Effects of the surface morphologies on the plasma facing materials during the long pulse discharge in the large-sized plasma confinement devices

• Project/Area Number: 26420857
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Nuclear fusion studies
• Research Institution: National Institute for Fusion Science
• Principal Investigator: Tokitani Masayuki 核融合科学研究所, ヘリカル研究部, 助教 (30455208)
• Co-Investigator(Kenkyū-buntansha): 宮本 光貴 島根大学, 総合理工学研究科, 准教授 (80379693) ; 笠原 寛史 核融合科学研究所, ヘリカル研究部, 准教授 (50435517) ; 吉村 泰夫 核融合科学研究所, ヘリカル研究部, 准教授 (90300730)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Project Status: Completed (Fiscal Year 2016)
• Budget Amount: ¥5,070,000 (Direct Cost: ¥3,900,000、Indirect Cost: ¥1,170,000); Fiscal Year 2016: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000); Fiscal Year 2015: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000); Fiscal Year 2014: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
• Keywords: プラズマ・壁相互作用 / プラズマ核融合 / 電子顕微鏡 / プラズマ・核融合

Outline of Final Research Achievements

Effects of the surface morphologies on the plasma facing materials during the long pulse discharge in the large helical devices (LHD) were studied by means of material exposure experiments with a nano-fabrication technique and a quantitative analysis of the retained plasma particles on the plasma facing materials.
It was clarified that two major issues of the "dynamic change of the wall pumping rate" and the "termination of the discharge with the exfoliation of the mixed-material deposition layer" interrupt the steady-state plasma operation. Two physical processes of the "helium radiation effects" and the "formation of the mixed-material deposition layer" can change and control two major issues. If we wish to suppress two major issues, the plasma facing materials should be composed by single element, and low sputtering yield materials are possibly advantageous for reducing the thickness of the mixed-material deposition layer.

