Hannover 2010 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 7: Poster: Dusty Plasmas
P 7.18: Poster
Dienstag, 9. März 2010, 16:00–18:00, Lichthof
LIF Measurements of Metastable Densities in Complex Plasmas — •Brankica Sikimić1, Ilija Stefanović1, Nader Sadeghi2, and Jörg Winter1 — 1Institut für Experimental Physik II, Ruhr Universität Bochum, Germany — 2Laboratoire de Spectometrie Physique, University Joseph Fourier and CNRS, Grenoble, France
Dynamics of metastable argon atoms (Ar*(3P2) state) in continuous wave complex plasma has been investigated by laser induced fluorescence. Different mixtures of argon plasma with acetylene have been used, including nanometer-sized dust particles produced by reactive plasma polymerization. Experiments were performed in 0.1 mbar, symmetrically driven CCP discharge at 13.56 MHz. Density and axial distribution of metastable atoms have been deduced by absorption and LIF experiments with an external cavity single-mode diode laser. The axial distribution of metastable atoms is recorded within a cycle of growth of dust particles and the formation of a void (dust-free region in the plasma). In pure argon plasma, ionization is located in the negative glow near electrodes. After introducing acetylene, metastable density decreases due to the quenching of Ar* by acetylene. Formation of negatively charged nanoparticles leads to an increase of the ionization rate, sustaining of the discharge and provokes the enhancement of metastable density. After 20 minutes, the void starts to form, leading to the decrease of the dust density and the ionization rate. Due to this effect, the metastable density decays until the dust particles disappear and a new cycle of dust formation starts. We discuss different mechanisms responsible for the behavior of metastable atoms.