Analysis of the critical current and electromagnetic forces of HTS segments in multiple pairs of current leads used in the current lead box of a fusion reactor

The high-temperature superconducting current leads (HTS CLs) used in fusion reactors require multiple HTS CLs to be placed inside the current lead box (CLB) of specified dimensions. Each HTS CL not only carries a large current but also has very high safety requirements. This study, based on the first generation HTS tapes (Bi-2223/Ag-Au), analyzed the critical current distribution of a 60 kA HTS CL and evaluated optimal power supply configurations for eight HTS CLs within the CLB. It also determined the optimal distance of each lead from the center of the CLB. Through ANSYS APDL calculations, we first obtained the critical current distribution of each panel of a single CL. The analysis results indicated that the HTS segment has a current carrying capacity of 78 kA at 65 K. Secondly, the optimal power supply option adopted a positive–negative alternating approach. When the distance is 1200 mm, the total current carrying capacity of the eight CLs is 605 kA, with relatively minor differences among the minimum panels of each lead, and the electromagnetic forces for each current lead were all below 1000 N. In addition, the relationships of the critical currents, surface areas of the CLB and electromagnetic forces of eight CLs with distance were obtained. Based on the above analysis, the distance of each lead from the center of the CLB was determined to be at least 800 mm.