A Modified Internal Tin Tube Nb3Sn Conductor for Higher Non-Copper Critical Current Density

Future magnets for High Energy Physics (HEP) require superconductors with improved high critical current carrying capacity at high magnetic fields, decreased effective filament sizes and lower cost. An improved method of fabricating such superconductors is being investigated using the Internal Tin Tube (ITT) Process that will improve the critical current density achievable. In Phase I, Sn-Ta alloys were fabricated by melt diffusion of mixed powders. The alloys were rolled to foil and placed at the interface between the niobium and the high tin copper-clad tin cores of ITT monofilaments. Thick Nb3Sn layers were formed after heat treatment. Fine grained Nb3Sn was observed in composites containing the alloys, but not in a control composite that did not contain Sn-Ta alloy. In Phase II, the Sn-Ta alloy homogeneity will be improved. The alloy compostion and thickness will be optimized. The process will be scaled-up to a commercial level, with conductor lengths and filament sizes suitable for high energy physics applications. Commercial Applications and Other Benefits: Future accelerator and related superconducting magnets for HEP applications will become more feasible if this project is successful. Additionally, the technology developed if this project is successful can find application in commercial high field magnets for NMR, FT-ICR, and other analytic magnet applications.