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P: Fachverband Plasmaphysik

P 18: Poster: Diagnostics

P 18.9: Poster

Donnerstag, 11. März 2010, 16:00–18:00, Lichthof

Field Evolution and Optical Excitation in Inductively Coupled Plasmas — •Dominik Winter, Yusuf Celik, Dirk Luggenhölscher, and Uwe Czarnetzki — Ruhr University Bochum

The evolution of electromagnetic fields within a planar coil, inductively coupled rf plasma is investigated. A comparison between results obtained by an analytical model, finite element simulation (COMSOL Multiphysics) and experimental data is shown. The analytical model describes the plasma as a conductive medium with a given homogeneous electron density and a constant phenomenological collision frequency over the entire discharge volume. The vacuum case is included in the limit of zero conductivity. The propagation of the electric field into the plasma chamber obtained by the model is in very good agreement with the simulation. On the other hand, the electrical field distribution is obtained experimentally by two independent techniques: B-dot probe and radio-frequency modulation spectroscopy (RF-MOS). The former measures the time varying magnetic field. Via Faradays law the electric field is inferred. The latter is a recently developed emission spectroscopic diagnostic for inductively coupled plasmas. It measures primarily the temporal modulation of the local electron energy distribution function (EEDF) by detecting small modulations in the percentage range of the optical line emission from the plasma. This can then be related to the local electric field. The spatial electric field distribution leads to the real and imaginary part of the dielectric constant of the plasma and finally to a value for the electron density and collision frequency.