Filamentary A15 Superconductors

Compound superconductors with the Al5 structure carry the promise of the second generation in practical superconductivity. They will provide higher operating magnetic fields at higher tem­ peratures than the preceding alloy superconductors. To fulfill this promise, their brittle nature must be accommodated in a fila­ mentary structure. Achieving this has been no simple task and imaginative research and clever production techniques have led to many usable conductor configurations. In addition, several new and exciting possibilities are being proposed; for example, in situ processing promises easier production with improved strain toler­ ance. It is timely, therefore, to take measure of what we have achieved and to assess our understanding so that we may choose, with some confidence, paths for future research and potential ap­ plications. To meet these needs, the International Cryogenic Materials Conference Board has sponsored this special topic conference on Filamentary Al5 Superconductors bringing together superconductiv­ ity researchers, superconducting wire producers, and high field magnet users to discuss current research problems. That the in­ formation exchange was intensive and successful is evidenced by the excellent papers in this volume. In order to capture some of the synergistic wisdom generated in discussions at the conference several people were asked to assemble and interpret the comments and concerns of the fusion, high energy physics, solid state phys­ ics, and metallurgy groups.

Contenu

Conventional Composites and National Reviews.- Development of A15 Filamentary Composite Superconductors in Japan.- Development of A15 Multifilamentary Superconductors.- Work in the U.K. on Filamentary A15 Conductor Development.- Development of A15 Multifilamentary Superconductors at Airco.- Review of Superconductor Activities at IGC on A15 Conductors.- Filamentary Nb3Sn Superconductor Manufactured by the Solid-Liquid Diffusion Method.- Multifilamentary Nb3Sn by an Improved External Diffusion Method.- Effects of Formation Temperature on the Superconducting Properties of V3Ga Wires.- Development of Multifilamentary Compound Superconductors.- Flux Pinning in Bronze-Processed Nb3Sn Wires.- An Auger Electron Spectroscopy Study of Bronze Route Niobium-Tin Diffusion Layers.- Mechanical Properties.- The Importance of Being Prestressed.- Studies of the Strain-Dependent Properties of A15 Filamentary Conductors at Brookhaven National Laboratory.- Strain Scaling Law and the Prediction of Uniaxial and Bending Strain Effects in Multifilamentary Superconductors.- Evidence for Microstructural Effects under Strain in Bronze Process Nb3Sn.- Mechanical Properties of High-Current Multifilamentary Nb3Sn Conductors.- Stress Effects on W/Cu Reinforced Nb3Sn Composite Conductors.- Multiply Connected Superconductors.- In Situ and Powder Metallurgy Multifilamentary Superconductors: Fabrication and Properties.- Preparation and Properties of In Situ Prepared Filamentary Nb3Sn-Cu Superconducting Wire.- Superconducting Properties and Coupling Mechanisms in In Situ Filamentary Composites.- Powder Metallurgically Prepared A15 Microcomposite Superconductors.- Critical Currents of Cu-(Nb1?xTax)3Sn In Situ Multifilamentary Wires.- Magnetic Properties of Multifilamentary Nb3Sn Composites.- Alternating Current Losses in Twisted In-Situ Composite Wires.- A15 Multifilamentary Superconductors by the Infiltration Process.- Group Comments.- Report of Magentic Fusion Energy Group.- Report of High Energy Physics Group.- Report of Solid State Physics Group.- Report of Metallurgy Group.- Indexes.- Contributor Index.