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Greeting from the Director

Zensho Yoshida Director Department of Fusion ScienceApril, 2021

In the old days, all wisdom explorers thought of themselves as “philosophers”, those who love (philein) wisdom (Sophos). For example, what we call “natural science” was called “natural philosophy”. Physics was the philosophy about nature (Newton gave his book the title “Philosophiæ Naturalis Principia Mathematica”). I want students to study philosophy at the University. Recently, we often rephrase philosophy as science, but it remains firmly in the title PhD (Philosophiæ Doctor), the degree you are aiming at.

When we speak of “science”, the “systematic” aspect of study is emphasized, which causes bifurcations into specialized disciplines. In recent times, only professional philosophers advocate philosophy; it seems to reflect the social tendency to evaluate only professionalism. Of course, by the time you graduate, you need to acquire expertise for your future career. However, it might fall short of the purpose of studying here. I encourage you to spend this important time of your life for philosophical thinking.

Fusion science is a comprehensive field that integrates various disciplines of science and technology. It is a venture into the unknown world, about which we have yet to create systematic knowledge. Those who are going to participate in this challenge should not consider science and technology separately. We should learn all subjects of physics, encompassing classical mechanics, quantum mechanics, thermodynamics, statistical physics, field theories, and so on; it is not a narrow discipline pertinent to a subdomain separated from entire physics. In experiments, we make use of all technologies of vacuum, cryogenic, ultra-high temperature, high voltage, high frequency, and so on. In order to master all of these, one needs strong spirit of inquiry born of love for knowledge. I hope you have a literal philosophical mind.

Department of Fusion Science has many experts who support your study. The teachers are those who love knowledge, not only being specialists of the field. Please learn not only the methods of research, but also the attitude to think what we should elucidate and how we can explore. I hope that the students of this Department will reveal the unknown world in the future.

History and Organization – SOKENDAI

1988 Oct The SOKENDAI (Graduate University for Advanced Studies) was established with a three-year PH.D. program system.
1989 May The National Institute for Fusion Science (NIFS) was established in Nagoya.
1992 Apr The Department of Fusion Science established at the School of Mathematical and Physical Science were established.
Atsuo Iiyoshi inaugurated as the first Chair of the Department.
1997 Jul NIFS moved to Toki city, in Gifu Prefecture.
1997 Dec Construction of the LHD was completed.
1999 Apr Masami Fujiwara inaugurated as the second Chair of the Department.
2003 Apr Osamu Motojima inaugurated as the third Chair of the Department.
2004 Apr A National Unicersity Corporation reformulated SOKENDAI.
2006 Apr The 5-year Ph.D. program system was introduced.
2009 Apr Akio Komori inaugurated as the fourth Chair of the Department.
2015 Apr Yasuhiko Takeiri inaugurated as the fifth Chair of the Department.
2021 Apr Zensho Yoshida inaugurated as the sixth Chair of the Department.


Organization chart

About Us


SOKENDAI is a graduate university which provides superior doctoral studies programs in international research fields and learning environments. Students develop an outstanding knowledge of scientific frontiers while working with leading researchers in the world. SOKENDAI was established in 1988 as the first independent graduate university in Japan that does not provide undergraduate courses.

The administrative office of SOKENDAI is in Hayama-cho, Kanagawa Prefecture. Other campuses where academic activities are promoted in fields ranging from the arts and humanities to science and engineering are located in various areas of Japan.

To develop fusion power as a future energy source, scientific understanding of high temperature plasma physics and advanced engineering for realizing a fusion power plant are absolutely necessary. For these purposes, we promote a complementary approach of high temperature plasma experiments, integrated theoretical research, numerical simulations using a supercomputer, and material studies.

The unique point of the department is that students learn a wide range of cutting edge scientific and engineering knowledge such as plasma physics, atomic physics, electrical and mechanical engineering, superconductivity engineering, material engineering, vacuum engineering, and information engineering. This is because fusion science requires highly integrated synthetic research.

