Browsing by Author "Van Gaens, W."

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    Numerical analysis of the effect of nitrogen and oxygen admixtures on the chemistry of an argon plasma jet operating at atmospheric pressure
    ([London] : IOP, 2015) Van Gaens, W.; Iseni, S.; Schmidt-Bleker, A.; Weltmann, K.-D.; Reuter, S.; Bogaerts, A.
    In this paper we study the cold atmospheric pressure plasma jet, called kinpen, operating in Ar with different admixture fractions up to 1% pure ${{{\rm N}}_{2}}$, ${{{\rm O}}_{2}}$ and ${{{\rm N}}_{2}}$ + ${{{\rm O}}_{2}}$. Moreover, the device is operating with a gas curtain of dry air. The absolute net production rates of the biologically active ozone (${{{\rm O}}_{3}}$) and nitrogen dioxide (${\rm N}{{{\rm O}}_{2}}$) species are measured in the far effluent by quantum cascade laser absorption spectroscopy in the mid-infrared. Additionally, a zero-dimensional semi-empirical reaction kinetics model is used to calculate the net production rates of these reactive molecules, which are compared to the experimental data. The latter model is applied throughout the entire plasma jet, starting already within the device itself. Very good qualitative and even quantitative agreement between the calculated and measured data is demonstrated. The numerical model thus yields very useful information about the chemical pathways of both the ${{{\rm O}}_{3}}$ and the ${\rm N}{{{\rm O}}_{2}}$ generation. It is shown that the production of these species can be manipulated by up to one order of magnitude by varying the amount of admixture or the admixture type, since this affects the electron kinetics significantly at these low concentration levels.
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    Numerical analysis of the NO and O generation mechanism in a needle-type plasma jet
    ([London] : IOP, 2014) Van Gaens, W.; Bruggeman, P. J.; Bogaerts, A.
    In this paper we study two cold atmospheric pressure plasma jets, operating in Ar + 2% air, with a different electrode geometry but with the same power dissipated in the plasma. The density profiles of the biomedically active NO and O species throughout the plasma jet, previously obtained by laser diagnostics, are calculated by means of a zero-dimensional semi-empirical reaction kinetics model. A good agreement between the calculated and measured data is demonstrated. Furthermore, the most probable spatial power distribution in an RF driven plasma jet is obtained for the first time by comparing measured and calculated species density profiles. This was possible due to the strong effect of the power distribution on the NO and O density profiles. In addition the dominant reaction pathways for both the NO and the O species are identified. The model allows us to obtain key information on the reactive species production inside the jet, which is difficult to access by laser diagnostics in a coaxial geometry. Finally, we demonstrate that water impurities in the order of 100 ppm in the gas feed can have a significant effect on the spatial distribution of the NO and O density. © 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.