Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Ohshima, Hiroyuki; Morishita, Masaki*; Aizawa, Kosuke; Ando, Masanori; Ashida, Takashi; Chikazawa, Yoshitaka; Doda, Norihiro; Enuma, Yasuhiro; Ezure, Toshiki; Fukano, Yoshitaka; et al.
Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07
This book is a collection of the past experience of design, construction, and operation of two reactors, the latest knowledge and technology for SFR designs, and the future prospects of SFR development in Japan. It is intended to provide the perspective and the relevant knowledge to enable readers to become more familiar with SFR technology.
Yogo, Akifumi; Kondo, Kiminori; Mori, Michiaki; Kiriyama, Hiromitsu; Ogura, Koichi; Shimomura, Takuya; Inoue, Norihiro*; Fukuda, Yuji; Sakaki, Hironao; Jinno, Satoshi; et al.
Optics Express (Internet), 22(2), p.2060 - 2069, 2014/01
Times Cited Count：10 Percentile：49.33(Optics)Sherrill, M. E.*; Abdallah, J.*; Csanak, G.*; Dodd, E. S.*; Fukuda, Yuji; Akahane, Yutaka; Aoyama, Makoto; Inoue, Norihiro*; Ueda, Hideki*; Yamakawa, Koichi; et al.
High-Power Laser Ablation VII (Proceedings of SPIE Vol.7005), p.70051R_1 - 70051R_11, 2008/06
Fukuda, Yuji; Akahane, Yutaka; Aoyama, Makoto; Hayashi, Yukio; Homma, Takayuki; Inoue, Norihiro*; Kando, Masaki; Kanazawa, Shuhei; Kiriyama, Hiromitsu; Kondo, Shuji; et al.
Physics Letters A, 363(2-3), p.130 - 135, 2007/02
Collimated relativistic electrons up to 58 MeV with an electron charge of 2.1 nC were generated by the interaction of intense laser pulses with the Ar cluster target at the laser intensity of 3.5
10
W/cm
. The resulting spectrum does not fit a Maxwellian distribution, but is well described by a two-temperature Maxwellian, which indicates two mechanisms of the electron acceleration. Two dimensional particle-in-cell simulations demonstrate an important role of clusters. The higher energy electrons are injected when they are expelled from the clusters by the laser pulse field. They then gain their energy during the direct acceleration by the laser pulse, whose phase velocity in the underdense plasma is larger than speed of light in vacuum. The lower energy electrons, which are injected during the plasma wave breaking, are accelerated by the wakefield.
Sugita, Akihiro; Yokoyama, Keiichi; Yamada, Hidetaka; Inoue, Norihiro*; Aoyama, Makoto; Yamakawa, Koichi
Japanese Journal of Applied Physics, Part 1, 46(1), p.226 - 228, 2007/01
Times Cited Count：7 Percentile：30.11(Physics, Applied)Generation of broadband mid-infrared (MIR) laser pulses by difference frequency mixing (DFM) is reported. Two-color femtosecond pulses from a Ti: Sapphire laser system is mixed in an AgGaS
crystal utilizing a noncollinear phase matching scheme. The relative bandwidth of the generated MIR pulse has been measured to be 23 % to the central frequency, the broadest in DFM-based MIR sources reported so far. It is found that the type-I crystal can give broader phase matching range of spectrum than the type-II crystal within this scheme.
Sherrill, M. E.*; Abdallah, J. Jr.*; Csanak, G.*; Dodd, E. S.*; Fukuda, Yuji; Akahane, Yutaka; Aoyama, Makoto; Inoue, Norihiro*; Ueda, Hideki*; Yamakawa, Koichi; et al.
Physical Review E, 73(6), p.066404_1 - 066404_6, 2006/06
Times Cited Count：29 Percentile：75.69(Physics, Fluids & Plasmas)A model that solves simultaneously both the electron and atomic kinetics was used to generate synthetic He
X-ray spectra to characterize a high intensity ultrashort laser driven Ar cluster target experiment. In particular, level populations were obtained from a detailed collisional-radiative model where collisional rates were computed from a time varying electron distribution function obtained from the solution of the zero dimensional Boltzmann equation. In addition, aparticle-in-cell simulation was used to model the laser interaction with the cluster target and provided the initial electron energy distribution function (EEDF) for the Boltzmann solver. This study suggests that the high density plasma contribution to the time-integrated He spectrum was in a highly non-equilibrium state in both the EEDF and the ion level populations and provides a prediction of 5.7 ps for the average cluster integrity time for this high density state.
