Plasma motor/generator reference system designs for power and propulsion

Four Plasma Motor/Generator (PMG) Reference Systems, hollow cathode-based versions of the electrodynamic tether concept which are to be used in study and analysis of future propulsion and power applications, are discussed. These systems are equally applicable for use as electric generators to provide power to a spacecraft or as electric motors using power from the spacecraft. Operating at relatively high current and low voltage, the PMGs avoid requirements for technological advances to handle very high voltages. Permanent deployment with passive I x B control of tether dynamics eliminates the complexity and weight of a TSS style tether reel. A 20 kW PMG uses 10 km of number two aluminum wire, weighs 1200 kg, and has an electrical efficiency of 93 percent. A larger 200 kW system uses 20 km of number 00 aluminum wire, weighs 4200 kg, and operates at 87 percent efficiency.