Aachen PK 2003 – wissenschaftliches Programm
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P: Plasmaphysik
P 4: Poster I
P 4.11: Poster
Montag, 17. März 2003, 17:45–19:15, Foyer
Analysis of several population densities in molecular hydrogen and their application for diagnostic purposes — •J. Günther, U. Fantz, and K. Behringer — Lehrstuhl für Experimentelle Plasmaphysik, Institut für Physik, Universität Augsburg, D-86135 Augsburg
Population densities of several electronic states of H2 (3p 3Πu, 3p 3Σu+, 3d 1Σg+ and 3d 1Πg) in a surface wave excited H2/He plasma are measured by optical emission spectroscopy (OES). To obtain Te and n(H2) from the population of these excited states a collisional radiative model (CR) for H2 is applied. It predicts population densities depending on the plasma parameters Te and ne. Te is determined by OES using the absolute intensity of a helium line or by a Langmuir probe. ne is also obtained by different techniques: besides interferometry and Langmuir probe a simplifying method is applied, i.e. the ratio of helium emission lines. Since the knowledge of the population of metastable He is essential for the interpretation of the measured data, absorption spectroscopy is carried out as well. The results will be compared for Te and ne. On the basis of these parameters the population densities of H2 are calculated by the CR-model and compared to the measured data. The dependencies, deviations and preferred electronic states for diagnostics will bediscussed.