Loss and Thermal Analysis of a High Temperature Superconducting Central Solenoid for Tokamak

During operation, the central solenoid (CS) magnet in the Tokamak undergoes rapid charging-discharging cycles, resulting in significant AC losses. In this study, a loss and thermal analysis of a high temperature superconducting (HTS) CS magnet during operation was conducted. The magnet consists of 6 sub-magnets, each with 19 double pancakes (DPs), which are cooled to 20 K by helium gas in the cooling plates. The T-A model coupled with the equivalent circuit model was employed to calculate the hysteresis and coupling losses in the REBCO stacks. Additionally, eddy current losses in the copper layer of the REBCO tapes and the magnet structure were evaluated through the analytical formula and Finite Element Method (FEM) model under the uniform current assumption, respectively. A thermal model incorporating helium gas flow was developed to predict the temperature rise within the CS magnet. AC losses calculated during operation were integrated into the thermal model as heat sources, enabling quantitative analysis of the magnet's temperature evolution.