Remanent Flux Distribution and Critical Current Density

Abstract

From Sect. 12.1.4 it could be concluded that the measurement of the remanent flux distribution of a superconducting sample is a better test of sample quality than the measurement of the spatial distribution of the levitation force. In fact the scanning Hall probe experiment appears to be a good method for nondestructive testing of superconductors. The measurement of remanent flux distribution in superconductors by a Hall probe has been reported in the literature [152,154,221,274]. At the present time several groups have set up Hall probe experiments to examine the homogeneity of superconducting samples [120,136,211,262]. However, in most cases only magnetic-field distributions are measured, which give a qualitative measure of the homogeneity of the superconductor, while in our experiments a method is proposed to evaluate the critical current density from the remanent flux distribution, yielding a more quantiative determination of the quality of the samples. In the following our own experiments will be described in more detail.