AC Losses in HTSC Conductor Elements

AC self-field losses and de "dynamic resistivity" in HTSC conductor elements have been measured. The data are discussed with reference to the relevant theory. For two very different sample types, the J(c) calculated on the basis of the ac self-field loss is about an order of magnitude lower than the J(c) based on the 1 mu V/cm dc voltage drop criterion often employed for HTSC materials. This is attributed to the onset of resistive behavior at currents much lower than the reported J(c) based on the 1 mu V/cm criterion. The J(c) determined from measurements of the dynamic resistivity of a melt-textured YBCO fiber is within 15% of that determined by magnetic measurements.