Simulations of ion thruster plumes in ground facilities using adaptive mesh refinement

Ion thruster plumes are simulated under a recently developed computer framework inside a vacuum chamber at various background pressures for single- and triple-thruster configurations. Momentum and charge-exchange collisions occurring between neutral and ion species, as well as the induced electric field due to ions, are performed using multiple adaptive mesh refinement meshes to study the spatial variance of neutrals and ions while analyzing the effect of vacuum chamber conditions. Comparisons between vacuum chamber and space simulations show that the spatial distribution of the neutral densities are different in the far downstream region of the ion thruster. The change in the background density is also found to affect the spatial distributions of the charge-exchange ions in the domain. The triple-thruster cases show that the background density levels are approximately proportional to the number of thrusters being operated. The adaptive mesh refinement capability is shown to be able to capture the confinement effect of the flow in the vacuum chamber.