Improved Fin Designs to Reduce Deffective in Internal-Tin Nb3Sn

75077S An economical process will be needed to produce super conducting 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 super conducting units into which these conductors are divided. This project will accomplish this goal by dividing the super conducting units (the subelements) with radial fins of non-superconductors. In Phase I, three different designs of small diameter billets with fins were assembled, extruded, and processed to wire. Reductions in the hysteresis losses were shown in most of the individual subelements and in several of the 18-subelement restacks. In Phase II, the most promising designs will be selected, the process will be scaled up to full sized billets, and material will be supplied to the National Laboratories for coil winding experiments. Commercial Applications and Other Benefits as described by the awardee: In addition to its use in HEP accelerator applications, the material should be useful in magnets for open-area Magnetic Resonance Imaging (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.