Composition of a plasma generated from N2–O2 by an Ar ion jet in a low pressure reactor

Abstract

The expansion of a supersonic Ar+ ion jet in a low pressure (0.2 Torr) reactor filled with N2 and O2 has been investigated by means of hydrodynamic modelling. The gas velocity fields and the gas temperature distribution in the three-dimensional reactor have been determined. The formation of different species through the molecular kinetics triggered by the collision of Ar+ ions with N2 and O2 molecules has been studied. We have investigated the effect of the ions velocity and molecular gas flow rates on the gas temperature and species density distributions. We have shown that the main difference between this system and an N2–O2 post-discharge lies in the dissociation degrees of N2 and O2. While in an N2–O2 post-discharge the N2 dissociation degree is low and that of O2 is high, in the present system this can be varied through the gas flow rate of the molecular gases. We have also shown that the NO(X) molecules formation is governed by the surface processes, which is strongly influenced by the state of the surface.