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353 results on '"Yamanoi, Kohei"'

1. Realizing Laser-driven Deuteron Acceleration with Low Energy Spread via In-situ D$_2$O-deposited Target

Author

Wei, Tianyun, Arikawa, Yasunobu, Mirfayzi, Seyed Reza, Gu, Yanjun, Hayakawa, Takehito, Morace, Alessio, Mima, Kunioki, Lan, Zechen, Yamada, Ryuya, Yamanoi, Kohei, Honda, Koichi, Bulanov, Sergei V., and Yogo, Akifumi

Subjects
Physics - Plasma Physics
Abstract

Generation of quasi-monoenergetic ion pulse by laser-driven acceleration is one of the hot topics in laser plasma physics. In this study, we present a new method for the \textit{In-situ} deposition of an ultra-thin D$_2$O layer on the surface of an aluminum foil target utilizing a spherical D$_2$O capsule. Employing a 10$^{19}$ W/cm$^2$ laser, we achieve the acceleration of 10.8 MeV deuterons with an energy spread of $\Delta$E/E = 4.6% in the most favorable shot. The energy spread depends on the exposure time of the D$_2$O capsule in the vacuum chamber. This method has the potential to extend its applicability to other ion species.

Published
2024
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8. Peta-Pascal Pressure Driven by Fast Isochoric Heating with Multi-Picosecond Intense Laser Pulse

Author

Matsuo, Kazuki, Higashi, Naoki, Iwata, Natsumi, Sakata, Shohei, Lee, Seungho, Johzaki, Tomoyuki, Sawada, Hiroshi, Iwasa, Yuki, Law, King Fai Farley, Morita, Hiroki, Ochiai, Yugo, Kojima, Sadaoki, Abe, Yuki, Hata, Masayasu, Sano, Takayoshi, Nagatomo, Hideo, Sunahara, Atsushi, Morace, Alessio, Yogo, Akifumi, Nakai, Mitsuo, Sakagami, Hitoshi, Ozaki, Tetsuo, Yamanoi, Kohei, Norimatsu, Takayoshi, Nakata, Yoshiki, Tokita, Shigeki, Kawanaka, Junji, Shiraga, Hiroyuki, Mima, Kunioki, Azechi, Hiroshi, Kodama, Ryosuke, Arikawa, Yasunobu, Sentoku, Yasuhiko, and Fujioka, Shinsuke

Subjects
Physics - Plasma Physics
Abstract

Fast isochoric laser heating is a scheme to heat a matter with relativistic-intensity ($>$ 10$^{18}$ W/cm$^2$) laser pulse or X-ray free electron laser pulse. The fast isochoric laser heating has been studied for creating efficiently ultra-high-energy-density (UHED) state. We demonstrate an fast isochoric heating of an imploded dense plasma using a multi-picosecond kJ-class petawatt laser with an assistance of externally applied kilo-tesla magnetic fields for guiding fast electrons to the dense plasma.The UHED state with 2.2 Peta-Pascal is achieved experimentally with 4.6 kJ of total laser energy that is one order of magnitude lower than the energy used in the conventional implosion scheme. A two-dimensional particle-in-cell simulation reveals that diffusive heating from a laser-plasma interaction zone to the dense plasma plays an essential role to the efficient creation of the UHED state., Comment: 8 pages, 4 figures, 1 table

Published
2019
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9. Magnetized Fast Isochoric Laser Heating for Efficient Creation of Ultra-High-Energy-Density States

Author

Sakata, Shohei, Lee, Seungho, Johzaki, Tomoyuki, Sawada, Hiroshi, Iwasa, Yuki, Morita, Hiroki, Matsuo, Kazuki, Law, King Fai Farley, Yao, Akira, Hata, Masayasu, Sunahara, Atsushi, Kojima, Sadaoki, Abe, Yuki, Kishimoto, Hidetaka, Syuhada, Aneez, Shiroto, Takashi, Morace, Alessio, Yogo, Akifumi, Iwata, Natsumi, Nakai, Mitsuo, Sakagami, Hitoshi, Ozaki, Tetsuo, Yamanoi, Kohei, Norimatsu, Takayoshi, Nakata, Yoshiki, Tokita, Shigeki, Miyanaga, Noriaki, Kawanaka, Junji, Shiraga, Hiroyuki, Mima, Kunioki, Nishimura, Hiroaki, Bailly-Grandvaux, Mathieu, Santos, Joao Jorge, Nagatomo, Hideo, Azechi, Hiroshi, Kodama, Ryosuke, Arikawa, Yasunobu, Sentoku, Yasuhiko, and Fujioka, Shinsuke

