coupling between turbulent transport and magnetic topology

• Project/Area Number: 15H02336
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Nuclear fusion studies
• Research Institution: National Institute for Fusion Science
• Principal Investigator: 居田 克巳 核融合科学研究所, ヘリカル研究部, 教授 (00184599)
• Co-Investigator(Kenkyū-buntansha): 吉沼 幹朗 核融合科学研究所, ヘリカル研究部, 助教 (20323058) ; 小林 達哉 核融合科学研究所, ヘリカル研究部, 助教 (30733703) ; 徳沢 季彦 核融合科学研究所, ヘリカル研究部, 准教授 (90311208)
• Project Period (FY): 2015-04-01 – 2020-03-31
• Project Status: Granted (Fiscal Year 2019)
• Budget Amount: ¥42,900,000 (Direct Cost: ¥33,000,000、Indirect Cost: ¥9,900,000); Fiscal Year 2019: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2018: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2017: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2016: ¥14,430,000 (Direct Cost: ¥11,100,000、Indirect Cost: ¥3,330,000); Fiscal Year 2015: ¥15,600,000 (Direct Cost: ¥12,000,000、Indirect Cost: ¥3,600,000)
• Keywords: プラズマ核融合 / プラズマ・核融合 / 磁場トポロジー / 乱流 / 磁気島 / ビーム放射分光

Outline of Annual Research Achievements

核融合装置では外部から与えたトーラス型をした入れ子状の磁場の中にプラズマを生成・加熱し、高温高圧のプラズマをどのようにして維持するかが重要な課題となっている。この入れ子状の磁場は、プラズマ中に発生した電流の影響で変化し、そのトポロジーを変化させる。よく知られたトポロジー変化として、磁気島と呼ばれる三日月型のトポロジーを持つ磁気面が成長する場合や、さらに異なるモード数に磁気島が重なり合う為に磁気面が失われてしまう場合（ストキャスティック化）がある。特に。このストキャスティック化は、プラズマが突然消滅する電流崩壊という現象の原因にとなっており、核融合プラズマの維持において、極めて重要な課題である。

プラズマの乱流と磁場トポロジーはお互いに相互作用すると考えられる。すなわち、磁場トポロジーの変化によりプラズマの乱流が変化するのみならず、プラズマの乱流が、プラズマの流れに影響を及ぼして磁場トポロジーを変化させる。従って、磁場トポロジーによるプラズマの乱流の変化の計測は、プラズマの振る舞いを理解する上で重要な課題となっている。

本年度はDIII-D装置での実験結果を解析した。磁気島やストキャスティック領域が現れる場所での乱流計測から、磁気島のO点に比べてX点での乱流が大きいことを明らかにした。また、ヒートパルスの伝播と乱流の伝播との時間差を計測し、X点ではヒートパルスが先に、O点では乱流が先に到達しているを実験で見出した。

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

本研究に必要なビーム放射分光のコンポーネントであるイメージ光ファイバー・イメージフィルター分光器・多チャンネルアバランシェダイオード検出器のすべての制作を終えて、分光システムの調整・動作チェック・データ処理ソフトの開発・解析手法の確立などの予備的な実験を開始した。

Strategy for Future Research Activity

LHDプラズマにおいて乱流計測を引き続き行い、ビーム放射分光では２次元の長波長揺動が観測できると言う特徴を生かして、マイクロ波反射で計測した短波長揺動との組み合わせた解析も行う予定である

