that of bulk Nb and shows good agreement with BCS calculation which takes into account the effects of mean free path. The temperature dependence of R/sub s/indicates a normalized film gap parameter, /spl utri/(0)/KT/sub c/, nearly equivalent to the bulk value for most of the films. At low temperatures, R/sub s/is dominated by residual resistance (R/sub 0/) which approaches 1 /spl mu//spl Omega/. The overall characteristics of Nb on Cu (Nb/Cu) indicate that this composite material is potentially useful in applications requiring high rf field as well as high thermal stability.         Generation of high-power microwave pulses using a spherical superconducting cavity and interference-type switch    R. Alvarez, D. Birx, D. Byrne, M. Mendonca and R. Johnson Summary: We have generated 150 kW pulses of 2 /spl mu/sec duration at 8.2 GHz frequency by rapidly dumping the energy stored in a nearly spherical superconducting cavity of 1.5l volume. The cavity was constructed of copper and electroplated with lead. A small geometrical perturbation was introduced to define a polar axis and suppress some unwanted modes. The mode excited was a fairly pure TE/sub 320/mode. Intrinsic Q values greater than 10/sup 9/were achieved at 1.7 K, which allowed an energy accumulation of /spl sim/ 0.3 joule with a drive power of about 300 watts. Energy input and pulse extraction were both achieved through a single aperture coupled to a rectangular waveguide by an interference type switch and variable coupler.         Test of a /spl Beta//spl sime/ 0.1 superconducting split ring resonator    J. Delayen, G. Dick and J. Mercereau Summary: A split-ring resonator of /spl beta/sub 0/ /spl sime/ 0.1designed for use in the Stony Brook heavy-ion booster has been developed and tested. The resonator, operating at 150 MHz and with an effective length of 21 cm was constructed of OFHC copper and electroplated with lead. Losses of 8.5 W at an accelerating field of 3.0 MV/m and 11 W at 3.25 MV/m were obtained; the resonator could be operated continuously up to at least 3.5 MV/m without breakdown or thermal run-away. Vibration-induced frequency excursions were found to be small (/spl sim/ 20 Hz pp). Under these conditions the split-ring resonator was electronically stabilized to an accuracy of 0.005 radian at 2.5 MV/m.         On residual RF losses and tunnel currents caused by interface states    J. Halbritter Summary: Superconducting rf cavities show large residual losses R/sub res/which limit the application of such cavities Beside the coherent phonon excitation by interface states (IS), the up till now neglected incoherent phonon excitation will be discussed as cause for residual losses R/sub res/. But IS also weaken the superconducting interaction and enhance the current through the oxide by resonance tunneling, e.g., as super, - leakage - or assisted current in tunnel junctions. Parameters influencing the IS and the residual losses, the weakening of the superconducting interaction and the enhanced tunnel currents will be worked out for Nb-Nb/sub 2/O/sub 2/-interfaces.         Field strength limitations in superconducting cavities-multipacting and thermal breakdown    H. Padamsee, D. Proch, P. Kneisel and J. Mioduszewski Summary: High field strengths in Niobium cavities can be achieved if multipacting (MP) and "thermal magnetic" breakdown phenomena are understood and arrested. Substantial progress has already been made with respect to multipacting, opening the possibility for low frequency superconducting accelerators for high energy physics applications. The techniques used hitherto, are, however, structure dependent and thereby sensitive to detail cell geometry. We report on a successfully applied, new technique that is structure independent and therefore holds promise for more general application. The essential idea is to incorporate deep grooves within the multipacting surface.         On the temperature and frequency dependence of the surface resistance of superconducting Nb    A. Philipp and J. Halbritter Summary: Surface resistances R(T,f)of superconducting Nb show /spl utri/-values well below the bulk value and a frequency dependence deviating from homogeneous Nb. So, surface resistances in various modes between 12 and 18 GHz have been measured for the first time. As results, /spl utri//kT/sub c/is increasing from 1.83 to 1.87 with frequency, andR_{sc}(4.2 K) \propto f^{1.63 \pm 0.02}has been fitted to the data. This with f improving agreement with what is anticipated from the BCS theory of homogeneous Nb can either be explained by rf induced superconductivity or by h.f being larger than the smearing of the density of states by weak superconducting spots.         The properties of superconducting resonators on sapphire    V. Braginskii, V. Panov and S. Vasiliev Summary: Superconducting resonators are widely used in experimental methods. Their high Q-values and stability give the opportunities to improve the limit possibilities in various methods of research and create autooscillator with narrow bandwidth. The results of the research of TM/sub 010/ superconducting resonators at /spl sime/ 3GHz consisting of sapphire coated with niobium and lead films are presented in this report.         