ENERGY-DISSIPATION IN HIGH-TEMPERATURE CERAMIC SUPERCONDUCTORS

Losses in high-T-c superconductors are of vital importance in practica l applications. The mechanisms are similar to those in low-T-c materia ls but there are a number of complications. In this paper the loss mec hanisms in different regimes are summarized and simple approximate exp ressions obtained. Losses due to the transport current are analysed wi th the theory of Norris for elliptical conductors. This predicts diffe rent loss voltages according to where the voltage contacts are placed on the conductor which has been confirmed experimentally. This poses d ifficulties in turning experimental data into reliable loss measuremen ts, but a series of experiments with different contact layouts and pha se setting techniques is found to give consistent results, in good agr eement with theory.