Kiel 2011 – scientific programme

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P: Fachverband Plasmaphysik

P 7: Poster: Modellierung und Simulation von Niederdruckplasmen

P 7.10: Poster

Tuesday, March 29, 2011, 17:00–19:00, Foyer

Modelling of rf excited filaments occurring in a jet plasma — •F. Sigeneger, J. Schäfer, R. Foest, and K.-D. Weltmann — INP Greifswald, Felix-Hausdorff-Str. 2, 17489 Greifswald

Discharge filaments which occur in a miniaturized non-thermal atmospheric pressure plasma jet have been investigated by a self-consistent fluid model. The filaments are generated by an rf voltage at 27.12 MHz applied between two cylindric electrodes which are attached alongside the outer quartz capillary of the plasma jet. Argon gas flows between the outer and the inner quartz capillary with flow rates between 0.1 and 2 slm. Depending on the applied power and flow rate, stationary or rotating discharge filaments are observed between the upper driven and the lower grounded electrode.

A single stationary filament is investigated using a simplified geometry. The model includes electrons, atomic and molecular argon ions as well as excited argon atoms. The set of equations comprises continuity equations for these species, Poisson's equation, the electron energy balance and balance equations for the charges on the dielectric surfaces. The electron transport and rate coefficients have been prepared as functions of the mean energy and ionization degree by solving the 0D electron Boltzmann equation. A relatively high electron density has been found which qualitatively agrees with results of spectroscopic measurements. Moreover, the results show the structural change of the filament from the dielectric surface through the sheath to the column.

The work was supported by the Deutsche Forschungsgemeinschaft within SFB-TR 24.