A gas phase kinetic model for the CF���/O��� microwave discharge plasma and afterglow of our laboratory has been developed. A reaction pathway identifying the major chemical reactions is proposed. The rate coefficients of the electron impact dissociation reactions are determined at three different plasma powers using both published electron molecule collision cross section data and plug flow analysis of data collected in our system. Agreement between calculated and experimental rate coefficients is better than 20%. Fluid simulations of a two-dimensional mathematical model were performed using computational fluid dynamics. It is found that the model reproduced qualitatively the general trends of the experimental data. The effects of plasma power, feed gas composition, residence time and pressure on the product distribution of the system are studied. CF��� conversion increases with power and residence time. The variation of CF��� conversion and carbon containing species
distribution falls into two regimes. In the oxygen rich regime (below 25 mole % CF��� in the feed), CO��� is found to be the major product of CF��� decomposition; homogeneous recombination reactions between atomic oxygen and the free radicals are found to be the dominant mechanism in the afterglow region resulting in high CF��� conversions. Homogeneous reactions convert CO to CO���. In the CF��� rich regime (above 50 mole % CF���), COF��� is found to be the major product of CF��� decomposition. Recombination reactions of CF��� with atomic fluorine dominate in the afterglow region and limit conversion. Lowering pressures result in increased conversion of CF��� and increased concentration of the carbon containing species. / Graduation date: 1998
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33745 |
| Date | 05 December 1997 |
| Creators | Camara, Amadou Tidiane |
| Contributors | Koretsky, Milo D. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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