Sherrill, M. E.*; Abdallah, J. Jr.*; Csanak, G.*; Kilcrease, D. P.*; Dodd, E. S.*; Fukuda, Yuji; Akahane, Yutaka; Aoyama, Makoto; Inoue, Norihiro*; Ueda, Hideki; et al.
Journal of Quantitative Spectroscopy & Radiative Transfer, 99(1-3), p.584 - 594, 2006/05
Times Cited Count：3 Percentile：18.42(Optics)In this work, we present a model that solves self-consistently the electron and atomic kinetics to characterize highly non-equilibrium plasmas, in particular for those systems where both the electron distribution function is far from Maxwellian and the evolution of the ion level populations are dominated by time dependent atomic kinetics. In this model, level populations are obtained from a detailed collisional-radiative model where collision rates are computed from a time varying electron distribution function obtained from the solution of the zero-dimensional Boltzmann equation. The Boltzmann collision term includes the effects of electron-electron collisions, electron collisional ionization, excitation and de-excitation. An application for He spectra from a short pulse laser irradiated argon cluster target will be shown to illustrate the results of our model.
Kiriyama, Hiromitsu; Inoue, Norihiro*; Akahane, Yutaka; Yamakawa, Koichi
Optics Express (Internet), 14(1), p.438 - 445, 2006/01
Times Cited Count：23 Percentile：68.38(Optics)no abstracts in English
) and Cs(7
) by femtosecond laser pulsesYamada, Hidetaka; Yokoyama, Keiichi; Teranishi, Yoshiaki*; Sugita, Akihiro; Shirai, Toshizo*; Aoyama, Makoto; Akahane, Yutaka; Inoue, Norihiro*; Ueda, Hideki*; Yamakawa, Koichi; et al.
Physical Review A, 72(6), p.063404_1 - 063404_5, 2005/12
Times Cited Count：6 Percentile：31.21(Optics)A demonstration of coherent quantum control for ultrafast precise selection of closely-lying states is reported. A phase-locked pair of femtosecond laser pulses is generated through a pulse shaper to excite the ground-state cesium atom to the Cs(7) and Cs(7) states by two-photon absorption. The excited state population is measured by detecting fluorescence from each spin-orbit state. By controlling the phase-difference of the pulse pair, an ultrafast precise selection is accomplished. The contrast ratio of the maximal to minimal selection ratio exceeds 10
with the delay less than 400 fs.
W/cm intensity by focusing wavefront corrected 100 TW, 10 Hz laser pulsesAkahane, Yutaka; Ma, J.; Fukuda, Yuji; Aoyama, Makoto; Kiriyama, Hiromitsu; Inoue, Norihiro*; Tsuji, Koichi*; Nakai, Yoshiki*; Yamamoto, Yoichi*; Sheldakova, J. V.*; et al.
Japanese Journal of Applied Physics, Part 1, 44(8), p.6087 - 6089, 2005/08
Times Cited Count：1 Percentile：4.7(Physics, Applied)An improvement of laser-focused peak intensity has been achieved in a JAERI 100 TW Ti:sapphire chirped-pulse amplifier chain with a feedback-controlled adaptive optics system. Measurements of optical parameters of the laser pulse and an experimental tunneling ionization ratio of a rare gas atom with laser energy scaling have practically confirmed an ultrarelativistic intensity of over 10 W/cm operating at a 10 Hz repetition rate.
' X-ray transitions from 
1 
m Kr clusters irradiated by high-intensity femtosecond laser pulsesHansen, S. B.*; Fournier, K. B.*; Faenov, A. Y.*; Magunov, A. I.*; Pikuz, T. A.*; Skobelev, I. Y.*; Fukuda, Yuji; Akahane, Yutaka; Aoyama, Makoto; Inoue, Norihiro*; et al.
Physical Review E, 71(1), p.016408_1 - 016408_9, 2005/01
Times Cited Count：16 Percentile：57.67(Physics, Fluids & Plasmas)X-ray line emission from ' transitions in Ne-like Kr and nearby ions has been observed from 1 m Kr clusters irradiated by fs-scale laser pulses at the JAERI facility in Kyoto, Japan. The dependence of X-ray spectral features and intensity on the incident laser intensity is rather weak, indicating that the 1-2 ps cluster lifetimes limit the number of ions beyond Ne-like Kr that can be produced by collisional ionization. A collisional-radiative model based on the relativistic multiconfigured FAC code has been constructed and used to determine that the cluster plasma has electron densities near 10
cm
, temperature of a few hundred eV and hot electron fraction of a few percent.
