Yuichi Ogawa / Professor / Division of Transdisciplinary Sciences
Department of Advanced Energy / / Fusion energy, Plasma science

Career Summary
1976: B. Eng., Faculty of Engineering (the University of Tokyo)
1981: M. Eng., Graduate School of Engineering (the University of Tokyo)
1981: Ph.D Eng., The University of Tokyo
1981-1991: Research Associate (Nagoya University)
1991-1999: Associate Professor (the University of Tokyo)
1999-present: Professor (the University of Tokyo)

Educational Activities
Graduate school: Plasma Physics and Controlled Nuclear Fusion, Fundamentals of Plasma Physics,
Faculty of Engineering: Engineering on Fusion Energy, Science on Electricity and Magnetism
Research Activities
A nuclear fusion reactor is a miniature Sun, in other words a star on the earth, because the energy resource of the sun and stars is based on nuclear fusion reaction. The core of a nuclear fusion reactor is plasma, which is a mixture of ions and electrons with a temperature of more than 100 million Kelvin. Since the dynamics of plasma is quite complicated, as can be seen in the motion of a solar flare, the control of high temperature plasma is quite difficult.
I have carried out experimental research for magnetically confined plasmas, such as tokamak, helical, and reversed field pinch, and revealed common features among these different magnetic configurations. In a magnetic confinement system, a beta value defined by the ratio of the plasma pressure to the magnetic pressure is a key parameter. High beta plasma is preferable for designing a compact fusion reactor, and ultra high beta plasma (e.g., typically the beta value is around unity) is required for an advanced reactor such as a D-3He reactor. Recently, the innovative idea that strongly flowing plasma reveals a new relaxed state has been proposed by Mahajan and Yoshida. To study this idea, an internal coil device Mini-RT has been constructed, where a high temperature superconductor made of Bi-2223 tape floats for a few hours in a vacuum vessel. In collaborating with the National Institute for Fusion Science, we have developed several new technologies, such as a persistent current switch, a demountable transfer tube in the ultra vacuum condition, and a demountable electrode. In the Mini-RT device, the plasma is produced by 2.45 GHz microwaves, and so-called overdense plasmas have been produced. Because we hypothesize that the electron Bernstein wave (EBW) might be playing an important role for this overdense plasma, we are studying the characteristics of the EBW.
The International Tokamak Experimental Reactor (ITER) project is promoted to demonstrate a fusion-burning plasma. In addition, a roadmap to a DEMO fusion reactor, in which electric power is expected to be produced, is intensively discussed. We are promoting a tokamak fusion reactor design, in addition to laser and helical reactors. A system code for these reactor designs has been developed, and common features between different reactors have been studied. One common and important issue for fusion reactors is the compatibility of the core plasma and first wall/divertor plate. The divertor plate is strongly irradiated by hot plasmas, and the mitigation of the heat load to the divertor plate is quite important. We are exploring the compatibility between core and scrape-off-layer plasmas in ITER and DEMO.

1)Y. Ogawa et al., High Power ICRF Heating Experiments on the JIPP T-IIU Tokamak, Nuclear Fusion 29 (1989), 1873-1885.
2)Y. Ogawa et al., Analysis of the Loading Resistance for ICRF Heating Experiments in ASDEX, Plasma Physics and Controlled Fusion 33 (1991), 155-168.
3)Y. Ogawa et al., Analysis of Neoclassical Transport in the Banana Regime with the DKES code for the Large Helical Device, Nuclear Fusion 32 (1992), 119-132.
4)Y. Ogawa and N. Inoue, Cost Analysis of IDLT Reactors Using the ARIES System Code, Journal of Plasma and Fusion Research 72 (1996), 953-959.
5)Y. Ogawa et al., A New Poloidal-bundle Divertor for a Spherical Tokamak, Fusion Engineering and Design, 48 (2000) 339-45.
6)Y. Ogawa, "Research on High Beta Plasma Based on Two-fluid Relaxation Theory with an Internal Coil Device", Transactions of Fusion Science and Technology, 43 203-207 (2003).
7) Y. Ogawa et al., ECH Plasma Experiments on an Internal Coil Device with a High Temperature Superconductor Coil, Transactions of Fusion Science and Technology, 47 63-70 (2005).
Other Activities
Administrative board member, Japanese Society of Plasma Science and Nuclear Fusion Research(1999-2003)
Steering Committee member, National Institute for Fusion Science
Future Plan
Nuclear fusion research is entering a new era, i.e., an ITER era, and we could achieve a fusion-burning plasma in the near future, although several issues should be overcome for ITER construction and operation. In addition, we can design a fusion reactor based on present knowledge and reasonable extension of plasma physics and technologies. It is, therefore, quite important to demonstrate feasible engineering for a fusion reactor by identifying a critical path and/or critical issues for achieving such a reactor in the near future. Fusion energy might be expected to overcome a global warming problem because it does not emit CO2 and it has a huge amount of energy resource. I am strongly promoting fusion research activities from various standpoints, e.g., fusion reactor design on various configurations, core and divertor plasma control, public acceptance for fusion energy, experimental research for high performance plasmas with an innovative idea, and advanced technology development for fusion plasma experiments.
Messages to Students
All experiences are quite important, even if they are unhappy. In addition, a diversity of experiences will be fruitful and valuable for making decisions in the future. I hope, therefore, you will live for the moment.
Sometimes people stress the importance of on-the-job training. I expect you will be challenged with innovative research, even if you are inexperienced and it is unknown to you. When you enthusiastically carry out your research, you will take joy in that research.