Progress on Internal-Tin Route Nb₃Sn Superconducting Strand for ITER in China

Abstract:

Multi-filamentary Nb₃Sn strand for ITER has been successfully fabricated by a conventional internal-tin (IT) route at Western Superconducting Technologies, Co. Ltd. All the performances of the IT Nb₃Sn strand is able tomeet the ITER specifications. In 2010, one hundred kilograms of IT Nb₃Sn strand has been cabled, jacketed and integrated into conductor sample titled with TFCN2 by ASIPP in China and tested in CRPP, Switzerland. After 1200 cycles warm-up and cooling down, T_cs of the TFCN2 Sultan sample at 10.78 T, 4.5 K are 6.35 K for the left leg and 6.37 K for the right leg, respectively, which is larger than the ITER lower limit of 5.7 K. This is the first successful Sultan sample made of Chinese Nb₃Sn strand. In 2011, the influence of applied axial strain on critical current (I_c) was investigated using TFCN2 strand in the University of Twente, the Netherland. The irreversible degradation of I_c starts around +0.23% tensile intrinsic strain. The heat treatment influence of the duration at 650 °C on microstructure and performance was also studied. It was found that the fraction of un-reacted Nb after heat treatment is dependent on the position in the cross section. The hysteresis loss increases much faster than I_c when the duration at 650 °C increased.

• Periodical: Materials Science Forum (Volumes 745-746)
• Pages: 158-162
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.745-746.158
• Online since: February 2013
• Authors: Jian Wei Liu, Ke Zhang, Jian Feng Li, Sheng Liu, Xian De Tang, She Jun Du, Xiang Hong Liu, Yong Feng, Ping Xiang Zhang
• Keywords: Critical Current, Heat Treatment, Hysteresis Loss, Microstructure, Nb₃Sn Strands

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