Heat-flow change induced by active radiation loss in open magnetic flux of steady-state spherical tokamak

• Project/Area Number: 15K17800
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Plasma science
• Research Institution: Kyushu University
• Principal Investigator: Onchi Takumi 九州大学, 応用力学研究所, 学術研究員 (00727216)
• Project Period (FY): 2015-04-01 – 2017-03-31
• Project Status: Completed (Fiscal Year 2016)
• Budget Amount: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2016: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000); Fiscal Year 2015: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
• Keywords: プラズマ熱流束 / 放射損失 / 球状トカマク / スクレイプオフ層 / プラズマ / 熱流束 / 長時間放電

Outline of Final Research Achievements

Damage of plasma facing component (PFC) is a serious issue for future nuclear fusion reactor, where plasma is confined magnetically. Active radiation-loss is one of the methods to reduce heat flux on PFCs. This experiment is a bench test to investigate effect of active radiation-loss. In the spherical tokamak QUEST, electron temperature, density, heat flux, and velocity of plasma flow are measured in the far scrape-off layer (SOL) and the end-plate. Substantial flow of particles and heat from the SOL to the end-plate is observed after strong gas puffing with high radiation-loss. Increase of electron density and decrease of electron temperature occur before a disruption with high H alpha line-emission in a 2 hours-long pulse tokamak operation. In addition, a system for super-sonic molecular beam injection to induce local radiation-loss has been prepared.