Experimental and theoretical investigations of losses in a multifilament composite subjected to transient axial fields    F. Lefevre and B. Turck Summary: In a twisted multifilament composite subjected to transient axial fields three kinds of currents are induced: azimuthal currents in the matrix, azimuthal currents and coupling longitudinal currents in the filaments. Considering only the currents in the filament themselves, the hysteretic losses due to the azimuthal component J/sub c/of the critical current density are usually the largest. However, when the coupling longitudinal currents flow in the outer layers of filaments in the same direction than the transport current their contribution become preponderant. Again, the theory shows three regimes depending only on the ratio of the amplitude of the changing field over a given threshold field, proportional to the twist pitch length of the composite. Experimental results clearly confirm the theory, in particular the increase of losses with transport current in a multifilament when only little effect was observed in a monofilament.         A high-field bipolar loss measurement apparatus    P. Thullen, D. Weldon and J. Wollan Summary: An apparatus has been constructed to measure dissipation in superconducting wire in high alternating fields. The apparatus will be used to make measurements on conductors which must operate in fields up to 7.0 T and rates of field change up to 15 T/s. The magnet for this facility is wound of uninsulated, 15 strand Rutherford cable in which the strand is a 0.812 mm diameter, fully mixed matrix, Cu plus CuNi, multifilament NbTi conductor. The coil is wound in a bath cooled configuration with an overall current density of 7.8 kA/cm/sup 2/. The circuit incorporates a pair of locomotive traction motors as the capacitive circuit element for the bipolar swing. The design, construction and operating characteristics of the field coil and the associated circuitry are described.         Transient field losses in multifilamentary composite conductors carrying transport currents    T. Ogasawara, M. Itoh, Y. Kubota, K. Kanbara, Y. Takahashi, K. Yasohama and K. Yasukochi Summary: Investigations of the losses in multifilamentary composite conductors which result from the simultaneous change of the external field B/sub e/and transport current I are presented. The total loss is best characterized by a maximum normalized transport current i/sub m/= I/sub m//I/sub c/(I/sub c/= critical current) and a dimensionless field-change rate /spl beta/ = /spl tau//spl dot B/sub e//B/sub p/, where /spl tau/ is the relaxation time of the coupling current and B/sub p/is the full-penetration field of a solid superconductor equivalent to the multifilamentary composite. For /spl beta/ /spl gsim/ 1, the composite conductor behaves like a solid and a saturation effect occurs in the loss. The characteristic feature of the composite appears only for /spl beta//spl lsim/ 1. The increase in losses arising from the non-zero transport current theoretically, is not larger than about 30 percent. For practical calculations, the experimental results over a wide range of /spl beta/ and i/sub m/agree well with the theory.         Losses in superconducting magnets under fast ramp rate operation    D. Ito, Y. Nakayama and T. Ogasawara Summary: AC losses in superconducting Pulse magnets have been investigated in order to establish a method which yields a quantitative calculation of the losses. The pulse magnets, l/sub c/ /spl sim/ 1000 A and B/sub max/ /spl sim/ 5T, wound from different kinds of Nb-Ti multifilament superconductors, were operated at the ramp rate over the range from 0.1T/sec to 40T/sec. The associated losses were measured by the calorimetric method. The conductor types employed in the present magnets were a monolith with Cu-matrix, a monolith with Cu-Ni barriers and a stranded cable. The transient losses in the magnet wound with the Cu-matrix monolithic conductor were found to be saturated at the ramp rate in excess of 0.25T/sec. In these experiments, no quench was observed. The results were discussed in terms of our loss model: The parameter which characterizes the loss is a dimensionless sweep rate /spl beta/= /spl tau//spl dot/B/sub e/B/sub p/, where /spl tau/ is the relaxation time for the coupling current, /spl dot/ B/sub e/is the external field and B/sub p/is the full-penetration field for the composite. For /spl beta/ /spl ges/ 1, the composite behaves like a solid conductor, so that the AC loss is expected to be saturated as observed.         Influence of surface layer and trapped flux on minimum A.C. losses in superconductors    M. Ciszek, S. Golab, G. Kozlowski and P. Tekiel Summary: The influence of a surface layer trapped magnetic flux on low frequency (115 Hz) losses in Nb - 50% Ti superconducting alloy were investigated in the presence of a static and an alternating magnetic field, both parallel to the long side of the sample. A minimum in the a.c. loss versus the bias magnetic field was observed at a constant value of the magnetic field amplitude which exceeded the first penetration field. It is shown that the minimum of the a.c. loss is strongly influenced by trapped flux in the sample. The depth of a. c. loss minimum is decreased as the trapped magnetic flux increases. The position of the minimum as a function of the static magnetic field is studied for different amplitudes and the trapping field.         