Spatio-temporal evolution of the dust particle size distribution in dusty argon rf plasmas

An imaging Mie scattering technique has been developed to measure the spatially resolved size distribution of dust particles in extended dust clouds. For large dust clouds of micrometre-sized plastic particles confined in an radio frequency (rf) discharge, a segmentation of the dust cloud into popul...

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Bibliographic Details
Published in:Plasma sources science & technology 2015-04, Vol.24 (2), p.25029-10
Main Authors: Killer, Carsten, Mulsow, Matthias, Melzer, André
Format: Article
Language:English
Subjects:
Argon plasma
Clouds
Density
Dust
dusty plasma
Infrared absorption
Mie scattering
Outgassing
Particle size distribution
plasma diagnostics
Plasmas
Populations
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Summary:An imaging Mie scattering technique has been developed to measure the spatially resolved size distribution of dust particles in extended dust clouds. For large dust clouds of micrometre-sized plastic particles confined in an radio frequency (rf) discharge, a segmentation of the dust cloud into populations of different sizes is observed, even though the size differences are very small. The dust size dispersion inside a population is much smaller than the difference between the populations. Furthermore, the dust size is found to be constantly decreasing over time while the particles are confined in an inert argon plasma. The processes responsible for the shrinking of the dust in the plasma have been addressed by mass spectrometry, ex situ microscopy of the dust size, dust resonance measurements, in situ determination of the dust surface temperature and Fourier transform infrared absorption (FT-IR). It is concluded that both a reduction of dust size and its mass density due to outgassing of water and other volatile constituents as well as chemical etching by oxygen impurities are responsible for the observations.
ISSN:0963-0252
1361-6595
DOI:10.1088/0963-0252/24/2/025029