Subjects
Physics - Plasma Physics
Abstract

The quest for the inertial confinement fusion (ICF) ignition is a grand challenge, as exemplified by extraordinary large laser facilities. Fast isochoric heating of a pre-compressed plasma core with a high-intensity short-pulse laser is an attractive and alternative approach to create ultra-high-energy-density states like those found in ICF ignition sparks. This avoids the ignition quench caused by the hot spark mixing with the surrounding cold fuel, which is the crucial problem of the currently pursued ignition scheme. High-intensity lasers efficiently produce relativistic electron beams (REB). A part of the REB kinetic energy is deposited in the core, and then the heated region becomes the hot spark to trigger the ignition. However, only a small portion of the REB collides with the core because of its large divergence. Here we have demonstrated enhanced laser-to-core energy coupling with the magnetized fast isochoric heating. The method employs a kilo-tesla-level magnetic field that is applied to the transport region from the REB generation point to the core which results in guiding the REB along the magnetic field lines to the core. 7.7 $\pm$ 1.3 % of the maximum coupling was achieved even with a relatively small radial area density core ($\rho R$ $\sim$ 0.1 g/cm$^2$). The guided REB transport was clearly visualized in a pre-compressed core by using Cu-$K_\alpha$ imaging technique. A simplified model coupled with the comprehensive diagnostics yields 6.2\% of the coupling that agrees fairly with the measured coupling. This model also reveals that an ignition-scale areal density core ($\rho R$ $\sim$ 0.4 g/cm$^2$) leads to much higher laser-to-core coupling ($>$ 15%), this is much higher than that achieved by the current scheme.

Published
2017
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11. Electronic, Optical and Thermoelectric Properties of Two-Dimensional Molybdenum Carbon Mo 2 C-MXenes.

Author

Anh, Doan Thi Kieu, Minh, Pham Hong, Yamanoi, Kohei, Cadatal-Raduban, Marilou, Mui, Luong Viet, Hieu, Do Minh, and Hung, Nguyen Dai

Abstract

We investigate the structural, electronic, optical, and thermoelectric properties of three compositions of Mo2C-MXenes (Mo2CF2, Mo2C(OH)2, and Mo2CO2) from monolayer to multilayer by first principles calculation within Density Functional Theory (DFT) and Boltzmann transport theory. Firstly, the atomic structures of Mo2C-MXenes are optimized, and their respective structures are created with comparative research. Secondly, their electronic band structures and optical properties are studied in detail. The estimation of the bandgap energy of Mo2C-MXenes with its functionalization reveal that most Mo2CF2 and Mo2C(OH)2 layers are semiconductors, while Mo2CO2 behaves as a metal. The electrical and optical properties can be altered by controlling the on-surface functional groups and the number of layers. Computation of the thermoelectric (TE) properties of Mo2C-MXenes reveals that, upon heating to 600 K, Mo2CF2 and Mo2C(OH)2 exhibit a high Seebeck coefficient and a relatively high electrical conductivity. The Seebeck coefficient reaches ~400 µV K−1 at room temperature for all layers of Mo2CF2 MXenes. Our results prove that Mo2CF2 is considered a promising material for thermoelectric devices, while Mo2CO2 does not possess better thermoelectric performance. Mo2C-MXenes from monolayer to multilayer have outstanding properties, such as flexible bandgap energy and high thermal stability, making them promising candidates for many applications, including energy storage and electrode applications. [ABSTRACT FROM AUTHOR]

Published
2024
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14. Ultrafast UV Luminescence of ZnO Films: Sub‐30 ps Decay Time with Suppressed Visible Component

