Institute of Laser Engineering, Osaka University


Laser-Based Inertial Fusion Energy Research

Laser Fusion Energy Development Project


Fast ignition is a scheme to produce efficiently the ignition condition of nuclear fusion. The first phase of the Fast Ignition Realization EXperiment (FIREX) project, which is one of the nuclear fusion research activities prioritized in Japan, is conducted as an academic research that is necessary for the development of innovative technologies. Under the bilateral collaboration framework with the National Institute for Fusion Science, experimental and theoretical investigations aiming the realization of laser fusion energy are performed with a variety of collaborators from domestic and international universities and institutions.

Research period

Started in April 2001

Outline of the plan

1.Formation of high-density plasma

For realizing nuclear fusion ignition with acceptable laser energy, the fusion fuel must be compressed to 1000 times solid density or more. Since the compression process of the fuel is hydrodynamically unstable, it is necessary to improve the uniformity of the fuel surface and the irradiation laser intensity profile and design a fuel structure to reduce hydrodynamic instability growth. In order to achieve the ultrahigh density, it is necessary to suppress the increment of fuel entropy. This means that quasi-static compression is required with controlling precisely the time history of pressure. Multidimensional radiative hydrodynamics simulation is required for the optimal design. At the same time, it is also important to develop diagnostics to measure the formation of the ultra-high-density plasma.

2.Acceleration and propagation of energetic particle beams produced by interactions between high intensity laser and plasma

In the fast ignition scheme, a high-intensity laser is converted into an energetic charged particle (electron/ion) beam through laser-plasma interactions. The high-density plasma is heated by the energetic particle beam. It is important to understand and to control the particle acceleration mechanism, propagation, and control of the particle beam in plasma. Particle acceleration by a multi-pico-second laser pulse, which is required for the ignition, is a new area of the laser-plasma interactions. Laser-produced kilo-tesla magnetic field has been studied to control particle beam propagation. In order to measure acceleration and propagation of high-energy particles, we are developing new diagnostics that uses fluorescent X-ray, bremsstrahlung X-ray, transition radiation and so on. These are ultra-fast phenomena that change rapidly within very small spatial and temporal scales, theory and simulation play important roles in understanding the phenomena.

3.Demonstration of Ignition Temperature with Fast Ignition Scheme

We aim to realize 50 million degrees of the nuclear fusion ignition temperature by heating an ultra-densely compressed fuel with a laser-accelerated particle beam. X-ray spectroscopy and neutron diagnostics are important for plasma temperature measurement. Development of diagnostics to obtain physical information under the harsh environment, under which signal is contaminated by intense noise generated by laser-plasma interactions, is underway by utilizing time gate, track detection of nuclear reaction neutron, etc.. Development of integrated simulation code dealing with multi-dimensional and multi-scale physics is underway for extrapolation of the obtained results to the fusion ignition.

4.Laser Fusion Energy Furnace Engineering

Tritium engineering, material engineering, safety engineering, and heat transfer engineering are necessary for realizing the nuclear fusion power plant. These state-of-the-art engineering must be integrated into one fusion power generation system. We have established a research network for promoting activities to realize nuclear fusion energy.

Outline of progress and results

The progress of the FIREX project was reported in the Fusion Science and Technology Committee, and the committee members visited GEKKO-XII and LFEX facilities in FY2016. Summary of the current status and evaluation plan of the project were announced after the report.

Domestic collaborating organization

Hokkaido University, Tohoku University, University of Tokyo, Tokyo Institute of Technology, Toyama University, Graduate School for the Creation of New Photon Industries, Gifu University, National Institute of Fusion Science, Fukui Institute of Technology, Kyoto University, Osaka University, Setsunan University, University of Hyogo, Hiroshima University, Kyushu University etc.