Mechanisms of methane decomposition in nitrogen afterglow plasma

Chemical reactions initiated by the dissociation of methane in the nitrogen flowing afterglow have been studied by the computer modelling. The input experimental data were obtained from the microwave CH4/N-2 plasma. The modelling of methane decomposition was based on a macroscopic kinetic approach. The 24 neutral and excited species were introduced: electrons, hydrocarbons, radicals, neutral and excited gases, and nitrogen containing species. Between these species 61 chemical reactions were studied. It was found that in the flowing afterglow conditions, where the energy of excited particles is reduced, the limited amount of reactions is really important. With the aid of this simplified model of 18 chemical reactions the yield of stable products and the detailed kinetics of their creation in the dependence on activity of individual species were studied. Special attention was devoted to the study of reaction kinetics in dependence on the afterglow time in accordance with experimental data. (C) 1998 Elsevier Science Ltd. All rights reserved.