Current Drive in Spherical Tokamak Plasmas by the Lower Hybrid Wave

2013 Fiscal Year Final Research Report

• Project/Area Number: 21226021
• Research Category: Grant-in-Aid for Scientific Research (S)
• Allocation Type: Single-year Grants
• Research Field: Nuclear fusion studies
• Research Institution: The University of Tokyo
• Principal Investigator: TAKASE Yuichi 東京大学, 新領域創成科学研究科, 教授 (70292828)
• Co-Investigator(Kenkyū-buntansha): EJIRI Akira 東京大学, 大学院新領域創成科学研究科, 准教授 (30249966) ; NAGASHIMA Yoshihiko 九州大学, 応用力学研究所, 准教授 (90390632) ; TSUJII Naoto 東京大学, 大学院新領域創成科学研究科, 助教 (20707351)
• Project Period (FY): 2009-05-11 – 2014-03-31
• Keywords: 炉心プラズマ / プラズマ・核融合 / 球状トカマク / 高周波 / 電流駆動 / 自己組織化

Research Abstract

The purpose of this research is to show that the plasma current needed for spherical tokamaks can be driven by high frequency waves. Plasma currents of over 10kA were driven successfully using the 200MHz lower hybrid wave. Comparing the experimental results obtained using 3 types of antennas, many important results that contribute to the physics understanding, such as self-formation of the spherical tokamak configuration, characterization of nonlinear wave phenomena by wave measurements and of fast electrons by X-ray diagnostics, optimization of wavenumber spectrum, and development of a new antenna, were obtained. Presently, the current drive efficiency is limited by fast electron losses, but according to numerical modeling, a large improvement is expected by operating at higher magnetic field and higher plasma current. These results open up a possibility of improving the economic competitiveness of a fusion reactor.

Research Products

• [Journal Article] Non-inductive plasma initiation and plasma current ramp-up on the TST-2 spherical tokamak (2013)
  • Author(s): Y. Takase, A. Ejiri, H. Kakuda, T. Oosako, T. Shinya, T.Wakatsuki, T. Ambo, H. Furui, T. Hashimoto, J. Hiratsuka, H. Kasahara, K. Kato, R. Kumazawa, C.P. Moeller, T. Mutoh, A. Nakanishi, Y. Nagashima, K. Saito, T. Sakamoto, T. Seki, M. Sonehara, R. Shino, H. Togashi, O. Watanabe, T. Yamaguchi
  • Journal Title: Nucl. Fusion Volume: 53(6) Pages: 063006 (6)
  • DOI: 10.1088/0029-5515/53/6/063006
  • Peer Reviewed
• [Journal Article] X-ray Measurements during Plasma Current Start-up Experiments using the Lower Hybrid Wave on the TST-2 Spherical Tokamak (2012)
  • Author(s): T. Wakatsuki, A. Ejiri, H. Kakuda, Y. Takase, T. Ambo, H. Furui, T. Hashimoto, J. Hiratsuka, H. Kasahara, K. Kato, R. Kumazawa, Y. Nagashima, K. Saito, T. Sakamoto, T. Seki, F. Shimpo, R. Shino, T. Shinya, M. Sonehara, O. Watanabe, T. Yamaguchi, C. P. Moeller
  • Journal Title: IEEJ Trans. FM Volume: 132(7) Pages: 485-489 (5)
  • DOI: 10.1541/ieejfms.132.485
  • Peer Reviewed
• [Journal Article] Development of a plasma current ramp-up technique for spherical tokamaks by the lower hybrid wave (2011)
  • Author(s): Y. Takase, A. Ejiri, H. Kakuda, Y. Nagashima, T. Wakatsuki, O.Watanabe, P. Bonoli, O. Meneghini, S. Shiraiwa, J. Wright, C. Moeller, H. Kasahara, R. Kumazawa, T. Mutoh, K. Saito, TST-2 Group
  • Journal Title: Nucl. Fusion Volume: 51 Pages: 063017 (9)
  • DOI: 10.1088/0029-5515/51/6/063017
  • Peer Reviewed
• [Journal Article] Comparison of Hydrogen and Deuterium Plasmas in ECH Start-Up Experiment in the TST-2 Spherical Tokamak (2010)
  • Author(s): O. Watanabe, A. Ejiri, H. Kurashina, T. Ohsako, Y. Nagashima, T. Yamaguchi, T. Sakamoto, B.I. An, H. Hayashi, H. Kobayashi, K. Yamada, H. Kakuda, J. Hiratsuka, K. Hanashima, T. Wakatsuki, Y. Takase
