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.