High Current Density (Jc), Low AC Loss, Low Cost Internal-Tin Superconductors

70027 Although internal tin Nb3Sn has been shown to have current densities close to the objectives of magnet designers for future particle accelerators, the AC losses and costs are too high. This project will combine the best features of the internal tin and modified jelly roll (MJR) processes to reduce the losses and costs. To lower the losses, multiple barrier restacks containing a range of different numbers of subelements will be prepared and tested in Phase I. In particular, three restacks with 18, 39, and 60 subelements containing an extruded barrier will be tested for current density, AC losses, and RRR (residual resistance ratio). The degree of reaction and the quality of the barriers will be determined metallographically. The most promising design will be selected, optimized, and scaled up in Phase II. Commercial Applications and Other Benefits as described by the awardee: Applications for the technology include open area MRI (MRI is the largest commercial application of low temperature superconductors), small magnets for high field laboratory applications and NMR, and fusion and leviated transportation projects.