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.