Numerical Study of Plasma Effect on Electric Field Distribution in 2.45 GHz Microwave Electrothermal Thruster Resonant Cavity
by Mehmet Serhan Yildiz, Murat Celik

Electrothermal thrusters which are a subclass of the electric propulsion systems use elec- trical energy to increase the propellant thermal energy. Energized gas thermal energy is transformed into kinetic energy when the gas is expanded through a structure like a nozzle. In microwave electrothermal thruster (MET) concept microwaves are used for the propellant heating. The conversion of microwave energy into propellant kinetic energy is materialized inside a resonant cavity. Proper electric field distribution in the resonant cavity is very important for initiating and maintaining the plasma discharge. At the resonant conditions, reflections diminish significantly. In this study plasmas effect on the electric field distribution is simulated by using a commercial software. Simulations are made for a cavity fed with a coaxial port which has a power input of 1 kW at 2.45 GHz frequency. Cavity radius is maintained at constant 50.8 mm and height is varied in 5 mm range with 0.1 mm steps for a parametric sweep. The eects of the mentioned plasma non-uniformities, and the required geometry optimization of the resonant cavity are studied and the results are presented.