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Yuichi Takase / Professor / Division of Transdisciplinary Sciences
Department of Complexity Science and Engineering / / Plasma physics and nuclear fusion
http://fusion.k.u-tokyo.ac.jp/index-e.html

Career Summary
1978: Graduated, Faculty of Science, The University of Tokyo
1983: Doctor of Science from Massachusetts Institute of Technology
1983: Postdoctoral Associate, Massachusetts Institute of Technology
1984: Research Scientist, Massachusetts Institute of Technology
1992: Principal Research Scientist, Massachusetts Institute of Technology
1997: Professor, The University of Tokyo

Educational Activities
Graduate school: Plasma Wave Physics, Plasma Physics I, Fusion Practical Training, Complexity Experiment
Undergraduate school: Plasma Physics, Fluid Mechanics, Electromagnetism II

Research Activities
Our research group is performing experimental research on high-temperature plasmas with the aim of realizing fusion energy. Plasmas, which are collections of charged particles (ions and electrons), exhibit collective motion under the influence of externally imposed and self-generated electromagnetic fields, and they are typical examples of nonlinear complex systems. In addition to being important for fusion research, plasmas are also interesting physical entities in their own right. The greatest problems that need to be solved in fusion research are establishing a method to confine a plasma with sufficiently high density for long enough time, and to heat the plasma efficiently to very high temperatures (approximately 100 million degrees). In our laboratory, research is performed on the TST-2 spherical tokamak, which was constructed in 1999 (Ref. 1). Research topics include: development of a new method to start up the plasma without using a central solenoid (CS) (Refs. 2-3), development of heating and current drive techniques using radiofrequency (RF) waves (Refs. 4-10), study of plasma instabilities and methods for their suppression, and energy and particle transport processes and methods for their control. Fusion devices are becoming larger in scale, as exemplified by the next-step fusion experimental facility, the International Thermonuclear Experimental Reactor (ITER), which is being constructed under international collaboration. Using a new confinement concept, the spherical tokamak (ST) is capable of producing high-performance plasmas in a compact device, and may provide a way to realize an economically competitive fusion reactor. As a result, ST research is making rapid progress globally. Based on our past research achievements, research at our laboratory focuses primarily on plasma heating and current drive by radiofrequency waves, plasma performance improvement (in plasma confinement and stability at high plasma pressures), and plasma start-up without using the central solenoid, which is indispensable for realizing a fusion reactor based on the ST concept. In addition, various diagnostics for high-temperature plasmas based on a variety of physical processes are being developed.

Literature
1) Y. Takase, et al., Nucl. Fusion 41, 1543 (2001).
2) S. Shiraiwa, et al., Phys. Rev. Lett. 92, 035001 (2004).
3) M. Ushigome, et al., Nucl. Fusion 46, 207 (2006).
4) S. Shiraiwa, et al., Phys. Rev. Lett. 98, 185003 (2006).
5) A. Ejiri, et al., Nucl. Fusion 46, 709 (2006).
6) Y. Takase, et al., Nucl. Fusion 46, S598 (2006).
7) A. Ejiri, et al., Nucl. Fusion 49, 065010 (2009).
8) Y. Takase, et al., Nucl. Fusion 51, 063017 (2011).
9) Y. Takase, et al., Nucl. Fusion 53, 063006 (2013).
10) Y. Shinya, et al., Nucl. Fusion 57, 036006 (2017).

Other Activities
American Physics Society (APS)
Physical Society of Japan (JPS)
Japan Society for Plasma and Fusion Research (JSPF)
Coordinating Committee, Fusion Energy Forum of Japan (QST)
ITER-BA Technical Promotion Committee (QST)
Chair, Fusion Plasma Joint Planning Committee (QST)
Fusion Science Network (NIFS)
Japan-US Scientific Collaboration Fusion Area Research Planning Committee (JSPS)
Chair, ST Coordination Committee (NIFS)
Coordinator, QUEST Experiment Promotion Committee (Kyushu Univ.)
Chair, ST Implementing Agreement Executive Committee (IEA)

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Future Plan
Research and education at the Graduate School of Frontier Sciences are centered on experimental research on collective phenomena in high-temperature plasmas using the TST-2 spherical tokamak. In experimental fusion plasma physics, it is extremely important for students to learn how to operate the experiment and to control the plasma. TST-2 is a unique and valuable research and educational facility in the world in that it provides students with the opportunity to control all aspects of a serious fusion plasma experimental device. Through performing experimental research using this device, we aim to train young scientists and provide them with comprehensive experience so that they can become world leaders. We also strive to gain a comprehensive understanding of the physics of collective phenomena in high-temperature plasmas through collaborative research on larger, world-class fusion experiments including the LHD helical device at NIFS, the NSTX-U spherical tokamak at PPPL (USA), and the MAST-U spherical tokamak at CCFE (UK). In addition, our group provides leadership in the ITER Project, the JT-60SA Tokamak Project at QST, and the All-Japan ST Research Program, and we will continue to play central roles in the fields of plasma physics and nuclear fusion research.

Messages to Students
Fusion is a promising candidate for a future energy source. Japan has a large population and high energy consumption, but is poor in energy resources. Thus, the realization of fusion energy is particularly important for Japan. Japan has been leading the world with top-level research in fusion. The next-step research of fusion burning plasmas has exceeded the scale of a national project and has now been launched as an international collaboration project. Our laboratory aims to train world-class leaders who can helm international collaboration research projects, and we seek active, motivated students. The activities of our laboratory are summarized on our homepage (http://fusion.k.u-tokyo.ac.jp/index-e.html).

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