Hannover 2010 – scientific programme

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P: Fachverband Plasmaphysik

P 18: Poster: Diagnostics

P 18.6: Poster

Thursday, March 11, 2010, 16:00–18:00, Lichthof

Electron density measurements in an inductively coupled radio frequency discharge by optical emission spectroscopy — •Sarah Siepa, Edmund Schüngel, Julian Schulze, Dirk Luggenhölscher, and Uwe Czarnetzki — Institute for Atomic and Plasma Physics, Ruhr-University Bochum, Germany

Optical emission spectroscopy (OES) is a non-intrusive diagnostic that provides access to plasma parameters such as the electron density and temperature. In this work the OES line-ratio technique developed by Pu et al. [1] is used to measure the electron density in an inductively coupled RF discharge operated in argon. Based on a collisional-radiative model and for a given electron temperature, the electron density is determined by measuring the ratio of the intensities of specifically chosen emission lines without the need of any absolute calibration of the setup. A Maxwellian electron energy distribution function is assumed for the calculation of rate coefficients, which is well justified under the discharge conditions investigated as demonstrated by Celik [2]. Three different line-ratios have been used under various pressures and RF powers. The comparison of the results with Langmuir probe measurements of the electron density [2] shows that the OES line ratio technique works well. However, some limitations are found. For instance, the choice of emission lines is found to affect the results and a particular line pair is identified that yields optimum agreement with probe measurements. [1] X.-M. Zhu, W.-C. Chen, J. Li, Y.-K. Pu, J.Phys. D: Appl. Phys. 42 025203 (2009) [2] Aufbau und Erprobung eines Langmuir-Sondensystems, Y. Celik (2007)