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Volume 49, Issue 3
Special Issues on Progress of Fast Ignition in Laser Fusion −Towards Realization of Ignition and Burning−
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Special Issues on Progress of Fast Ignition in Laser Fusion -Towards Realization of Ignition and Burning-
Special Issue
Laser Review
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Yoshitaka MORI, Yasuhiko SENTOKU2021 Volume 49 Issue 3 Pages 128-
Published: 2021
Released on J-STAGE: April 11, 2024
JOURNAL FREE ACCESSRecent progresses of laser inertial conferment fusion activities in Japan are reported in the following special issues. We review the Japanese laser fusion activities including an introduction of laser fusion experiments facilities in Institute of Laser Engineering, Osaka University and Hamamatsu alliance (Hamamatsu Photonics K. K., and the Graduate School for the Creation of New Photonics Industries), and proposed researches from laser fusion strategy committee.View full abstractDownload PDF (243K) -
Shinsuke FUJIOKA, Yasuhiko SENTOKU2021 Volume 49 Issue 3 Pages 130-
Published: 2021
Released on J-STAGE: April 11, 2024
JOURNAL FREE ACCESSWe tried to summarize the status of the laser fusion research in the world as the beginning of this review series. The mainstream of laser fusion research is the central ignition scheme. We explain processes to realize the fusion ignition by the central ignition scheme and then describe briefly progresses of the central ignition studies in the United States, Europe/UK, and China. In addition, we introduce progresses of the fast-ignition method, which aims to realize fusion energy by avoiding the barriers of the central ignition scheme.View full abstractDownload PDF (852K) -
Tomoyuki JOHZAKI2021 Volume 49 Issue 3 Pages 135-
Published: 2021
Released on J-STAGE: April 11, 2024
JOURNAL FREE ACCESSIn Fast Ignition Realization Experiment (FIREX) project, the efficient core heating has been demonstrated, where the core was heated to the temperature of 2 keV. Based on this successful results, I discuss the physical issues and the scenario for achieving ignition and burn in fast ignition laser fusion. Also I present the ignition condition and the requirement for high gain evaluated by the simple model analysis.View full abstractDownload PDF (1418K) -
Hideaki HABARA, Tao GONG, Kazuo A. TANAKA2021 Volume 49 Issue 3 Pages 143-
Published: 2021
Released on J-STAGE: April 11, 2024
JOURNAL FREE ACCESSWe investigated the direct irradiation of ultra-intense laser (UIL) light into imploded plasma. Due to the relativistic effects of UIL, laser light can penetrate deeper inside an over-critical density surface. We demonstrated a stable, single plasma channel in mm-size coronal plasma, the penetration of UIL into overdense plasma, and heating by the created fast electron beam. From these results, we expect more than 10% energy coupling from UIL to the fuel core by reducing the electron beam divergence angle within 30°.View full abstractDownload PDF (1111K) -
Yoneyoshi KITAGAWA, Yasunobu ARIKAWA, Eisuke MIURA, Tetsuo OZAKI, Osam ...2021 Volume 49 Issue 3 Pages 149-
Published: 2021
Released on J-STAGE: April 11, 2024
JOURNAL FREE ACCESSThis study investigates the heating efficiency of the fast heating when the imploded core is directly illuminated with an ultraintense laser. Six counterbeams of the GEKKO XII (GXII) green laser at the Institute of Laser Engineering (ILE), Osaka University, of which the output was 1.6 kJ, imploded a spherical CD shell target of 500 μm in diameter and formed a dense core. DD-reacted protons and the x-ray core emissions showed a core density of 2.8 ~ 2.7 g/cm 3. The thermal neutron yields were used to estimate the core temperature determined as 850 eV. The core was then directly heated by a laser for fast-ignition experiments (LFEX), which is an extremely energetic ultrashort pulse laser at the ILE with its axis lying to the GXII bundle axis. The LFEX increased the core temperature to 890 eV, giving a heating efficiency of 1.3% for 261 J LFEX. The efficiency was compared to that from the uniformly imploded core, which was 4.8%.View full abstractDownload PDF (1328K) -
