Self-Consistent Numerical 0D/3D Hybrid Modeling of Radio-Frequency Ion Thrusters

Abstract

In this paper, we show a numerical model of gridded radio-frequency (RF) ion thrusters. The model consists of a set of self-consistently coupled equations based on conservation of charge, energy, and mass inside the system. Those 0D models are again coupled to a 3D quasi-stationary electromagnetic field solver which offers the opportunity of evaluating arbitrary induction coil and discharge chamber geometries in fairly reasonable simulation time. Several input parameter sets can be computed in parallel due to multi-core implementation. Therefore, the model presented can be regarded as a toolbox for ion thruster engineering purposes and rapid virtual prototyping. The model predicts electrical parameters such as thruster and plasma impedance as well as propulsive performance data. It is thus possible to use it for finding optimized coil and chamber geometries together with optimized input parameters (coil current, volumetric propellant flow rate, and extraction grid voltages) in order to obtain improved mass and electrical efficiency. To prove the validity of the model, performance mappings experimentally performed on a RIM-4 RF ion thruster assembled at the University of Giessen are used to verify the computed data.

Radio-Frequency Ion Thrusters—Power Measurement and Power Distribution Modeling

“…But it can be related to changes in the plasma, and those can be stimulated by the input parameters, which aect those local distributions that in turn can be attributed to the particular terms in Eq. (14). This equation essentially is a conservation equation for electrical energy.…”

“…All other important quantitites, such as coil current, applied frequency, and plasma parameters, are calculated within the model. The model's complete architecture and other detailed information can be found in [13,14].…”

“…To close the loop, the amount of neutral gas leaving the thruster γ n is also calculated as shown in [13,14]. This allows for determination of the mass usage eciency…”

“…The denition of the mass usage eciency used in this work is based on singly ionized species only and accounts for the ionized vs un-ionized propellant [14].…”

“…The resistive and reactive components of the load impedance can be derived from Eq. (14). Furthermore, the propulsive performance of the thruster such as thrust and specic impulse can be obtained from the converged solution.…”