Experimental verification of Boltzmann equilibrium for negative ions in weakly collisional electronegative plasmas

Journal Article · Mon Apr 13 00:00:00 EDT 2009 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.3119627· OSTI ID:21294012

Ghim, Young-chul ^[1]; Hershkowitz, Noah ^[2]

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1. Department of Physics, University of Oxford, Oxford OX1 3NP (United Kingdom)
2. Department of Engineering Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

Weakly collisional Ar-O{sub 2} electronegative plasmas are investigated in a dc multidipole chamber. An electronegative core and an electropositive halo are observed. The density ratio of negative ions to electrons ({alpha}) in the nondrifting bulk is found to be 0.43. The profile of {alpha} is found using both the phase velocity of ion acoustic waves and the drift velocity of positive ions determined by laser-induced fluorescence. The experiment shows that negative ions are in Boltzmann equilibrium with a temperature of 0.06{+-}0.02 eV. Double layers are not found separating the electronegative core and the electropositive halo.

• OSTI ID: 21294012
• Journal Information: Applied Physics Letters, Vol. 94, Issue 15; Other Information: DOI: 10.1063/1.3119627; (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANIONS
CATIONS
ELECTRONEGATIVITY
ELECTRONS
FLUORESCENCE
ION ACOUSTIC WAVES
LASERS
LAYERS
PHASE VELOCITY
PLASMA