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Author Praburam, G. ♦ Goree, J.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword PLASMA PHYSICS AND FUSION ♦ PLASMA IMPURITIES ♦ PLASMA WAVES ♦ CARBON ♦ ELECTRIC DISCHARGES ♦ IONIZED GASES ♦ FLUCTUATIONS ♦ SOUND WAVES ♦ DUSTS
Abstract Images of a cloud of grains in a dusty plasma reveal a pair of very low-frequency modes, termed here the filamentary and great void modes. The plasma was a radio-frequency discharge formed between parallel-plate graphite electrodes. A cloud of 100 nm carbon particles was produced by accretion of carbon atoms produced by sputtering the graphite. The cloud was illuminated with a laser sheet and imaged with a video camera. The great void mode was a spoke-shaped region of the cloud that was free of dust and rotated azimuthally in the discharge. The filamentary mode had the appearance of turbulent striations, with a smaller amplitude than the great void. The filamentary mode sometimes appeared as a distinctive vortex, curling in the poloidal direction. Both modes had a very low frequency, on the order of 10 Hz. Two possible causes of the modes are discussed. The low phase velocity of the modes may be consistent with a dust-acoustic wave. Alternatively, the great void may be an ionization wave that moved the dust about, since a modulation in the glow was seen moving at the same speed as the void. It is argued that existing theories of waves in dusty plasmas assume weakly collisional plasmas, which may be unsuitable for explaining experimental results in laboratory dusty plasmas, since they are often strongly coupled. {copyright} {ital 1996 American Institute of Physics.}
ISSN 1070664X
Educational Use Research
Learning Resource Type Article
Publisher Date 1996-04-01
Publisher Place United States
Journal Physics of Plasmas
Volume Number 3
Issue Number 4


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