SUPERCOOLED ROTOR COIL TYPE ELECTRIC MACHINE

An electric rotary machine having an armature coil at ambient temperature disposed on the stator and a supercooled field coil disposed on the rotor and enclosed in a container which is integral with said rotor, a major part of the outer surface of said container being coated with a thermal insulation layer, the supercooling liquid being introduced into the container through a tube inserted into the rotor along the rotational axis of the rotor, and the evaporated gas of the supercooling medium being discharged through a labyrinthine path or a series of partitioned compartments provided at each axial end of the container to establishing a uniform temperature gradient along the shaft of the rotor between the inside of the supercooled rotor and the axial ends thereof which are at ambient temperature.