Overview of the different aspects in modelling moderate pressure H2 and H2/CH4 microwave discharges

This paper deals with the modelling of moderate pressure H2 and H2/CH4 microwave plasmas used for diamond deposition. The first part of the paper reports on the development of a detailed collisional radiative model for moderate pressure pure H2 plasma. Several effects related to electron kinetics, H2 vibrational kinetics and H2 and H excited states kinetics and their effect on the overall dissociation and ionization kinetics are analysed with the model developed. This allows us to propose a reduced model which can be used for the self-consistent modelling of H2 discharges or as the modelling of the more complex H2/CH4 plasmas. The second part of the paper deals with the two-dimensional self consistent modelling of H2 plasmas obtained in a microwave cavity coupling system. The procedure used for coupling the plasma transport equations to the electromagnetic field equations is first discussed and some self-consistent simulation results with respect to the power deposition and plasma temperature and density distributions in the investigated plasma device are given. The last part of the work addresses the one-dimensional transport modelling of H2/CH4 plasmas used for diamond deposition. The spatial variations of neutral and charged hydrocarbon species densities on the reactor axis are presented and the main phenomena and processes that govern these variations are discussed