Unifying the computational modeling process of a radio-frequency gridded ion thruster

A gridded ion thruster powered by inductively coupled plasma (ICP), commonly known as a radio-frequency (RF) ion thruster (RIT), offers high specific impulse and efficiency suitable for deep space missions. However, experimental testing of RITs requires large vacuum facilities and costly instruments, leading many preliminary studies to rely on numerical simulations for design and optimization. Sophisticated numerical models can accurately predict ion thruster performances, including plasma characteristics and ion extraction. Nevertheless, prior studies typically treat gas dynamics, plasma discharges, and grid ion optics separately due to disparate spatial and temporal scales. In this study, we present a unified simulation methodology using COMSOL Multiphysics, which models the entire 10-s mN-class RIT system—from propellant injection to thruster performance—in a two-dimensional axisymmetric domain. Naturally, the realistic hole-type grid structure is simplified to a coaxial annular slit-type grid while maintaining key parameters, such as the cross-sectional geometry of each open grid region, the open screen grid area and the beam diameter. To reconcile the simplified geometry with a practical hole-type grid, three correction factors—gas flow correction, ion extraction probability correction, and ion beam divergence angle correction—are introduced. This method enables the investigation of plasma properties, including electron temperatures, densities, and plasma potentials, as well as thruster performance metrics, such as thrust, the mass utilization factor, electrical efficiency, and overall thruster efficiency. The simulation is completed within reasonable time and memory constraints. Simulated results are in good agreement with the previous experimental and numerical studies, demonstrating the validity of the unified simulation approach.