Numerical Simulation of Permanent Magnet Method for Measuring Critical Current Density in Superconducting Film: Dominant Experimental Conditions for Crack Detection

The scanning permanent magnet method for measuring the critical current density in a high-temperature superconduct- ing (HTS) film has been reproduced numerically. For this purpose, a numerical code has been developed for analyzing the time evolution of a shielding current density in an HTS film with a crack. The results of computations show that the attractive force Fr and repulsive one Fa are observed near the endpoints of the crack when the symmetry axis of the magnet approaches the crack. In addition, the both forces, Fr and Fa, have the maximum value only when the magnet is located above the crack. This means that the crack size and position can be estimated by using the scanning method.