A 10-MJ compact homopolar generator

The design and initial testing of a light-weight (5 kJ/kg) iron-cored homopolar generator is described. The machine employs an external power supply to motor up to operating speed (12,500 rpm) at which point 10-MJ of energy is stored in the all-steel rotor. Copper-graphite brushes in the stator, actuated by pneumatic actuators, make contact with the rotor surface and permit the inertial energy to be transferred to a load circuit at current levels up to 1.5 MA and voltages up to 60 V. A companion paper describes a 10-MJ cryogenic inductor which, with this machine, provides a 10-MJ power source suitable for electromagnetic launcher component testing.