Spatial distribution of the charged particles and potentials during beam extraction in a negative-ion source
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- K. Tsumori
- National Institute for Fusion Science 1 , 322-1 Oroshi Toki-city, Figu 509-5292, Japan
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- H. Nakano
- National Institute for Fusion Science 1 , 322-1 Oroshi Toki-city, Figu 509-5292, Japan
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- M. Kisaki
- National Institute for Fusion Science 1 , 322-1 Oroshi Toki-city, Figu 509-5292, Japan
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- K. Ikeda
- National Institute for Fusion Science 1 , 322-1 Oroshi Toki-city, Figu 509-5292, Japan
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- K. Nagaoka
- National Institute for Fusion Science 1 , 322-1 Oroshi Toki-city, Figu 509-5292, Japan
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- M. Osakabe
- National Institute for Fusion Science 1 , 322-1 Oroshi Toki-city, Figu 509-5292, Japan
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- Y. Takeiri
- National Institute for Fusion Science 1 , 322-1 Oroshi Toki-city, Figu 509-5292, Japan
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- O. Kaneko
- National Institute for Fusion Science 1 , 322-1 Oroshi Toki-city, Figu 509-5292, Japan
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- M. Shibuya
- National Institute for Fusion Science 1 , 322-1 Oroshi Toki-city, Figu 509-5292, Japan
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- E. Asano
- National Institute for Fusion Science 1 , 322-1 Oroshi Toki-city, Figu 509-5292, Japan
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- T. Kondo
- National Institute for Fusion Science 1 , 322-1 Oroshi Toki-city, Figu 509-5292, Japan
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- M. Sato
- National Institute for Fusion Science 1 , 322-1 Oroshi Toki-city, Figu 509-5292, Japan
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- S. Komada
- National Institute for Fusion Science 1 , 322-1 Oroshi Toki-city, Figu 509-5292, Japan
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- H. Sekiguchi
- National Institute for Fusion Science 1 , 322-1 Oroshi Toki-city, Figu 509-5292, Japan
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- N. Kameyama
- Keio University 2 , 3-14-1 Hiyoshi, Kouhoku-ku, Yokohama 223-8522, Japan
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- T. Fukuyama
- Keio University 2 , 3-14-1 Hiyoshi, Kouhoku-ku, Yokohama 223-8522, Japan
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- S. Wada
- Keio University 2 , 3-14-1 Hiyoshi, Kouhoku-ku, Yokohama 223-8522, Japan
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- A. Hatayama
- Keio University 2 , 3-14-1 Hiyoshi, Kouhoku-ku, Yokohama 223-8522, Japan
Abstract
<jats:p>We report on the characteristics of the electronegative plasma in a large-scale hydrogen negative ion (H−) source. The measurement has been made with a time-resolved Langmuir probe installed in the beam extraction region. The H− density is monitored with a cavity ring-down system to identify the electrons in the negative charges. The electron-saturation current decreases rapidly after starting to seed Cs, and ion-ion plasma is observed in the extraction region. The H− density steps down during the beam extraction and the electron density jumps up correspondingly. The time integral of the decreasing H− charge density agrees well with the electron charge collected with the probe. The agreement of the charges is interpreted to indicate that the H− density decreasing at the beam extraction is compensated by the electrons diffusing from the driver region. In the plasmas with very low electron density, the pre-sheath of the extraction field penetrates deeply inside the plasmas. That is because the shielding length in those plasmas is longer than that in the usual electron-ion plasmas, and furthermore the electrons are suppressed to diffuse to the extraction region due to the strong magnetic field.</jats:p>
Journal
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- Review of Scientific Instruments
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Review of Scientific Instruments 83 (2), 02B116-, 2012-02-01
AIP Publishing
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Details 詳細情報について
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- CRID
- 1361699993511863296
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- ISSN
- 10897623
- 00346748
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- Data Source
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- Crossref