Kando, Masaki; Masuda, Shinichi; Zhidkov, A.*; Yamazaki, Atsushi; Kotaki, Hideyuki; Kondo, Shuji; Homma, Takayuki*; Kanazawa, Shuhei; Nakajima, Kazuhisa; Hayashi, Yukio; et al.
Physical Review E, 71(1), p.015403_1 - 015403_4, 2005/01
Times Cited Count：33 Percentile：77.37(Physics, Fluids & Plasmas)no abstracts in English
Fukuda, Yuji; Akahane, Yutaka; Aoyama, Makoto; Inoue, Norihiro*; Ueda, Hideki; Nakai, Yoshiki*; Tsuji, Koichi*; Yamakawa, Koichi; Hironaka, Yoichiro*; Kishimura, Hiroaki*; et al.
Applied Physics Letters, 85(21), p.5099 - 5101, 2004/11
Times Cited Count：11 Percentile：42.77(Physics, Applied)We have demonstrated diffraction from Si(111) crystal using X-rays from highly ionized Ar ions produced by laser irradiation with an intensity of 610
W/cm and a pulse duration of 30 fs acting upon micron-sized Ar clusters. The measured total photon flux and line width in the He
line (3.14 keV) were 410
photons/shot/4
sr and 3.7 eV (FWHM), respectively, which is sufficient to utilize as a debris-free light source for time-resolved X-ray diffraction studies.
Fukuda, Yuji; Akahane, Yutaka; Aoyama, Makoto; Inoue, Norihiro*; Ueda, Hideki; Kishimoto, Yasuaki; Yamakawa, Koichi; Faenov, A. Y.*; Magunov, A. I.*; Pikuz, T. A.*; et al.
Laser and Particle Beams, 22(3), p.215 - 220, 2004/07
Times Cited Count：41 Percentile：78.95(Physics, Applied)High resolution K-shell spectra of a plasma created by superintense laser irradiation of micron-sized Ar clusters have been measured with an intensity above 10 W/cm
and a pulse duration of 30 fs. The total photon flux of 210
photons/pulse was achieved for He resonant line of Ar (
=3.9491 AA , 3.14 keV). In parallel with X-ray measurements, energy distributions of emitted ions have been measured. The multiply-charged ions with kinetic energies up to 800 keV were observed. It is found that hot electrons produced by high contrast laser pulses allow the isochoric heating of clusters and shift the ion balance towards the higher charge states, which enhances both the X-ray line yield of the He-like argon ion and the ion kinetic energy.
Smirnov, M. B.*; Skobelev, I. Y.*; Magunov, A. I.*; Faenov, A. Y.*; Pikuz, T. A.*; Fukuda, Yuji; Yamakawa, Koichi; Akahane, Yutaka; Aoyama, Makoto; Inoue, Norihiro*; et al.
Journal of Experimental and Theoretical Physics, 98(6), p.1123 - 1132, 2004/06
Interaction between high-power ultrashort laser pulse and giant clusters (microdroplets) consisting of 10
to 10
atoms is considered. The microdroplet size is comparable to the laser wavelength. A model of the evolution of a microdroplet plasma induced by a high-power laser pulse is developed, and the processes taking place after interaction with the pulse are analyzed. It is shown theoretically that the plasma is superheated: its temperature is approximately equal to the ionization potential of an ion having a typical charge. The microdroplet plasma parameters are independent of the pulse shape and duration. The theoretical conclusions are supported by experimental studies of X-ray spectra conducted at JAERI, where a 100-terawatt Ti-sapphire lasersystem was used to irradiate krypton and xenon microdroplets by laser pulses with pulse widths of 30 to 500 fs and intensities of 610
to 210 W/cm.
Yokoyama, Keiichi; Teranishi, Yoshiaki; Toya, Yukio; Shirai, Toshizo; Fukuda, Yuji; Aoyama, Makoto; Akahane, Yutaka; Inoue, Norihiro*; Ueda, Hideki; Yamakawa, Koichi; et al.
