Numerical Investigation on Crack Detection in HTS Film: Accuracy of Scanning Permanent Magnet Method

By simulating two types of the contactless methods for measuring the critical current density, the resolution of the crack detection in a high-temperature superconducting (HTS) film has been investigated. To this end, a numerical code has been developed for analyzing the shielding current density in an HTS film with a crack. By using the code, the scanning permanent magnet method and the inductive one have been reproduced numerically. The results of computations show that the scanning permanent magnet method shows a relatively poor accuracy for the crack detection. If the inductive method is applied to the region obtained by the scanning method, the detection accuracy of the crack is drastically improved. The crack can be detected with high speed and high accuracy by combining the inductive method and the scanning method.