Development of Internal-Tin Nb/Sn Strand for High Field Accelerator Dipole Applications

72192S03-I Future high field (15+) dipole magnets will require superconductors with high current density and lower cost. These objectives could be accomplished by increasing the current density and lowering the fabrication cost of NbSn subelements. The Phase I project will develop technology for lowering the cost of fabricating Nb/Cu filaments for subelement extrusion billets, for increasing the Nb/Cu ratio of the filaments for subelement extrusion billets, and for providing a more uniform diffusion of Ti into each filament of the subelement extrusion billet. After inserting tin in the center of these extruded subelements, they will be drawn down, restacked into a billet, and then drawn down to final strand size. The final strands will be characterized for critical current density Jc, alternating current loss, and Sn and Ti diffusion. Commercial Applications and Other Benefits as described by awardee: The largest market for the technology should be for accelerator and fusion magnets. However, high field magnets (above 5 tesla) can be used for MRI, NMR, high gradient magnetic separators, and superconducting magnetic energy storage applications.