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-ironHirayama, Shintaro*; Sato, Koichi*; Kato, Daiji*; Iwakiri, Hirotomo*; Yamaguchi, Masatake; Watanabe, Yoshiyuki*; Nozawa, Takashi*
Nuclear Materials and Energy (Internet), 31, p.101179_1 - 101179_9, 2022/06
Times Cited Count：1 Percentile：49.42(Nuclear Science & Technology)no abstracts in English
X raysOkumura, Takuma*; Azuma, Toshiyuki*; Bennet, D. A.*; Caradonna, P.*; Chiu, I. H.*; Doriese, W. B.*; Durkin, M. S.*; Fowler, J. W.*; Gard, J. D.*; Hashimoto, Tadashi; et al.
Physical Review Letters, 127(5), p.053001_1 - 053001_7, 2021/07
Times Cited Count：9 Percentile：76.2(Physics, Multidisciplinary)We observed electronic X rays emitted from muonic iron atoms using a superconducting transition-edge-type sensor microcalorimeter. The energy resolution of 5.2 eV in FWHM allowed us to observe the asymmetric broad profile of the electronic characteristic and 
X rays together with the hypersatellite X rays around 6 keV. This signature reflects the time-dependent screening of the nuclear charge by the negative muon and the 
-shell electrons, accompanied by electron side-feeding. Assisted by a simulation, this data clearly reveals the electronic - and -shell hole production and their temporal evolution during the muon cascade process.
Watanabe, Yoshiyuki; Iwakiri, Hirotomo*; Murayoshi, Norihiko*; Kato, Daiji*; Tanigawa, Hiroyasu
Plasma and Fusion Research (Internet), 10, p.1205086_1 - 1205086_2, 2015/12
In this paper, formation energy of isolated hydrogen atom in Cr
C
has been theoretically investigated with atomistic calculation based on the density functional theory. The lowest calculated formation energy of a hydrogen atom is -0.48 eV with a trigonal bipyramidal configuration surrounded by five regular Cr lattice atoms. A comparison of the formation energy of hydrogen atom in bcc-iron may indicate that hydrogen atoms in F82H steel are more energetically favorable in CrC-based precipitate rather than Fe-based matrix, leading to an increase of the tritium retention in the precipitate.
Koike, Fumihiro*; Funaba, Hisamichi*; Goto, Motoshi*; Kato, Daiji*; Kato, Takako*; Morita, Shigeru*; Murakami, Izumi*; Sakaue, Hiroyuki*; Sudo, Shigeru*; Suzuki, Chihiro*; et al.
AIP Conference Proceedings 1545, p.202 - 211, 2013/07
Times Cited Count：4 Percentile：84.06Atomic ionic states and transition properties of elements with atomic numbers Z ranging from 50 to 80 are discussed as these are important to the understanding of plasmas containing such heavy elements. As such, data productions and the current status of theoretical calculations in this field are discussed. Further, recent spectroscopic measurements and respective theoretical analyses for W, Gd, and Nd are provided.
Morita, Shigeru*; Dong, C. F.*; Goto, Motoshi*; Kato, Daiji*; Murakami, Izumi*; Sakaue, Hiroyuki*; Hasuo, Masahiro*; Koike, Fumihiro*; Nakamura, Nobuyuki*; Oishi, Tetsutaro*; et al.
AIP Conference Proceedings 1545, p.143 - 152, 2013/07
Times Cited Count：28 Percentile：99.21Tungsten spectra have been observed from Large Helical Device (LHD) and Compact electron Beam Ion Trap (CoBIT) in wavelength ranges of visible to EUV. The tungsten spectra from LHD are well analyzed based on the knowledge from CoBIT tungsten spectra. The C-R model code has been developed to explain the UTA spectra in details. Radial profiles of EUV spectra from highly ionized tungsten ions have been measured and analyzed by impurity transport simulation code with ADPAK atomic database code to examine the ionization balance determined by ionization and recombination rate coefficients. The ablation cloud of the impurity pellet is directly measured with visible spectroscopy.
Ueda, Yoshio*; Oya, Kaoru*; Ashikawa, Naoko*; Ito, Atsushi*; Ono, Tadayoshi*; Kato, Daiji*; Kawashima, Hisato; Kawamura, Gakushi*; Kenmotsu, Takahiro*; Saito, Seiki*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 88(9), p.484 - 502, 2012/09
no abstracts in English
Oya, Kaoru*; Inai, Kensuke*; Shimizu, Katsuhiro; Takizuka, Tomonori; Kawashima, Hisato; Hoshino, Kazuo; Hatayama, Akiyoshi*; Toma, Mitsunori*; Tomita, Yukihiro*; Kawamura, Gakushi*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 85(10), p.695 - 703, 2009/10
no abstracts in English
Suzuki, Chihiro*; Kato, Takako*; Sato, Kuninori*; Tamura, Naoki*; Kato, Daiji*; Sudo, Shigeru*; Yamamoto, Norimasa*; Tanuma, Hajime*; Ohashi, Hayato*; Suda, Shintaro*; et al.
Journal of Physics; Conference Series, 163, p.012019_1 - 012019_4, 2009/06
Times Cited Count：10 Percentile：93.72We have measured EUV spectra from highly charged tin ions in low density plasmas produced in the Large Helical Device (LHD). The well known dense spectral structure around 13.5 nm is measured when the plasma is rapidly cooled and approaching radioactive collapse, while the sparse spectrum with several unidentified discrete lines from 13.8-14.6 nm is observed if the plasma is cooled more slowly. The dominant charge states in the former case are Sn
-Sn
. The latter case may be explained by considering the spectral lines from charge states higher than Sn
.
Watanabe, Hirofumi*; Nakamura, Nobuyuki*; Kato, Daiji*; Nakano, Tomohide; Otani, Shunsuke*
Plasma and Fusion Research (Internet), 2, p.027_1 - 027_3, 2007/06
X-ray spectra from highly charged W ions have been observed in the interaction with an electron beam at the energies ranged from 14 to 1.5 keV by using the Tokyo-EBIT. In this energy range, resonant X-ray transitions at around 9 keV are predominantly taken place through dielectronic recombination processes. The measured spectra are compared with the theoretical calculation with HULLAC.
Sasaki, Akira; Jo, Kazuki*; Kashiwagi, Hiroe*; Watanabe, Chiemi*; Suzuki, Manabu*; Lucas, P.*; Oishi, Masatoshi*; Kato, Daiji*; Kato, Masatoshi*; