应变对Nb_3Sn股线临界特性退化影响

为应对12 T以上的磁场影响,国际热核聚变反应堆ITER和国内CFETR装置上环向和中心螺线磁体系统已采用Nb3Sn材料;而低温下临界温度和分流温度是超导体稳定运行的重要因素,由于缺乏应变效应对临界温度和分流温度影响的研究,为此,本研究利用模拟应变作用的周期载荷,对Nb3Sn超导股线样品的临界温度和分流温度进行了测试以及数值模拟计算,分析获得扭距等作用使临界温度和分流温度随模拟应变载荷周期退化的结果。同时,推导分流温度随周期载荷变化的双对数分布模型,模型可以描述股线样品中由周期载荷导致的弯曲应变所产生的股线性能降级情况。

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