Explanipedia

Predicting laser-induced surface modifications on metals in laser surface processing using a hybrid deep learning approach Open

Konika Rani, Norimasa Ozaki, Kazumune Hashimoto, Ryosuke Kodama, Miyake Yoishihiro , et al. · 2025

Laser-induced surface modification (LISM) is essential for precise surface functionalization in laser surface processing (LSP). This study examines the performance of a hybrid deep learning model, which combines a convolutional neural netw…

Boosting fast ignition heating through interaction between ultrahigh-contrast heating lasers and a cone-shaped target Open

Ryunosuke Takizawa, A. Morace, Y. Abe, Yasunobu Arikawa, Baojun Zhu , et al. · 2025

In pursuing a carbon-neutral society, inertial fusion energy is a pivotal technology, offering a sustainable and virtually limitless energy source. Enhancing plasma heating efficiency is crucial for inertial fusion energy, following the ig…

Excavation Effective Energy Improvement of the Impact Crater Scaling Laws Open

Junichiro Nakazawa, Hideo Nagatomo, Hajime Yano · 2025

Formation of high areal density core using an efficient and robust implosion method for fast ignition Open

Hideo Nagatomo, T. Johzaki, Ryunosuke Takizawa, Shinsuke Fujioka · 2024

A new fuel compression method for a fast ignition scheme is discussed. To form a high areal density fuel plasma for the ignition condition, homogenous isentropic compression (HIC) with solid spherical target is effective. We improve a mult…

Effect of irradiation uniformity on quasi-isentropic shock compression of solid spheres Open

Ryunosuke Takizawa, Sakagami Hitoshi, Hideo Nagatomo, Yasunobu Arikawa, Hiroki Morita , et al. · 2024

In inertial confinement fusion using central ignition, the ignition hot spot is generated through self-heating during fuel compression. In contrast, fast ignition creates the hot spot through external heating. This difference allows the fa…

Generations of spiral laser beam, spiral electron beam and longitudinal magnetic fields in hole-boring Open

K. Mima, Martin Matys, Y. Sentoku, Hideo Nagatomo, Natsumi Iwata , et al. · 2024

The hole-boring by intense laser is one of the key issues for fast ignition laser fusion, laser radiation pressure ion acceleration, generation of high energy radiations, and so on. In the hole-boring, laser pulse propagation and generatio…

Indispensability of Ultra-High-Contrast Heating Lasers for Fast Ignition Open

Ryunosuke Takizawa, A. Morace, Y. Abe, Yasunobu Arikawa, Baojun Zhu , et al. · 2023

The enhancement of plasma heating efficiency is important for realizing inertial fusion energy, which follows the ignition achieved with the laser-indirect-drive central-ignition approach. An increase in the relativistic electron beam (REB…

Effects of hydrogen concentration in ablator material on stimulated Raman scattering, two-plasmon decay, and hot electrons for direct-drive inertial confinement fusion Open

K. Kawasaki, G. Cristoforetti, T. Idesaka, Yoichiro Hironaka, Daisuke Tanaka , et al. · 2023

Laser plasma instabilities, such as stimulated Raman scattering (SRS) and two-plasmon decay (TPD), are basic phenomena in intense laser science and applications. In direct-drive inertial confinement fusion (ICF) where a fuel capsule is imp…

Prediction of the superimposed laser shot number for copper using a deep convolutional neural network Open

K. Sudha Rani, Norimasa Ozaki, Y. Hironaka, Kazuhito Hashimoto, R. Kodama , et al. · 2023

Image-based deep learning (IBDL) is an advanced technique for predicting the surface irradiation conditions of laser surface processing technology. In pulsed-laser surface processing techniques, the number of superimposed laser shots is on…

Demonstration of efficient relativistic electron acceleration by surface plasmonics with sequential target processing using high repetition lasers Open

