Conceptual design of a 20-MJ superconducting forced cooled ohmic-heating coil

Conceptual design of a 20 MJ superconducting coil is described which was developed to demonstrate the feasibility of an ohmic-heating system. The superconductor material was Nb3Sn for a 9 tesla maximum field. Cabled and braided conductors were investigated and the braided conductors were identified as the best alternates due to their high operating current densities and because of its porosity. The coil was designed to be cryostable for bipolar operation from +9 tesla to -9 tesla maximum field within 1 second. The forced cooled design utilizes cross flow cooling. The coil was designed to generate the flux swing while simultaneously meeting the limitations imposed by cooling, insulation, current density and stresses in the materials