Author

Cadatal‐Raduban, Marilou, primary, Olejníček, Jiří, additional, Hibino, Kota, additional, Maruyama, Yuki, additional, Písaříková, Aneta, additional, Shinohara, Keito, additional, Asaka, Toru, additional, Lebedová Volfová, Lenka, additional, Kohout, Michal, additional, Jiaqi, Zhang, additional, Akabe, Yugo, additional, Nakajima, Makoto, additional, Harrison, John A., additional, Hippler, Rainer, additional, Sarukura, Nobuhiko, additional, Ono, Shingo, additional, Hubička, Zdeněk, additional, and Yamanoi, Kohei, additional

Published
2024
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22. Realizing laser-driven deuteron acceleration with low energy spread via in situ D2O-deposited target.

Author

Wei, Tianyun, Arikawa, Yasunobu, Mirfayzi, Seyed Reza, Gu, Yanjun, Hayakawa, Takehito, Morace, Alessio, Mima, Kunioki, Lan, Zechen, Yamada, Ryuya, Yamanoi, Kohei, Honda, Koichi, Bulanov, Sergei V., and Yogo, Akifumi

Abstract

Generation of quasi-monoenergetic ion pulse by laser-driven acceleration is one of the hot topics in laser plasma physics. In this study, we present a new method for the in situ deposition of an ultra-thin D2O layer on the surface of an aluminum foil target utilizing a spherical D2O capsule. Employing a 1019 W/cm2 laser, we achieve the acceleration of 10.8 MeV deuterons with an energy spread of ΔE/E = 4.6% in the most favorable shot. The energy spread depends on the exposure time of the D2O capsule in the vacuum chamber. This method has the potential to extend its applicability to other ion species. [ABSTRACT FROM AUTHOR]

Published
2024
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26. Crystal growth, luminescence, and scintillation properties of Er-doped La2Hf2O7 single crystal

Author

Hayashi, Naomoto, primary, Yokota, Yuui, additional, Horiai, Takahiko, additional, Yamanoi, Kohei, additional, Yoshino, Masao, additional, Yamaji, Akihiro, additional, Murakami, Rikito, additional, Hanada, Takashi, additional, Sato, Hiroki, additional, Ohashi, Yuji, additional, Kurosawa, Shunsuke, additional, Kamada, Kei, additional, Sarukura, Nobuhiko, additional, and Yoshikawa, Akira, additional

Published
2024
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29. A new separation method of hydrogen isotope by dynamically created nonequilibrium state.

Author

Yabe, Takashi, Norimatsu, Takayoshi, Yamanoi, Kohei, and Xiao, Feng

Abstract

Composition of deuterium (heavy) water in light water was drastically reduced to one-half by one stage of a newly invented device that can create a nonequilibrium vapor state driven by a dynamic system. Vapor density of heavy and light water is arbitrarily controlled. This system works at 20–60°C, even under atmospheric pressure. The mechanism should equally work even for tritium water, as tritium-contaminated water is a problem in the treatment of nuclear reactors as well as fusion reactors. [ABSTRACT FROM AUTHOR]

Published
2024
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38. Refractive Index Measurements of Solid Hydrogen Isotopologues

Author

Zhang, Jiaqi, Iwamoto, Akifumi, Shigemori, Keisuke, Hara, Masanori, and Yamanoi, Kohei

Abstract

AbstractFuel pellets made of a solid deuterium-tritium (D-T) mixture are supplied for inertial confinement fusion. Characterization of the D-T mixture is fundamental for the design and production of high-quality fuel pellets. However, during the phase transition, isotopologue fractionation may lead to fractional crystallization in the solid phase of the hydrogen isotopologue mixture. If this phenomenon occurs in solid D-T fuel, it will reduce the reaction efficiency of nuclear fusion. Currently, there is no effective observation method for fractional crystallization. This study aims to quantify the degree of fractional crystallization of the hydrogen isotopologues mixture in the solid phase using the refractive index measurement. For this method, refractive index information on the hydrogen isotopologues is necessary, therefore the temperature and wavelength dependences of the refractive index of hydrogen isotopologues need to be measured. Then, using the refractive index distribution of the solid D-T will show the composition distribution of isotopologues for assessing the fractional crystallization. Particularly, as far as we know, this is the first time that the measured values of the refractive index versus wavelength of solid D2have been obtained. Understanding the wavelength dependence of the refractive index for the dispersion compensation allows for a wider application of the fractionated crystallographic observation method.

