| Project/Area Number |
17206092
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nuclear fusion studies
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| Research Institution | Kyushu University |
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Principal Investigator |
TANABE Tetsuo Kyushu University, Advanced Energy Engineering Science, Prof. (00029331)
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| Co-Investigator(Kenkyū-buntansha) |
OHYA Kaoru Tokushima University, 大学院・ソシオテクノサイエンス研究部, Prof. (10108855)
SAKAWA Youichi Osaka University, Laser Fusion Center, Assoc. Prof. (70242881)
HIROHATA Yuko Hokkaido University, Department of Nuclear Eng., Assoc. Prof. (00189896)
MIYA Naoyuki Japan Atomic Energy Institute, 那珂研究所・核融合研究開発部門, Principal Researcher (60343901)
MASAKI Kei Japan Atomic Energy Institute, 核融合研究開発部門, Researcher (10354648)
橋爪 健一 九州大学, 大学院・総合理工学研究院, 准教授 (70243912)
大矢 恭久 静岡大学, 理学部附属放射化学研究施設, 助教授 (80334291)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥49,010,000 (Direct Cost: ¥37,700,000、Indirect Cost: ¥11,310,000)
Fiscal Year 2007: ¥14,820,000 (Direct Cost: ¥11,400,000、Indirect Cost: ¥3,420,000)
Fiscal Year 2006: ¥18,720,000 (Direct Cost: ¥14,400,000、Indirect Cost: ¥4,320,000)
Fiscal Year 2005: ¥15,470,000 (Direct Cost: ¥11,900,000、Indirect Cost: ¥3,570,000)
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| Keywords | Plasma wall interactions / Carbon materials / erosion / Deposition / Hydrogen retention / Tritium / Tritium removal / Laser ablation / プラズマ対向壁 / 炭素タイル / 蓄積 / 再堆積 / 水素リテンション |
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| Research Abstract |
Retention of hydrogen isotopes (H, D, and 1) and erosion/deposition in plasma facing carbon materials as well as dust sampling in JT-60U and the results are studied and compared with those of JET. In D-D discharge machines like JT-60U, tritium produced by D-D reaction does not fully lose its initial energy of 1 MeV and is implanted into plasma facing wall more than 1μm in depth. Hence tritium retention profile is separated from carbon deposition profiles. On the other hand, in JT-60U, H+D retention profiles in the diverter region are well correlated with the carbon deposition profiles and the deposition dominated inner diverter tiles show high retention, while the erosion dominated outer diverter tiles show low retention. Nevertheless the retained amount in the redeposited layers is smaller than those observed in JET, which is attributed to temperature rise of the redeposited layers probably owing to their poor thermal contact to the substrate. Carbon deposition on the plasma shadowed
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area and remote area like pumping ducts is very small and only small amount of dust is collected. Low deposition in the remote area in JT-60U could be attributed to the precise alignment of diverter tiles both toroidally and poloidally. It is suggested that divertor geometry could have rather strong effects on carbon deposition or carbon transport.
Pulsed-laser induced desorption of hydrogen from co-deposits on JT-60 open-divertor tile was also investigated. The fundamental (1064 nm) and fourth harmonic (266 nm) emission of a 20 ps-Nd: YAG laser were used, and dependences of hydrogen desorption on laser intensity IL and wavelength λ were studied. Hydrogen-desorption efficiency, defined as the ratio between the number of desorbed hydrogen by laser irradiation and that of hydrogen retained in the ablated volume, was largest in the region, where strong ionization of C+ occurred, and was larger for λ = 266 nm, in which a laser photon can cut C-H bond, compared with that for λ=1064 nm. For the ablative removal of hydrogen, a short-wavelength and high-power laser is desirable. Less
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