Design, Fabrication and Testing of a Fast Discharge Homopolar Machine (FDX)

The Fast Discharge Experiment (FDX) is a 0.36 MJ, 200 V homopolar machine designed to discharge in one millisecond. All components, including dual brush actuation systems, a room-temperature 2 x 106 A-t pulsed copper coil, two aluminum rotors with copper slip rings, low inductance return conductors, coaxial transmission line, four fast closing (30 μsec), megamp switches, hydrostatic journal bearings, squeeze film thrust bearings and a fiberglass reinforced epoxy structure have been fabricated and assembled. The detail design of machine components is presented. Preliminary testing, including rotor spin-ups, brush actuation, switch making, and pulsed field coil tests have been concluded. A low speed, short-circuit discharge of FOX has recently been conducted. Experimental data from these tests are compared with theoretical predictions.