Study of high-speed solid pellet injection by two-stage gas acceleration using innovative piston

• Project/Area Number: 15K18307
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Nuclear fusion studies
• Research Institution: National Institute for Fusion Science
• Principal Investigator: MOTOJIMA Gen 核融合科学研究所, ヘリカル研究部, 准教授 (00509507)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000); Fiscal Year 2017: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2016: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2015: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
• Keywords: 燃料供給 / 固体水素ペレット / 高速化 / アイスピストン / ２段加速 / ２段ガス加速 / 2段ガス加速

Outline of Final Research Achievements

The high-speed solid pellet injection by two-stage gas acceleration using an innovative piston has been developed. The innovative idea in this study is the use of solid-ice (ice piston) instead of the metal for the material of the piston. In this study, the fast valve with a large amount of gas flow was manufactured. The test chamber with the valve and a compact cryocooler was prepared. The compression test shows that high pressure over 30 MPa was attained using the ice piston.

Academic Significance and Societal Importance of the Research Achievements

本研究で行ったアイスピストンを用いた加速方式は、原理的に、「高速」かつ「繰り返し」で、物体を加速することが可能な方式である。よって、核融合燃料供給として本成果を活かすことが可能であるのはもちろんのこと、核融合燃料供給の研究だけにとどまらず、スペースデブリ実験など、物体を加速させることが必要な実験にも応用できるものである。

Research Products

• [Journal Article] High-density experiments with hydrogen ice pellet injection and analysis of pellet penetration depth in Heliotron J (2019)
  • Author(s): Gen Motojima, Hiroyuki Okada, Hisashi Okazaki, S Kobayashi, Kazunobu Nagasaki, Ryuichi Sakamoto, Hiroshi Yamada, Shinichiro Kado, Shinsuke Ohshima, T Minami, Naoki Kenmochi, Yoshiaki Ohtani, Yuuki Nozaki, Yuma Yonemura, Yuji Nakamura, Shigeru Konoshima, Satoshi Yamamoto, Tohru Mizuuchi and Kiyomasa Watanabe
  • Journal Title: Plasma Physics and Controlled Fusion Volume: 印刷中 Issue: 7 Pages: 075014-075014
  • DOI: 10.1088/1361-6587/ab1d40
  • Peer Reviewed
• [Journal Article] 中型プラズマ実験装置用ペレット入射のためのテーパ構造を有する射出バレル (2016)
  • Author(s): G. Motojima R. Sakamoto H. Okada, K. Nagasaki, H. Yamada, Y. Nakamura, S. Kado, S. Kobayashi, S. Konoshima, T. Minami, S. Ohshima, S. Yamamoto, T. Mizuuchi, and T. Mutoh,
  • Journal Title: REVIEW OF SCIENTIFIC INSTRUMENTS Volume: 87 Issue: 10 Pages: 103503-103503
  • DOI: 10.1063/1.4964476
  • Peer Reviewed
• [Presentation] High-density experiments with pellet injection and analysis of pellet penetration depth in Heliotron J (2019)
  • Author(s): G. Motojima, H. Okada, H. Okazaki, S. Kobayashi, K. Nagasaki, N. Panadero, R. Sakamoto, H. Yamada, S. Kado, S. Ohshima, T. Minami, N. Kenmochi, Y. Ohtani, Y. Nakamura, S. Konoshima, S. Yamamoto, T. Mizuuchi and K.Y. Watanabe
  • Organizer: 19th Coordinated Working Group Meeting
• [Presentation] Pellet injection to high density plasmas on Heliotron J (2018)
  • Author(s): G. Motojima, H. Okada, H. Okazaki, S. Kobayashi, N. Kenmochi, S. Ohshima, S. Kado, R. Sakamoto, K. Nagasaki, H. Yamada, T. Minami, Y. Nakamura, S. Konoshima, S. Yamamoto and T. Mizuuchi
  • Organizer: 18th Coordinated Working Group Meeting