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P: Plasmaphysik

P 4: Poster I

P 4.9: Poster

Montag, 17. März 2003, 17:45–19:15, Foyer

Self-consistent modelling of a low-pressure He-Xe discharge — •Sergej Gortchakov, Hartmut Lange, Detlef Loffhagen, and Dirk Uhrlandt — Institut für Niedertemperatur-Plasmaphysik, 17489 Greifswald, Germany

Glow discharges in mixtures of xenon and helium at low pressure represent a prospective alternative to replace plasmas containing mercury in VUV radiation and light sources. Low-pressure dc and ac discharges can be applied for publicity lighting purposes. The discharge properties and optimum operation conditions of such glows can be determined by a self-consistent analysis of the column plasma. For the analysis of the dc operation regime two approaches for the description of the cylindrical plasma have been used. Each approach includes a kinetic treatment of the plasma electrons, a detailed balance description of the excited states in xenon and a self-consistent determination of the axial heating field. The space-dependent approach is based on a radially resolved treatment of the plasma components and of the radial space-charge field in steady state. The time-dependent approach uses a radially averaged description of the electron and heavy particle kinetics, while steady state plasma parameters are determined by means of a temporal relaxation procedure. It can be also applied to study the ac discharge operation regime. Dc discharges in mixtures of helium and 2% xenon are studied. Results of probe and tunable diode laser absorption diagnostics are used to evaluate the calculated electric field strength and absolute densities of excited xenon states. Advantages and disadvantages of both approaches are assessed and perspectives for studying the ac operation regime are discussed.