Conceptual designs of 50 kA 20 MJ superconducting ohmic heating coils

Two conceptual designs of 20 MJ superconducting coils are described which were developed to demonstrate the feasibility of an ohmic heating system. Both NbTi and Nb3Sn superconductors were considered for both 7 tesla and 9 tesla maximum fields. Cabled and braided conductors were investigated and the braided conductors are identified as the best alternative due to their high operating current densities and because of its porosity. The coils are designed to be cryostable for bipolar operation from +7 tesla to -7 tesla and from +9 tesla to -9 tesla maximum fields within 1 second. The structural design addresses the distribution of structure and structural materials used in the pulsed field environment. Both the immersion cooled (pool boil) and the forced flow cooled coils are described.