Numerical Study on AC Loss Reduction of Multi-Pole HTS Coil by Optimal Design of Winding Cross Section of Element Coil

We study the optimal design of 2- and 4-pole coils wound by YBCO tapes as the case studies of the optimal design of the multiple-coil system based on the AC loss minimization. The winding cross sections of the element coils of the 2- and 4-pole coils were optimized starting from the conventional rectangular cross section to minimize the AC loss. The result shows that the AC loss in the optimized coil is significantly reduced and the critical current of the optimized coil is increased compared with the base coil. According to the results, the validity of our optimal design method is verified to effectively reduce the AC loss in the multi-pole coils wound by the YBCO tapes. Some disadvantageous points of the optimized coil are also discussed.