Yasunobu Arikawa, A. Morace, Y. Abe, Natsumi Iwata, Y. Sentoku , et al. · 2023

For high repetition ultrahigh-intensity laser system, automatic alignment of structured target is key to achieving consistent particle acceleration and plasma heating. In this work, we demonstrate efficient electron acceleration with two s…

Digital Transformation of Operation and Usage of Power Laser GEKKO-XII and Laser for Fast Ignition Experiment (LFEX) Open

Hiroyuki Oku, Keisuke Takahashi, Hideo Nagatomo, Mizuho Nagata, Yoshinori Kubota , et al. · 2022

Preliminary Cryogenic Layering by the Infrared Heating Method Modified with Cone Temperature Control for the Polystyrene Shell FIREX Target Open

Keisuke Iwano, A. Iwamoto, Kohei Yamanoi, Yasunobu Arikawa, Hideo Nagatomo , et al. · 2021

The infrared (IR) heating method for a central ignition target with spherical symmetry is modified for the axisymmetric Fast Ignition Realization EXperiment (FIREX) target. The challenge is that the FIREX target pretends to be a thermally …

Enhancement of Ablative Rayleigh-Taylor Instability Growth by Thermal Conduction Suppression in a Magnetic Field Open

Kazuki Matsuo, Takayoshi Sano, Hideo Nagatomo, Toshihiro Somekawa, King Fai Farley Law , et al. · 2021

Ablative Rayleigh-Taylor instability growth was investigated to elucidate the fundamental physics of thermal conduction suppression in a magnetic field. Experiments found that unstable modulation growth is faster in an external magnetic fi…

Progress of Various Ignition Schemes Open

T. Johzaki, Hideo Nagatomo · 2021

1.はじめに

Surface structure on diamond foils generated by spatially nonuniform laser irradiation Open

Hiroki Kato, Hideo Nagatomo, M. Nakai, Tatsuhiro Sakaiya, Hidenori Terasaki , et al. · 2020

Here we report on the effects of material strength factors on the generation of surface structure due to nonuniform laser irradiation. The influence of material strength on the generation of perturbation on a diamond surface subjected to n…

Petapascal Pressure Driven by Fast Isochoric Heating with a Multipicosecond Intense Laser Pulse Open

Kazuki Matsuo, Naoki Higashi, Natsumi Iwata, Shohei Sakata, Seungho Lee , et al. · 2020

Fast isochoric laser heating is a scheme to heat matter with a relativistic intensity (>10^{18} W/cm^{2}) laser pulse for producing an ultrahigh-energy-density (UHED) state. We have demonstrated an efficient fast isochoric heating of a com…

Direct observation of imploded core heating via fast electrons with super-penetration scheme Open

Tao Gong, H. Habara, K. Sumioka, Makoto Yoshimoto, Y. Hayashi , et al. · 2019

Electromagnetic field growth triggering super-ponderomotive electron acceleration during multi-picosecond laser-plasma interaction Open

Sadaoki Kojima, M. Hata, Natsumi Iwata, Yasunobu Arikawa, A. Morace , et al. · 2019

The dependence of the mean kinetic energy of laser-accelerated relativistic electrons (REs) on the laser intensity, so-called ponderomotive scaling, explains well the experimental results to date; however, this scaling is no longer applica…

Efficient laser acceleration of deuteron ions through optimization of pre-plasma formation for neutron source development Open

Atsushi Sunahara, Takashi Asahina, Hideo Nagatomo, Ryohei Hanayama, K. Mima , et al. · 2018

With the objective to develop a compact neutron source with laser accelerated ions, optimization of pre-formed plasmas for efficient target normal sheath acceleration (TNSA) of deuteron ions is investigated using two-dimensional radiation …

Magnetized fast isochoric laser heating for efficient creation of ultra-high-energy-density states Open

Shohei Sakata, Seungho Lee, Hiroki Morita, T. Johzaki, Hiroshi Sawada , et al. · 2018

Super-ponderomotive electron acceleration in blowout plasma heated by multi-picosecond relativistic intensity laser pulse Open