Kazuki MATSUO2021 Volume 49 Issue 3 Pages 155-
Published: 2021
Released on J-STAGE: April 11, 2024
JOURNAL FREE ACCESSWe demonstrate the fast isochoric heating of an imploded dense plasma using a multi-picosecond kJclass petawatt laser at the GEKKO-LFEX laser facility at the Institute of Laser Engineering, Osaka University. We experimentally achieved 2.2 petapascal pressure of an ultra-high-energy-density state with 4.6 kJ of total laser energy that is one order of magnitude lower than the energy used in the conventional implosion scheme. These findings clarified that the scheme is an efficient way to create the petapascal pressure state, which is a unique testbed for fast ignition schemes. In this paper, we describe the heating mechanism of fast isochoric heating and X-ray measurements using doped targets that can characterize plasmas above the keV temperature and solid density.View full abstractDownload PDF (1156K) -
Yoshitaka MORI, Yasuhiko NISHIMURA, Osamu KOMEDA, Takashi SEKINE, ...2021 Volume 49 Issue 3 Pages 161-
Published: 2021
Released on J-STAGE: April 11, 2024
JOURNAL FREE ACCESSCounter illuminating ultra intense laser pulses into the high energy density plasma are expected to create a novel heating mechanism by electromagnetic fields driven by counter fast electron flows. A heating mechanism with electromagnetic fields can lead to efficient plasma heating toward inertial confinement fusion by assisting a conventional fast electron energy deposition based on a beam-plasma collision model. This paper reviewed the experiment results of plasma heating by counter illuminating laser pulses with a joule-class Ti:sapphire laser HAMA as well as the present activities related to the counter-illumination of ultra intense laser pulses.View full abstractDownload PDF (1941K) -
Yoshitaka MORI, Yasuhiko NISHIMURA, Osamu KOMEDA, Akifumi IWAMOTO, ...2021 Volume 49 Issue 3 Pages 167-
Published: 2021
Released on J-STAGE: April 11, 2024
JOURNAL FREE ACCESSRepetitive fusion fuel injection and laser engagement are key technologies for achieving laser inertial confinement fusion reactors. This paper reports the present status of fusion fuel injection system and neutron generation conducted at the Graduate School for the Creation of New Photonics Industries with collaborators. A 1-mm diameter bead-pellet injection system engaged by ultra-intense counter laser beams respectively demonstrated 1 Hz/28 minute and 10 Hz/2 minute operation with the laser-hit-ratios to the pellet of 70% and 40%, respectively. The maximum neutron yield was 4 × 105 n/shot. In addition, a testbed of a 0.5 mm diameter spherical shell pellet injection demonstrated that (i) repetitive implosion (maximum frequency: 0.5 Hz) of shell injection was possible for more than ten shells at a shell speed of 191 mm/s, and (ii) the distribution of the injected shells after a 18 cm free-fall was within a circular region, 6.4 mm in diameter circular region. The estimated laser-hit-ratio to the spherical shell pellets was 10%.View full abstractDownload PDF (1438K) -
Takeshi WATARI, Takashi SEKINE, Takashi KURITA,, Yuki MURAMATSU, Y ...2021 Volume 49 Issue 3 Pages 173-
Published: 2021
Released on J-STAGE: April 11, 2024
JOURNAL FREE ACCESSSince 2010 at Hamamatsu Photonics K.K., we’ve been constructing a 100-Joule class, diode-pumped solid-state laser (DPSSL) based facility called TERU for research and development on component technologies and related industrial applications. Critical technologies and design parameters for kilo-Joule class DPSSLs have been evaluated through the development of a DPSSL driver for TERU. Laser irradiation experiments have started to research the fundamental physics of ICF’s implosion process at the TERU facility. Its commissioning started with a DPSSL output of 50 J in nanoseconds at 0.5 HzView full abstractDownload PDF (1178K)
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