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P: Fachverband Plasmaphysik

P 9: Poster: Niedertemperaturplasmen

P 9.22: Poster

Tuesday, March 31, 2009, 17:30–19:30, Foyer des IfP

Dissociation of nitrogen atoms in Hollow Cathode Arc — Igor Vinogradov and •Achim Lunk — Institut für Plasmaforschung, Universität Stuttgart

Measurements of following plasma parameter in HCA by OES will be presented: EEDF, electron density, dissociation degree of nitrogen. Spectroscopic measurement of EEDF is based on the analysis of the molecular spectra of nitrogen and the atomic spectra of He, N and Ar. The shape of the EEDF was evaluated by Langmuir probe measurements. Investigations were performed in Ar/He, Ar/N2, N2/He mixtures at gas pressure 0.3 - 1 Pa. A spectrometer of 75 cm focal length together with a CCD-camera was used in OES . Discharge current is varied in the range of 20 - 110 A, voltage in the range of 32 - 50 V. An inhomogeneous magnet field was applied and its influence on plasma parameter was studied. The electron temperature does not strongly depend on the discharge current and the composition of gas mixture. Its averaged value is about (4.0 +/- 0.5) eV. The electron density depends sensitively on magnetic field and can be increased by a factor of 10 if magnet field is increased from 0 to 20 mT. Dissociation degree of nitrogen increases linearly with increasing discharge current.