Critical-current densities of bronze-processed Nb3(Sn1−<i>x</i>Ga<i>x</i>) wires up to 23.5 T

Abstract

Gallium additions to the Cu-Sn bronze matrix in the production of Nb3Sn wires by solid-state diffusion raise Hc2(4.2 K) of the resulting compound to ∼25 T. This increase in Hc2, which is not accompanied by any significant increase in Tc, is associated with the incorporation of gallium into the A-15 compound which has the approximate composition Nb3(Sn0.9Ga0.1). Critical currents in a variety of Ga-containing wires, all reacted at 700 °C, have been measured in fields up to 23.5 T. This is the highest field at which steady-state current measurements have yet been made. The pinning force is found to be closely proportional to h1/2 (1−h)2, where h is the reduced field.