Research Products

• [Int'l Joint Research] General Atomics/University of Wisconsin(U.S.A.)
• [Int'l Joint Research] General Atomics/University of Wisconsin(U.S.A.)
• [Int'l Joint Research] General Atomics/University of Texas/Oak Ridge National Laboratory(U.S.A)
• [Journal Article] Exhaust of turbulence cloud at the tongue shaped deformation event (2018)
  • Author(s): K. Ida T. Kobayashi, T. Tokuzawa, T. Akiyama, H. Tanaka, M. Yoshinuma, K. Itoh
  • Journal Title: Nuclear Fusion Volume: 58
  • Peer Reviewed
• [Journal Article] Trigger mechanism for the abrupt loss of energetic ions in magnetically confined plasmas (2018)
  • Author(s): Ida K.、Kobayashi T.、Yoshinuma M.、Akiyama T.、Tokuzawa T.、Tsuchiya H.、Itoh K.、Itoh S.-I.
  • Journal Title: Scientific Reports Volume: 8 Pages: 2804-2804
  • DOI: 10.1038/s41598-018-21128-z
  • Peer Reviewed / Open Access
• [Journal Article] Internal transport barrier in tokamak and helical plasmas (2017)
  • Author(s): K. Ida, and T Fujita
  • Journal Title: Plasma Physics and Controlled Fusion Volume: 60 Pages: 033001-033001
  • DOI: 10.1088/1361-6587/aa9b03
  • Peer Reviewed
• [Journal Article] Observation of distorted Maxwell-Boltzmann distribution of epithermal ions in LHD (2017)
  • Author(s): Ida K.、Kobayashi T.、Yoshinuma M.、Akiyama T.、Tokuzawa T.、Tsuchiya H.、Itoh K.、LHD Experiment Group
  • Journal Title: Physics of Plasmas Volume: 24 Pages: 122502-122502
  • DOI: 10.1063/1.4999644
  • Peer Reviewed
• [Journal Article] Response of plasma toroidal flow to the transition between nested and stochastic magnetic field in LHD (2017)
  • Author(s): K. Ida, M. Yoshinuma, H. Tsuchiya, T. Kobayashi, C. Suzuki, M. Yokoyama, A. Shimizu, K. Nagaoka, S. Inagaki, K. Itoh,
  • Journal Title: Nuclear Fusion Volume: 57 Pages: 076032-076032
  • DOI: 10.1088/1741-4326/aa6f84
  • Peer Reviewed
• [Journal Article] Abrupt onset of tongue deformation and phase space response of ions in magnetically- confined plasmas (2016)
  • Author(s): K. Ida, T. Kobayashi, K. Itoh, M. Yoshinuma, T. Tokuzawa, T. Akiyama, C. Moon, H. Tsuchiya, S. Inagaki and S.-I. Itoh
  • Journal Title: Scientific Reports Volume: 6 Pages: 36217-36217
  • DOI: 10.1038/srep36217
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Bifurcation physics of magnetic islands and stochasticity explored by heat pulse propagation studies in toroidal plasmas (2016)
  • Author(s): K. Ida, T. Kobayashi, M. Yoshinuma1, Y. Suzuki, Y. Narushima, T.E. Evans, S. Ohdachi, H. Tsuchiya, S. Inagaki and K. Itoh
  • Journal Title: Nuclear Fusion Volume: 56 Pages: 092001-092001
  • DOI: 10.1088/0029-5515/56/9/092001
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Helium transport in the core and stochastic edge layer in LHD (2016)
  • Author(s): K Ida, M Yoshinuma, M Goto, O Schmitz, S Dai, A Bader, M Kobayashi, G Kawamura, C Moon, Y Nakamura1 and The LHD Experiment Group
  • Journal Title: Plasma Physics and Controlled Fusion Volume: 58 Pages: 074010-074010
  • DOI: 10.1088/0741-3335/58/7/074010
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Bifurcation physics of magnetic islands and stochasticity explored by heat pulse propagation studies in toroidal plasmas (2016)
  • Author(s): K. Ida, T. Kobayashi, M. Yoshinuma, Y. Suzuki, Y. Narushima, T.E. Evans. Ohdachi, H. Tsuchiya. Inagaki, and K. Itoh
  • Journal Title: Nuclear Fusion Volume: 56 Pages: 000000-000000
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Self-regulated oscillation of transport and topology of magnetic islands in toroidal plasmas (2015)
  • Author(s): K. Ida, T. Kobayashi, T. E. Evans, S. Inagaki, M. E. Austin, M. W. Shafer, S. Ohdachi, Y. Suzuki, S.-I. Itoh, K. Itoh
  • Journal Title: Scientific Reports Volume: 5 Pages: 161651-10
  • DOI: 10.1038/srep16165
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Presentation] Bifurcation physics of magnetic islands and stochasticity explored by heat pulse propagation studies in totoidal plasmas (2018)
  • Author(s): K.Ida
  • Organizer: KSTAR conference
