Spatially Resolved Collisional-Radiative Model for a Rarefied Plasma Plume

Abstract The VKI DRAG-ON facility was designed to replicate Very Low Earth Orbit flow conditions, to study Air-Breathing Electric Propulsion intakes and gas-surface interaction physics. Its Particle Flow Generator produces a low-density, low-temperature argon plasma plume. This study investigates the flow’s thermochemical non-equilibrium by comparing synthetic spectra from Collisional-Radiative modeling to Optical Emission Spectroscopy measurements. A Lagrangian reactor approach is used to account for the reacting species advection, as the chemical and flow timescales are shown to be comparable. The results also highlight the importance of the assumption on the Electron Energy Distribution Function shape. Model-experiment comparisons reveal potential for plasma diagnostics and suggest targeted chemical model refinements.