Influence of the annealing time of internal tin Nb 3Sn strands on the critical current and the magnetization losses

Abstract

Internal tin Nb 3Sn strands manufactured by Europa Metalli where subjected to heat treatments at a final annealing temperature of 675 °C at variable time from 1 to several hundred hours. The growth of the Nb 3Sn layer and grains is monitored using LVSEM, EDX and TEM. The critical parameters (critical temperature T C, upper critical field H C2 and the scaling parameter C) as well as hysteresis and coupling losses and the magneto resistance of these strands have been deduced by experiment. From these results we will show, that the behavior of a given strand can be optimized with respect to the desired conditions of operation.