A5029279143- Laser-Plasma Interactions and Diagnostics
- Computational Fluid Dynamics and Aerodynamics
- Plasma and Flow Control in Aerodynamics
- Gas Dynamics and Kinetic Theory
- Plasma Diagnostics and Applications
- Laser-induced spectroscopy and plasma
- Plasma Applications and Diagnostics
- Fluid Dynamics and Turbulent Flows
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Aerosol Filtration and Electrostatic Precipitation
- Astro and Planetary Science
- Space Satellite Systems and Control
- Particle accelerators and beam dynamics
- Laser-Matter Interactions and Applications
- Pulsars and Gravitational Waves Research
- High-pressure geophysics and materials
- Combustion and Detonation Processes
- Magnetic confinement fusion research
- Neutrino Physics Research
- Laser Material Processing Techniques
- Particle Dynamics in Fluid Flows
- Electrohydrodynamics and Fluid Dynamics
- Dust and Plasma Wave Phenomena
- Gyrotron and Vacuum Electronics Research
Tohoku University
2016-2025
Tohoku Institute of Technology
2023-2024
Tokyo University of Science
2022
Tohoku University Hospital
2018-2020
National Institutes for Quantum Science and Technology
2018
Osaka University
1999-2016
Lawrence Livermore National Laboratory
2007-2016
University of California, San Diego
2016
University of Rochester
2016
Energetics (United States)
2016
We have numerically studied the instability of spherically symmetric standing accretion shock wave against non-spherical perturbations. in mind application to collapse-driven supernovae post bounce phase, where prompt generated by core is commonly stalled. take an experimental stand point this paper. Using symmetric, completely steady, shocked flows as unperturbed states, we clearly observed both linear growth and subsequent nonlinear saturation instability. In so doing, employed a realistic...
We have studied nonaxisymmetric standing accretion shock instabilities, or SASI, using three-dimensional (3D) hydrodynamical simulations. This is an extension of our previous study axisymmetric SASI. prepared a spherically symmetric and steady flow through wave onto proto-neutron star, taking into account realistic equation state neutrino heating cooling. unperturbed model meant to represent approximately the typical postbounce phase core-collapse supernovae. then added small perturbation...
Electrohydrodynamic (EHD) force is used for active control of fluid motion and the generation propulsive thrust by inducing ionic wind with no moving parts. We propose a method successively generating accelerating induced surface dielectric-barrier-discharge (DBD), referred to as DBD plasma actuator multiple electrodes. A conventional fails generate unidirectional wind, due counter ionic-wind electrodes actuator. However, can be obtained designing an applied voltage waveform electrode...
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...
This paper proposes a novel proper orthogonal decomposition method for constructing reduced-order model. model effectively computes solutions various initial conditions in time-dependent partial differential equations. The mode obtained from the proposed captures both fluctuating component and mean-field of solution. In this mode, eigenvalues representing mean-field, are significantly larger than those component. Consequently, determining number modes required solution cannot rely solely on...
Abstract Dielectric barrier discharge (DBD) plasma actuators are devices that actively control the airflow using nonequilibrium atmospheric-pressure plasmas, showing promise for practical applications in field of aerospace engineering. Numerous studies have revealed dynamics surface and process generating electrohydrodynamic (EHD) forces detail. The performance DBD has improved continuously over past 20 years. However, there is a need further improvement EHD force generation to enable...
The correction of the blockage effect is crucial in wind tunnel experiments, particularly for drag forces on bluff bodies with a large flow separation at leading edge. Maskell’s wake widely used method bodies. However, limited to separated that does not reattach. In this study, and methods were investigated due presence or absence leading-edge-separated shear layer reattachment field non-support interference produced using magnetic suspension balance system (MSBS). coefficient without wall...
We present the possibility of energy transfer and budget analysis for transient flow using eigenmodes operator from Navier-Stokes equation. derive equation, which provides eigenmodes, through Galerkin projection equation bi-orthogonality adjoint mode. Energy between modes were conducted two-dimensional around a cylinder with growing or decaying steady flow. Using linearized global stability analysis, we identify spatial distribution that determine mode growth rates. Moreover, are realized by...
A scheme to suppress the Rayleigh-Taylor instability has been investigated for a direct-drive inertial fusion target. In high-Z doped-plastic target, two ablation surfaces are formed separately-one driven by thermal radiation and other electron conduction. The growth of is significantly suppressed on radiation-driven surface inside target due large velocity long density scale length. significant reduction rate was observed in simulations experiments using brominated plastic new pellet...
We study the effects of rotation on standing accretion shock instability (SASI) by performing three-dimensional hydrodynamics simulations. Taking into account a realistic equation state and neutrino heating/cooling, we prepare spherically symmetric steady flow through wave onto proto-neutron star (PNS). When SASI enters nonlinear phase, impose uniform advecting from outer boundary iron core, whose specific angular momentum is assumed to agree with recent stellar evolution models. Using...
We study the properties of gravitational waves (GWs) based on three-dimensional (3D) simulations, which demonstrate neutrino-driven explosions aided by standing accretion shock instability (SASI). Pushed evidence supporting slow rotation prior to core collapse, we focus asphericities in neutrino emissions and matter motions outside protoneutron star. By performing a ray-tracing calculation 3D, estimate accurately waveforms from anisotropic emissions. In contrast previous work assuming...
