Superconductors with 2.5 Micron NbTi Filaments

Abstract

Multifilamentary superconductors with 2.5 micron sized NbTi filaments are being proposed for the High Energy Booster part of the SSC project. The small filament size and the large number of filaments in the superconductor strands make the fabrication a challenge, especially in view of the high critical current performance required of them. IGC has produced two 309 mm diameter prototype billets and fabricated both the “Inner” and the “Outer” grade strands. The production approach was based on a triple extrusion process incorporating Cu − 0.6 wt.% Mn as the interfilament matrix material. The results of this pilot development effort, in terms of critical current density and mechanical properties, will be presented in this paper. Appropriate comparisons with past performances will be made.