A5035916063- Laser-Plasma Interactions and Diagnostics
- Laser-induced spectroscopy and plasma
- Nuclear Physics and Applications
- High-pressure geophysics and materials
- Laser-Matter Interactions and Applications
- Magnetic confinement fusion research
- Atomic and Molecular Physics
- Laser Design and Applications
- Nuclear physics research studies
- Rare-earth and actinide compounds
- Ion-surface interactions and analysis
- Particle Accelerators and Free-Electron Lasers
- Radiation Detection and Scintillator Technologies
- Plasma Diagnostics and Applications
- Fusion materials and technologies
- Laser Material Processing Techniques
- Advanced X-ray Imaging Techniques
- Pulsed Power Technology Applications
- Mass Spectrometry Techniques and Applications
- Quantum Chromodynamics and Particle Interactions
- Particle Detector Development and Performance
- Geomagnetism and Paleomagnetism Studies
- Calibration and Measurement Techniques
- Photocathodes and Microchannel Plates
- Advanced Semiconductor Detectors and Materials
National Institutes for Quantum Science and Technology
2020-2023
Kansai Photon Science Institute
2023
Tokyo Institute of Technology
2019-2021
RIKEN Nishina Center
2020-2021
Osaka University
2012-2020
Kyoto University
1993-2020
Kyoto University Institute for Chemical Research
2018-2020
Institute for Laser Technology
2013-2018
Kyoto Pharmaceutical University
1993
Quasi-static magnetic-fields up to 800 T are generated in the interaction of intense laser pulses (500 J, 1 ns, ) with capacitor-coil targets different materials. The reproducible magnetic-field peak and rise-time, consistent pulse duration, were accurately inferred from measurements GHz-bandwidth inductor pickup coils (B-dot probes). Results Faraday rotation polarized optical light deflectometry energetic proton beams B-dot probe at early stages target charging, then disturbed by radiation...
A kilo-tesla level, quasi-static magnetic field (B-field), which is generated with an intense laser-driven capacitor-coil target, was measured by proton deflectometry a proper plasma shielding. Proton direct and reliable method to diagnose strong, mm3-scale laser-produced B-field; however, this not successful in the previous experiment. target-normal-sheath-accelerated beam deflected Lorentz force resulting deflection pattern recorded on radiochromic film stack. 610 ± 30 T of B-field...
The quest for the inertial confinement fusion (ICF) ignition is a grand challenge, as exemplified by extraordinary large laser facilities. Fast isochoric heating of pre-compressed plasma core with high-intensity short-pulse an attractive and alternative approach to create ultra-high-energy-density states like those found in ICF sparks. This avoids quench caused hot spark mixing surrounding cold fuel, which crucial problem currently pursued scheme. High-intensity lasers efficiently produce...
Abstract Intense lasers interacting with dense targets accelerate relativistic electron beams, which transport part of the laser energy into target depth. However, overall laser-to-target coupling efficiency is impaired by large divergence beam, intrinsic to laser–plasma interaction. Here we demonstrate that an efficient guiding MeV electrons about 30 MA current in solid matter obtained imposing a laser-driven longitudinal magnetostatic field 600 T. In magnetized conditions transported...
Abstract Using one of the world most powerful laser facility, we demonstrate for first time that high-contrast multi-picosecond pulses are advantageous proton acceleration. By extending pulse duration from 1.5 to 6 ps with fixed intensity 10 18 W cm −2 , maximum energy is improved more than twice (from 13 33 MeV). At same time, laser-energy conversion efficiency into MeV protons enhanced an order magnitude, achieving 5% above duration. The energies observed discussed using a plasma expansion...
Powerful laser-plasma processes are explored to generate discharge currents of a few $100\,$kA in coil targets, yielding magnetostatic fields (B-fields) excess $0.5\,$kT. The quasi-static provided from hot electron ejection the laser-irradiated surface. According our model, describing qualitatively evolution current, major control parameter is laser irradiance $I_{\mathrm{las}}\lambda_{\mathrm{las}}^2$. space-time B-fields experimentally characterized by high-frequency bandwidth B-dot probes...