Published
2024
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40. ZnO crystal as a potential damage-recoverable window material for fusion reactors

Author

Yamanoi, Kohei, Empizo, Melvin John F., Mori, Kazuyuki, Iwano, Keisuke, Minami, Yuki, Arita, Ren, Iwasa, Yuki, Fukuda, Kazuhito, Kato, Kosaku, Takano, Keisuke, Shimizu, Toshihiko, Nakajima, Makoto, Yoshimura, Masashi, Sarukura, Nobuhiko, Norimatsu, Takayoshi, Hangyo, Masanori, Azechi, Hiroshi, Fukuda, Tsuguo, Singidas, Bess G., Sarmago, Roland V., Oya, Makoto, and Ueda, Yoshio

Published
2016
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44. Refractive index measurement of hydrogen isotopologue mixture and applicability for homogeneity of hydrogen solid at cryogenic temperature in fusion fuel system

Author

Zhang, Jiaqi, 1000000260050, Iwamoto, Akifumi, 1000050335395, 0000-0002-3978-8427, Shigemori, Keisuke, 1000000334714, Hara, Masanori, 1000030722813, 0000-0003-4492-4099, Yamanoi, Kohei, Zhang, Jiaqi, 1000000260050, Iwamoto, Akifumi, 1000050335395, 0000-0002-3978-8427, Shigemori, Keisuke, 1000000334714, Hara, Masanori, 1000030722813, 0000-0003-4492-4099, and Yamanoi, Kohei

Abstract

Zhang J., Iwamoto A., Shigemori K., et al. Refractive index measurement of hydrogen isotopologue mixture and applicability for homogeneity of hydrogen solid at cryogenic temperature in fusion fuel system. Nuclear Fusion 63, 076020 (2023); https://doi.org/10.1088/1741-4326/acd015., Deuterium (D)-Tritium (T) nuclear fusion reaction has potential as an energy source in the future. In both magnetic confinement and inertial confinement fusion reactors, solid D-T will generally be supplied as fusion fuel. The efficiency of the nuclear fusion reaction depends on the quality of solid D-T fuel, which is related to the composition, homogeneity, helium-3 (3He) content, and so on. However, there is no technique for in-situ examination of solid D-T fuel. In this study, we consider a simple and precise method for the characterization of solid hydrogen isotopologues at cryogenic temperature using refractive index measurement, and evaluate the distribution of hydrogen isotopologue composition and homogeneity. To evaluate without the effect of tritium decay, the homogeneity of the hydrogen (H2)-deuterium (D2) mixture is measured at first. By the in-situ refractive index measurement at cryogenic temperature, the homogeneity of solid H2-D2 mixture is roughly quantified. The phase diagram of the H2-D2 mixture shows a solid solution type. D2-rich crystal first appears from the liquid phase as a primary crystal. The composition of D2 in liquid phase ias homogeneous, whereas it reduces by obeying the liquidus line in the phase diagram with the crystallization. On the other hand, the composition of the H2-D2 mixture in solid phase is inhomogeneous because the mobility of H2 and D2 in solid phase was too slow to be homogeneous and solid. The compositions of H2-D2 mixture in liquid and solid phases could be evaluated by the in-situ refractive index measurement in time. Consequently, the refractive index measurement shows great potential as an inspection method of solid D-T fuel in fusion reactors.

Published
2023

50. Elastic Scattering Time–Gated Multi–Static Lidar Scheme for Mapping and Identifying Contaminated Atmospheric Droplets

Author

Mui, Luong Viet, primary, Hung, Tran Ngoc, additional, Shinohara, Keito, additional, Yamanoi, Kohei, additional, Shimizu, Toshihiko, additional, Sarukura, Nobuhiko, additional, Shimadera, Hikari, additional, Kondo, Akira, additional, Sumimura, Yoshinori, additional, Hai, Bui Van, additional, Nguyen, Diep Van, additional, Minh, Pham Hong, additional, Trung, Dinh Van, additional, and Cadatal-Raduban, Marilou, additional

Published
2022
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