Trial Fabrication and 20K-Operation of Bi-2212 Superconducting Magnet with a R. T. Bore of 45mm in Diameter

Abstract

A Bi-2212 superconducting magnet with a practical size room temperature (R. T.) bore of 45mm in diameter been fabricated. The magnet has been cooled by a GM-cryocooler which generated a magnetic field up to 0.68T at 20K. Oxide superconducting magnet with such a large R. T. bore requires high homogeneity in critical current density of silver-sheathed Bi-2212 tape in a long range such as 1500m. This problem has been solved by optimizing the time for calcination of Bi-2212 powder and employing a new heat-process.