Research Products

• [Journal Article] Spatial distribution of atomic and ion hydrogen flux and its effect on hydrogen recycling in long duration confined and non-confined plasmas (2017)
  • Author(s): A. Kuzmin, H. Zushi, I. Takagia, S. K. Sharma, M. Kobayashi, Y. Hirooka, T. Onchi, K. Hanada, N. Yoshida, K. Nakamura, A. Fujisawa, H. Idei, Y. Nagashima, M. Hasegawa, T. Mutoh, K. Mishra, H. Ohwada
  • Journal Title: Nuclear Materials and Energy Volume: 印刷中 Pages: 627-632
  • DOI: 10.1016/j.nme.2017.03.027
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Permutation entropy and statistical complexity in characterizing low-aspect-ratio reversed-field pinch plasma (2017)
  • Author(s): T. Onchi, A. Fujisawa, A. Sanpei, H. Himura, S. Masamune
  • Journal Title: Physica Scripta Volume: 92 Issue: 5 Pages: 055601-055601
  • DOI: 10.1088/1402-4896/aa6689
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Hydrogen flux measurements with permeation probes in speherical tokamak QUEST (2016)
  • Author(s): A.Kuzmin, H.Zushi, I.Takagi, S.K.Sharma, Y.Hirooka, M.Kobayashi, M.Sakamoto, K.Hanada, T.Onchi, Y.Oyama, N.Yoshida, K.Nakamura, A.Fujisawa, H.Idei, Y.Nagashima, M.Hasegawa, K.Mishra
  • Journal Title: Vacuum Volume: 129 Pages: 178-182
  • DOI: 10.1016/j.vacuum.2016.04.025
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Observation of an edge coherent mode and poloidal flow in the electron cyclotron wave induced high βp plasma in QUEST (2016)
  • Author(s): Santanu Banerjee, H. Zushi, N. Nishino, K. Mishra, Y. Mahira, S. Tashima, A. Ejiri, T. Yamaguchi, T. Onchi, Y. Nagashima, K. Hanada, K. Nakamura, H. Idei, M. Hasegawa, A. Fujisawa, A. Kuzmin and K. Matsuoka
  • Journal Title: Physics of Plasmas Volume: 23 Issue: 8 Pages: 082507-082507
  • DOI: 10.1063/1.4960117
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Comparative studies of inner and outer divertor discharges and a fueling study in QUEST (2016)
  • Author(s): O. Mitarai, K. Nakamura, M. Hasegawa, T. Onchi, H. Idei, A. Fujisawa, K. Hanada, H. Zushi, A. Higashijima, H. Nakashima, S. Kawasaki, QUEST group, K. Matsuoka, S. Koike, T. Takahashi, H. Tsutsui
  • Journal Title: Fusion Engineering and Design Volume: 109-111, PartB Pages: 1624-1630
  • DOI: 10.1016/j.fusengdes.2015.12.022
  • Peer Reviewed / Open Access
• [Journal Article] Response of the far scrape-off layer plasma to strong gas puffing in the high poloidal beta configuration on the QUEST spherical tokamak (2016)
  • Author(s): Onchi, Takumi; Zushi, Hideki; Mishra, Kishore; Oyama, Yuya; Nagashima, Yoshihiko; Hanada, Kazuaki; Idei, Hiroshi; Hasegawa, Makoto; Kuzmin, Arseniy; Miura, Hiroki; Nakamura, K; Fujisawa, Akihide; Nagaoka, Kenichi
  • Journal Title: Plasma Physics and Controlled Fusion Volume: 58 Issue: 11 Pages: 115004-115004
  • DOI: 10.1088/0741-3335/58/11/115004
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Tomography as a promising diagnostic tool for plasma turbulence (2016)
  • Author(s): A. Fujisawa, Y. Nagashima, S. Inagaki, T. Onchi, S. Ohshima, A. Shimizu
  • Journal Title: Plasma Phys. Control. Fusion Volume: 58 Issue: 2 Pages: 0250051-10
  • DOI: 10.1088/0741-3335/58/2/025005
  • Peer Reviewed
• [Journal Article] Multiple wall-reflection effect in adaptive-array differential-phase reflectometry on QUEST (2016)
  • Author(s): H Idei, K Mishra, MK Yamamoto, A Fujisawa, Y Nagashima, M Hamasaki, Y Hayashi, T Onchi, K Hanada, H Zushi
  • Journal Title: Journal of Instrumentation Volume: 11 Issue: 01 Pages: C01014-C01014
  • DOI: 10.1088/1748-0221/11/01/c01014
  • Peer Reviewed
• [Journal Article] Development Toward a Repetitive Compact Torus Injector (2016)
  • Author(s): T. Onchi, D. McColl, A. Rohollahi, C. Xiao, A. Hirose, M. Dreval, and S. Wolfe
  • Journal Title: IEEE TRANSACTIONS ON PLASMA SCIENCE Volume: 44 Issue: 2 Pages: 195-195
  • DOI: 10.1109/tps.2015.2499218
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Dynamical programming based turbulence velocimetry for fast visible imaging of tokamak plasma (2015)
