Observation of self-organized FRC formation in a collisional-merging experiment

• Project/Area Number: 19K21868
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 14:Plasma science and related fields
• Research Institution: Nihon University
• Principal Investigator: ASAI Tomohiko 日本大学, 理工学部, 教授 (00386004)
• Co-Investigator(Kenkyū-buntansha): 長山 好夫 日本大学, 核融合科学研究所, 名誉教授 (10126138) ; 高橋 俊樹 群馬大学, 大学院理工学府, 准教授 (10302457) ; 比村 治彦 京都工芸繊維大学, 電気電子工学系, 教授 (30311632) ; 高橋 努 日本大学, 理工学部, 教授 (50179496) ; 水口 直紀 核融合科学研究所, ヘリカル研究部, 准教授 (70332187)
• Project Period (FY): 2019-06-28 – 2022-03-31
• Project Status: Completed (Fiscal Year 2021)
• Budget Amount: ¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000); Fiscal Year 2021: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2020: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2019: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
• Keywords: 磁場閉じ込めプラズマ / 自己組織化 / 高ベータ磁化プラズモイド / 磁化プラズモイド / 高ベータ / 運動論効果 / 非MHD効果

Outline of Research at the Start

一般に磁化プラズマの巨視的振る舞いはMHDにより記述でき，磁気ヘリシティ保存の下，磁気エネルギー最小の状態へ緩和する。しかし，ポロイダル磁場とそれと直交する反磁性電流のみで配位が形成され，磁気ヘリシティがゼロのFRC配位は，MHD緩和状態にないにも関わらずアルヴェン時間の数十～数百倍の時間，制御なしで安定に存在する。磁場中に短時間で密度勾配を形成することで反磁性電流によりFRCが生成できる可能性もあるが，ヘリシティゼロのプラズマ中に閉じた磁場構造が形成される過程はMHDでは記述できない。本研究は，磁場中に高速にプラズマ圧力を形成し自己組織化的に生じる磁場構造を観測する前例のない実験研究である。

Outline of Final Research Achievements

Self-organized field-reversed configuration-like (FRC) formation was observed after the super-sonic/Alfvenic collisional merging of two FRCs. In this experiment, two FRCs were generated initially in two separate field-reversed theta-pinch (FRTP) type formation regions. Those two formation regions are coaxially connected to opposite ends of a cylindrical confinement chamber. The formed FRCs are oppositely-translated and collide in the middle of the confinement chamber at super- sonic/Alfvenic velocity. During the collision, the merged plasmoid experiences destructive disturbance and loses its fast toroidal flow and characteristic FRC property of having a field-reversed magnetic configuration to become a magnetized plasma without ordered structure. After this dynamic collision, a magnetic configuration of FRC with fast toroidal rotation is self-organized within a few tens of microseconds. This observation indicates robustness of the extremly high-beta, simple magnetic configuration.

Academic Significance and Societal Importance of the Research Achievements

小型で効率が高い核融合炉心や中性子排出のない先進燃料核融合の実現には，高ベータ化が必須であり，これを極限まで突き詰めると，プラズマ電流と閉じ込め磁場が完全に直交し，トーラス中心に穴が開いていないFRCとなる。その特異な磁場配位のため，局所βはその大部分で１を超え，したがってイオンは磁化していないなど，多くの点で他の磁場配位と異なる性質を示し，同時にその緩和のメカニズムには未解明な点も多い。本研究成果は，このFRCの堅固な安定性を示す結果であり，米国の民間企業などでも開発が開始されたFRCによる超高ベータ核融合炉心の実現に貢献する結果である。

