周期电磁载荷下Nb3Sn导体耦合损耗计算模型

在国际热核试验反应堆ITER上，已采用铌三锡(Nb3Sn)复合股线来满足导体遭受12T以上的磁场冲击，但Nb3Sn运行时的洛伦兹力会导致临界电流和耦合损耗时间常数的变化，但Nb3Sn基CICC (cable-in-conduit conductor)性能退化研究还有待加强，而且应变下接触特性对耦合损耗时间常数的影响也仍在探索中。为了快速精确计算耦合损耗，本文提出新的最小二乘法计算耦合损耗时间常数的方法，它采用绞缆序列比、电磁载荷应变作用下的接触电阻和空隙率等参数的线性关系来表示。在该模型中，不仅给出绞缆序列比的计算表达，而且也给出电磁载荷周期应变下接触电阻和空隙率的经验计算。与Gandalf及传统的数值计算相比，本文采用的绞缆序列比、接触电阻和空隙率组合计算耦合损耗误差较小，非常接近工程测试值。

Calculation model of coupling loss time constant for Nb3Sn conductor under cyclic electromagnetic load

On ITER (International Thermal Nuclear Experimental Reactor) superconducting fusion device, the Nb₃Sn composite strands have been applied to CICC (cable-in-conduit conductor) to meet the impact of the magnet field above 12 T. The strain of Nb₃Sn-based conductor due to Lorentz forces leads to the change of critical current and coupling loss time constant. However, the study on critical performance degradation of CICC is still inadequate. Moreover, the most important is that the influence exploration of the contact properties with strain on coupling loss time constant is also insufficient. In order to calculate coupling loss accurately and quickly, a new calculation model of coupling loss time constant was put forward in this paper, which is expressed with a linear equation using some parameters that is the cabling sequence ratio, the contact resistance and the void fraction with strain main from electromagnetic force. In this model, not only the computation expression of cabling sequence ratio is given, but also the contact resistance and the void fraction is obtained with strain (from electromagnetic load cycle). Compared with numerical calculation using Gandalf and traditional method, the error of coupling loss calculated with the combination of the cabling sequence ratio, the contact resistance and the void fraction with strain is small, which is close to the engineering measured value.