Improved Fin Designs to Reduce Deffective in Internal-Tin Nb3Sn

75077-An economical process will be needed to produce superconducting material for the high field magnets that will be used in future accelerators for High Energy Physics (HEP) research. To achieve this economy, it will be necessary to reduce the hysteresis losses that occur in the new high-current-density conductors. One way of doing this is to reduce the size of the filamentary units into which these conductors are divided. This project will achieve this goal by dividing the superconducting unit areas (the subelements) with radial fins of non-superconductors. Three different designs of these fins will be tried in Phase I using small subelement billets. The first will have three pure tantalum (Ta) fins, significantly thicker than previously used, with a ¿channel shaped¿ design to reduce the tendency of Nb3Sn to bridge around it. The second billet will have laminated fins in which a thinner Ta layer is spaced with a layer of ferromagnetic nickel (Ni) to kill any weak superconducting link that may exist across the fins after the heat treatment reaction. The design of the third billet will await the testing of the first two so that lessons learned can be used to optimize its design. Commercial Applications and Other Benefits as described by the awardee: In addition to its use in HEP accelerator applications, the more economical magnets that result from this work should be useful for open-area MRI, where the patient is more accessible to the surgeon. (MRI is the largest commercial application of low temperature superconductors.) Fusion and levitated transportation projects represent other possible applications.