Research Products

• [Int'l Joint Research] TAE Technologies Inc/University of California at Irvine(米国)
• [Int'l Joint Research] Queen's University at Kingston(カナダ)
• [Int'l Joint Research] University of California, Irvine/TAE Technologies, Inc(米国)
• [Journal Article] Energy Flow in the Super Alfvénic/Sonic Collisional Merging Process of Field-Reversed Configurations (2021)
  • Author(s): Daichi KOBAYASHI, Tomohiko ASAI, Tsutomu TAKAHASHI, Arisa TATSUMI, Naoto SAHARA, Tatsuhiro WATANABE, Daisuke HARASHIMA, Hiroshi GOTA and Thomas ROCHE
  • Journal Title: Plasma and Fusion Research Volume: 16 Issue: 0 Pages: 2402050-2402050
  • DOI: 10.1585/pfr.16.2402050
  • NAID: 130008033379
  • ISSN: 1880-6821
  • Year and Date: 2021-04-09
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Acceleration of Magnetized Plasmoid by Pulsed Magnetic Coil (2021)
  • Author(s): Taichi SEKI, Tomohiko ASAI, Daichi KOBAYASHI, Ryotaro YANAGI, Hiroshi GOTA, Thomas ROCHE and Tadafumi MATSUMOTO
  • Journal Title: Plasma and Fusion Research Volume: 16 Issue: 0 Pages: 2401020-2401020
  • DOI: 10.1585/pfr.16.2401020
  • NAID: 130007994292
  • ISSN: 1880-6821
  • Year and Date: 2021-02-10
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Numerical simulation of wave propagation and plasma response excited in field-reversed configuration plasma (2021)
  • Author(s): Takahiro Urano, Toshiki Takahashi, Tomohiko Asai and Shigefumi Okada
  • Journal Title: Nuclear Fusion Volume: 62 Issue: 2 Pages: 026019-026019
  • DOI: 10.1088/1741-4326/ac3a19
  • Peer Reviewed
• [Journal Article] Observation of self-organized FRC formation in a collisional-merging experiment (2021)
  • Author(s): Tomohiko Asai, Daichi Kobayashi, Taichi Seki, Yasuaki Tamura, Tatsuhiro Watanabe, Naoto Sahara, Tsutomu Takahashi, Jordan Morelli, Hiroshi Gota, Thomas Roche, Richard Magee, Michl Binderbauer, Toshiki Tajima, Michiaki Inomoto and Toshiki Takahashi
  • Journal Title: Nuclear Fusion Volume: 61 Issue: 9 Pages: 096032-096032
  • DOI: 10.1088/1741-4326/ac189c
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Overview of C-2W: High-temperature, steady-state beam-driven field-reversed configuration plasmas (2021)
  • Author(s): H. Gota, M. W Binderbauer, T. Tajima, A. Smirnov, Sergei Putvinski, M. Tuszewski, S. Dettrick, D. Gupta, S. Korepanov, R. Magee, J. Park, T. Roche, J. Romero, E. Trask, X. Yang, P. Yushmanov, K. Zhai, L. Schmitz, Z. Lin, A. Ivanov, T. Asai, T. Baltz and J. Plat
  • Journal Title: Nuclear Fusion Volume: 61 Issue: 10 Pages: 106039-106039
  • DOI: 10.1088/1741-4326/ac2521
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Internal magnetic measurement in collisional-merging process of a field-reversed configuration (2021)
  • Author(s): T. Watanabe, T. Asai, Ts. Takahashi, D. Kobayashi, D. Harashima
  • Journal Title: Review of Scientific Instruments Volume: 92 Issue: 5
  • DOI: 10.1063/5.0043785
  • Peer Reviewed
• [Journal Article] MHD simulation of supersonic FRC merging corrected by non-invasive magnetic measurements (2021)
  • Author(s): D. Kobayashi, T. Asai, Ts. Takahashi, T. Watanabe, T. Yoshino, D. Harashima, S. Dettrick, Y. Mok, and H. Gota
  • Journal Title: Review of Scientific Instruments Volume: 92 Issue: 5
  • DOI: 10.1063/5.0043711
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Experimental evidence for super-Alfvénic acceleration of the field-reversed configuration due to a magnetic pressure gradient (2021)
  • Author(s): Daichi Kobayashi and Tomohiko Asai
  • Journal Title: Physics of Plasmas Volume: 28 Issue: 2 Pages: 022101-022101
  • DOI: 10.1063/5.0026146
  • Peer Reviewed
• [Journal Article] Evaluation of Translation Velocity Control by Auxiliary Coils for the Collisional Merging Formation of FRCs by 2-D Resistive MHD Simulation (2020)