  • Journal Title: Plasma Fusion Res Volume: 5 Pages: S2032 (4)
  • DOI: 10.1585/pfr.5.S2032
  • Peer Reviewed
• [Journal Article] Electron Density Measurements of Non-inductive Start-up Plasmas in the TST-2 Spherical Tokamak (2010)
  • Author(s): H. Kurashina, A. Ejiri, Y. Takase, K. Hanashima, T. Sakamoto, O. Watanabe, Y. Nagashima, T. Yamaguchi, B. I. An, H. Kobayashi, H. Hayashi, K. Yamada, H. Matsuzawa, H. Kakuda, J. Hiratsuka, T. Wakatsuki, T. Oosako
  • Journal Title: Plasma and Fusion Res Volume: 5 Pages: 024 (3)
  • DOI: 10.1585/pfr.5.024
  • Peer Reviewed
• [Journal Article] Direct measurements of the high harmonic fast wave profile in the UTST spherical tokamak plasma (2010)
  • Author(s): T. Wakatsuki, Y. Nagashima, T. Oosako, H. Kobayashi, B. I. An, H. Kakuda, T. Yamada, R. Imazawa, O. Watanabe, T. Yamaguchi, H. Kurashina, H. Hayashi, K. Yamada, T. Sakamoto, K. Hanashima, J. Hiratsuka, S. Kamio, R. Hihara, K. Abe, M. Sakumura, Q. Cao, M. Inomoto, Y. Ono, A. Ejiri, Y. Takase
  • Journal Title: Plasma and Fusion Res Volume: 5 Pages: 018 (3)
  • DOI: 10.1585/pfr.5.018
  • Peer Reviewed
• [Journal Article] Observation of beat oscillation generation by coupled waves associated with parametric decay during radio frequency wave heating of a spherical tokamak plasma (2010)
  • Author(s): Y. Nagashima, T. Oosako, Y. Takase, A. Ejiri, O. Watanabe, H. Kobayashi, Y. Adachi, H. Tojo, T. Yamaguchi, H. Kurashina, K. Yamada, B. I. An, H. Kasahara, F. Shimpo, R. Kumazawa, H. Hayashi, H. Matsuzawa, J. Hiratsuka, K. Hanashima, H. Kakuda, T. Sakamoto, T. Wakatsuki
  • Journal Title: Phys. Rev. Lett Volume: 104(24) Pages: 245002 (4)
  • DOI: 10.1103/PhysRevLett.104.245002
  • Peer Reviewed
• [Journal Article] Parametric decay instability during high harmonic fast wave heating experiments on the TST-2 spherical tokamak (2009)
  • Author(s): T. Oosako, Y. Takase, A. Ejiri, Y. Nagashima, Y. Adachi, H. Kasahara, T. Yamada, O. Watanabe, H. Tojo, S. Kainaga, J. Sugiyama, T. Yamaguchi, B. An, H. Hayashi, H. Kobayashi, H. Kurashina, H. Matsuzawa, K. Yamada, R. Kumazawa, F. Shimpo, Y. Ono, T. Masuda and M. Sasaki
  • Journal Title: Nucl. Fusion Volume: 49 Pages: 065020 (6)
  • DOI: 10.1088/0029-5515/49/6/065020
  • Peer Reviewed
• [Journal Article] Non-inductive plasma current start-up by EC and RF power in the TST-2 spherical tokamak (2009)
  • Author(s): A. Ejiri, Y. Takase, T. Oosako, T. Yamaguchi, Y. Adachi, O. Watanabe, Y. Nagashima, B.I. An, H. Kobayashi, H. Kurashina, H. Hayashi, H. Matsuzawa, K. Yamada, H. Tojo, T. Masuda, M. Sasaki, R. Kumazawa, H. Kasahara and F. Shimpo
  • Journal Title: Nucl. Fusion Volume: 49 Pages: 065010 (12)
  • DOI: 10.1088/0029-5515/49/6/065010
  • Peer Reviewed
• [Presentation] Key issues, results and next research of TST-2 RF-only plasma experiments (2014)
  • Author(s): Y. Takase, et al.
  • Organizer: 2nd Workshop on QUEST and Related ST RF Startup and Sustainment Plasma Research, RIAM
  • Place of Presentation: Kyushu Univ
  • Year and Date: 20140224-26
• [Presentation] Diagnostic results and needs of flowing plasma equilibrium in TST-2 (2014)
  • Author(s): A. Ejiri, et al.
  • Organizer: 2nd Workshop on QUEST and Related ST RF Startup and Sustainment Plasma Research
  • Place of Presentation: Kyushu Univ
  • Year and Date: 20140224-26
• [Presentation] Overview of TST-2 experiment (2014)
  • Author(s): Y. Takase, et al.
