GRAIN-ALIGNED YBCO SUPERCONDUCTING CURRENT LEADS FOR CONDUCTION-COOLED APPLICATIONS

Grain-aligned YBCO superconductors have been developed for use in a conduction-cooled, cryogen-free superconducting magnet application. A magnetic alignment technique has been used to orient the c-axis of the YBCO grains. Current leads 0.3 x 1.4 x 6.4 cm were fabricated and thermally connected between the first and second stage of a Gifford-McMahon (G-M) cryocooler. The heat conduction down the leads was determined from a load map of the cryocooler. With operating temperatures of 40K on the first stage and 10K on the second stage, the measured heat leak was 0.15 watts/lead. The YBCO current leads were used to power a conduction-cooled Nb3Sn magnet at 10K to 250 amperes. Test results for the YBCO leads are reported.