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Pure Appl. Chem., 2010, Vol. 82, No. 6, pp. 1209-1222

Published online 2010-04-20

Diagnostic-based modeling on a micro-scale atmospheric-pressure plasma jet

Jochen Waskoenig1, Kari Niemi1, Nikolas Knake2, Lucy Marie Graham1, Stephan Reuter1, Volker Schulz-von der Gathen2 and Timo Gans1*

1 Centre for Plasma Physics, Queen’s University Belfast, Belfast BT7 1NN, Northern Ireland, UK
2 Institute for Experimental Physics II: Applied Plasma Physics, Ruhr-Universität Bochum, 44801 Bochum, Germany

Abstract: Diagnostic-based modeling (DBM) actively combines complementary advantages of numerical plasma simulations and relatively simple optical emission spectroscopy (OES). DBM is applied to determine spatial absolute atomic oxygen ground-state density profiles in a micro atmospheric-pressure plasma jet operated in He–O2. A 1D fluid model with semi-kinetic treatment of the electrons yields detailed information on the electron dynamics and the corresponding spatio-temporal electron energy distribution function. Benchmarking this time- and space-resolved simulation with phase-resolved OES (PROES) allows subsequent derivation of effective excitation rates as the basis for DBM. The population dynamics of the upper O(3p3P) oxygen state (λ = 844 nm) is governed by direct electron impact excitation, dissociative excitation, radiation losses, and collisional induced quenching. Absolute values for atomic oxygen densities are obtained through tracer comparison with the upper Ar(2p1) state (λ = 750.4 nm). The resulting spatial profile for the absolute atomic oxygen density shows an excellent quantitative agreement to a density profile obtained by two-photon absorption laser-induced fluorescence spectroscopy.