AC losses in Nb/sub 3/Al-Nb layered multifilamentary wires    M. Asdente and A. Ricca Summary: AC power losses of monofilamentary and multifilamentary wires, whose filaments have a layered Nb/sub 3/Al - Nb structure, have been measured. We have investigated the role of the two superconductors present in the wire (Nb/sub 3/Al and Nb) and the relevance of the reaction,time between Nb and Al, for the superconducting properties of the wire.         Critical current density and low field losses in Nb/sub 3/Sn    J. Charlesworth Summary: Assuming a dependence of critical current density J/sub c/on magnetic field H of the form J/sub c/=/spl beta/H/sup -p/, where /spl beta/ and p are positive constants, ac losses have been calculated and compared with measured losses in multifilamentary Nb/sub 3/Sn. For p=0.5, good agreement is found for fields parallel to the filament axes, provided a strongly field dependent surface current is taken into account. A small discrepancy between critical current densities calculated from losses and those measured directly may arise from the irregular filament shape. In transverse field, surface effects can be neglected but good agreement with theory is found only when filament cross-linkage is absent. Comparison of calculated and directly measured critical current densities may indicate that the theory requires a minor modification. Losses measured as a function of bias field show a well-defined minimum which, in parallel field, agrees with a surface screening model. In transverse field no agreement with theoretical models is found but the influence of the reversible magnetisation may be observable.         Studies on "in situ" processed V/sub 3/Ga composite superconductors    K. Togano, H. Kumakura and K. Tachikawa Summary: A systematic study on the 'in situ' process for the fabrication of V/sub 3/Ga composite superconductors has been carried out, because V/sub 3/Ga exhibits larger critical current density at high magnetic fields than any other practical superconductor. A method for producing the in situ composites of long length has been also attempted in the present study, utilizing a nonconsumable electrode continuous arc casting and a continuous gallium coating by dipping process. It has been found that both the superconducting properties and mechanical properties of the in situ V/sub 3/Ga composite are strongly dependent on its composition. An overall J/sub c/of about 10/sup 5/A/cm/sup 2/at 4.2 K and 13 T was obtained for the external diffusion processed in situ V/sub 3/Ga composite, which is superior to those of the commercial V/sub 3/Ga multifilamentary wires fabricated by the conventional bronze process. The performance of the in situ V/sub 3/Ga composite superconductors has been evaluated taking into account the results of the stress effect measurements under tensile and bending deformations.         Further development of powder processed multifilamentary superconductors    R. Murphy, R. Akihama, S. Foner and B. Schwartz Summary: Progress in the development of powder metallurgy (P/M) processing of multifilamentary superconductors is discussed for 4 approaches: 1) Cu-Nb-Sn wires were fabricated using internal microscopic diffusion of Sn produced by Sn powder or prealloyed (SnCu) powder; 2) Cu-NbTa-Sn was produced with prealloyed Nb 4 wt % Ta and Nb 7 wt % Ta powders and external Sn diffusion; 3) hot processing was demonstrated using sintering or hydrostatic extrusions with Cu and Nb, or Cu and NbTa powders with or without Al as a function of particle size; and 4) Nb-Al material was develop ed with a (P/M) process. All show high overall critical currents at high field, good strain tolerance, and promise for scaleup processing.         Degradation of transition temperature and critical current density in neutron irradiated Nb/sub 3/Sn and V/sub 3/Ga    S. Shiota, S. Nishijima and T. Okada Summary: The effects of neutron irradiation on transition temperature of Nb/sub 3/Sn wire and V/sub 3/Ga tape conductors have been investigated. Samples were irradiated in the Japan Material Testing Reactor (JMTR) at = 150/spl deg/C with the neutron flux (E/sub n/> 1 MeV) of 1x10/sup 13/n.cm/sup -2/.sec/sup -1/. Transition temperature, critical current density and long range order parameter were followed on V/sub 3/Ga against neutron fluence up to 2.9 X 10/sup 19/n.cm/sup -2/. It was found that the irradiation reduces T/sub c/as much as 60% in V/sub 3/Ga for a fluence of 2.9x10/sup 19/n.cm/sup -2/. Study on T/sub c/change together with annealing behavior strongly suggests the necessity of appropriate shielding in its application to fusion magnets.         