Optimization of a radio-frequency inductively coupled plasma thruster

Radio-Frequency (RF) Inductively Coupled Plasma (ICP) thrusters are an emerging electrothermal propulsion technology that creates a high-density plasma to heat propellant which is then accelerated through a converging-diverging nozzle. Using a multi-physics model accounting for plasma production, plasma-coil electromagnetic coupling, heat transfer, and impedance matching, this work investigates optimization of a complete RF ICP propulsion system for small satellite missions by varying important design and operating parameters including thruster size, propellant type, mass flow rate, and RF frequency. Aside from thruster performance, an important optimization metric is minimization of the total propulsion system mass, and for a representative small satellite mission power and total impulse of 100 W and 1 kNs respectively, xenon is found to be an attractive propellant because of its low ionization threshold, high atomic mass, and high storage density. This not only reduces propulsion system inert mass, but also yields a thrust-to-power ratio almost ten times higher than other electric propulsion technologies such as gridded ion or Hall thrusters.