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P: Fachverband Plasmaphysik

P 27: Complex Plasmas and Dusty Plasmas II

P 27.2: Vortrag

Donnerstag, 8. März 2018, 14:25–14:40, KI 1.174

Plasma dynamics around a dust cluster embedded in the sheath of a rf discharge — Jens Schleede, Lars Lewerentz, •Franz Xaver Bronold, Ralf Schneider, and Holger Fehske — Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald, Germany

We employ a PIC-MCC/PPPM simulation to investigate the plasma dynamics around a three-dimensional dust cluster of 44 particles embedded in the sheath of an argon rf discharge. Our approach tracks self-consistently the charge of the particles and the plasma flow towards and through them. The geometry of the cluster, its position in the sheath, both assumed to be fixed, and the plasma parameters are essentially identical to the experimental setups for investigating dust clouds in plasmas. We find strong shadowing and focusing effects leading to a broad distribution of the charges accumulated by the grains suggesting that theoretical models studying dynamical effects of the cluster which assume identical charges and reciprocal forces between the grains may have to be modified to be also applicable to dust arrangements trapped in the sheath of a rf discharge. From the time-resolved electron fluxes, visualized by tracer particles, we moreover identify density fronts and convection patters driven by the repulsion between the incoming electrons and the electrons collected by the particles. As expected the electron flux is neither isotropic nor laminar. Charging models developed for an isolated particle are thus also not applicable to an arrangement of grains trapped in the sheath of a rf discharge. – Supported by DFG through CRC/Transregio TRR24.