Aachen PK 2003 – scientific programme

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P: Plasmaphysik

P 3: Low Temperature Plasmas, Plasma Technology

P 3.2: Talk

Monday, March 17, 2003, 16:05–16:25, FO4

Spatial density distributions of atomic oxygen in an rf discharge — •S. Peters, B. Krames, A. Mengel, and J. Meichsner — Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, Germany

Spatial density distributions of O atoms in a capacitively coupled asymmetric rf discharge are carried out by two photon laser induced fluorescence spectroscopy (TALIF). With a reference measurement at a spectrally close two-photon resonance of xenon the data are calibrated.

The asymmetric axial profiles can be described by different similarity parameters. This can be explained by the diffusion dominated transport of the O atoms, their loss at the electrode surfaces and the properties of the discharge. In radial direction the concentration profiles show symmetric shapes with a flat decrease to the electrode edge. Some millimeters in front of the electrodes the density increases rapidly in the region of the grounded shielding. Here, the density reaches a maximum in the spatial afterglow of the discharge. The position of this maximum depends on the self–bias voltage.