High field Nb3Sn conductor development at Oxford Superconducting Technology

Oxford Instruments, Superconducting Technology (OI-ST) produces Nb₃Sn wire via several "internal Sn" routes. Recently, 12 T, 4.2 K non-Cu critical current density (J_c) values of ∼2900 A/mm² 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_e) values of 170 A/mm² 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 Nb₃Al precursor strand development are presented. PIT strands have irreversibility fields over 26 T at 4.2 K, while Nb₃Al precursor strand has been produced by a route that promotes bonding of the billet components.