A petawatt laser for fast ignition experiments (LFEX) system [N. Miyanaga et al., J. Phys. IV France 133, 81 (2006)], which is currently capable of delivering 2 kJ in a 1.5 ps pulse using 4 beams, has been constructed beside the GEKKO-XII facility demonstrating efficient heating dense plasma up to temperature under auspices Fast Ignition Realization EXperiment (FIREX) project [H. Azechi Nucl. Fusion 49, 104024 (2009)]. In FIREX experiment, cone attached spherical target containing fuel...
A universal procedure was developed to calibrate image plate scanners using radioisotope sources. Techniques and sources, as well cross-calibrate scanner models, are described convert dosage into physical units. This allows for the direct comparison of quantitative data between any facility scanner. An empirical relation also derived establish sensitivity response settings arbitrary gain settings. In practice, these methods may be extended scanning system.
High-power lasers in the relativistic intensity regime with multi-picosecond pulse durations are available many laboratories around world. Laser pulses at these intensities reach giga-bar level radiation pressures, which can push plasma critical surface where laser light is reflected. This process referred to as hole boring (HB), for heating, hence essential laser-based applications. Here we derive limit density HB, maximum reach, a function of intensity. The time scale when reaches also...
Fast isochoric laser heating is a scheme to heat matter with relativistic intensity ($>{10}^{18}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$) pulse for producing an ultrahigh-energy-density (UHED) state. We have demonstrated efficient fast of compressed dense plasma core multipicosecond kilojoule-class petawatt and assistance externally applied kilotesla magnetic fields guiding electrons the plasma. A UHED state 2.2 PPa achieved experimentally 4.6 kJ total energy that one order magnitude...
Laser pulse contrast exceeding 1011 was demonstrated on a kilojoule-class petawatt laser for fast ignition experiments (LFEX) system [J. Phys. IV France133, 81 (2006)10.1051/jp4:2006133016] by implementing 2 in. plasma mirror. beams of up to 1.2 kJ striking the mirror with duration 1.5 ps were reflected and focused onto target without significant distortions in focal spot. Transmitted light from reveals that it has high reflectivity before main peak. The estimated at 1 ns No preformed...
Recent progress in the generation laboratory of a strong ($>100$-T) magnetic field enables us to investigate experimentally unexplored magnetohydrodynamics phenomena high-energy-density plasma, which an external 200--300 T notably affects due anisotropic thermal conduction, even when pressure is much lower than plasma pressure. The reduces electron conduction across lines because Larmor radius electrons shorter mean free path electrons. velocity thin polystyrene foil driven by intense...
We report new results from the intense laser target interaction experiment that produces relativistic electron–positron pairs. Laser to electron energy transfer, inferred using x-ray and neutron measurements, was found be consistent with measured positrons. To increase number of positrons, one needs deliver a greater electrons laser–plasma high Z gold target. A large preplasma have negative impact for this purpose, while could produce hotter in such preplasma. The peak shift positron...
A series of experiments were carried out to evaluate the energy-coupling efficiency from heating laser a fuel core in fast-ignition scheme laser-driven inertial confinement fusion. Although is determined by wide variety complex physics, intense plasma interactions properties high-energy density plasmas and transport relativistic electron beams (REB), here we simplify physics breaking down into three measurable parameters: (i) energy conversion ratio REB, (ii) probability collision between...
The generation of high-peak-intensity neutrons through a photonuclear reaction was demonstrated using the Laser for Fast Ignition Experiments (LFEX) at Osaka University. Up to 109 neutrons/shot were generated from 1 mm sized gold target. Using Monte Carlo simulations, neutron spectrum keV MeV found be independent γ-ray spectrum. typical peak intensity 1021 /cm2/s target surface estimated, and it should useful tool nuclear synthesis experiments.
