High field Nb/sub 3/Sn conductor development at Oxford Superconducting Technology

Oxford Instruments, Superconducting Technology (OI-ST) produces Nb/sub 3/Sn wire via several "internal Sn" routes. Recently, 12 T, 4.2 K non-Cu critical current density (J/sub c/) values of /spl sim/2900 A/mm/sup 2/ have been achieved by increasing the Nb and Sn fractions of the filament subelements. Similar conductors for high field use have shown engineering current density (J/sub e/) values of 170 A/mm/sup 2/ at 23.5 T, 1.8 K. OI-ST is also involved with research for the High Energy Physics (HEP) National Conductor Program. Results on composites made entirely by hot extrusion are described. Finally, the present status of Ta-Sn powder-in-tube (PIT) and Nb/sub 3/Al precursor strand development are presented. PIT strands have irreversibility fields over 26 T at 4.2 K, while Nb/sub 3/Al precursor strand has been produced by a route that promotes bonding of the billet components.