WireDev

The collaboration develops recipes and methods for fabricating Nb3Sn multifilamentary wires with enhanced current-carrying capability. It implements the internal oxidation technique to increase the critical current density Jc, combined with conventional Ta or Ti doping of Nb3Sn to enhance the upper critical field Bc2. Since Jc in Nb3Sn is proportional to the grain boundary density, internal oxidation forms a dispersion of oxide nano-inclusions that refines the grain size of the superconductor down to about 50 nm — two to three times smaller than in state-of-the-art conductors — and increases Jc accordingly. To suit accelerator magnets, the prototype wires must also meet requirements beyond high Jc: good thermal stability, tolerance to mechanical loads, and a small superconducting filament size to reduce magnetization. The fabrication routes must also be scalable at industrial level.