Fast Current Distribution Simulation Method for No-Insulation HTS Coil With Defects

This paper presents a numerical method for fast simulation of current distribution in a no-insulation (NI) high temperature superconductor (HTS) coil with defects. A refined distributed-circuit model based on the partial element equivalent circuit (PEEC) approach is adopted to calculate the transient current distribution due to screening current. To reduce the time required for the simulation, a nonuniform axial segmentation method is presented in which the outer axially-subdivided azimuthal element is narrower than the inner element. In order to verify the simulation method, three NI HTS single-pancake coils are considered with the following characteristics: 1) the coil without any defects; 2) with one defect; 3) with two defects. The simulation results of current distribution due to screening current, total azimuthal current, radial current, and central magnetic field are presented. Moreover, it is proved that the time required for the simulation can be reduced by the nonuniform axial segmentation method without significant discrepancies in results.