A Comparison of Force-Reduced Toroidal Geometries and Conventional Superconducting Magnets

Abstract

The discovery of ‘high-T _c ’ superconductors has led to renewed interest in large-scale applications of superconductivity, such as electromagnetic energy storage and magnetohydrodynamic propulsion; however, an upper limit on the magnetic field and size of such devices remains the difficulty in supporting the large Lorentz forces. Here, a new approach to winding toroidal magnets in a force-reduced geometry is proposed. As force-free finite geometries are not possible due to the limits of the Virial theorem, the proposed system is based on a force-free solution to Ampere’s Law for the inner leg mated to conventional dee-shaped outer legs. Preliminary results from finite element calculations indicate that this design may offer substantial improvement over conventional approaches. In addition to force reduction, the need for either wedging or bucking in the inner leg is eliminated. Further analysis is necessary to fully quantify the relative merits of this approach.