Optimized Heat Treatment of Internal Tin Nb Sn Strands

The hysteresis and coupling losses, the magneto resis- tance of the strands designed by Europa Metalli to reach ITER HP I specifications have been deduced by magnetization—and mag- neto resistance measurements. Additionally, the critical current density and the -values have been examined. By varying the temperature and the duration of the final an- nealing step, a better understanding of the interplay of the an- nealing parameters with the intrinsic properties can be gained. From these results we will show, that for the use in ITER shorter annealing times at higher annealing temperatures lead to a dra- matic decrease of hysteresis and coupling losses accompanied by a decrease of annealing costs.