Numerical simulation of critical current and n-value in NbSn strand subjected to bending strain

Murakami, Haruyuki*; Ishiyama, Atsushi*; Ueda, Hiroshi*; Koizumi, Norikiyo; Okuno, Kiyoshi

Critical current of ITER mode coil degraded as increase of electromagnetic force. It was shown that the periodic bending of the strand caused this degradation from analysis based on results of experiments in which periodic transverse load is artificially applied to single strand. However, since the experiments were carried out under a certain condition, general relation between transverse load and critical current was not obtained. The authors therefore developed a numerical simulation code. The simulation results are in good agreement with test results. The general dependence of the critical current on temperature and pitch of periodic load is studied using our code. The simulation results reveal that the reduced critical current depends on the temperature and is a function of the bending strain independent of the pitch of the periodic load.