S. Egashira
A5001168865- Laser-induced spectroscopy and plasma
- Laser-Plasma Interactions and Diagnostics
- Diamond and Carbon-based Materials Research
- Magnetic confinement fusion research
- High-pressure geophysics and materials
- Plasma Diagnostics and Applications
- Atomic and Molecular Physics
- Ionosphere and magnetosphere dynamics
- Ion-surface interactions and analysis
- Laser-Matter Interactions and Applications
- Solar and Space Plasma Dynamics
- Molecular Junctions and Nanostructures
- Colorectal Cancer Screening and Detection
- Space Satellite Systems and Control
- Particle accelerators and beam dynamics
- Astro and Planetary Science
- Genetic factors in colorectal cancer
- Diverticular Disease and Complications
- Gamma-ray bursts and supernovae
- Astrophysics and Star Formation Studies
- Surface and Thin Film Phenomena
- Electronic and Structural Properties of Oxides
- Geomagnetism and Paleomagnetism Studies
Matsuyama Red Cross Hospital
2024
Osaka University
2019-2023
The motion of line defects (dislocations) has been studied for more than 60 years, but the maximum speed at which they can move is unresolved. Recent models and atomistic simulations predict existence a limiting velocity dislocation between transonic subsonic ranges self-energy diverges, though do not deny possibility dislocations. We used femtosecond x-ray radiography to track ultrafast in shock-compressed single-crystal diamond. By visualizing stacking faults extending faster slowest sound...
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 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...
Magnetic reconnection is a universal process in space, astrophysical, and laboratory plasmas. It alters magnetic field topology results energy release to the plasma. Here we report experimental of pure electron outflow reconnection, which not accompanied with ion flows. By controlling an applied laser produced plasma, have constructed experiment that magnetizes electrons but ions. This allows us isolate dynamics from Collective Thomson scattering measurements reveal Alfvénic without outflow....
A developing supercritical collisionless shock propagating in a homogeneously magnetized plasma of ambient gas origin having higher uniformity than the previous experiments is formed by using high-power laser experiment. The not contaminated produced early time after shot. While observed does have stationary downstream structure, it possesses some characteristics shock, which are supported one-dimensional full particle-in-cell simulation taking effect finite laser-target interaction into account.
Laser experiments are becoming established as tools for astronomical research that complement observations and theoretical modeling. Localized strong magnetic fields have been observed at a shock front of supernova explosions. Experimental confirmation identification the physical mechanism this observation great importance in understanding evolution interstellar medium. However, it has challenging to treat interaction between hydrodynamic instabilities an ambient field laboratory. Here, we...
Magnetic reconnection in laser-produced magnetized plasma is investigated by using optical diagnostics. The magnetic field generated via Biermann battery effect, and the inversely directed lines interact with each other. It shown self-emission measurement that two colliding plasmas stagnate on a mid-plane forming planar dense regions, they later time. Laser Thomson scattering spectra are distorted direction of self-generated field, indicating asymmetric ion velocity distribution...
Abstract The first laboratory evidence of a radiative shock (RS) decelerating during its free expansion phase in an optically thick medium is presented. A generated multilayer solid target under the irradiation high-power laser at GEKKO XII facility. rear surface connected to gas cell filled with Xe. Upon breakout, RS, characterized by low Boltzmann number Bo ≪ 1 and Mihalas R ≈ 10, generated. Experimental results reveal that losses through precursor cause lose energy decelerate. model...
We developed an experimental platform for studying magnetic reconnection in external field with simultaneous measurements of plasma imaging, flow velocity, and magnetic-field variation. Here, we investigate the stagnation acceleration counterstreaming plasmas generated by high-power laser beams. A perpendicular to initial directions is measured Thomson scattering. The is, interestingly, accelerated toward high-density region, which opposite direction pressure gradients. This possibly...
An experimental investigation of collisionless shock ion acceleration is presented using a multicomponent plasma and high-intensity picosecond duration laser pulse. Protons are the only accelerated ions when near-critical-density driven by with modest normalized vector potential. The results particle-in-cell simulations imply that may accelerate protons alone selectively, which can be an important tool for understanding physics inaccessible shocks in space astrophysical plasma.
In their comment (1), Hawreliak et al. claims that our observation of stacking fault formation and transonic dislocation propagation in diamond (2) is not valid as they interpret the observed features cracks. this response letter, we describe rationale for interpreting faults. We also address other points raised comments, including clarifications how results Makarov (3) are conflict with study.
Abstract The aim of this study was to clarify the endoscopic characteristics colorectal hamartomatous polyps, including solitary juvenile polyp (JP) and Peutz-Jeghers (PJP). We reviewed clinicopathological findings 151 polyps with a diagnosis JP or PJP. 119 JPs 32 PJPs were retrospectively compared. Endoscopic included significantly higher incidences erosion, whitish exudates, chicken-skin mucosa in compared PJPs. A lobular surface more common Magnified narrow-band imaging indicated that...
Abstract Atomically thin graphene is a transparent, highly electrically and thermally conductive, light-weight, the strongest material. To date, has found applications in many aspects including transport, medicine, electronics, energy, defense, desalination. We demonstrate another disruptive application of field laser-ion acceleration, which unique features play indispensable role. Laser driven ion sources have been widely investigated for pure science, plasma diagnostics, medical...
The motion of line defects (dislocations), the primary driver plasticity, has been studied for almost a century but one most fundamental questions remains unsolved: what defines maximum speed at which dislocations can propagate? Early interpretations based on elasticity theory suggest that dislocation should not exceed transverse wave speed, recent models and atomistic simulations predict is forbidden upper limit. We use femtosecond x-ray radiography to observe how in shock-compressed...