AC loss test and analysis of the prototype CIC conductor joint for CFETR CSMC

The Central Solenoid Model Coil (CSMC) project has been launched at the Institute of Plasma and Physics Chinese Academy of Sciences (ASIPP) for China Fusion Engineering Test Reactor (CFETR). Electrical joints are important aspect for CSMC, because the local heating from resistive losses can drive the superconductor into a less stable regime and result in premature quench. So part of the project is to develop joints with low DC resistance and AC loss. AC loss power and local heating of the full-size prototype conductor joint in the preliminary test scenario of CSMC are evaluated experimentally and numerically in this paper. The AC loss of the joint sample is measured in SULTAN facility with an applied harmonic field and wider frequency range. Based on the experimental results, the AC loss of the joint is characterized by Multizones Partial Shielding (MPAS) model. Then, the AC loss power of the joint is calculated in the test scenario. The temperature rise of joint is investigated numerically due to the simulated AC loss in the test scenario. The simulation results show the temperature rise in the joint is relatively higher which affects the stability greatly not only in joints, but also the coils. So the joint structure and test scenario of CSMC need to be optimized to reduce the AC loss and ensure safe operation. The way to reduce the AC loss deposit in the joint is also discussed.