Journal of Chemical Physics, 120(20), p.9446 - 9449, 2004/05
Times Cited Count：6 Percentile：18.77(Chemistry, Physical)Optimal laser control for ultrafast selection of closely-lying excited states, whose energy separation is smaller than the laser bandwidth, is reported on the two-photon transition of atomic cesium; Cs(6S 
7D
, J = 5/2 and 3/2). Selective excitation was carried out by pulse shaping of ultrashort laser pulses which were adaptively modulated in a closed-loop learning system handling eight parameters representing the electric field. Two-color fluorescence from the respective excited states was monitored to measure the selectivity. The fitness used in the learning algorithm was evaluated from the ratio of the fluorescence yield. After fifty generations, a pair of nearly transform-limitted pulses were obtained as an optimal pulse shape, proving the effectiveness of "Ramsey fringes" mechanism. The contrast of the selection ratio was improved by 
30 % from the simple "Ramsey fringes" experiment.
Yamakawa, Koichi; Akahane, Yutaka; Fukuda, Yuji; Aoyama, Makoto; Inoue, Norihiro*; Ueda, Hideki; Utsumi, Takayuki*
Physical Review Letters, 92(12), p.123001_1 - 123001_4, 2004/03
Times Cited Count：68 Percentile：87.93(Physics, Multidisciplinary)We report on detailed investigations of ionization dynamics of a Xe atom exposed to intense 800-nm pulses of 20-fs duration in the extensive intensity range from 10
to 10 W/cm. Ion yields of Xe
to Xe
were observed as a function of laser intensity and compared with the results from a single active electron based Ammosov-Delone-Krainov model. Unexpected ionization probabilities for lower charge states and also no interplay between the inner- and outer-shells by screening are inferred. Suppression of nonsequential ionization towards higher intensity and few optical cycle regimes is also proved.
Fukuda, Yuji; Akahane, Yutaka; Aoyama, Makoto; Inoue, Norihiro*; Ueda, Hideki; Kishimoto, Yasuaki; Yamakawa, Koichi; Faenov, A. Y.*; Magunov, A. I.*; Pikuz, T. A.*; et al.
Laser-Generated & Other Lab. X-Ray & EUV Sources (Proceedings of SPIE Vol.5196), p.234 - 243, 2004/00
High resolution X-ray emission spectra of plasma created by laser irradiation of rare-gas (Ar, Kr, Xe) clusters have been measured at laser intensities over 10 W/cm and 30-fs pulse duration. To make these measurements possible, in addition to the effort to decrease a prepulse intensity using Pockels cell switches, micron-size clusters were produced using a specially designed conical nozzle. The Boltzmann equation and a detailed collisional radiative model are solved simultaneously as a function of time to model the time integrated X-ray spectra of the transient plasma. The results are quantitatively in good agreement with the experimentally observed X-ray emission spectra of Ar clusters.
Yamakawa, Koichi; Akahane, Yutaka; Fukuda, Yuji; Aoyama, Makoto; Inoue, Norihiro*; Ueda, Hideki; Utsumi, Takayuki*
JAERI-Research 2003-030, 14 Pages, 2003/12
JAERI-Research-2003-030.pdf:0.75MB
We report on detailed investigations of ionization dynamics of a xenon atom exposed to intense 800-nm pulses of 20-fs duration in the extensiveintensity range from 10 to 10W/cm.Ion yields of Xe to Xe were observed as a function of laser intensity and compared with the results from a single active electron(SAE) based Ammosov-Delone-Krainov(ADK) model.Unexpected ionization probabilities for lower charge states and also no interplay between the inner-and outer-shells by screening are inferred.Suppression of nonsequential ionization towards higher intensity and few optical cycle regimesis also proved.
Abdallah, J. Jr.*; Csanak, G.*; Fukuda, Yuji; Akahane, Yutaka; Aoyama, Makoto; Inoue, Norihiro*; Ueda, Hideki; Yamakawa, Koichi; Faenov, A. Y.*; Magunov, A. I.*; et al.
Physical Review A, 68(6), p.063201_1 - 063201_8, 2003/12
Times Cited Count：53 Percentile：87.19(Optics)The Boltzmann Equation and a detailed collisional radiative model are solved simultaneously as a function of time to model the time integrated X-ray spectra of the transient plasma produced by a high intensity ultrafast laser source. The results are in agreement with highly resolved F-like to He-like K-shell emission spectra recorded recently during ultrashort laser experiments with argon cluster targets in Japan.
