Progress and Status of Multifilamentary Nb_3Sn Strands Fabricated by Internal-tin Process for ITER in China

摘要

The multifilamentary Nb3Sn strands with a diameter of 0.820 mm and a unit length longer than 5000 m have been successfully fabricated by an internal tin process. The highest transport J_(c-non) value of 1249 A/mm~2 at 4.2K, 12 T has been obtained. The n value of Nb_3Sn strands is larger than 20 and the residual resistance ratio (RRR) lies between 150 and 220. The relationship between Jc, n-values and strain were measured, respectively in the axial strain range from -0.8 % (compressive) to + 0.7 %(tensile ) at 4.2K,12T. The influence of twist process on Jc and hysteresis loss for Nb_3Sn strands has been investigated.