  • Author(s): Santanu Banerjee, H. Zushi, N. Nishino, K. Mishra, T. Onchi, A. Kuzmin, Y. Nagashima, K. Hanada, K. Nakamura, H. Idei, M.Hasegawa, and A. Fujisawa
  • Journal Title: Review of Scientific Instruments Volume: 86 Issue: 3 Pages: 033505-033505
  • DOI: 10.1063/1.4914838
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Self organization of high beta_p plasma equilibrium with an inboard poloidal magnetic field null in QUEST (2015)
  • Author(s): Kishore Mishra, H Zushi, H Idei, M Hasegawa, T Onchi, S Tashima, S Banerjee, H Hanada, H Togashi, T Yamaguchi, A Ejiri, Y Takase, K Nakamura, A Fujisawa, Y Nagashima, A Kuzmin
  • Journal Title: Nuclear Fusion Volume: 55 Issue: 8 Pages: 083009-083009
  • DOI: 10.1088/0029-5515/55/8/083009
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Heat flux and plasma flow in the far scrape-off layer of the inboard poloidal field null configuration in QUEST (2015)
  • Author(s): T Onchi, H Zushi, K Mishra, Y Mahira, K Nagaoka, K Hanada, H Idei, M Hasegawa, K Nakamura, A Fujisawa, Y Nagashima, K Matsuoka, S Tashima, S Banerjee, A Kuzmin, S Kawasaki, H Nakashima, A Higashijima, O Watanabe
  • Journal Title: Physics of Plasmas (1994-present) Volume: 22 Issue: 8 Pages: 082513-082513
  • DOI: 10.1063/1.4928878
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Global gas balance and peculiarities of atomic hydrogen influence on hydrogen wall inventory in steady-state operation of QUEST tokamak (2015)
  • Author(s): A.Kuzmin, H. Zushi, I.Takagi, S.K. Sharma, A. Rusinov, Y. Inoue, Y. Hirooka, H. Zhou, M. Kobayashi, M. Sakamoto, K. Hanada, N. Yoshida, K. Nakamura, A. Fujisawa, M.Matsuoka, H. Idei, Y. Nagashima, M. Hasegawa, T.Onchi, S. Banerjee, K. Mishira
  • Journal Title: Journal of Nuclear Materials Volume: in press Pages: 1087-1087
  • DOI: 10.1016/j.jnucmat.2014.12.092
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Observation of heat flux and plasma flow in scrapr off layer in QUEST (2015)
  • Author(s): T. Onchi, Y. Mahira, K. Nagaoka, S. Tashima, S. Banerjee, K. Mishra, H. Idei, K. Hanada, K. Nakamura, A. Fujisawa, Y. Nagashima, M.Hasegawa, K. Matsuoka, A. Kuzmin, O. Watanabe, S. Kawasaki, H. Nakashima, A. Higashijima
  • Journal Title: Journal of Nuclear Materials Volume: in press Pages: 428-428
  • DOI: 10.1016/j.jnucmat.2014.11.136
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Particle balance in long duration RF driven plasmas on QUEST (2015)
  • Author(s): K. Hanada, H. Zushi, N. Yoshida, M. Hasegawa, K. Mishra, Kuzumin, K. Nakamura, A. Fujisawa, H. Idei, Y. Nagashima, O. Watanabe, T. Onchi, H. Watanabe, K. Tokunaga, A. Higashijima, S.Kawasaki, H.Nakashima, Y.Takase, A.Fukuyama, O.Mitarai, T.Maekawa and M. Peng
  • Journal Title: Journal of Nuclear Materials Volume: 463 Pages: 1084-1084
  • DOI: 10.1016/j.jnucmat.2015.01.013
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Presentation] Non-inductive current built-up by local electron cyclotron heating and current drive with a 28 GHz focused beam on QUEST (2016)
  • Author(s): Takumi Onchi
  • Organizer: APS Division of Plasma Physics Meeting 2016, abstract #PP10.025
  • Place of Presentation: San Jose, California, United States of America
  • Year and Date: 2016-10-31
  • Int'l Joint Research
• [Presentation] QUEST - IPN 配位における ガスパフ入射時の遠方 SOL 流の振る舞い (2016)
  • Author(s): 恩地拓己，図子秀樹， Kishore Mishra ，小山雄也 A ，永島芳彦，花田和明，出射 浩，長谷川真，藤澤彰英，中村一男， Arseniy Kuzmin, QUEST team
  • Organizer: 日本物理学会 第71回年次大会
  • Place of Presentation: 東北学院大学泉キャンパス
  • Year and Date: 2016-03-19
• [Presentation] Modification of far-SOL flow by substantial gas injection in the inboard poloidal field null configuration on QUEST (2015)
  • Author(s): T Onchi, H Zushi, Y Oyama, K Mishra, Y Nagashima, K Hanada, H Idei, M Hasegawa, A Kuzmin, K Nakamura, A Fujisawa, K Nagaoka
  • Organizer: American Physical Society
  • Place of Presentation: Savannah, GA, USA
  • Year and Date: 2015-11-16
  • Int'l Joint Research