Fabrication of Bi-2212-Ag composite solenoid type superconducting magnet by partial melt process under high [formula omitted

Abstract

Partial melt process under high oxygen partial pressure ( P O 2 ) has been attempted to obtain a well-aligned structure in Bi-2212-Ag composite tapes. Critical current density ( J c) of Bi-2212-Ag composite tapes increased from 4.5 × 10 4 to 2.2 × 10 5 A/cm 2 at 4.2 K in zero magnetic field with increasing P O 2 from 0.1 to 1.0 bar. This process was also effective to improve J c of round and rectangular conductors. These results were explained by the idea that crystallization of the Bi-2212 system started at the interface between the liquid phase and the oxygen-rich gaseous phase. J c of the round and rectangular conductors in short length reached 7.8 × 10 3 and 1.4 × 10 4 A/cm 2 in 21 T at 4.2K, respectively. Fabrication of a solenoid type magnet has been attempted using a rectangular conductor under P O 2 . J c of this solenoid type magnet reached 4.2 × 10 4 A/cm 2 under generating a self-magnetic field of 0.89 T at 4.2 K.