Superconducting current leads of Bi-based oxide

The application of Bi-based oxide bulk superconductors to current leads for various types of superconducting devices was investigated. The bulk was manufactured in the form of a cylindrical tube (inner diameter: 10 to 30 mm; wall thickness: 1.2 to 1.4 mm; length: 200 mm) and had the composition (Bi+Pb):Sr:Ca:Cu=2:2:2:3. Values greater than 1000 A/cm/sup 2/ were obtained for critical current density at 77 K under self-magnetic field. The maximum critical current was 1600 A. Heat leakage was measured between 77 K and 4.2 K while a DC current was passed through the conductor. The heat leakage of a bulk lead pair was 0.16 W, less than one-tenth of that of conventional gas-cooled Cu leads.<
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