Sadaoki Kojima, M. Hata, Natsumi Iwata, Yasunobu Arikawa, A. Morace , et al. · 2018

The dependence of the mean kinetic energy of laser-accelerated electrons on the laser intensity, so-called ponderomotive scaling, was derived theoretically with consideration of the motion of a single electron in oscillating laser fields. …

Effect of equation of state on laser imprinting by comparing diamond and polystyrene foils Open

Hiroki Kato, K. Shigemori, Hideo Nagatomo, M. Nakai, T. Sakaiya , et al. · 2018

We present herein a comprehensive study of how the equation of state affects laser imprinting by nonuniform laser irradiation of an inertial fusion target. It has been suggested that a stiffer and denser material would reduce laser imprint…

Characteristics of Laser-Driven Neutron Sources Open

Yoshitaka Mori, Y. Abe, Hiroki Tanaka, Ryohei Hanayama, Yoshiaki Kiyanagi , et al. · 2018

Laser-driven neutron sources offer a unique characteristic as a brightness neutron source because they provide a short pulse duration (less than ns) in time and a small spot size (a few mm2) in space at the source point. The peak flux per …

Fast ion acceleration in a foil plasma heated by a multi-picosecond high intensity laser Open

Natsumi Iwata, K. Mima, Y. Sentoku, Akifumi Yogo, Hideo Nagatomo , et al. · 2017

We study the one-dimensional expansion of a thin foil plasma irradiated by a high intensity laser with multi-picosecond (ps) pulse durations by using particle-in-cell simulation. Electrons are found to recirculate around the expanding plas…

Boosting laser-ion acceleration with multi-picosecond pulses Open

Akifumi Yogo, K. Mima, Natsumi Iwata, S. Tosaki, A. Morace , et al. · 2017

Laser-ion acceleration via anomalous electron heating Open

Akifumi Yogo, K. Mima, Natsumi Iwata, S. Tosaki, A. Morace , et al. · 2016

Using a kilojoule class laser, we demonstrate for the first time that high-contrast picosecond pulses are advantageous for ion acceleration. We show that a laser pulse with optimum duration and a large focal spot accelerates electrons beyo…

Flash Kα radiography of laser-driven solid sphere compression for fast ignition Open

Hiroshi Sawada, Seungho Lee, Takashi Shiroto, Hideo Nagatomo, Yasunobu Arikawa , et al. · 2016

Time-resolved compression of a laser-driven solid deuterated plastic sphere with a cone was measured with flash Kα x-ray radiography. A spherically converging shockwave launched by nanosecond GEKKO XII beams was used for compression while …

Development of 4.5 keV monochromatic X-ray radiography using the high-energy, picosecond LFEX laser Open

Hiroshi Sawada, Shinsuke Fujioka, Takahiro Hosoda, Zhe Zhang, Yasunobu Arikawa , et al. · 2016

Development of a monochromatic x-ray imaging system using a high-energy short- pulse laser LFEX and a spherical crystal is reported. Irradiation of the intense short-pulse laser produces a flash of 4.51 keV Ti K-alpha x-ray while the spher…

Simulation analysis for ion assisted fast ignition using structured targets Open

H. Sakagami, T. Johzaki, Atsushi Sunahara, Hideo Nagatomo · 2016

As the heating efficiency by fast electrons in the fast ignition scheme is estimated to be very low due to their large divergence angle and high energy. To mitigate this problem, low-density plastic foam, which can generate not only proton…

Electron transport estimated from electron spectra using electron spectrometer in LFEX laser target experiments Open

T. Ozaki, M. Hata, Kazuki Matsuo, Sadaoki Kojima, Yasunobu Arikawa , et al. · 2016

Hot electrons which are generated from targets irradiated by a high-intense laser are measured by two electron spectrometers (ESMs). However, total electron energy observed by the ESM is only less than 1%. Hot electrons are confined by sel…

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