Frustum Shaped Cavity Based Microwave Electrothermal Thruster For Nanosatellites

Abstract

Microwave Electrothermal Thruster (MET) is a type of the space propulsion system that heats the propellant by passing it through the plasma. The mission is to provide the exhaust velocity to the nanosatellite in the geostationary orbit. The paper presents the design optimization for frustum and cylindrical cavity based MET system to compare their performance for nanosatellite application. The performance parameters include electric field, electron density, electron temperature, ion temperature and input power. Upper radius of frustum is less than cylindrical cavity so it occupies less area which lead to miniaturization of device and decrease in input power. Frustum is giving higher electric field intensity, electron density, electron temperature, ion temperature and specific impulse as compared to the cylindrical cavity at same frequency [30GHz] and for same input power (6W). As ion temperature increases, exhaust velocity of the propellant and specific impulse increases. Increase in specific impulse lead to decrease in mass of propellant expelled through the nozzle per second which lead to increase in lifetime and payload capacity of thruster. Hence MET with frustum cavity can be a better choice for nanosatellites at 30GHz. Argon is used to create the plasma and is also used as propellant in the nozzle. The parameters are calculated and analyzed using Comsol Multiphysics software.