  • Organizer: The Second A3 Foresight Workshop on Spherical Torus
  • Place of Presentation: Tsinghua University, Beijing, China
  • Year and Date: 20140106-08
  • Invited
• [Presentation] Measurements of Lower-Hybrid Waves with an Interferometer on the TST-2 Spherical Tokamak (2013)
  • Author(s): N. Tsujii, et al.
  • Organizer: 55th Annual Meeting of the APS Division of Plasma Physics
  • Place of Presentation: Denver, CO, USA
  • Year and Date: 20131111-15
• [Presentation] Studies of Lower-hybrid Startup Scenario on TST-2 (2013)
  • Author(s): N. Tsujii, et al.
  • Organizer: US-Japan Workshop on Physics of RF Heating of Fusion Plasmas 2013
  • Place of Presentation: MIT, Cambridge, MA, USA
  • Year and Date: 20130924-26
• [Presentation] RF Plasma Start-up and Plasma Current Ramp-up Studies on TST-2 (2013)
  • Author(s): Y. Takase, et al.
  • Organizer: 17th International Spherical Torus Workshop
  • Place of Presentation: University of York, York, UK
  • Year and Date: 20130924-26
  • Invited
• [Presentation] Plasma Current Start-up and Self-Formation of Toroidal Configuration in Spherical Tokamak Devices (2013)
  • Author(s): Y. Takase, et al.
  • Organizer: Workshop on "Research on Advanced Material Systems in Joint Collaboration : RAIJIN under PIRE
  • Place of Presentation: Rhiga Royal Hotel, Kyoto
  • Year and Date: 20130916-19
  • Invited
• [Presentation] Characteristics of a Novel Lower Hybrid Wave Antenna for the TST-2 Spherical Tokamak (2013)
  • Author(s): Y. Takase, et al.
  • Organizer: 20th Topical Conference on Radio Frequency Power in Plasmas
  • Place of Presentation: Sorrento, Italy
  • Year and Date: 20130625-28
• [Presentation] Plasma Start-up by LHW on TST-2 (2013)
  • Author(s): Y. Takase, et al.
  • Organizer: Workshop on RF Startup and Sustainment, RIAM
  • Place of Presentation: Kyushu Univ
  • Year and Date: 20130226-0301
  • Invited
• [Presentation] TST-2 : present status and future plan (2013)
  • Author(s): Y. Takase, et al.
  • Organizer: 1^<st> A3 Foresight Workshop on Spherical Torus
  • Place of Presentation: Seoul National University, Korea
  • Year and Date: 20130114-16
  • Invited
• [Presentation] Non-inductive Plasma Initiation and Plasma Current Ramp-up on the TST-2 Spherical Tokamak (2012)
  • Author(s): Y. Takase, et al.
  • Organizer: 24^<th> IAEA Fusion Energy Conference
  • Place of Presentation: San Diego, CA, USA
  • Year and Date: 20121008-13
• [Presentation] Plasma current ramp-up by waves in the lower hybrid frequency range on TST-2 (2011)
  • Author(s): Y. Takase, et al.
  • Organizer: 53rd Annual Meeting of the APS Division of Plasma Physics
  • Place of Presentation: Salt Lake City, UT, USA
  • Year and Date: 20111114-18
• [Presentation] Equilibrium analysis of the RF start-up plasma on the TST-2 spherical tokamak device (2011)
  • Author(s): A. Ejiri, et al.
  • Organizer: The Joint Meeting of 5th IAEA Technical Meeting on Spherical Tori & 16th International Workshop on Spherical Torus (ISTW2011) & 2011 US-Japan Workshop on ST Plasma
  • Place of Presentation: Toki
  • Year and Date: 20110927-30
• [Presentation] Plasma Curent Start-up Experiment using Waves in the Lower Hybrid Frequency Range in TST-2 (2011)
  • Author(s): Y. Takase, et al.
  • Organizer: Joint Meeting of the 19th Topical Conference on Radio Frequency Power in Plasmas and the US-Japan RF Physics Workshop
  • Place of Presentation: Newport, RI, USA
  • Year and Date: 20110601-03
• [Presentation] Development of a Plasma Current Ramp-up Technique for Spherical Tokamaks by the Lower-Hybrid Wave (2010)
  • Author(s): Y. Takase, et al.
  • Organizer: 23rd IAEA Fusion Energy Conference
  • Place of Presentation: Daejeon, Korea
  • Year and Date: 20101011-16
• [Presentation] Non-inductive Plasma Current Start-up Experiments in the TST-2 Spherical Tokamak (2010)
  • Author(s): A. Ejiri, et al.
