Fabrication of Bi-2212/Ag magnets for high magnetic field applications

Bi-2212/Ag multifilamentary tapes show practical transport properties in high magnetic field regions above 20 T and 4.2 K, where it is considered difficult to use metallic superconductors. In this paper, the recent progress of the authors' development for the Bi-2212/Ag insert magnets is presented. The Bi-2212/Ag stacked double pancake coils with a 45-150 mm outer diameter, 15-55 mm inner diameter and 50-220 mm in height have been fabricated and tested in various backup magnetic fields up to 20 T at the Tsukuba Magnet Laboratory of NRIM. A high resolution X-ray CT apparatus was used to observe a cross section of the magnet nondestructively. The transport properties of the magnets are discussed in relation to the defects of the coil identified by this X-ray CT observation.