Electromagnetic properties of bronze processed Nb/sub 3/Sn superconducting wires and multi-strand cables for AC use with a Cu-Sn-X(X; Ge,Ni,Mn,Si) matrix and a Nb-Ta core

A bronze processed 0.275 mm-dia. Nb/sub 3/Sn strand composed of Nb-0.5at%Ta cores and a Cu-2.7at%Sn-1.0at%Ge matrix was fabricated into cables of 6 and 36 strands. Each strand contained 75990 filaments 0.28 /spl mu/m in diameter. The AC quench current for the 36-strand cable reached 2500 A/sub peak/ at 50 Hz and 0.5 T DC field. The 6-strand cable showed a significantly improved irreversible bending strain limit of over 10% due to the fine filament size. This result enabled building of a magnet through the react and wind method. A 50 mm-bore 2T-class magnet wound by the 6 strand cable was successfully operated at 52.7 Hz and 4.2 K. In order to reduce AC losses another bronze processed 0.218 mm-dia. Nb/sub 3/Sn strand with 147510 0.15 /spl mu/m-dia. filaments was fabricated from Nb05%Ta/Cu-4.9%Sn-2.0%Ge/Cu-2.7%Sn-2%Ni-1%Mn double matrix composite. The strand showed a hysteresis loss of 447J/m/sup 3/ at /spl plusmn/0.5 T/cycle and /spl lambda/J/sub c/ of 857A/mm/sup 2/ at 0.5 T after the heat treatment at 500/spl deg/C for 100 h.