Augsburg 2006 – wissenschaftliches Programm
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P: Plasmaphysik
P 15: Diagnostik 2; Niedertemperaturplasmen / Plasmatechnologie 5; Plasma-Wand Wechselwirkung 1
P 15.28: Poster
Dienstag, 28. März 2006, 17:00–19:00, Flure
Analysis of the chemistry in methane discharges by means of tunable diode laser absorption spectroscopy — •Anna Serdyuchenko, Ivonne Möller, and Henning Soltwisch — Institut für Experimentalphysik V, Ruhr-Universität Bochum, 44780 Bochum, Germany
The chemical composition in a methane discharge is strongly influenced by the electron impact dissociation rate coefficients, which are directly dependent on the electron energy distribution function (EEDF). Unfortunately the direct measurement of the EEDF is hampered by the reactivity of the plasma and relatively low electron densities.
In this work we try to estimate the rate coefficients of several dissociation reactions from relatively simple rate equations for the main plasma species (CH4, CH3, C2H2, C2H4 and C2H6), which have been measured by tunable diode laser spectroscopy. By comparing these rate coefficients with calculated values resulting from appropriately chosen EEDFs, the mean energy for different plasma conditions can be evaluated. The various loss channels (pumping, dissociation, chemical reactions) have been investigated under different flow conditions. Simple analytical approximations for the dominant plasma species allow us to find out the main reaction channels.