Darmstadt 2008 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P IV: Poster: Niedertemperaturplasmen II, Astrophysikalische Plasmen, Magnetischer Einschluss, Plasma-Wand-Wechselwirkung
P IV.24: Poster
Donnerstag, 13. März 2008, 16:00–18:30, Poster C2
Metastable Argon Atoms in RF-sheath of Capacitively Coupled 13.56 MHz Plasma — •Kristian Dittmann1, Nader Sadeghi2, and Jürgen Meichsner1 — 1University of Greifswald, Institute of Physics, Greifswald, Germany — 2Université Joseph Fourier & CNRS, Laboratoire de Spectrometrie Physique, Grenoble, France
Axially resolved density profiles of metastable excited Argon atoms, Ar(3P2), from laser absorption spectroscopy at 772 nm in an asymmetrical argon rf plasma (ccp) show a significant density maximum located at the mean rf sheath boundary. The density rises with increasing rf-power (30 to 130 W) and total pressure (20 to 100 Pa). The population of the metastables is mainly caused by rf sheath electron heating and electron impact excitation. An increasing metastable density is additionally found in axial direction towards the rf-electrode surface. In comparison with results from optical emission spectroscopy an intensive emission of Argon atoms was found at the mean rf sheath boundary similar to the metastable density generated by sheath electrons. Surprisingly, an increasing optical emission of Argon in front of the rf-electrode was only found for transitions (e.g. 772.38 nm, 772.42 nm and 763.51 nm) which are in relation to the metastable levels, Ar(3P2) and Ar(3P0).