  • Int'l Joint Research / Invited
• [Presentation] Interaction between resonant and non-resonant MHD: A trigger mechanism of collapse of magnetically confined plasmas (2017)
  • Author(s): K. Ida, T. Kobayashi, M. Yoshinuma, T. Tokuzawa, T. Akiyama, H. Tsuchiya, K. Itoh, & S.-I. Itoh
  • Organizer: The 26th International Toki Conference (ITC-26) & The 11th Asia Plasma and Fusion Association Conference (APFA-11)
  • Int'l Joint Research / Invited
• [Presentation] Modulation method as a tool to measure three dimensional magnetic field structures in toroidal plasmas (2017)
  • Author(s): K.Ida, T.Kobayashi, W.H.Ko, H.H.Lee, Y.In, H.S.Kim
  • Organizer: 59th Annual Meeting of the APS Division of Plasma Physics
  • Int'l Joint Research
• [Presentation] Decoupling in Transport Channels: Impurity Transport in Stellarators/Heliotrons (2017)
  • Author(s): K. Ida
  • Organizer: 21th International Stellarator-Heliotron Workshop (ISHW 2017)
  • Int'l Joint Research / Invited
• [Presentation] Abrupt onset of tongue deformation in LHD plasmas (2017)
  • Author(s): K. Ida, T. Kobayashi, M. Yoshinuma, T. Tokuzawa, T. Akiyama, C. Moon, H. Tsuchiya, K. Itoh, S. Inagaki & S.-I. Itoh
  • Organizer: 1st Asia-Pacific Conference on Plasma Physics
  • Int'l Joint Research / Invited
• [Presentation] Exhaust of turbulence cloud at the MHD burst triggered by tongue deformation (2017)
  • Author(s): ;K. Ida, T. Kobayashi, T.Tokuzawa, T.Akiyama, M.Yoshinuma, K.Itoh
  • Organizer: 16th International Workshop on H-mode Physics and Transport Barriers
  • Int'l Joint Research
• [Presentation] Transition from MHD mode to tongue deformation before the collapse events in LHD (2017)
  • Author(s): K.Ida, T. Kobayashi, M.Yoshinuma, T.Akiyama, H.Tsuchiya, K. Itoh
  • Organizer: 7th Asia-Pacific Transport Working Group (APTWG) International Conference
  • Int'l Joint Research
• [Presentation] Interaction between Transport MHD and energetic particle (2017)
  • Author(s): K. Ida
  • Organizer: 643rd Wilhelm and Else Heraeus Seminar on “Impact of 3D magnetic fields on hot plasmas
  • Invited
• [Presentation] Magnetic island and stochastic magnetic field in toroidal plasmas (2017)
  • Author(s): K.Ida
  • Organizer: 18th International RFP Workshop
  • Place of Presentation: Kyoto Institute of Technology, Kyoto
  • Year and Date: 2017-03-26
  • Int'l Joint Research / Invited
• [Presentation] Beam Spectroscopy in Plasma (2016)
  • Author(s): K.Ida, and LHD experiment group
  • Organizer: 8th Korea-Japan Diagnostic Seminar
  • Place of Presentation: Citadines Haeundae Busan, Korea
  • Year and Date: 2016-08-24
  • Int'l Joint Research / Invited
• [Presentation] Explore of a magnetic topology by heat pulse propagation method (2016)
  • Author(s): Katsumi Ida
  • Organizer: 6th East-Asia School and Workshop on Laboratory, Space, Astrophysical Plasmas
  • Place of Presentation: International Congress Center, Epochal Tsukuba, Tuskuba
  • Year and Date: 2016-07-11
  • Int'l Joint Research / Invited
• [Presentation] Bifurcation physics of a magnetic island and its stochastization in totoidal plasmas (2016)
  • Author(s): K.Ida, T.Kobayashi, T.E.Evans, H. Tsuchiya, S. Inagaki, K. Itoh, M. Yoshinuma, Y. Suzuki, S. Ohdachi
  • Organizer: 6th Asia Pacific Transport Working Group
  • Place of Presentation: Korea University Seoul Korea
  • Year and Date: 2016-06-21
  • Int'l Joint Research / Invited
• [Presentation] トロイダルプラズマの磁気島における輸送とトポロジーの自励振動 (2015)
  • Author(s): 居田克巳、小林達哉、稲垣滋、トッド・エバンス
  • Organizer: 閉じ込め・輸送研究会
  • Place of Presentation: 核融合科学研究所・土岐
  • Year and Date: 2015-12-07
  • Invited
• [Presentation] Physics of magnetic reconnection, magnetic islands and stochasticity in fusion plasmas (2015)
  • Author(s): K.Ida, T.Tokuzawa, T.Kobayashi, S.Inagaki, K.Itoh
  • Organizer: 597th Wilhelm and Else Heraeus Seminar on ”Stochasticity in Fusion Plasmas”
  • Place of Presentation: Physikzentrum Bad Honnef, Germany
  • Year and Date: 2015-09-10
  • Int'l Joint Research / Invited