| Project/Area Number |
10558069
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Nuclear fusion studies
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| Research Institution | Osaka University |
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Principal Investigator |
HORIIKE Hiroshi Graduate School of Engineering, Osaka University Professor, 大学院・工学研究科, 教授 (20252611)
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| Co-Investigator(Kenkyū-buntansha) |
INOUE Shoji Graduate School of Engineering, Osaka University Research Associate, 大学院・工学研究科, 助手 (10203233)
MIYAZAKI Keiji Graduate School of Engineering Osaka University Professor, 大学院・工学研究科, 教授 (40029202)
IIDA Toshiyuki Graduate School of Engineering Osaka University Professor, 大学院・工学研究科, 教授 (60115988)
MIYAMOTO Seiji Graduate School of Engineering, Osaka University Research Associate, 大学院・工学研究科, 助手 (50294046)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥11,800,000 (Direct Cost: ¥11,800,000)
Fiscal Year 1999: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1998: ¥11,100,000 (Direct Cost: ¥11,100,000)
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| Keywords | negative ion source / neutralization efficiency / plasma / nuclear fusion / heating / magnetic multi-pole ion source / bucket ion source / ionization ratio / 負イオンビーム / プラズマ中性化セル / アーク放電 |
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| Research Abstract |
In the design of negative-ion based neutral beam injection (NBI) system, neutralization efficiency from ion to neutral beam can be improved by utilizing plasma neutralizer. In the case of gas neutralizer, the conversion efficiency is 59% maximum. In the case of plasma neutralizer, efficiency of 70% can be achieved, because of reduced double stripping reaction in which a negative ion is converted to a positive ion. This requires the plasma with as high ionization ratio as possible (10%>).
To get high ionization ratio, it is important to produce plasma at low pressure with using a container of good confinement. For that purpose, we made a cylindrical discharge with vessel of the size of 310mm in diam and 1400mm in length with cusp magnetic field. Discharge characteristics and plasma confinement properties were studied using hydrogen, argon and xenon as working gas with arc discharges by filaments. It is found that in the case of gas pressure higher than 0.2 Pa, the plasma density was higher than n>10ィイD111ィエD1 cmィイD1-3ィエD1, but the ionization ratio was smaller than 1%. But, in the case of the gas pressure under 0.2 Pa, the ionization ratio increased rapidly as the pressure decreased. It is however difficult to keep the stable plasma discharge at the gas pressure less than 0.1 Pa, hence the plasma efficiency of the confinement properties of the vessel determines minimum gas pressure and the highest ionization. In this study, the pressure of 0.03 Pa was the lowest and the ionization ratio of 1.3% for hydrogen, 3.2% for argon and 8% for xenon were achieved. It was also found that the plasma density and ionization ratio could be higher with improving the confinement. We obtained prospect of the plasma neutralizer which would have an enough density and the ionization ratio of more than 10%.
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