Effects of Reaction Temperature and Alloying on Performance of Restack-Rod-Process ${\rm Nb}_{3}{\rm Sn}$

A K Ghosh,L D Cooley,S Hong,M B Field,J A Parrell,Y Zhang

doi:10.1109/tasc.2007.898165

Abstract

Final reactions of 48 or 50 hours were given in a range of temperature from 635 o C to 695 o C to high-J c Ta- and Ti-alloyed Restack-Rod-Process Nb 3 Sn strands to investigate the changes in critical current density and the superconducting properties. J c is the current density in the non-copper region of the wire. Measurements of J c were made at 4.2 K temperature and from 8 to 11.5 T field at BNL and from 12 to 16 T at OST, and these data were fitted to the Summers expression for J c to extrapolate the scaling field . B c2 * ldr All three(Nb, Ta) 3 Sn strand designs investigated displayed peak J c values of ~3000 A/mm 2 at 12 T and ~at 1500 A/mm 2 at 15 T for 665 and 680 o C reactions. B c2 * increased monotonically with increasing reaction temperature, a (Nb, Ti) 3 , By comparison, at each reaction temperature, a strand under development had a B c2 * higher than any of the Ta-alloyed strands. This suggests that Ti-alloyed strands could improve high-field performance if further development can bring their J c values closer to those of the Ta-alloyed strands. Other implications are also discussed.

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