Study of microwave discharges in air on the basis of extended fluid-dynamic model

The present study is devoted to modeling a high-frequency plasma discharge in air based on an extended fluid-dynamic model. The aim of the work is to study the influence of various physico-chemical processes on the gas parameters. A numerical model was de-veloped for propagation of electro-magnetic waves through the mixture of nitrogen and oxygen in a microwave plasma reactor, in which a discharge occurs due to microwave radiation with a frequency of 2.45 GHz. The model is based on a reduced set of plasma chemical reactions, which includes ionization of atoms and molecules of nitrogen and oxygen, excitation of electronic degrees of freedom, dissociation of molecules, their re-combination and other chemical reactions that occur in plasma. Modeling was performed for two pressure values: 150 Torr and 760 Torr. Distribution fields of plasma parameters such as electron density, gas temperature, and heating source power for each mechanism are obtained. Results are analyzed and conclusions are drawn about the influence of pressure and fast heating mechanisms on plasma parameters. It is shown that nitrogen dissociation and elastic collisions of electrons with molecules make the most important contribution to the gas heating; on the opposite, reactions involving nitrogen molecule electronic states weakly affect the heating.

microwave plasma, fluid-dynamic model, CFD, fast gas heating

Исследование СВЧ разряда в воздухе на основе расширенной гидродинамической модели

В работе представлена самосогласованная физико-математическая модель, описы-вающая СВЧ-разряд на поверхностной волне с частотой 2.45 ГГЦ в потоке воздуха (смеси кислорода и азота). Модель основана на расширенном гидродинамическом описании плазмы и включает в себя достаточно подробный набор элементарных процессов, в который входят ионизация атомов и молекул азота и кислорода, воз-буждение электронных степеней свободы, диссоциация молекул, их рекомбинация и другие плазмохимические реакции. Расчёт был произведён для двух значений давления: 150 Торр и 760 Торр. Получены основные параметры СВЧ-разряда: кон-центрация электронов, температура газа, мощности источников нагрева для каждо-го механизма. На основе анализа полученных результатов были сделаны выводы о влиянии давления и механизмов быстрого нагрева на параметры плазмы. Показан существенный вклад диссоциации молекул азота и упругих соударений электронов с молекулами в общий нагрев газа и слабое влияние на нагрев реакций с изменени-ем электронных состояний молекулы азота.

СВЧ-плазма, гидродинамическая модель, численное моделирование, быстрый нагрев

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