DEVELOPMENT OF HIGH-T-C SUPERCONDUCTING BI-2223 TAPE JOINTS

High-T-c superconducting joints between Ag-clad Bi-2223 tapes have bee n developed for persistent current applications. Two presintered tapes with one side of the silver stripped were lapped and then wrapped by a silver foil. The complex was uniaxially pressed followed by appropri ate sintering to form a high-T-c superconducting tape joint. It was fo und that the ratio of critical currents through the joint to that of t he tape, I-cj/I-c, depended on the uniaxial pressure and the sintering conduction. At liquid-nitrogen temperature 77 K, I-cj/I-c = 99% has b een achieved. Persistent current loops formed by Bi-2223 tapes have al so been fabricated and tested. Joint resistance of a loop was determin ed to be similar to 4 x 10(-13) Ohm between the decay time of 120 and 3600 sec.