  • Author(s): Daichi KOBAYASHI, Tomohiko ASAI, Tsutomu TAKAHASHI, Junichi SEKIGUCHI, Hiroshi GOTA, Sean DETTRICK, Yung MOK, Michl BINDERBAUER, Toshiki TAJIMA and Toshiki TAJIMA
  • Journal Title: Plasma and Fusion Research Volume: 15 Issue: 0 Pages: 2402020-2402020
  • DOI: 10.1585/pfr.15.2402020
  • NAID: 130007840494
  • ISSN: 1880-6821
  • Year and Date: 2020-04-14
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Behavior of a Tracer-Containing Compact Toroid in a Transverse Magnetic Field (2020)
  • Author(s): Taichi SEKI, Daichi KOBAYASHI, Rika SASAKI, Asuna MINAMIGI, Tomohiko ASAI, Hiroshi GOTA, Thomas ROCHE, Tadafumi MATSUMOTO, Toshiki TAKAHASHI, Naoki TAMURA, Yoshiro NARUSHIMA
  • Journal Title: Plasma and Fusion Research Volume: 15 Issue: 0 Pages: 2402069-2402069
  • DOI: 10.1585/pfr.15.2402069
  • NAID: 130007903702
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] 超音速プラズモイド衝突過程における構造遷移 (2022)
  • Author(s): 浅井朋彦, 関太一, 小林大地, 髙橋努, 稲垣滋, 井通暁, 髙橋俊樹, 岸本泰明
  • Organizer: 日本物理学会第77回年次大会
• [Presentation] FRC の超音速衝突衝突と自己組織化的配位形成 (2021)
  • Author(s): 浅井朋彦
  • Organizer: 令和3年度 核融合科学研究所共同研究研究会「自己組織化過程を用いた高ベータトーラスプラズマの性能改善」
• [Presentation] FRCの衝突合体生成過程における内部ロゴスキーコイルによる局所電流計測 (2021)
  • Author(s): 小笠原樹利，関太一，渡邉達大，明石和久，田村康明，小林大地，髙橋努，稲垣滋，浅井朋彦
  • Organizer: プラズマ・核融合学会 第38回年会
• [Presentation] FRC衝突合体実験における反転磁場形成条件 (2021)
  • Author(s): 原島大輔，小林大地，関太一，渡邉達大，髙橋努，浅井朋彦
  • Organizer: プラズマ・核融合学会 第38回年会
• [Presentation] 衝突合体実験におけるFRCの自己組織化的形成 (2021)
  • Author(s): 浅井朋彦, 小林大地, 関太一, 田村康明, 高橋努, 髙橋俊樹, 井通暁, 稲垣滋, 岸本泰明
  • Organizer: 日本物理学会2021年秋季大会
• [Presentation] 極限的高ベータプラズモイドの超音速・超アルヴェン速度衝突による衝撃波励起 (2020)
  • Author(s): 小林大地，浅井朋彦，高橋 努，渡邉達大，原島大輔，巽 ありさ，佐原直人，三浦圭介，飯嶋祐佳，山中拓人，明石和久，田村康明，染谷絋希，郷田博司，Thomas ROCHE
  • Organizer: 第37回 プラズマ・核融合学会年会
• [Presentation] パルス磁場印加による磁化プラズモイドの加速実験 (2020)
  • Author(s): 関 太一，浅井朋彦，小林大地，柳 凌太郎
  • Organizer: 第37回 プラズマ・核融合学会年会
• [Presentation] 高ベータプラズモイドの超音速衝突時の中性子の観測 (2020)
  • Author(s): 佐原直人，渡邉達大，小林大地，小川 洋，髙橋 努，浅井朋彦，Richard Magee
  • Organizer: 第37回 プラズマ・核融合学会年会
• [Presentation] MHD Simulation of Supersonic FRC Merging Compensated by Non-Invasive Magnetic Measurements (2020)
  • Author(s): Daichi Kobayashi, Tomohiko Asai, Tsutomu Takahashi, Junichi Sekiguchi, Masaya Watanabe, Tomoya Yoshino, Sean Dettrick, Yung Mok, and Hiroshi Gota
  • Organizer: 23rd Topical Conference on High Temperature Plasma Diagnostics
  • Int'l Joint Research
• [Presentation] Internal Magnetic Measurement in Collisional Merging Process of a Field-ReversedConfiguration (2020)
  • Author(s): Tatsuhiro Watanabe, Tomohiko Asai, Tsutomu Takahashi, Daichi Kobayashi,and Daisuke Harashima
  • Organizer: 23rd Topical Conference on High Temperature Plasma Diagnostics
  • Int'l Joint Research
• [Presentation] Development of Langmuir Probe Array for Radial Potential Profile Measurement in a Collisional Merging Formation FRC (2020)
  • Author(s): Kazuhisa Akashi, Yuka Iijima, Daichi Kobayashi, Tomohiko Asai, Jordan Morelli, and Thomas Roche
  • Organizer: 23rd Topical Conference on High Temperature Plasma Diagnostics
  • Int'l Joint Research
• [Presentation] FRCの移送・合体過程の3次元MHDシミュレーション (2019)
  • Author(s): 水口直紀，小林大地，徐 旻昊，浅井朋彦
  • Organizer: 第36回プラズマ・核融合学会年会
• [Presentation] Evaluation of Translation Velocity Control by Auxiliary Coils for Collisional Merging Formation of FRCs by 2-D Resistive MHD Simulation (2019)
  • Author(s): Daichi KOBAYASHI, Tomohiko ASAI, Tsutomu TAKAHASHI, Junichi SEKIGUCHI, Hiroshi GOTA, Sean DETTRICK, Yung MOK, Michl BINDERBAUER, Toshiki TAJIMA
  • Organizer: The 28th International Toki Conference on Plasma and Fusion Research
  • Int'l Joint Research
• [Presentation] MHD simulation of FRCs for velocity control in the collisional merging process (2019)
  • Author(s): D. Kobayashi, T. Asai, Ts. Takahashi, J. Sekiguchi, H. Gota, S. Dettrick, Y. Mok, M. Binderbauer, and T. Tajima
  • Organizer: US-Japan Workshop on Compact Tori 201 9
  • Int'l Joint Research