Abstract Graphene is known as an atomically thin, transparent, highly electrically and thermally conductive, light-weight, the strongest 2D material. We investigate disruptive application of graphene a target laser-driven ion acceleration. develop large-area suspended (LSG) by transferring layer we control thickness with precision down to single atomic layer. Direct irradiations LSG targets generate MeV protons carbons from sub-relativistic relativistic laser intensities low contrast high...
We have investigated space and astrophysical phenomena in nonrelativistic laboratory plasmas with long high-power lasers, such as collisionless shocks magnetic reconnections, been exploring relativistic regimes intense short pulse energetic ion acceleration using large-area suspended graphene. Increasing the intensity repetition rate of we to handle large amounts data from experiments well control parameters laser beamlines. Artificial intelligence (AI) machine learning neural networks may...
A trajectory-based heating analysis of the Galileo probe entry flowfield is attempted to reproduce heat-shield recession data obtained during flight. In calculation, mass conservation equations for freestream gas (hydrogen-helium mixture) and ablation product are solved with an assumption thermochemical equilibrium. The process assumed be quasi steady coupled calculation. radiative energy transfer calculation tightly where absorption coefficients mixture given by multiband radiation model...
We present the results of numerical experiments, in which we study how asphericities induced by growth standing accretion shock instability (SASI) produce gravitational waveforms postbounce phase core-collapse supernovae. To obtain neutrino-driven explosions, parameterize neutrino fluxes emitted from central protoneutron star and approximate transfer a light-bulb scheme. find that due to anisotropic emissions show monotonic increase with time, whose amplitudes are up two order-of-magnitudes...
We present the results of numerical analysis wave drag reduction by a single-pulse energy deposition in supersonic flow field around sphere. The for sphere was reduced as result interaction between low-density core following blast produced and bow shock developed front investigated mechanism terms unsteady induced interaction. effects deposited location on were examined parametric study. From obtained results, we refined parameters, utilizing baroclinic source term that vorticity vortex...
We report the experimental results of a turbulent electric field driven by Kelvin-Helmholtz instability associated with laser produced collisionless shock waves. By irradiating an aluminum double plane target high-power laser, counterstreaming plasma flows are generated. As consequence two interactions, waves and contact surface excited. The transverse modulation observed proton radiography. Performing hydrodynamic simulations, we reproduce time evolutions reverse shocks instability.
By performing three-dimensional (3D) simulations that demonstrate the neutrino-driven core-collapse supernovae aided by standing accretion shock instability (SASI), we study how spiral modes of SASI can impact properties gravitational-wave (GW) emission. To see effects rotation in nonlinear postbounce phase, give a uniform on flow advecting from outer boundary iron core, specific angular momentum which is assumed to agree with recent stellar evolution models. We compute fifteen 3D models...
Time-resolved compression of a laser-driven solid deuterated plastic sphere with cone was measured flash Kα x-ray radiography. A spherically converging shockwave launched by nanosecond GEKKO XII beams used for while 4.51 keV Ti backlighter produced high-intensity, picosecond laser LFEX (Laser Fast ignition EXperiment) near peak Areal densities the compressed core were inferred from two-dimensional backlit images recorded narrow-band spherical crystal imager. The maximum areal density in...
We present an experimental method to generate quasiperpendicular supercritical magnetized collisionless shocks. In our experiment, ambient nitrogen (N) plasma is at rest and well magnetized, it has uniform mass density. The pushed by laser-driven ablation aluminum (Al) plasma. Streaked optical pyrometry spatially resolved laser collective Thomson scattering clarify structures of density temperatures, which are compared with one-dimensional particle-in-cell simulations. It indicated that just...
We present the results of numerical experiments, in which we have investigated influence inelastic neutrino-helium interactions on standing accretion shock instability supposed to occur post-bounce supernova core. The axisymmetric hydrodynamical simulations flows through wave onto protoneutron star show that are relatively minor and linear growth is hardly affected. extra heating given by reactions becomes important for revival after enters non-linear regime, but only when neutrino...
We propose a ray-tracing method to estimate gravitational waves (GWs) generated by anisotropic neutrino emission in supernova cores. To calculate the waveforms, we derive analytic formulae useful form, which are applicable also for three-dimensional computations. Pushed evidence of slow rotation prior core-collapse, focus on asphericities and matter motions outside protoneutron star. Based two-dimensional (2D) models, mimic SASI-aided heating explosions, compute anisotropies via...
To improve the in-air flight performance of a laser propulsion vehicle, it is helpful to develop computational model that can reproduce full dynamics, including impulsive vehicle motion driven by interaction with blast wave. The authors have developed three-dimensional hydrodynamics code coupled six-degree-of-freedom equations for analyzing dynamics through numerically simulating flowfield interacting unsteady vehicle. Using ray tracing, asymmetrically deposited energy corresponding offsets...
Breakdown physics induced by a subcritical microwave was numerically reproduced using two-dimensional effective diffusion model for plasma transport and combining it with Maxwell's equations neutral gas dynamics equation. A discrete structure obtained when E0,rms/Ec≧0.69, where E0,rms is the root-mean-square of incident electric field Ec breakdown threshold, because an overcritical that exceeded threshold formed in region away from bulk wave reflection reflectivity increased joule heating....