Hannover 2010 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 7: Poster: Dusty Plasmas
P 7.19: Poster
Dienstag, 9. März 2010, 16:00–18:00, Lichthof
Measurements of Ion Densities in Pulsed Complex Plasmas — •Brankica Sikimić1, Ilija Stefanović1, Igor Denysenko2, and Jörg Winter1 — 1Institut für Experimental Physik II, Ruhr Universität Bochum, Germany — 2School of Physics and Technology, Kharkiv National University, 61077 Kharkiv, Ukraine
A non-invasive diagnostic method for measurement of ion densities in pulsed complex plasma is proposed. Ion densities were measured in argon plasma with acetylene as a precursor gas, including nanometer-sized dust particles produced by reactive plasma polymerization. The experiments were performed in low-pressure capacitively-coupled discharge, symmetrically driven by radio frequency. The signal from the RF generator was square wave modulated at 100 Hz. The densities of ions were deduced from the change of electrode voltage in the plasma afterglow. The electrode voltage remained negative, repelling the free electrons and collecting the positive ions. The ion density was obtained by dividing the collected charge by the active plasma volume, assuming no other significant loss channels for the ions. Ion densities were compared with electron densities measured independently and simultaneously by microwave interferometry. An excellent agreement for pure argon and argon-acetylene plasma was found. In dusty plasmas, the expected decrease of electron densities was observed. A numerical model for this discharge can explain the behaviour of species densities in plasma afterglow and estimate loss channels of the ions to the walls and to the dust particles.