Bi-2212 Ag-Sheathed Round Cross Section Wires

Bi-2212 Ag-sheathed round cross sectional wires which are suited as winding materials for realizing high homogeneity superconducting magnets have been successfully fabricated by the powder-in-tube technique. High overall critical current density, Jc, up to 2.8x104 A/cm4 at 4.2 K, 10 T was achieved in the multifilamentary wire consisting of 37 double tubed core filaments. Highly deformed Bi-2212 microstructures which were formed along a small curvature Ag sheath surfaces of the core filaments were observed, which might be responsible for the high Jc properties. Effects of wire bending before the heat treatment on the Jc property have been examined with respect to a solenoid winding. It was confirmed that the decrease in Ic in a 40 mm bore solenoid compared with that of short sample is estimated to remain less than about 15%.