Test result of a full-size NbSn conductor developed for the ITER TF coils

Nunoya, Yoshihiko; Nabara, Yoshihiro; Yoshikawa, Masatoshi*; Matsui, Kunihiro; Hemmi, Tsutomu; Takahashi, Yoshikazu; Isono, Takaaki; Koizumi, Norikiyo; Nakajima, Hideo; Stephanov, B.*; et al.

IEEE Transactions on Applied Superconductivity, 21(3), p.1982 - 1986, 2011/06

https://doi.org/10.1109/TASC.2010.2093488

Japan Atomic Energy Agency (JAEA) has developed ITER TF NbSn conductors that fulfill ITER requirements and then commenced fabricating conductors to be used for ITER TF coils. As a qualification of conductor fabrication, two full-size conductor samples named as JATF4 were prepared and tested by the SULTAN facility at CRPP in Switzerland. The length of the samples was about 3 m, and temperature sensors and voltage taps were attached on conductors to measure the current sharing temperature (Tcs). The measurement was performed at the beginning of the test campaign, during cyclic test, and at the end of the campaign that corresponded to after once warm up and cool down. The Tcs values electrically assessed by the agreed procedure at outer magnetic fields of 10.78 T were 6.5 K and 6.2 K at the beginning and 6.1 K and 6.0 K at the end of the campaign for each conductor, respectively. These values concluded that the conductors have enough Tcs margin to satisfy the criterion of 5.7 K as ITER TF conductor, and conductor fabrication is qualified. Detail of the test results will be presented and discussed.