Accurate Calculation of Shielding Current Density in HTS Thin Film

A numerical method has been developed for calculating the shielding current density in a high temperature superconducting (HTS) thin film. When the initial-boundary-value problem of the shielding current density is discretized with respect to time and space, improper integrals appear as coefficients of the nonlinear system. In order to evaluate the coefficients accurately, both the double exponential formula and the Gauss-Legendre formula are applied to the improper integrals. As a result, the shielding current density can be accurately determined even in the thin film. As an application of the method, the contactless method for measuring the critical current density has been investigated numerically. The results of computations show a qualitative agreement with the experimental results.