Active species in a large volume N2–O2 post-discharge reactor

Abstract

A large volume post-discharge reactor placed downstream from a flowing N2–O2 microwave discharge is modelled using a three-dimensional hydrodynamic model. The density distributions of the most populated active species present in the reactor—O(3P), O2(a 1 Δg), , NO(X 2 Π), NO(A 2 Σ+), NO(B 2 Π), NO2(X), O3, and N(4S)—are calculated and the main source and loss processes for each species are identified for two discharge conditions: (i) p = 2 Torr, f = 2450 MHz, and (ii) p = 8 Torr, f = 915 MHz; in the case of a N2–2%O2 mixture composition and gas flow rate of 2 × 103 sccm. The modification of the species relative densities by changing the oxygen percentage in the initial gas mixture composition, in the 0.2%–5% range, are presented. The possible tuning of the species concentrations in the reactor by changing the size of the connecting afterglow tube between the active discharge and the large post-discharge reactor is investigated as well.