Numerical investigation of the plasma processes for propellant heating in electrothermal plasma thruster for nanosatellites

Abstract

Numerical investigation of the plasma processes in a cylindrical chamber with small dimensions of a novel microwave electrothermal plasma thruster for nanosatellites has been conducted. The absorbed microwave power from the electrons in the plasma column of the surface wave discharge is included in the computational model as a heat source with Gaussian distribution. The computational model takes into account the elastic and inelastic collisions of the electrons with the atoms in the ground state and two excited states (−s, −p) and the processes of recombination and deactivation of the plasma species in the volume and on the walls of the chamber. The computational model includes the flow of neutral gas and the processes in the plasma for effective heating of neutral particles by collisions not only with electrons but also with ions. Selected combinations of input power and propellant mass flow rates are used as initial parameters for the numerical investigation. The results show that at higher mass flow rates the heating of the neutral gas is more effective and at power levels of 4 W and propellant mass flow rate of 3 mg/s the electrothermal plasma thruster demonstrates effective performance and thrust levels in the order of 1 mN.

Microwave electrothermal thruster with surface wave plasma

“…[ 11 ] Direct comparison of our theoretical [ 18 ] and experimental results presented here is hampered by the difference in the gas flow and the nozzle diameter, but our theoretical model correctly shows that the chamber pressure increases with increasing gas flow and increasing absorbed microwave power. Simulations of the heating process in the thruster [ 18 ] show that gas temperatures at higher flow rates are determined mainly by the elastic collisions of electrons and atoms rather than by the heating process in the radial field.…”

“…The charged particles (electrons and positive ions) in the non-isothermal high-density SW plasma have higher temperatures (the electron energy distribution function in a SW plasma is close to the Maxwellian energy distribution function) [17,18] than the temperature of the neutral particles. Electrons and ions transfer part of their energy to the neutral particles (gas heating) by elastic, nonelastic collisions, and heating in a radial electric field.…”

“…Electrons and ions transfer part of their energy to the neutral particles (gas heating) by elastic, nonelastic collisions, and heating in a radial electric field. [ 18 ] The thermal expansion accelerates the gas flow through the nozzle and thus, it creates thrust. The experimental investigation of this thruster is implemented by using two types of resonant chambers.…”

“…In this study, we present a new type of a microwave electrothermal plasma thruster, [ 12 ] which uses SW plasma [ 13 ] with longitudinal plasma resonances [ 14 ] for heating up the gas in an alumina chamber. It has a low average power consumption (2–3 W) and is suitable for applications in nanosatellites, following the CubeSat standard.…”