CO and C2 excited states relaxation in CO2 plasmas derived from a Collisional-Radiative model

Abstract

In order to explain the behavior of the main excited electronic states of CO and C2 molecules formed in CO2 entry or ground test facilities plasmas, a time-dependent Collisional-Radiative (CR) model is elaborated. This CR model is then included in the general balance equation of the species to give an insight on the influence of the transport and elementary processes. The related flows are generally observed under relatively low temperature owing to the numerous internal degrees of freedom to be excited, leading to a rather weak ionization degree. The electron-induced processes are even so taken into account: their influence is studied and commented. The conditions to reach non-equilibrium steady states and the related characteristic time scales are discussed as well.