Effect of winding methods: transport AC losses in CORC coils

Abstract

Abstract AC losses undoubtedly increase the burden on the cooling system and affect the overall performance of high-temperature superconducting (HTS) cables. Therefore, AC losses in HTS cables are important design factors for large-scale HTS equipments. Extensive research has been conducted on straight, densely wound conductors. However, AC losses of bending/circular HTS cable conductors have not been sufficiently studied. In this article, the transport AC losses in a circular HTS conductor coil bended by a conductor on round core (CORC) type cable were investigated using experiments and numerical simulations. The effect of different winding methods was also studied. First, the modeling method of the three-dimensional simulation and the experimental procedures were presented. The simulation results of the straight densely wound conductor (SDWC) and circular densely wound coil (CDWC) were compared with the corresponding experimental results. Finally, the winding method for the CDWC was optimized using both the simulation and experimental approaches. Both the experiments and simulations showed that reducing the tape-to-tape frontal area was able to decrease the transport AC loss, and the results show that the optimum winding angle of the HTS CORC coil was 24.15°. Overall, the modeling and experiments provide useful optimization strategies for designing winding structures of high-performance CORC coils/magnets.