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Author Marshall, Ryan S. ♦ Chai, Kil-Byoung ♦ Bellan, Paul M.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword ASTROPHYSICS, COSMOLOGY AND ASTRONOMY ♦ ASTROPHYSICS ♦ COLLISIONS ♦ DENSITY ♦ DISTRIBUTION ♦ DUSTS ♦ FRACTALS ♦ GRAIN GROWTH ♦ ICE ♦ LENSES ♦ MICROSCOPES ♦ MOLECULES ♦ PLANETS ♦ PLASMA ♦ PROTOPLANETS ♦ SATELLITES ♦ VELOCITY ♦ WATER
Abstract The grain growth process in the Caltech water–ice dusty plasma experiment has been studied using a high-speed camera and a long-distance microscope lens. It is observed that (i) the ice grain number density decreases fourfold as the average grain major axis increases from 20 to 80 μ m, (ii) the major axis length has a log-normal distribution rather than a power-law dependence, and (iii) no collisions between ice grains are apparent. The grains have a large negative charge resulting in strong mutual repulsion and this, combined with the fractal character of the ice grains, prevents them from agglomerating. In order for the grain kinetic energy to be sufficiently small to prevent collisions between ice grains, the volumetric packing factor (i.e., ratio of the actual volume to the volume of a circumscribing ellipsoid) of the ice grains must be less than ∼0.1 depending on the exact relative velocity of the grains in question. Thus, it is concluded that direct accretion of water molecules is very likely to dominate the observed ice grain growth.
ISSN 0004637X
Educational Use Research
Learning Resource Type Article
Publisher Date 2017-03-01
Publisher Place United States
Journal Astrophysical Journal
Volume Number 837
Issue Number 1


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