Abstract
Previously studied electromagnetic launchers have contained either copper magnets or superconducting magnets wound from tape. However, an attractive alternative to use of wound magnets is use of monolithic magnets made by improved melt-texturing techniques. Melt-textured monolithic magnets can have good energy density and very high effective power when converting magnetic to kinetic energy. One of the difficulties associated with monolithic magnets, which is addressed in this paper, is their nonuniform current density. We have measured the energy conversion efficiency for 28 YBCO magnet combinations. A scaling parameter for predicting efficiency as a function of geometry and critical current is proposed. We then searched for an optimally shaped magnet by using a numerical model with a genetic algorithm. The best individuals were found to be shaped like an hourglass. A magnet of this shape was fabricated, and measured to have a conversion efficiency of 84%.