The RF plasma thruster has considerable potential to ease the impact of severe constraints on power, mass, volume and lifetime of microsatellite propulsion systems. This concept is classified as an electrothermal propulsion system and exploits RF capacitively coupled discharge (RFCCD) for heating of a propellant. The plasma is characterized as a low-power discharge possessing a low-current density with high uniformity and propagating through low-pressure gas. To assess computationally the thruster’s propulsive capabilities as a function of mass flow rate, electrode separation, RF frequency and power input, a numerical model comprises particle-in-cell/Monte Carlo (PIC/MCC) and Direct Simulation Monte Carlo (DSMC) algorithms. Thruster performance is investigated by permuting electrode geometry (0.5 - 2 cm), chamber pressure (0.05 - 50 Torr), applied voltage (100 - 500 V), and frequency (10 - 1000 MHz). For this parameter space, PIC/MCC determines overall trends in plasma characteristics. One selected case (3 Torr, 500 V, 200 MHz) and its set of conditions (plasma density, plasma heating, gas temperature, etc.) form the basis for an in-depth flow field and thrust performance analysis with DSMC. Assuming adiabatic wall conditions, the RF plasma thruster achieves a specific impulse of 104.4 s with Argon at the throat Reynolds number of 25. The RF heating increases the specific impulse by 125 %. This study shows that propulsive capability of the RF plasma thruster can be enhanced by increasing the discharge chamber length, redesigning the nozzle contour, and using propellants with lower molecular weights.
Date of this Version
Stein, William B.; Alexeenko, Alina A.; Hrbud, Ivana; and Bondar, Evgeniy, "Performance Modeling of an RF Coaxial Plasma Thruster" (2007). School of Aeronautics and Astronautics Faculty Publications. Paper 15.