OPTIMIZATION OF HIGH-TEMPERATURE SUPERCONDUCTOR CURRENT LEADS

Methods to improve the performance of high-temperature superconducting current leads are analyzed. Designs are considered Chat are inherentl y safe from burnup, even if the lead enters the normal state, The effe ct of a tapered lead that takes advantage of the increase in critical current density with decreasing temperature will decrease helium boilo ff by about a factor of two for an area ratio of four, A new concept, in which Ag powder is distributed in increasing concentration from the cold end to the hot end of a sintered YBCO lead, is shown to have com parable performance to that of leads made with Ag-alloy sheaths. Perfo rmance of the best inherently safe designs is about one order of magni tude better than. that of optimized nonsuperconducting leads. BSCCO le ads with Ag-alloy sheaths show improved performance for Au fractions u p to approximate to 3%, after which increases in Au fraction yield neg ligible improvement in performance.