Negative hydrogen ion densities and drift velocities in a multicusp ion source

We have determined densities of negative hydrogen ions in a discharge by a laser detachment technique. We measured the electron density, the electron temperature, and the positive ion density using a Langmuir probe. We also performed extraction measurements. Combination of H− density measurements an...

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Bibliographic Details
Published in:Journal of applied physics 1990, Vol.67 (1), p.85-96
Main Authors: EENSHUISTRA, P. J, GOCHITASHVILI, M, BECKER, R, KLEYN, A. W, HOPMAN, H. J
Format: Article
Language:English
Subjects:
640301 - Atomic, Molecular & Chemical Physics- Beams & their Reactions
CHARGED PARTICLES
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
DISSOCIATION
ELECTRIC DISCHARGES
ELECTRIC PROBES
ELECTROMAGNETIC RADIATION
ELECTRON ATTACHMENT
ELECTRON DENSITY
ELECTRON TEMPERATURE
Exact sciences and technology
HYDROGEN IONS
ION DENSITY
ION SOURCES
IONS
LANGMUIR PROBE
LASER RADIATION
MATHEMATICAL MODELS
Physics
Physics of gases, plasmas and electric discharges
Physics of plasmas and electric discharges
Plasma devices
PROBES
RADIATIONS
SCALING LAWS
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Summary:We have determined densities of negative hydrogen ions in a discharge by a laser detachment technique. We measured the electron density, the electron temperature, and the positive ion density using a Langmuir probe. We also performed extraction measurements. Combination of H− density measurements and extraction measurements yields information about the H− drift velocity. It was found that the velocity scaled with the square root of the electron temperature. All measurements were done as a function of discharge voltage, discharge current, and gas pressure. The densities are compatible with a semiquantitative model in which H− is produced by dissociative attachment of plasma electrons to vibrationally excited molecules and destroyed by wall collisions at very low pressure and collisions with H atoms, positive ions and/or hot thermal electrons at higher pressure.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.345210