Abstract
New (Nb, Ta)3Sn conductors with excellent high-field performance have been fabricated using Ta-Sn powder as a core material. The Ta-Sn powder was easily synthesized by the melt diffusion reaction between Ta and Sn powders. The powder was encased in a Nb or Nb-Ta alloy sheath to form a composite, and then fabricated into wire and tape specimens. The resulting specimens were reacted at 800-925°C in vacuum. After the reaction a thick (Nb, Ta)3Sn layer, several tens micrometers in thickness, is formed between the sheath and the core. No void is formed in the core after the reaction. Ta is incorporated into the (Nb, Ta)3Sn layer from both the Ta-Sn core and the Nb-Ta sheath. The Jc of the (Nb, Ta)3Sn layer reaches 5×104A/cm2 at 23T and 4.2K. The tape specimens show large critical current at 23T due to the large thickness of the (Nb, Ta)3Sn layer.