Critical current density and superconducting parameters T/sub c/, H/sub c2/, and k in neutron-irradiated and annealed V/sub 3/Si    R. Meier-Hirmer, T. Reichert and H. Kupfer Summary: Single and polycrystalline V/sub 3/Si was neutron irradiated at 240/spl deg/C up to a fluence of 1.2x10/sup 19/cm/sup -2/and subsequently isochronally annealed up to 1330/spl deg/C. Measurements include the critical current density, j/sub c/, the critical temperature, T/sub c/, the upper critical field, H/sub c2/, and the residual resistance. Dislocation loops are identified by TEM as the part of the radiation induced defects responsible for j/sub c/. Two different annealing temperatures are found for T/sub c/and j/sub c/, respectively. Due to the high irradiation temperature, T/sub c/recovery occurs in one stage only, corresponding to thermally produced vacancles. All samples exhibit a scaling behavior of the volume pinning force between 0.9 and 0.6 reduced temperature. A j/sub c/(H) peak is observed at low fluences and high annealing temperatures. The explanation for this behavior is based on a concentration dependent reduction of the theoretical threshold. A saturation behavior of the volume plnning force for high fluences and low annealing temperatures is observed, which is in quantitative agreement with the high-field mechanism of Kramers model above 0.8 reduced field. With these results we can explain the field dependent enhancement of j/sub c/after neutron irradiation of A15 superconductors with grain boundary pinning.         Effect of the thickness of aluminum layer on the transport properties of Nb/sub 3/Al superconducting wires    B. Annaratone, R. Bruzzese, S. Ceresara, V. Pericoli-Ridolfini, G. Pitto and N. Sacchetti Summary: As reported in preceding papers multifilamentary Nb/sub 3/Al wires have been successfully developed by using a peculiar fabrication technique. Taking advantage of this technique it has been possible to investigate the effect of the thickness of aluminum layer on the transport properties of the superconducting compound Nb/sub 3/Al. This thickness plays an important role in the formation of the intermetallic compound with good superconducting properties as an aluminum thickness above a certain value leads to the presence of spurious phases. Experimental results concerning critical current densities, and critical temperatures are given and discussed in terms of their aluminum thickness dependence. As a general feature J/sub c/increases with decreasing aluminum thickness and this can be accounted for in terms of low temperature (<1000/spl deg/C) formation mechanisms of the superconducting phase.         Development of stabilized Nb/sub 3/Sn wire containing a reduced number of filaments    J. Elen, J. Schinkel, A. van Wees, C. van Beijnen, E. Hornsveld, T. Stahile, H. Veringa and A. Verkaik Summary: Progress is reported on the development of production techniques for stabilized Nb/sub 3/Sn multifilament wire based on reaction of niobium clad NbSn/sub 2/powder filaments. The superconducting properties - T/sub c/above 17.9 K and J/sub c/(4.2 K, 14 T) of 2.2x10/sup 9/A/m/sup 2/- are shown to be independent of filament diameter. The requirement of adiabatic stability imposes an upper limit of approximately 900 /spl mu/m/sup 2/on the cross sectional area of Nb/sub 3/Sn in the filaments. A production sequence based on wire drawing is illustrated by a 0.56 mm 19-filament wire with a Cu/s.c. ratio of 6.0, which has a critical current of 152 A at 4.2 K and 8 T. Development work on a more economic reduction by extrusion is being continued.         Development and fabrication of 12 tesla Nb/sub 3/Sn superconductors    C. Spencer, E. Adam, E. Gregory, S. Hong, D. Koop and G. Reverri Summary: The fabrication techniques for large pool boiling conductors for the High Field Test Facility (HFTF) , the General Dynamics-Airco 12 T model coil, or a Fusion Engineering Device (FED) are presented. These conductors are manufactured as follows: fabrication of long continuous lengths of a high-current core are fabricated by campacting a cable of small strands in a continuously seam welded copper tube. The operating current of the HFTF conductor is at 5000 A at 12 T/sup 1/. To provide additional wetted surface areas for cooling, the reacted compacted monolith is continuously soldered to embossed copper strips Bond quality is continuously monitored with ultrasonic testing techniques. The operating current of the General Dynamics-Airco 12 Tesla model coils 12.5 kA at 12 T/sup 2/and the compacted monolithic core is joined to a large aspect ratio copper stabilizer by brazing or diffusion bonding. Preliminary properties of brazed joints are reported.         Bronze for superconducting wires: The powder metallurgy approach    D. Holmes, A. Adair, C. Oberly and J. Ho Summary: Present methods for making high tin content bronze, suitable for use in superconductor wire, have proven difficult to scale up for production of large diameter billets. An homogeneous, fine grain size bronze is essential for fabrication of ultrafine filament Nb/sub 3/Sn composite wires, using the bronze process. A method for producing uniform powders by forced convective cooling of molten particles has made possible a uniform bronze powder, which can be formed into a billet by powder metallurgy techniques. Test billets, made by vacuum hot pressing the rapidly solidified powders inside containers, were examined for homogeneity, grain size, and compaction. As compared to vacuum or continuously cast bronzes, improvements in homogeneity and grain size were found for powders hot pressed for 2-4 hours at 500-700/spl deg/C.         