HIGH-TC SUPERCONDUCTORS AND CRITICAL CURRENT MEASUREMENT

With the introduction of high Tc superconductors, a number of problems associated with critical current, Ic, measurement have arisen. The existing Ic, measurement practices were developed and proved for low Tc superconductors. There are substantial differences between the two classes of materials. When the Ic concept was casually extended to the high Tc conductors, measurement inconsistency, ambiguity and, in some cases, invalidity followed. A discussion of the underlying philosophy of Ic measurement is presented and a number of measurement variables that can influence the measured Ic are discussed. Many of the problems stem from inadequate reporting practices, and recommendations are given for improving measurement reports. © 1990.