Modelling of an Ar-O-2 reactive magnetron discharge used for deposition of chromium oxide

In connection with experimental work on the optical emission spectroscopy (OES) analysis of a magnetron discharge working in reactive Ar-O-2 and N-2-O-2 gases, we developed a collisional-radiative model for the Ar-O-2 plasma. We consider here low-pressure conditions under which the transport of neutral particles corresponds to a free-fall regime rather than to a diffusive one. This model solves self-consistently the Boltzmann equation for electrons in the magnetized region (negative glow) of the discharge and the kinetic equations for argon and for molecular and atomic oxygen states. Positive and negative ion state densities are also calculated. We study the dependence of the densities of these species on experimental parameters such as the discharge current and the relative O-2 concentration. The results are compared with optical emission spectroscopy experimental results.