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

Abstract

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.

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ;  [1]
  1. National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan)
Publication Date:
OSTI Identifier:
21611682
Resource Type:
Journal Article
Journal Name:
AIP Conference Proceedings
Additional Journal Information:
Journal Volume: 1390; Journal 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); Journal ID: ISSN 0094-243X
Country of Publication:
United States
Language:
English
Subject:
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

Citation Formats

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., and Kaneko, O. Measurement of Electron Density near Plasma Grid of Large-scaled Negative Ion Source by Means of Millimeter-Wave Interferometer. United States: N. p., 2011. Web. doi:10.1063/1.3637408.
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. Measurement of Electron Density near Plasma Grid of Large-scaled Negative Ion Source by Means of Millimeter-Wave Interferometer. United States. doi:10.1063/1.3637408.
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., and Kaneko, O. Mon . "Measurement of Electron Density near Plasma Grid of Large-scaled Negative Ion Source by Means of Millimeter-Wave Interferometer". United States. doi:10.1063/1.3637408.
@article{osti_21611682,
title = {Measurement of Electron Density near Plasma Grid of Large-scaled Negative Ion Source by Means of Millimeter-Wave Interferometer},
author = {Nagaoka, K. and Tokuzawa, T. and Tsumori, K. and Nakano, H. and Ito, Y. and Osakabe, M. and Ikeda, K. and Kisaki, M. and Shibuya, M. and Sato, M. and Komada, S. and Kondo, T. and Hayashi, H. and Asano, E. and Takeiri, Y. and Kaneko, O.},
abstractNote = {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.},
doi = {10.1063/1.3637408},
journal = {AIP Conference Proceedings},
issn = {0094-243X},
number = 1,
volume = 1390,
place = {United States},
year = {2011},
month = {9}
}