FABRICATION OF BI-2212-AG COMPOSITE SOLENOID TYPE SUPERCONDUCTING MAGNET BY PARTIAL MELT PROCESS UNDER HIGH P-O2

Partial melt process under high oxygen partial pressure (P-O2) has bee n 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 x 10(4) to 2.2 x 10(5) A/cm(2) at 4.2 K in zero mag netic field with increasing P-O2 from 0.1 to 1.0 bar. This process was also effective to improve J(c) of round and rectangular conductors. T hese 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 conducto rs in short length reached 7.8 x 10(3) and 1.4 x 10(4) A/cm(2) in 21 T at 4.2 K, respectively. Fabrication of a solenoid type magnet has bee n attempted using a rectangular conductor under P-O2 = 2.4 bar. J(c) o f this solenoid type magnet reached 4.2 x 10(4) A/cm(2) under generati ng a self-magnetic field of 0.89 T at 4.2 K.