Research Products

• [Journal Article] Initial growth phase of W-fuzz formation in ultra-long pulse helium discharge in LHD (2017)
  • Author(s): M. Tokitani, S. Masuzaki, H. Kasahara, Y. Yoshimura, R. Sakamoto, N. Yoshida, Y. Ueda , T. Mutoh, LHD Experiment Group , S. Nagata
  • Journal Title: Nuclear Materials and Energy Volume: 印刷中 Pages: 1358-1362
  • DOI: 10.1016/j.nme.2016.11.023
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Progress of Steady State Operation Using RF Heating in the LHD (2016)
  • Author(s): Y. Yoshimura, H. Kasahara, S. Kamio, M. Tokitani, R. Sakamoto, Y. Ueda, S. Kubo, T. Shimozuma, H. Igami, H. Takahashi, T.I. Tsujimura, R. Makino, T. Seki, K. Saito, R. Seki, T. Akiyama, N. Ashikawa, S. Masuzaki, G. Motojima, M. Shoji, C. Suzuki, H. Tanaka, K. Tanaka, T. Tokuzawa, I. Yamada, H. Yamada, T. Mutoh et al.
  • Journal Title: Proceedings of IAEA FEC 2016 Volume: -
• [Journal Article] Progress of long pulse discharges by ECH in LHD (2016)
  • Author(s): Y. Yoshimura, H. Kasahara, M. Tokitani, R. Sakamoto, Y. Ueda, S. Ito, K. Okada, S. Kubo, T. Shimozuma, H. Igami, H. Takahashi, T.I. Tsujimura, R. Makino, S. Kobayashi, Y. Mizuno, T. Akiyama, N. Ashikawa, S. Masuzaki, G. Motojima, M. Shoji, C. Suzuki, H. Tanaka, K. Tanaka, T. Tokuzawa, H. Tsuchiya, I. Yamada et al.
  • Journal Title: Nuclear Fusion Volume: 56 Issue: 4 Pages: 046005-046005
  • DOI: 10.1088/0029-5515/56/4/046005
  • NAID: 120007176996
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Plasma wall interaction in long-pulse helium discharge in LHD - Microscopic modification of the wall surface and its impacton particle balance and impurity generation (2015)
  • Author(s): M. Tokitani, H. Kasahara, S. Masuzaki, G. Motojima, M. Shoji, Y. Ueda, N. Yoshida, Y. Yoshimura, K. Nagasaki, N. Ashikawa, T. Mutoh, H. Yamada, LHD Experiment Group, S. Nagata
  • Journal Title: Journal of Nuclear Materials Volume: 463 Pages: 91-98
  • DOI: 10.1016/j.jnucmat.2014.12.062
  • Peer Reviewed / Acknowledgement Compliant
• [Presentation] Progress of Steady State Operation Using RF Heating in the LHD (2016)
  • Author(s): Y. Yoshimura, H. Kasahara, S. Kamio, M. Tokitani, R. Sakamoto, Y. Ueda, S. Kubo, T. Shimozuma, H. Igami, H. Takahashi, T.I. Tsujimura, R. Makino, T. Seki, K. Saito, R. Seki, T. Akiyama, N. Ashikawa, S. Masuzaki, G. Motojima, M. Shoji, C. Suzuki, H. Tanaka, K. Tanaka, T. Tokuzawa, I. Yamada, H. Yamada, T. Mutoh et al.
  • Organizer: 26th IAEA Fusion Energy Conference
  • Place of Presentation: Kyoto, Japan
  • Year and Date: 2016-10-17
  • Int'l Joint Research
• [Presentation] Tungsten fiberform nanostructure (W-fuzz) formation in ultra-long pulse helium discharge in LHD (2016)
  • Author(s): M. Tokitani, S. Masuzaki, H. Kasahara, Y. Yoshimura, R. Sakamoto, N. Yoshida, Y. Ueda , T. Mutoh, LHD Experiment Group , S. Nagata
  • Organizer: 22nd International Conference on Plasma Surface Interactions in Controlled Fusion Devices
  • Place of Presentation: Rome, Italy
  • Year and Date: 2016-05-30
  • Int'l Joint Research
• [Presentation] LHD ヘリウム長時間放電におけるプラズマ壁相互作用 (2015)
  • Author(s): 時谷政行，笠原寛史，吉村泰夫，本島 厳，庄司 主，増崎 貴，宮本光貴，上田良夫，坂本隆一，坂本瑞樹，吉田直亮，武藤 敬，LHD実験グループ
  • Organizer: 第32回プラズマ・核融合学会 年会
  • Place of Presentation: 名古屋大学
  • Year and Date: 2015-11-24
• [Presentation] Microscopic modification of wall surface by helium bombardment and mixed-materialdeposition layer during a long pulse discharge in LHD ~its impact on steady state plasma operation~ (2015)
  • Author(s): M. Tokitani, H. Kasahara, Y. Yoshimura, G. Motojima, R. Sakamoto, S. Masuzaki, Y. Ueda, K. Nagasaki, M. Shoji, T. Mutoh, H. Yamada, Y. Takeiri, LHD experiment group
  • Organizer: 8th IAEA Technical Meeting on "Steady State Operations of Magnetic Fusion Devices"
  • Place of Presentation: Nara, Japan
  • Year and Date: 2015-05-26 – 2015-05-29
• [Presentation] Microscopic modification of wall surface by helium bombardment and mixed-material deposition layer during a long pulse discharge in LHD ~its impact on steady state plasma operation~ (2015)
  • Author(s): M. Tokitani, H. Kasahara, Y. Yoshimura, G. Motojima, R. Sakamoto, S. Masuzaki, Y. Ueda, K. Nagasaki, M. Shoji, T. Mutoh, H. Yamada, Y. Takeiri, LHD experiment group
  • Organizer: 8th IAEA Technical Meeting on Steady State Operation of Magnetic Fusion Devices
  • Place of Presentation: Nara, Japan
  • Year and Date: 2015-05-26
  • Int'l Joint Research
• [Presentation] Progress of Long Pulse Discharges by ECH in LHD (2015)
  • Author(s): Y. Yoshimura, H. Kasahara, M. Tokitani, R. Sakamoto, Y. Ueda, S. Ito, K. Okada, S. Kubo, T. Shimozuma, H. Igami, H. Takahashi, T. Ii, S. Kobayashi, Y. Mizuno, T. Akiyama, N. Ashikawa, S. Masuzaki, G. Motojima, M. Shoji, C. Suzuki, H. Tanaka, K. Tanaka, T. Tokuzawa, H. Tsuchiya, I. Yamada, R. Makino et al.
  • Organizer: 8th IAEA Technical Meeting on Steady State Operation of Magnetic Fusion Devices
  • Place of Presentation: Nara, Japan
  • Year and Date: 2015-05-26
  • Int'l Joint Research
• [Presentation] Microscopic modification of wall surface by helium bombardment and mixed-material deposition during long pulse discharges in LHD and its impact on the long pulse plasma operation (2014)
  • Author(s): M. Tokitani, H. Kasahara, S. Masuzaki, G. Motojima, M. Shoji, Y. Ueda, N. Yoshida, Y. Yoshimura, K. Nagasaki, N. Ashikawa, T. Mutoh, H. Yamada, LHD experiment group, S. Nagata
  • Organizer: 12th Japan-China Symposium on Materials for Advanced Energy Systems and Fission & Fusion Engineering
  • Place of Presentation: Shizuoka, Japan
  • Year and Date: 2014-09-17 – 2014-09-20
• [Presentation] Plasma wall interaction in long pulse helium discharge in LHD ~Microscopic modification of wall surface and its impact on particle balance and impurity generation~ (2014)
  • Author(s): M. Tokitani, H. Kasahara, S. Masuzaki, G. Motojima, M. Shoji, Y. Ueda, N. Yoshida, Y. Yoshimura, K. Nagasaki, N. Ashikawa, T. Mutoh, H. Yamada, LHD experiment group, S. Nagata
  • Organizer: 21st International Conference on Plasma Surface Interactions 2014
  • Place of Presentation: Kanazawa Ishikawa, Japan
  • Year and Date: 2014-05-26 – 2014-05-30
  • Invited