Preparation of high performance Nb/sub 3/Sn tape by a high tape rate CVD process    No author information available Summary: We have investigated some growth characteristics of Nb/sub 3/Sn layer in continuous CVD process. A new CVD technique has been developed by the authors for preparing commercial Nb/sub 3/Sn tapes (2.5 mm in width, 8-10 um thick layered films per side) so as to increase the tape productivity to 50-100 m/hn. In this case, the I/sub c/'s and J/sub c/'s of short samples have reached 600 780A and 1.4-1.6x10/sup 6/A/cm/sup 2/at 4.2 K and 4-5 T, respectively, and single long tapes of about 1000 m in length, wound into 18 mm I.D. and 100 mm high solenoids, have generated a /spl sim/10 T magnetic field as they carry a current of 150-180 A at 4.2 K; the corresponding values of J/sub c/(Nb/sub 3/Sn) and J/sub c/(conductor) have reached 3-5x10/sup 5/A/cm/sup 2/and 4-5x10/sup 4/A/cm/sup 2/, respectively.         Microstructure and superconductivity of some C15 laves phase alloys: V/sub 2/Hf, V/sub 2/Hf/sub .51//Nb/sub .49/ and V/sub 2/Hf/sub .51/Nb/sub .21/Ti/sub .28/    H. Khan and W. Schauer Summary: Effect of different heat treatments on the lattice structure, microstructure and superconductivity of the C15 phase materials: V/sub 2/Hf, V/sub 2/Hf/sub .51/Nb/sub .49/and V/sub 2/Hf/sub .51/Nb/sub .21/Ti/sub .28/are investigated. X-ray, optical microscopy and SEM investigations show the distribution of C15 phase filaments (10-25/spl mu/) in a bcc matrix for the V/sub 2/Hf/sub .51/Nb/sub .49/and V/sub 2/Hf/sub .51/Nb/sub .21/Ti/sub .28/materials. The composition of the filaments is sensitive to heat treatment and the maximum ratio of V to Hf, Nb and Ti atoms is obtained after annealing the V/sub 2/Hf/sub .51/Nb/sub .21/Ti/sub .28/at (1200/spl deg/C;6h). T/sub c/increases and the Vicker's hardness decreases after the substition of Nb and Ti for the Hf in V/sub 2/Hf compound. Maximum T/sub c/and H/sub c2/(8K) values of 9.76K and 9.4 Tesla are also observed for the annealed (1200/spl deg/C;6h) V/sub 2/Hf/sub .51/Nb/sub .21/Ti/sub .28/alloy. Anomalies in (R vs. T) and (/spl chi/sub m/ vs. T) curves are observed for the homogeneous V/sub 2/Hf (annealed 900/spl deg/C;70h) at /spl sim/130K and 150K respectively, whereas multifilamentary annealed (900/spl deg/C;70h) V/sub 2/Hf/sub .51/Nb/sub .49/and V/sub 2/Hf/sub .51/Nb/sub .21/Ti/sub .28/do not show such anomalies. T/sub c/values of annealed (900/spl deg/C;70h) V/sub 2/Hf, V/sub 2/Hf/sub .51/Nb/sub .49/and V/sub 2/Hf/sub .51/Nb/sub .21/Ti/sub .28/are 8.89K, 9.07 and 9.71K respectively. It is concluded that for these alloys the lattice instability is microstructure dependent and does not influence the superconducting parameters.         High critical currents obtained by heat treating rapidly quenched Hf-Zr-V metallic glasses    M. Tenhover Summary: We have found that metallic glasses can be formed in the Hf-V, Zr-V, and Hf-Zr-V systems by rapid quenching. The importance of this finding is threefold: 1) Like many metallic glasses these glasses exhibit excellent mechanical properties. 2) Using well established rapid quenching techniques the material can be economically produced as ribbon, filament, or powder. 3) Because the amorphous material is homogeneous on an atomic scale a variety of microstructures not obtainable by standard metallurgical procedures are possible. These glasses represent a potentially useful starting material for the fabrication of high field, high current superconducting devices. Completely amorphous samples were not found to be superconducting above 2 K. Controlled growth of the C-15 Laves phase compound by heat treating the glasses results in materials having J/sub c/(4.2 K) 10/sup 5/A/cm/sup 2/at H/sub applied/= 150 kOe.         The resistivity and plasmon energies of bcc and A-15 superconductors    F. Cadieu, L. Baumel and W. Yeh Summary: Measurements have been made of the plasmon energies in Nb, bcc Nb/sub 1-y/Ti/sub y/alloys as a function of y, and Nb/sub 1-x/Ge/sub x/samples as a function of x. The samples investigated are 1 micron thick film samples synthesized by selectively thermalized trisputtering. Samples of these systems can be synthesized in an amorphous as well as a crystalline state. Measurements of the plasmon energies have been made by electron energy loss spectroscopy. The measurements reported here were made with a primary electron beam energy of 80eV. For pure Nb a plasmon energy of 9.65/spl plusmn/0.10eV was measured. For A-15 Nb/sub 3/Ge a value of 4.91 /spl plusmn/ 0.08eV was measured. For Nb/sub 3/Ge from our resistivity data combined with this plasmon energy we calculate a value ofh\tau\min{ep}\max{-1} = 0.148\pm0.017eV for the electron phonon relaxation time. The intensity of the plasmon peak as a function of x and y was observed to correlate with the high T/sub c/composition region. Samples have been characterized by T/sub c/, resistivity, X-ray diffraction, X-ray fluorescence, and Auger measurements.         Preparation and superconducting properties of MoN and MoC in form of wires    E. Saur, H. Schechinger and L. Rinderer Summary: Methods for the preparation of MoN and MoC in form of wires by diffusion of N and C, resp. into Mo wires of 0.5 mm in diameter at high temperatures have been developed. MoN samples were made by heating the Mo wires at temperatures between 750 and 950/spl deg/C in a stream of ammonia gas under atmospheric pressure, whereas MoC samples were prepared by heating the Mo wires at temperatures between 1900 and 2160/spl deg/C in a methane gas stream under low pressure between 10 and 20 Torr. MoN crystallizes in the hexagonal WC type structure, but MoC prefers as many of these interstitial compounds the cubic NaCl type lattice. Both materials show fairly sharp transitions to superconductivity at temperatures (midpoints of the transition curves) of 12.95 K for MoN and 12.22 K for MoC. The composition of the samples has been controlled by microprobe analysis.         