High Emissivity Arcjet Thruster Anodes

High-power ammonia arcjet thrusters are being investigated as primary propulsion systems for carrying satellites into high altitude orbits. As a method to enhance the power levels and efficiency of the engine, the thermal emissivity of the outer anode surface must be substantially enhanced. Ideally, the anode material should be low density, both highly electrically and thermally conductive, and be chemically compatible with the reactive propulsion gases. The proposed research will investigate anode materials fabricated from directionally aligned carbon/carbon (C/C) composite. The inside surfaces of the plenum chamber, constrictor throat, and expansion nozzle will be coated with a layer of conductive tungsten metal to serve as the arc attachment surface and to protect the C/C composite surface will also ensure effective radiation of the heat flux generated by the arcjet plasma.