Fine filament NbTi conductors for the SSC

Inner and outer grades of wire have been processed with NbTi filament diameters of 5 to 9 μm, depending on the magnet design requirements. An increase in billet diameter from 10-in to 12-in resulted in an improved critical current density approaching 3000 A/mm ² at 5 T. The authors report on the electrical properties ( J_c and n value) and mechanical properties (tensile, springback, and bend characteristics) of the strand. Piece length distributions obtained for various production billets are presented. The performance of cables fabricated from the strand is discussed. Specifically, the critical current degradation due to cabling and residual twist in the cable are addressed