50-kA conductors for tokamak poloidal field coils

The Los Alamos Scientific Laboratory (LASL) is building a prototype 20-MJ, 50-kA superconducting poloidal field coil to demonstrate feasibility for tokamak poloidal field coil systems. The coil must be capable of being swung from +7 T to -7 T in one second. It must carry 50 kA at 7 T, be cryostable, but have low losses under pulsed operation. LASL contracted with Magnetic Corporation of America (MCA) and Intermagnetics General Corporation (IGC) to produce 7.6 m of prototype 50-kA conductors and longer lengths of the various subcable units. The cable designs and the manufacturing experiences of the MCA cable are discussed. Energy loss measurements on the subcables of the MCA cables and on prototype IGC conductors are presented and discussed in terms of projected losses for the 20-MJ coil.