Development of MgB2-Cabled Conductors for Fully Superconducting Rotating Electric Machines

High-speed, fully superconducting electric rotating machines are highly sought for naval and aerospace applications, to provide significantly higher power density than can be achieved by other means. We examined the use of an MgB
₂
-based, two-stage, cabled conductor for the armature winding of a medium power (10-15 MW) electric generator, operating near 20 K at a nominal peak phase current of 2 kA. We chose MgB
₂
because it is electromagnetically isotropic and can be manufactured as round, multifilamentary strands. This paper describes the proposed conductor and presents our prototype manufacturing efforts. Prototype cables were fabricated using fine filament (15-μm filament diameter) strand manufactured by Hyper Tech Research. AC losses in MgB
₂
triplet bundles were measured at 20 K using a calorimetric technique. We present measured AC loss data for the MgB
₂
triplets and evaluate those losses in relation to the strand composition and strand and cable configurations.