Gas Temperature and Nitrogen Atom Concentration Influence onthe Particle Kinetics in a Surface-Wave-Sustained N2Discharge

Abstract

A study has been performed to investigate the gas temperatureinfluence on the different particle balances of a low-pressuresurface-wave-sustained nitrogen discharge. The detailed kinetic modelincludes the local electron Boltzmann equation coupled to the set ofrate balance equations for theN2(X1Σg+, ν)levels, the most important electronically excited states and chargedspecies. The maintenance electric field strength is self-consistentlydetermined by solving the continuity equation for electrons and themain positive ions (N2+,N4+) together with the abovementioned set ofequations. The system for the vibrational levels takes into accountelectron–vibration (e–V), vibration–vibration(V–V), vibration–translation (V–T) energy exchangereactions and wall deactivation. It is demonstrated that the gastemperature variations essentially affect both the electron and heavyparticle kinetics through the dependence of the rate coefficients forvarious elementary processes on this plasma parameter. The influenceof the relative atom concentration onto the population of thevibrationally excited levels and the metastable stateN2(A 3Σu+) has alsobeen investigated. It is shown that the fast V–T exchangesassociated with N2–N collisions play an importantrole in the heavy particle kinetics, determining the efficientdepopulation of the higher vibrational levels of N2molecules. The theoretical results for the vibrational temperatureTν are compared with experimental data obtainedat the same discharge conditions.