Fusion Plasma Science (FPS)

Summary

FPS is a research group which is working on super-high-density implosion of the nuclear fusion fuel and its controlled heating to promote FIREX project aiming at proof-of-principle demonstration of Fast Ignition scheme for development of future energy source by laser-driven inertial confinement fusion.

Group website

Nakata-Tsubakimoto group as a part of the “Opto-Quantum System Research Area”, a cooperative laboratory (Shiraga’s lab.) for Division of Electrical, Electronic and Information Engineering, Graduate School of Engineering, is Here.

Research topics

Laser-driven inertial-confinement fusion by Fast Ignition scheme

Laser-driven inertial confinement fusion is an attractive scheme for controlled nuclear fusion as a future energy source. Fast Ignition scheme is composed of two stages: high-density implosion of the fuel plasma and its efficient heating to the self-ignition temperature.

Hydrodynamic implosion has been intensively studied since 1970’s, and the super-high-density compression to 600-times liquid density was achieved in 1990’s. However, in that stage, it was found that the central hot spark plasma was not successfully created because of the shell break-up due to the Rayleigh-Taylor instability. Fast Ignition is a scheme expected to realize controllable ignition by using external laser-driven heating. Research on efficient fast heating has been started in 2000’s, and is currently ongoing. Full system of the LFEX laser with four beams became operational as a heating laser since 2015. Various research and development of laser technology and plasma physics, such as harmonic wave generation of ultra-fast heating laser pulse to control the fast electron energy, pulse shaping of the driver laser for high-density implosion, as well as investigation of interference effect of the laser beams on plasma formation, have been performed to demonstrate efficient heating. Research on fast ignition driven by proton beams generated by intense laser is also pursued.

Development of Advanced Plasma Diagnostics

Highly advanced plasma diagnostics technique is essential for investigating the high-density and high-temperature imploded core plasma since it is created in a very small space typically of 50 microns and in a very short time such as 100 picosecond. For example, shown in the figure is the huge neutron detector system called “MANDALA”, which consists of 600-channel neutron scintillation counters. To enhance its diagnostic capability, new scintillator materials with higher performance are being developed to relieve difficulties caused by the intense hard x-ray backgrounds.

Application of Laser-Produced Plasmas

Laser fusion plasma acts also as an intensive pulsed and point neutron source. Such neutrons can be used for non-destructive inspection of large-sized objectives. We are developing such neutron radiograph technique by applying laser-produced plasmas.

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