LONG AG-CLAD BI-BASED SUPERCONDUCTING TAPES AND COILS

Ag-sheathed Bi-based superconducting single and multifilament tapes ha ve been fabricated using a powder-in-tube technique. A J(c) of 6,000 A /cm2 at 77 K over 12 meters of a single core tape is compared with 18, 500 A/cm2 for the tape processed by pressing. A J(c) of 11,000 A/cm2 a t 77 K and 137,000 A/cm2 at 4.2 K over 8 meters of a 49 multifilament tape has been achieved. Multiprobe measurements for a tape show that t here is no indication of accumulative grain boundary resistance over t he entire length at high temperatures. The J(c) remained unchanged whe n the tapes were rewound into a pancake coil and a solenoid with an in ternal diameter of 5 cm for single core tapes and of 1.4 cm for a 49 m ultifilament tape. Multifilament tapes exhibit robust mechanical prope rties and feasible for practical applications.