The impact of electromagnetic (EM) and thermal cyclic loading (referred as warm-up-cool-down—WUCD) on the Nb₃Sn cable in conduit conductors for the toroidal field magnets of the ITER tokamak should be carefully assessed for the proper operation of the machine. The experience gained during the production phases of the TF conductors revealed that a degradation occurs when thermal and EM cyclic loading is applied at the nominal operating conditions of 10.78 T and 68 kA. Since at the beginning of the tokamak operation the nominal conditions will not be achieved, it is worth investigating to what extent lower EM loads affect the conductor performance, and the threshold of EM load that triggers the WUCD degradation. The aim of this investigation is to identify critical levels which determine the onset of this degradation, both in terms of thermal and EM cycles, and to study the performance of strands from different suppliers. For this assessment, a set of conductor samples were manufactured including all types of strands to be used in the TF coils of the ITER machine. These samples were subjected to a set of EM and thermal cycles representing in a realistic way the actual operation of the conductors in the ITER machine. The tests were performed in the SULTAN facility of the Swiss Plasma Center at working conditions ranging from 5.4 T–34 kA to 10.78 T–68 kA. This work presents the results obtained in these tests in terms of current sharing temperature (T _cs), effective strain, rate of degradation at different working conditions and their implications for the prospected conductor performance in the machine.

电磁 (EM) 和热循环载荷（称为预热-冷却 - WUCD）对 Nb _{3 的影响}应仔细评估 ITER 托卡马克环形磁场磁铁导管导体中的 Sn 电缆，以确保机器正常运行。在 TF 导体的生产阶段获得的经验表明，在 10.78 T 和 68 kA 的标称工作条件下施加热和 EM 循环负载时会发生退化。由于在托卡马克操作开始时无法达到标称条件，因此值得研究较低的电磁负载在多大程度上影响导体性能，以及触发 WUCD 退化的电磁负载阈值。本次调查的目的是确定在热循环和电磁循环方面决定这种降解开始的临界水平，并研究来自不同供应商的钢绞线的性能。对于本次评估，制造了一组导体样品，包括用于 ITER 机器的 TF 线圈的所有类型的绞线。这些样品经受了一组 EM 和热循环，以真实的方式代表了 ITER 机器中导体的实际操作。测试在瑞士等离子体中心的 SULTAN 设施中进行，工作条件范围为 5.4 T–34 kA 到 10.78 T–68 kA。这项工作展示了这些测试在均流温度方面获得的结果（测试在瑞士等离子体中心的 SULTAN 设施中进行，工作条件范围为 5.4 T–34 kA 到 10.78 T–68 kA。这项工作展示了这些测试在均流温度方面获得的结果（测试在瑞士等离子体中心的 SULTAN 设施中进行，工作条件范围为 5.4 T–34 kA 到 10.78 T–68 kA。这项工作展示了这些测试在均流温度方面获得的结果（T _cs )、有效应变、不同工作条件下的退化率及其对机器中预期导体性能的影响。