Method of making continuous length superconducting wires using chemical vapor plating    G. Miller Summary: A method is described for making continuous lengths of superconducting wires using chemical vapor plating techniques and employing a radio-frequency standing wave for heating the substrate. This method was developed for making continuous wires of titanium diboride of high strength and melting point for ablative liners of rocket motors but is adaptable for making wires of niobium-germanium, niobium-gallium, niobium-tin or other similar superconducting materials. A unique feature involves controlled heating of substrate wires of about 0.5 mil diameter of zirconium, niobium, tungsten or other suitable metals by radio-frequency. This is accomplished by using an appropriate antenna arrangement which creates a standing wave to attain wire temperatures in a desired range of 800/spl deg/ to 1300/spl deg/C. Ordinary resistive heating cannot be used alone but may be used to augment the r.f. heating. Vaporized halide salts containing the substances to be plated are introduced into the plating chamber along with hydrogen and a suitable diluent such as argon. The substrate, drawn continuously through the chamber, and heated to the proper temperature receives the depositing superconducting material which builds up to a controlled diameter of 2 to 5 mils as desired. The continuous wire can be conveniently fabricated into superconducting motors, magnets, cables for power transmission, or other devices.         A solder bond requirement for large, built-up, high-performance conductors    R. Willig Summary: Some of the large built-up conductors being fabriccated for large superconducting magnets are designed to operate above the maximum recovery current. Because the stability of these conductors is sensitive to the quality of the solder bond joining the composite superconductor to the high-conductivity substrate, a minimum bond requirement is necessary for an acceptable design. The present analysis finds that the superconductor is unstable and becomes abruptly resistive when there are temperature excursions into the current sharing region of a poorly bonded conductor. This abrupt transition, in turn, produces eddy current heating in the vicinity of the superconducting filaments and causes a sharp reduction in the minimum propagating zone (MPZ) energy. This sensitivity of the MPZ energy to the solder bond contact area is used to specify a minimum bond requirement. For the superconducting MHD magnet being built by General Electric for the Component Development Integration Facility (CDIF), the minimum bonded surface area is .68 cm/sup 2//cm which is 44% of the composite perimeter.         Persistent normal regions in large conductors    M. Hilal, R. Willig and R. Thome Summary: Persistent normal regions, which continuously generate joule heat and reduce the stability of a conductor, can exist in the large built-up conductors being fabricated for large superconducting magnets. Many of these large conductors consist of a composite superconductor soldered to a high-conductivity substrate of copper or aluminum. For these conductors, delaminated lengths can exist which prevent full recovery and result in persistent normal zones. Delaminated lengths less than a certain critical length the conductor will always be able to recover. A simple analytic formula is derived for this length and compared with the results of a more accurate analysis. The critical length is found to be 2.1 cm for the conductor employed in superconducting magnet for the Component Development and Integration Facility (CDIF/SM) and 1.9 cm for the conductor employed in the General Dynamics Test Coil for the Large Coil Program. The length depends on the amount of normal metal in the composite and in the substrate, the bath temperature, the transition temperature of the superconductor, the operating current, and the critical current.         Effects of soldering void on recovery characteristics of a cryostable superconductor    Y. Huang and S.-T. Wang Summary: A conductor for a cryostable magnet is usually made by soldering a superconducting matrix to an OFHC copper strip. The presence of voids between the matrix and the stabilizer due to the imperfection in the soldering bond is of great concern to magnet designers. An experiment was set up to investigage the effect of the void on the characteristics of hot end recovery and cold end recovery for CFFF superconductors. Tests were made on samples having different lengths of soldering void under various magnetic field strengths and injecting energies. The recovery current and the temperature distributions along the matrix and the copper stabilizer were mentioned. The test results are presented.         