Analysis of Plasma Properties, Plasma Ignition and Erosion in Ion Gridded Thrusters Operating with Alternative Propellants

Abstract

This work presents a comprehensive computational investigation of alternative propellants and material response in plasma propulsion systems. A kinetic framework based on the Particle-in-Cell method coupled with Monte Carlo collisions (PIC–MCC) is implemented to evaluate the plasma behavior of krypton and iodine as candidate propellants for gridded ion thrusters. The model incorporates detailed collision processes, representative operating parameters, a simplified ion engine configuration, and an ion-optics design to characterize plasma dynamics. Variations in mesh resolution produce consistent qualitative trends in ion and electron energy distributions, although differences arise in total energy responses. The accumulation of particles leads to increased ionization, indicating continuous plasma generation across the ion engine model. In addition to ion propulsion modeling, this research examines a plasma-assisted combustion concept as an alternative propulsion-related application. A novel plasma ignition configuration is analyzed using Large Eddy Simulation (LES) to assess the interaction between electrode placement and supersonic pulsed discharge flow structures. The results demonstrate how geometric and electrical parameters influence cavity flow dynamics and ignition probability. Erosion and sputtering processes are investigated using molecular dynamics (MD) simulations. Sputtering yields and erosion rates are quantified for carbon, carbon–carbon composites, graphite, molybdenum, and tungsten, and are compared against predictions from an empirical model. Within the 200–1000 eV energy range, the empirical formulation predicts a steady increase in sputtering yield, while the MD results show a similar increasing trend in most configurations and an approximately constant response in one case. Angular sputtering analyses reveal energy-dependent increases at selected grid locations, with the empirical representation reproducing the characteristic rise and post-peak decline. Furthermore, the size of the simulation domain is found to influence the sputtering yield, with larger domains leading to clear changes in the computed yield. Erosion rate patterns remain generally consistent across grid sections and energy intervals, though localized increases are observed under specific conditions. The influence of incident angle further modifies these trends, producing an initial gradual rise followed by a stabilized erosion regime. Overall, this work integrates kinetic plasma modeling, large-eddy flow simulations, and atomistic-scale material analysis to advance the understanding of alternative propellants and erosion mechanisms in electric propulsion systems. The results contribute to the evaluation of krypton and iodine as viable candidates beyond xenon, while also providing insight into potential grid material options.