A5010001679- Laser-Plasma Interactions and Diagnostics
- Laser-induced spectroscopy and plasma
- Laser-Matter Interactions and Applications
- High-pressure geophysics and materials
- Laser Design and Applications
- Atomic and Molecular Physics
- Nuclear Physics and Applications
- Magnetic confinement fusion research
- Laser Material Processing Techniques
- Ion-surface interactions and analysis
- Ionosphere and magnetosphere dynamics
- Advanced X-ray Imaging Techniques
- Plasma Diagnostics and Applications
- Gyrotron and Vacuum Electronics Research
- Particle Accelerators and Free-Electron Lasers
- Spectroscopy and Laser Applications
- Electron and X-Ray Spectroscopy Techniques
- Terahertz technology and applications
- Solar and Space Plasma Dynamics
- Astro and Planetary Science
- Pulsed Power Technology Applications
- Particle accelerators and beam dynamics
- Energetic Materials and Combustion
- Dust and Plasma Wave Phenomena
- Solid State Laser Technologies
Osaka University
2004-2025
Institute for Laser Technology
1999-2025
National Institutes for Quantum Science and Technology
2020-2023
National Institute for Fusion Science
2023
Hiroshima University
2023
Utsunomiya University
2023
University of Nevada, Reno
2010-2021
Lawrence Livermore National Laboratory
2006-2021
The University of Texas at Austin
2021
Stanford University
2021
MeV-proton production from solid targets irradiated by 100-fs laser pulses at intensities above 1x10(20) W cm(-2) has been studied as a function of initial target thickness. For foils 100 microm thick the proton beam was characterized an energy spectrum temperature 1.4 MeV with cutoff 6.5 MeV. When thickness reduced to 3 3.2+/-0.3 24 These observations are consistent modeling showing enhanced density electrons rear surface for thinnest targets, which predicts increased acceleration and...
The generation of high energy protons from the interaction a short laser pulse with dense plasma, accompanied by preformed low density has been studied particle-in-cell simulations. proton acceleration toward direction in plasma is characterized time-dependent model and peak given. effect electron recirculation on rear side sheath discussed it found that increases inverse proportion to target thickness. These results shed light dependence intensity, length, Finally optimal parameters for...
The laser light propagation inside the conical target had been studied by three-dimensional particle-in-cell simulations. It is found that optically guided and focused at tip of cone. intensity increases up to several tens times in a micron focal spot. convergence hot electrons head cone observed as consequence surface electron flow self-generated quasistatic magnetic fields electrostatic sheath fields. As result, density locally ten greater than case using normal flat foil.
We present experimental results showing a laser-accelerated proton beam maximum energy cutoff of 67.5 MeV, with more than 5 × 106 protons per MeV at that energy, using flat-top hollow microcone targets. This result was obtained modest laser ∼80 J, on the high-contrast Trident Los Alamos National Laboratory. From 2D particle-in-cell simulations, we attribute source these enhanced energies to direct laser-light-pressure acceleration electrons along inner cone wall surface, where light wave...
We report new experimental results obtained on three different laser facilities that show directed laser-driven relativistic electron-positron jets with up to 30 times larger yields than previously and a quadratic (∼E_{L}^{2}) dependence of the positron yield energy. This favorable scaling stems from combination higher energy electrons due increased intensity recirculation MeV in mm-thick target. Based this scaling, first principles simulations predict possibility using such jets, produced...
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 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...
Laser produced hot electron transport in an overdense plasma is studied by three-dimensional particle-in-cell simulations. Hot currents into the generate neutralizing return cold electrons, leading to a configuration which unstable electromagnetic Weibel and tearing instabilities. The resulting current filaments self-organize through coalescence process finally settling single global channel. experiences strong anomalous resistivity due diffusive flow of electrons magnetic perturbations....
We propose a mechanism that leads to efficient acceleration of electrons in plasma by two counterpropagating laser pulses. It is triggered stochastic motion when the fields exceed some threshold amplitudes, as found single-electron dynamics. further confirmed particle-in-cell simulations. In vacuum or tenuous plasma, electron case with colliding pulses can be much more than one pulse only. at moderate densities, such few percent critical density, amplitude Raman-backscattered wave high...
The evolution of laser-generated MeV, MA electron beams propagating through conductors and insulators has been studied by comparing measurement modeling the distribution MeV protons that are sheath accelerated propagated electrons. We find flow metals is uniform can be laser imprinted, whereas propagation induces spatial disruption fast Agreement found with material dependent modeling.