Current sharing in an insulated multistrand cable in transient and steady state current conditions    D. Faivre and B. Turck Summary: In a cable mace of insulated strands, the current distrubution is fundamentally different in transient and steady state condition. During a current sweep, the current is redistributed as a function of the flux linked by each strand. Linear theory based on the knowledge of all the self and mutual inductances between strands, can to a first approximation account for determining the current in each strand. In a cable supplied with DC current, ony the lattice of parallel and series resistances plays a role in assigning the currents. In an actual cable, we show that, the current in a strand is function of the resistance of the transfer length region near the current leads.         Study of stress/strain effects on superconducting composite system a coil simulation experiment on potting    T. Okada, S. Nishijima and T. Horiuchi Summary: A new facility is completed which is capable to study stress/strain effects on "training" in 'race track' shaped small coil with 120 mm length and 14 mm width. Several potting materials were examined as the important component of "composite" and several new findings are reported.         Energy pulses required to quench potted superconducting magnets at constant field    D. Waltman, M. Superczynski, F. McDonald and D. Taylor Summary: Epoxy impregnated superconducting magnets can be subjected to energy inputs from external sources or from stored energy released in the coil composite. If the energy released is sufficiently large, the temperature will rise locally driving the conductor normal causing a magnet quench. Several superconducting coils were constructed to determine the magnitude and size of disturbances required to cause a quench. These coils were wound from multifilament NbTi conductor, then impregnated with epoxy which was fiberglass reinforced. Small electrical heaters of various sizes were embedded in the coils to initiate a normal zone. These coils were placed in a background magnetic field ranging from 0 to 5.5 T and the energy required to cause a quench was determined as a function of the ratio of operating current to critical current at a constant field. The different size heaters allowed the energy to be distributed over various conductor volumes and the effects of the energy spatial distribution was determined.         Mechanical and heat transfer models for frictional heating in superconducting coils    K. Tepper Summary: Some mechanisms which can cause slip in superconducting coils are identified. Simple worst case elasticity models are developed which predict the magnitude of the relative motions and the frictional heat generated. A general heat transfer model is presented which predicts temperature rises in the superconductors. The model is applicable to superconducting windings with turn-to-turn insulation, where the slip occurs at an insulation-to-insulation interface. The model assumes the slip occurs in zero time in order to take into account the possibility of "stick-slip".         Acoustic emission from superconducting magnets and superconductors    M. Sinclair, O. Tsukamoto and Y. Iwasa Summary: Acoustic emmission can provide information about the global state of a magnet, and this may give warning of an impending crisis. By montereying acoustic emmision signals of magnets being charged, we have been able to successfully predict quench points at a current level 75% of quence current. Acoustic emission, therefore, may be used as a diagnostic tool and has tremendous potential in quence prediction and in assuring safe operation of superconductiong magnets.         Frictional disturbances in superconducting magnets    R. Kensley, H. Maeda and Y. Iwasa Summary: In large superconduction magenets, the main source of hear input in the winding is frictional heating, which results from conductor movement. Since frictional heat is given by the procuct of friction force and sliding velocity, it is important to reduce the sliding velocity to limit the frictional and sliding behaviors at 4.2K of metal/sinsulator pairs commonly used in superconduction magnet windings, the following serious of experiments has been developed.         Effect of cable-in-conduit geometry on stability and quench characteristics    C. Marinucci and G. Vecsey Summary: The effect of cable-in-conduit geometry on stability and the quench characteristics of force-cooled superconductors is studied by numerical analysis. The transient stability model and its extension for quench calculations, developed last year at SIN, are modified using a simplified approach. The analysis is applied to one of the matrix conductors evaluated during the conceptual design phase of the Swiss LCT coil. Results show that the higher heat transfer coefficient affects only the stability margin, and that the higher frictional losses can affect stability and the quench characteristics.         Investigation of quench propagation and stability margin in a sample internally-cooled, cabled superconductor (ICCS)    K. Agatsuma, J. Maguire, A. Montgomery and Y. Iwasa Summary: A computer code, developed to predict stability and quench phenomena in internal-cooled, cabled superconductors (ICCS), has been applied to a single wire model ICCS. The code, slightly modified, is shown to be useful in determining stability and voltage propagation in the limited application of the code to experiments to date.         