Abstract Increasing the laser energy absorption into energetic particle beams represents a longstanding quest in intense laser-plasma physics. During interaction with matter, part of is converted relativistic electron beams, which are origin secondary sources ions, γ-rays and neutrons. Here we experimentally demonstrate that using multiple coherent beamlets spatially temporally overlapped, thus producing an interference pattern focus, significantly improves conversion efficiency hot...
Abstract The dependence of the mean kinetic energy laser-accelerated relativistic electrons (REs) on laser intensity, so-called ponderomotive scaling, explains well experimental results to date; however, this scaling is no longer applicable multi-picosecond (multi-ps) experiments. Here, production REs was experimentally investigated via multi-ps laser–plasma-interaction (LPI). lower slope temperature shows little pulse duration and close value, while higher appears be affected by duration....
This article reports the development of a compact Thomson parabola spectrometer for laser-accelerated ions that can measure angular distribution with high energy resolution and has variable measurable range. The angular-resolved spectra different ion species be measured in single shot, sampling angle selected from outside vacuum region. electric magnetic fields are applied to dispersion by using permanent circuit annulus sector-shaped electrodes wedge configuration. consists magnets, fixed...
In the fast-ignition scheme, very hard x-rays (hereinafter referred to as γ-rays) are generated by Bremsstrahlung radiation from fast electrons. Significant backgrounds were observed around deuterium-deuterium fusion neutron signals in experiment 2010. this paper studied detail, based on Monte Carlo simulations, and they confirmed be γ-rays target, scattered experimental bay walls (γ'-rays), neutrons (γ, n) reactions either target vacuum chamber or diagnostic instruments (γ-n neutrons).
This paper reports an experimental investigation of a scheme to produce intense, pulsed, point-like, and quasi-monoenergy neutron source. In this scheme, the inner wall deuterated plastic spherical cavity is mono-directionally irradiated by 2.4 kJ laser beam through open-tip gold cone inserted into cavity. The whole illuminated light owing multiple reflections, laser-ablated plasma stagnates near center cavity, at which several keV hot spot generated. Thermonuclear D-D fusion reactions occur...
The gyromagnetic factor of the low-lying E=251.96(9) keV isomeric state nucleus ^{99}Zr was measured using time-dependent perturbed angular distribution technique. This level is assigned a spin and parity J^{π}=7/2^{+}, with half-life T_{1/2}=336(5) ns. isomer produced aligned via abrasion-fission ^{238}U primary beam at RIKEN RIBF. A magnetic moment |μ|=2.31(14)μ_{N} deduced showing that this not single particle in nature. comparison experimental values interacting boson-fermion model...
Irradiating a metal wire with an intense femtosecond laser pulse induces terahertz (THz) surface wave that travels along the wire. Here, characteristics of THz generated by laser–wire interaction are investigated in detail using electro-optical method to determine dependence properties on energy and diameter. The is distributed Hankel function radial direction. On surface, electric field estimated be MV/cm. peak conversion efficiency from found proportional raised power 0.67 0.3, respectively.
Quasi-static magnetic-fields up to $800\,$T are generated in the interaction of intense laser pulses ($500\,$J, $1\,$ns, $10^{17}\,$W/cm$^2$) with capacitor-coil targets different materials. The reproducible magnetic-field peak and rise-time, consistent pulse duration, were accurately inferred from measurements GHz-bandwidth inductor pickup coils (B-dot probes). Results Faraday rotation polarized optical light deflectometry energetic proton beams B-dot probe at early stages target charging,...
The characteristics of oxygen-enriched liquid scintillators with very low afterglow are investigated and optimized for application to a single-hit neutron spectrometer fast ignition experiments. It is found that 1,2,4-trimethylbenzene has better as scintillator solvent than the conventional solvent, p-xylene. In addition, benzophenon-doped BBQ shown demonstrate rapid time response, therefore potential further use in diagnostics resolution.