The Frontier of Nuclear Fusion Research

Ultimate Energy for Creating the Future

All of the stars in the universe are bright because of nuclear fusion energy. It is a great dream for humanity to realize the controlled nuclear fusion reaction on Earth and utilize the energy for life.

The nuclear fusion reactor can produce a great amount of energy, and ensures safety, good environmental acceptability, and a rich resource. The nuclear fusion reactor has the following advantages and problems for its realization.

  • Advantages

    • The fuel is inexhaustible because it exists in the sea.
    • The emitted CO2 and/or air pollution material is small.
    • The produced energy density is high.
    • The nuclear fusion reaction is intrinsically safe. When accidents occur, the reaction automatically stops.
    • High-level radioactive waste is not generated.
  • Problems

    • The fuel plasma must be steadily confined at an extremely high temperature and in a high density condition. These have not yet been attained simultaneously.
    • The in-vessel structure of the reactor, which has the property of high heat resistance as well as low radioactivation, is under development.
    • A reliable system that converts the nuclear fusion energy to heat energy is being developed.
    • This costs a great amount of money because of the large facility that is necessary for research and development.

The nuclear fusion reactor is currently expected to be realized in 30 years.

Nuclear Fusion Research in the World

There are two principal systems for plasma confinement. One is the “magnetic confinement system” as represented by the helical type and the tokamak type. The other is the “inertial confinement system.” In the magnetic confinement system, high temperature plasmas are confined using a strong magnetic field. At the National Institute for Fusion Science, plasma physics, technology, and simulation research are being conducted concentrating on the Large Helical Device (LHD), which is the world’s largest helical system. The concept of the helical system originated in Japan. The helical system has the excellent property of steady-state plasma operation because the confinement magnetic field can be produced using only the external magnetic coils. The best performance of the steady-state plasma has been achieved at the LHD. Plasma research using a helical device has been conducted in Japan, Germany, Spain, Australia,and other countries. A tokamak-type device achieved the world record of the fusion criterion, which is determined as the product of the ion temperature, the ion density, and the energy confinement time. The tokamak system requires a plasma current to produce the confinement magnetic field. The accurate control method of the plasma current is one of the most important issues of the tokamak system in order to realize the steady-state operation. Tokamak plasma physics have been investigated in Japan, the United States, the United Kingdom, Germany, China, Korea, and other countries. For the inertial confinement system, the nuclear fusion reaction occurs by implosion of the fuel by an instantaneous strong force using high energy lasers or ion beams. The inertial confinement system has been investigated mainly in the United States and Japan.

  • Helical system
  • Tokamak system

TOPICInternational Thermonuclear Experimental Reactor (ITER)

  • ITER
  • he energy confinement property of fusion plasma improves as the plasma volume grows. Thus, the upsizing of the fusion experimental device and the increasing costs are inevitable for realizing the reactor. Also, there still remain technological problems relating to the reactor structure. In response to this present situation, the project of constructing the unprecedentedly large fusion experimental device to obtain comprehensive understanding of the fusion plasma has started under international collaboration.
    The device is a tokamak type and is called “International Thermonuclear Experimental Reactor (ITER).” The ITER project started in 1985, and Japan, the European Union, Russia, the United States, China, Korea, and India are participating in the project. ITER is now under construction at Cadarache in France with a total cost of 14.5 billion Euro. ITER is expected to operate for 20 years from 2020.

    In Japan, the “ITER Broader Approach (BA)” activity has been conducted. The objective of the ITER-BA is (1) to complement and support the ITER project and (2) the establishment of the technological basis required for the prototype reactor, in particular, the material testing of the reactor components, computer simulation of the fusion plasma, and the simulation experiment using a satellite tokamak device. The ITER project is typically called “big science”, and is now off and running.

Guide to Department of Fusion Science