YBa/sub 2/Cu/sub 3/O/sub x/ low loss current leads

The low thermal conductivity of high-temperature superconducting ceramic YBCO (<1 Wm/sup -1/ K/sup -1/ at 77 K) in comparison with normal metal such as copper (/spl sim/480 Wm/sup -1/ K/sup -1/ at 77 K) suggests their use as current leads. The authors demonstrate a modular lead design which has very low resistance contacts and where the power dissipated at an arbitrarily chosen current level of 100 A is several orders of magnitude lower than that dissipated by the normal metal leads presently used in such applications. This suggests that significant cost savings may be made resulting from the reduced liquid helium boil-off rate. The leads are fabricated by novel ceramic processing techniques which give a high degree of uniformity and reproducibility, and strengths in flexure approaching 200 MPa for the individual elements, the highest values reported.<>