Effect of strain on critical properties degradation of Nb3Sn strand

In response to the impact of magnet fields above 12 T (Tesla), Nb3Sn has been applied to the central solenoid and the toroidal field on fusion device such as International Thermal-nuclear Experimental Reactor and China Fusion Engineering Testing Reactor. The critical temperature and the current sharing temperature are the key factors for the steady operation of superconducting conductor at low temperature. However, the critical temperature and the current sharing temperature of Nb3Sn-based strand with strain have not been explored. In this paper, using simulation strain effect with load cycle, the critical temperature and the current sharing temperature of short samples was tested, and their values were calculated by a numerical model. The results show that the comprehensive effect of twist pitch leads to degradation of the critical temperature and the current sharing temperature with simulation strain load cycle. Moreover, the evolution model of current sharing temperature with load cycle is built with double logarithm, which can well describe the degradation of short samples resulted from bending strain by the periodic load. ©, 2015, Rare Metals Materials and Engineering Press. All right reserved.