A Solid Expellant Plasma Source/Contactor for Electrodynamic Tethers

The Solid Expellant Plasma Source/Contactor (SOLEX) is a new technological development that considerably simplifies the plasma generation and electron emission process. Under the Phase-1 effort, the preliminary work to demonstrate the feasibility of the SOLEX concept was accomplished. The intent of the proposed Phase-II effort is to develop a flight-level design for a SOLEX plasma generator, for electrodynamic tether systems, and fabricate an Engineering Unit test device that is appropriate for flight validation. The SOLEX will operate directly off of the tether-generated high-voltage (requiring no conditioned power or control electronics) and will eliminate the need for high-pressure gas containers, pressure regulators, plumbing and valves?required by present state-of-the-art Hollow Cathode devices. These are significant improvements over current state-of-the-art contactors that impinge heavily on spacecraft resources. Based on available flight data and Phase-I tests, current capacity can range from a few milli-amps to several amps. By nature of its design, the SOLEX should not be sensitive to contamination and should have essentially unlimited restart capability?both are issues with state-of-the-art contactors. Moreover, the simplicity of the design concept suggests that flight devices will be relatively inexpensive.