Design study and model tests of high Tc superconductor current leads

Current leads are the dominant source of the heat load in a common superconducting magnet system. Therefore, many theoretical and experimental studies have been made to apply high temperature superconductors (HTS) to the current leads. Westinghouse and Argonne National Laboratory, and the authors have demonstrated 25-40% reduction in required liquid helium consumption. Theoretical consideration showed that refrigerator input power can be decreased to 1/3 that of the conventional lead if a higher temperature coolant is utilized. In this paper, thermal performance calculations for a 6.6 kA current lead cooled by intermediate temperature coolant are given. Performances and applicability of the HTS lead depend on the material development. Some of the authors work concerning HTS material is presented. Their 1 kA model lead system was modified in order to test the cooling scheme using intermediate temperature coolant. Test results are presented