Numerical Investigation of Inductive and Permanent-Magnet Methods to Measure Critical Current Density of HTS Thin Films

The inductive method/permanent-magnet method for measuring the critical current density j_C in a high-temperature superconducting (HTS) tape have been simulated numerically. To this end, a numerical code has been developed for analyzing the time evolution of a shielding current density in an HTS sample. The results of computations show that, in the inductive method, the edge effects lead to the degradation of the j_C-measurement accuracy. In contrast, it is found that, even if the magnet is placed near the edge, the maximum repulsive force is roughly proportional to j_C. This means that the permanent-magnet method is applicable to measure j_C near the edge.