Düsseldorf 2007 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 16: Poster

P 16.12: Poster

Mittwoch, 21. März 2007, 16:30–18:30, Poster A

Experimental and theoretical investigations of a helium-xenon discharge in spot mode — •Jörn Winter, Hartmut Lange, Irina A. Porokhova, Florian Sigeneger, and Detlef Loffhagen — INP Greifswald, Felix-Hausdorff-Str. 2, 17489 Greifswald

Experimental and theoretical investigations of the cathode region of a dc helium-xenon discharge in spot mode are reported. The spatial profiles of the gas and the cathode surface temperature in the vicinity of the spot have been measured spectroscopically in dependence on the discharge current. Furthermore, the density of metastable xenon atoms were determined by diode laser absorption spectroscopy.

A two-dimensional fluid model was applied including particle balance equations for electrons, ions and metastable atoms, the energy balance equation for electrons and the Poisson equation. The required electron transport and collision rate coefficients were taken as functions of the mean electron energy from a pickup table which was generated by solving the steady-state spatially homogeneous electron Boltzmann equation. The profile of the electron thermionic emission flux was fixed using the temperature profile measured at the spot. The results show the broadening of the discharge from the narrow spot towards the anode which is connected with large spatial changes of the electric field in axial and radial direction including reversals of its direction. Qualitative agreement between the measured and calculated density profile of the metastable atoms has been obtained.

The work was supported by "Deutsche Bundesstiftung Umwelt".