Acceleration of electrons in a low-density plasma front solid target by propagating short ultraintense laser pulse is studied. When the reflected at surface accelerated electrons, with energy scaling as intensity, continue to move forward inertially and thus escape from pulse. Electrons backwards light can attain even higher energies due their longer acceleration length high initial momentum relativistic return current.
The comparative efficiency and beam characteristics of high-energy ions generated by high-intensity short-pulse lasers (approximately 1-6 x 10(19) W/cm2) from both the front rear surfaces thin metal foils have been measured under identical conditions. Using direct measurements nuclear activation techniques, we find that rear-surface acceleration produces higher energy particles with smaller divergence a than front-surface acceleration. Our observations are well reproduced realistic...
Abstract High-intensity lasers interacting with solid foils produce copious numbers of relativistic electrons, which in turn create strong sheath electric fields around the target. The proton beams accelerated such have remarkable properties, enabling ultrafast radiography plasma phenomena or isochoric heating dense materials. In view longer-term multidisciplinary purposes (e.g., spallation neutron sources cancer therapy), current challenge is to achieve energies well excess 100 MeV,...
In this paper, high temperature (~10 keV) solid density silver plasma is generated experimentally by exposing a thin foil to the extreme fields of tightly focused high-power laser. The authors demonstrate that such an efficient source highly charged, energy heavy ions, with generation ultra-strong electric
Experiments identify the mechanism that accelerates ions in a laser-driven neutron source (LDNS) as well scaling law for yield, key insights move LDNS closer to practical generation.
The magnetic instability driven by the relativistic electron stream generated ultra-intense laser is investigated with help of a two-dimensional particle-in-cell simulation, which includes binary collision. linear growth rate also studied using two-stream fluid model, consists fast current and return current. evaluated numerically from linearized equations fluids Maxwell equations. kinetic effects electrons on are found to reduce rate. maximum at wavelength near plasma skin length because...
Under optimal interaction conditions ions can be accelerated up to relativistic energies by a petawatt laser pulse in both underdense and overdense plasmas. Two-dimensional particle cell simulations show that the drills channel through an plasma slab due self-focusing. Both electrons are head region of channel. However, ion acceleration is more effective at end slab. Here from expand vacuum followed dragged Coulomb force arising charge separation. A similar mechanism occurs when superintense...
We study the angular distributions of fast electrons, ions, and bremsstrahlung x/ gamma-rays generated during interaction an ultrashort intense laser pulse with solid targets. A relation is found on directions for electrons ions as a function particle's kinetic energy, experienced Coulomb potential changes, incident angle pulse. It valid independent acceleration mechanisms polarization pulse, confirmed by particle-in-cell simulations. The distribution x/gamma-rays presented to show...
A beam of high energy ions and protons is observed from targets irradiated with intensities up to 5×1019 W/cm2. Maximum proton shown strongly correlate laser-irradiance on target. Energy spectra a magnetic spectrometer show plateau region near the maximum cutoff modulations in spectrum at approximately 65% energy. Presented two-dimensional particle-in-cell simulations suggest that are caused by presence multiple heavy-ion species expanding plasma.
Laser plasma interactions in a relativistic parameter regime have been intensively investigated for studying the possibility of fast ignition inertial confinement fusion (ICF). Using ultra-intense laser systems and particle-in-cell (PIC) simulation codes, light self-focusing, super hot electrons, ions, neutron production, are studied. The experiments performed with 50 J energy, 0.5–1 ps pulse at 1053 nm wavelength intensity 1019 W/cm2. Most shots studied under preformed conditions 100 μm...
Energy relaxation of the hot electron population generated by relativistic laser pulses in overdense plasma is analyzed for densities ranging from below to 1000 times solid density. It predicted that longitudinal beam-plasma instabilities, which dominate energy transfer between electrons and at lower densities, are suppressed collisions beyond The respective roles collisional modes, i.e., direct collisions, diffusion, resistive return current heating, identified with respect transition...
CR-39 film stacks are used to measure the energy and angular distribution of protons emitted from rear surface ultra-intense laser illuminated plastic foils. The experiment suggests that energetic dragged away surface, where hot electron formed a virtual cathode. two-dimensional particle in cell simulation supports this hypothesis. For 5 (100) μm thick target, 1.8×109 have slope temperature 3 (2) MeV. ring structure proton emission leads us hypothesis toroidal magnetic field associated with...