Numerical investigations on nondestructive and contactless method for measuring critical current density by permanent magnet method

摘要

The nondestructive and contactless method for measuring the critical current densityjc has been investigated by means of the numerical simulation. In the method, a permanent magnet is brought closer to a high-temperature superconducting film and the electromagnetic force is measured simultaneously. According to the experiment, the maximum repulsive force is proportional to J(c). For the purpose of reproducing the experimental result numerically, the behavior of the shielding current density is formulated by use of the current-vector-potential method. The numerical code has been developed for solving an initial-boundary-value problem of the resulting integral-differential equation and, by means of the code, the relation between the maximum repulsive force and the critical current density is determined. The results of computations show that there is direct proportionality between them. This tendency validates the nondestructive and contactless measurement method of j(c). (c) 2006 Elsevier B.V. All rights reserved.