Ionization Mechanism in a Direct Current Discharge Plasma in an Argon–Oxygen Mixture

We present the results of calculating the charged particle formation and decay rates in a dc discharge positive column in argon–oxygen mixture. The calculations are based on a combined solution to the Boltzmann equation; vibration kinetics equations for the ground state of the $\mathrm{O}_2$ molecule; and chemical kinetics equations for Ar and O atoms, $\mathrm{O}_2$ molecule, and their excited states under the experimentally determined reduced electric field strength, $E/N$, for various gas phase compositions, currents, and pressures. The role is clarified of particular components in the ionization processes. Electron and positive ion decay is shown to take place predominantly at the reactor walls on which they fall due to joint diffusion. The negative oxygen ions affect the diffusion rate.