Extended plateaux in the vibrational and electron distribution functions of O2/O reacting plasmas in discharge and post-discharge conditions

Abstract

An accurate state to state model describing the plasma kinetics in reacting oxygen plasma has been built up giving particular attention to vibrational–translational O–O2 processes, as well as O–O2(v) dissociation and recombination, direct electron impact dissociation, and resonant electron–vibration (e–V) processes for O2. Moderate and low pressure situations are investigated for both discharge and post-discharge conditions. In both cases, an important role of three body recombination of O atoms and of multi-quantum e–V processes is observed, the latter being particularly important at low pressure. The interplay of the different processes forms an extended plateaux on the vibrational distribution function (vdf) of O2 in both discharge and post-discharge conditions. A comparison between our calculated vdf and the corresponding experimental and theoretical results of Annusova et al. shows a good qualitative agreement. Declining plateaux are also observed in the electron energy distribution function. In this case, superelastic electronic collisions involving high lying electronic states of the O atom form important maxima over the declining plateau.