  • Organizer: 23rd IAEA Fusion Energy Conference
  • Place of Presentation: Daejeon, Korea
  • Year and Date: 20101011-16
• [Presentation] Nonlinear phenomena of edge fluctuations in RF range during high harmonic fast wave heating experiments in the TST-2 spherical tokamak (2010)
  • Author(s): Y. Nagashima, et al.
  • Organizer: 2010 US-Japan RF Workshop
  • Place of Presentation: San Diego, CA, USA
  • Year and Date: 20100308-10
• [Presentation] RF Experiments on TST-2 (2009)
  • Author(s): Y. Takase, et al.
  • Organizer: 52nd Annual Meeting of the APS Division of Plasma Physics
  • Place of Presentation: Atlanta, GA, USA
  • Year and Date: 20091102-06
• [Presentation] Observation of non-locality of parametric decay during rf injection experiments on TST-2 (2009)
  • Author(s): Y. Nagashima, et al.
  • Organizer: 52nd Annual Meeting of the APS Division of Plasma Physics, Atlanta
  • Place of Presentation: GA, USA
  • Year and Date: 20091102-06
• [Presentation] RF Start-up, Heating and Current Drive Studies on TST-2 and UTST (2009)
  • Author(s): Y. Takase, et al.
  • Organizer: 52nd Annual Meeting of the APS Division of Plasma Physic
  • Place of Presentation: Atlanta, GA, USA
  • Year and Date: 20091102-06
  • Invited
• [Presentation] Equilibrium Analysis of EC-Sustained and RF-Sustained ST Plasmas (2009)
  • Author(s): Y. Takase, et al.
  • Organizer: "The 18th Topical Conference on Radio Frequency Power in Plasmas
  • Place of Presentation: Gent, Belgium
  • Year and Date: 20090624-26
• [Book] "Characteristics of a Novel Lower Hybrid Wave Antenna for the TST-2 Spherical Tokamak," in Radiofrequency Power in Plasmas(Proc. 20th Top. Conf., Sorrento, Italy, 2013)
  • Author(s): Y. Takase, C. P. Moeller, T. Shinya, T. Wakatsuki, A. Ejiri, H. Furui, J. Hiratsuka, K. Imamura, T. Inada, H. Kakuda, K. Nakamura, A. Nakanishi, T. Oosako, M. Sonehara, H. Togashi, S. Tsuda, N. Tsujii, T. Yamaguchi
  • Total Pages: 462-465
  • Publisher: AIP, Melville, NY, 2014
• [Book] Results of Lower Hybrid Wave Experiments Using a Dielectric Loaded Waveguide Attay Antenna on TST-2," in Radiofrequency Power in Plasmas(Proc. 20th Top. Conf., Sorrento, Italy, 2013)
  • Author(s): T. Wakatsuki, A. Ejiri, T. Shinya, Y. Takase, H. Furui, J. Hiratsuka, K. Imamura, T. Inada, H. Kakuda, H. Kasahara, Y. Nagashima, K. Nakamura, A. Nakanishi, T. Oosako, K. Saito, T. Seki, F. Shimpo, M. Sonehara, H. Togashi, S. Tsuda, N. Tsujii, T. Yamaguchi
  • Total Pages: 422-425
  • Publisher: AIP, Melville, NY, 2014
• [Remarks] [1]球状トカマク研究の進展 -核融合エネルギー開発に向けて-プラズマ・核融合学会誌(小特集)T. Maekawa, Y. Takase, K. Hanada, N. Yoshida, M. Nagata, Y. Ono, M. Inomoto, Y. Nagashima, Y. Nagayama, J. Plasma Fusion Res. 88 (12), 706-760 (2012).
• [Remarks] [2]週刊エネルギー通信第1206号 平成23年12月23日(エンジニアリングニュース社)pp. 15-17ST トカマク進展 LH 波で電流駆動
• [Remarks] [3]第50回プラズマ若手夏の学校 2011年8月8日-11日プラズマ・核融合学会 プラズマ若手グループ(2011.8)プラズマ核融合学会球状トカマク(ST)pp.143-152
• [Remarks] 東京大学柏キャンパス一般公開で研究内容を紹介。参加者約2000名。2013年10月25-26日,2012年10月26-27日,2011年10月21-22日,2010年10月29-30日,2009年10月30-31日
• [Remarks] 前橋高校学生に研究を紹介。2010年11月11日。参加者50名。
• [Remarks] 柏市市民団体に研究を紹介。2009年7月13日。参加者26名。
• [Remarks]
  • URL: http://fusion.k.u-tokyo.ac.jp/research/kakenhi_h21.html