Erlangen 2018 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 8: Complex Plasmas and Dusty Plasmas I

P 8.1: Hauptvortrag

Dienstag, 6. März 2018, 10:30–11:00, KI 1.174

Life in the void: nanoparticle formation in reactive plasmas — •Ferdi van de Wetering — Eindhoven University of Technology, Department of Applied Physics, P.O. Box 513, 5600 MB Eindhoven, the Netherlands

Reactive plasmas are plasmas where nanoparticles spontaneously form in the volume from the feed gas molecules. This can be advantageous since the produced particles generally have a monodisperse size distribution and therefore have a multitude of applications. It can also be detrimental, especially in the semiconductor industry, where plasmas are widely used in the production of integrated circuits.

Nanoparticle formation in these plasmas is generally accepted to follow a step-wise process: polymerization of the feed gas molecules, nucleation, coagulation and accretion of plasma ions and radicals. The resulting particles charge negatively by attachment of plasma electrons and are therefore confined in the positive plasma glow. Under certain conditions this results in a dense cloud of solid nanoparticles levitated in the plasma.

Sometimes, a macroscopic dust-free zone (void) develops as a result of forces pushing particles outward (such as the ion drag force). A new cycle of nanoparticle formation is impeded in the nanoparticle cloud, but it can start in the void region. By employing several diagnostics, such as microwave cavity resonance spectroscopy, electron microscopy, Mie scattering and emission spectroscopy, as well as modeling, we are able to explain the peculiar and interesting dynamics of the void and link this directly to the step-wise and cyclic formation of nanoparticles.