Bochum 2015 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 5: Poster Session - Low Temperature Plasmas

P 5.10: Poster

Montag, 2. März 2015, 16:30–18:30, Foyer Audimax

Atomic processes in low-pressure argon afterglows — •Tsanko Vaskov Tsankov¹, Rainer Johnsen², and Uwe Czarnetzki¹ — ¹Institute for Plasma and Atomic Physics, Ruhr-University Bochum, 44780 Germany — ²Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh PA 15260, USA

Recently a comprehensive description of the kinetic processes in a low-pressure argon plasma afterglow was presented [1]. The experimental findings were supported by analytical models but some unknown quantities had to be adjusted by fitting the model predictions to experimental data. The main obstacle preventing a more quantitative description was the complex population dynamics of the excited states of the atoms in a recombination-dominated afterglow.

We have now remedied this problem by constructing a more complete collisional-radiative model of a recombining argon plasma. It allows the calculation of the population densities as well as of the net recombination rate. The model is coupled with the equations of the recombining plasma for the temporal evolution of the electron density and temperature. This allows a full ab initio calculation of the temporal evolution of a number of plasma characteristics, like the electron density and temperature as well as the metastable atom density. The calculated and measured temporal evolution of the various parameters are compared and an excellent quantitative agreement is found throughout. It is found that heating and cooling of the neutral gas has to be taken into account for an accurate fitting.

[1] Y. Celik et al., Phys. Rev. E 85 (2012) 056401