Influence of the spacers on the stability of channel cooled superconducting coils    C. Meuris and A. Mailfert Summary: In a previous paper, the thermal stability of channel cooled superconducting magnets was experimentally studied. Stable normal zones were observed within a range of currents and local disturbance energies. Usual theories fail to fully explain these results, owing to the fact that they take into account a heat transfer to liquid helium only function of the temperature of the conductor, whatever the position is. In a simplified theoretical analysis, it is shown that in a locally uncooled superconducting wire several stationary normal zones can exist. A criterion is derived that yields the recovery current as a function of the length of the uncooled region. Besides, a detailed numerical analysis determines the evolution of a normal zone in a channel cooled magnet. Theoretical calculations are compared with experimental results.         Metastable superconductive composites: Dependence of stability on copper-to-superconductor ratio    S. Elrod, J. Lue, J. Miller and L. Dresner Summary: The stability of composite superconductors operating in the metastable regime depends upon such factors as matrix resistivity, cooled surface dimensions, fraction of critical current, and volume fraction of stabilizer. By assuming constant thermophysical properties, we developed analytic expressions for the energy and voltage of the minimum propagating zone (MPZ). With other factors held constant these expressions have been used to predict composite superconductor stability as a function of copper fraction: lower copper fractions lead to higher MPZ energies. MPZ voltages have been measured for three NbTi/Cu composites having different copper fractions and different critical current densities for several magnetic fields and transport currents. Experimental MPZ voltages have been used to calculate an effective heat transfer coefficient, which is subsequently used to calculate the MPZ energy. The experimental MPZ energies support the theoretical expectation that lower copper fractions lead to higher stability in the metastable regime.         Vapor locking and heat transfer of multiple layers    C.-J. Chen, S.-T. Wang and J. Dawson Summary: This work was undertaken to study the vapor formation and heat transfer of multiple layers under both steady state and transient conditions. The change in capacitance between the two sides of the heated channel is measured to determine the volume fraction of the vapor in the cooling channel. It is found that the heat transfer characteristics depend on the vapor accumulation and the velocity of vapor flow. The vapor locking heat flux is decreased when the vapor accumulation is increased.         Ultrasonic surface acoustic wave investigation of thin films of superconducting NbN    H. Fredricksen, M. Levy, J. Gavaler and M. Ashkin Summary: Surface acoustic waves in the 700 MHz range were launched on two LiNbO/sub 3/substrates across thin films of sputter deposited NbN 0.1 microns thick using photodeposited interdigital electrodes. The attenuation monitored as a function of temperature in the 1.2 to 20 K range exhibited a very rapid change of 1 to 2 dB at T/sub c/. However as the temperature was lowered further the attenuation leveled off and began a much more gradual decrease which lasted for the rest of the range. The four-wire resistance of the film monitored simultaneously with a 10 /spl mu/A current dropped to zero within 1 K of T/sub c/. The data are analyzed in four different ways in order to extract information about a possible mechanism that is producing these unexpected results.         Critical currents and pinning forces in the PB - GE system    S. Alterovitz Summary: We have studied critical current densities J/sub c/, pinning force densities P and resistivities /spl rho/ in co-evaporated Pb-Ge mixtures in the range /spl ap/ 30-90 Vol.% Pb. Hot spot problems were eliminated by enhanced adhesion to the substrate. The films geometry was determined by lift-off photolithographic technique. Pinning force densities, estimated from the field dependence of J/sub c/, obey a scaling law. The absolute value of the pinning force density maximum P/sub max/increases markedly with decreasing Pb content, up to a maximum around /spl ap/ 50 Vol.% Pb. The self current density is not directly correlated with P/sub max/. At the lower part of Pb concentration, percolation effects have been observed. Values of /spl rho/J/sub c/and /spl rho/J/sub c//sup 2/were calculated showing that this system is inferior to existing A-15 materials for use as a superconducting switch material.         Effect of strain in multifilamentary Nb/sub 3/Sn conductors up to 23 T    G. Rupp Summary: Measurements of critical current of multifilamentary Nb/sub 3/Sn conductors as a function of strain were made in flux densities up to 23 T. The advantage of using high fields is that conductors with high critical current can be investigated without thermal instabilities. The results show that the upper critical field B/sub c2/which is about 2 T higher than the extrapolatedB*_{c2}varies with strain in approximately the same manner asB*_{c2}. A residual resistivity which appears in fields near B/sub c2/is strongly strain dependent indicating the existence of Nb/sub 3/Sn regions with slightly lower critical field.         Author Index (1980)    No author information available Summary: Not available

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