EFFECT OF HEAT-TREATMENT ON CRITICAL-CURRENT DENSITY AND N-VALUE OF (NB,TI)(3)SN MULTIFILAMENTARY SUPERCONDUCTING WIRE

Studies on the relationship between n-value and heat treat conditions of Nb3Sn multifilamentary wires in addition to those on Jc are presented. The wire was manufactured in bronze process. It was heated in various conditions, then voltage-current (V-I) characteristics of each specimen were measured. In the range of the heat treatment temperature, n-value increases with temperature but Jc decreases. The properties were discussed based on the results of microscopic observation and were investigated with upper critical field (Bc(2)) The results from these investigations suggest the dependence of n-value on Bc(2).