Measurement of Electron Density near Plasma Grid of Large-scaled Negative Ion Source by Means of Millimeter-Wave Interferometer

Journal Article · Mon Sep 26 00:00:00 EDT 2011 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3637408· OSTI ID:21611682

Nagaoka, K; Tokuzawa, T; Tsumori, K; Nakano, H; Ito, Y; Osakabe, M; Ikeda, K; Kisaki, M; Shibuya, M; Sato, M; Komada, S; Kondo, T; Hayashi, H; Asano, E; Takeiri, Y; Kaneko, O ^[1]

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1. National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan)

A millimeter-wave interferometer with the frequency of 39 GHz ({lambda} 7.7 mm) was newly installed to a large-scaled negative ion source. The measurable line-integrated electron density (n{sub e}l) is from 2x10{sup 16} to 7x10{sup 18} m{sup -2}, where n{sub e} and l represent an electron density and the plasma length along the millimeter-wave path, respectively. Our interest in this study is behavior of negative ions and reduction of electron density in the beam extraction region near the plasma grid. The first results show the possibility of the electron density measurement by the millimeter-wave interferometer in this region. The line-averaged electron density increases proportional to the arc power under the condition without cesium seeding. The significant decrease of the electron density and significant increase of the negative ion density were observed just after the cesium seeding. The electron density measured with the interferometer agrees well with that observed with a Langmuir probe. The very high negative ion ratio of n{sub H-}/(n{sub e}+n{sub H-}) = 0.85 was achieved within 400 min. after the cesium seeding.

• OSTI ID: 21611682
• Journal Information: AIP Conference Proceedings, Vol. 1390, Issue 1; Conference: 2. international symposium on negative ions, beams and sources, Takayama City (Japan), 16-19 Nov 2010; Other Information: DOI: 10.1063/1.3637408; (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
43 PARTICLE ACCELERATORS
ANIONS
BEAM EXTRACTION
CESIUM
ELECTRON DENSITY
ELECTROSTATIC ACCELERATORS
GHZ RANGE
ION SOURCES
LANGMUIR PROBE
OPTIMIZATION
PLASMA
PLASMA DIAGNOSTICS
ACCELERATORS
ALKALI METALS
CHARGED PARTICLES
ELECTRIC PROBES
ELEMENTS
FREQUENCY RANGE
IONS
METALS
PROBES