Characterization Techniques for Local Critical Current Densities in HTS Tapes

Abstract

The high spatial homogeneity of critical current density, J c , in HTS tape is one of the most important requirements to realize practical superconducting tapes. However, it is hardly possible to detect local J c distribution using conventional characterization techniques because the length scale of such J c variation is several orders smaller than that of the conventional techniques. We have succeeded in developing novel techniques such as low-temperature laser scanning microscopy and reel-toreel Hall probe scanning microscopy for spatially resolved measurements of local J c in HTS tapes of multiple lengths and operating conditions. In this paper, I summarize these techniques together with other useful methods including magneto-optical imaging and the Hall sensor array technique.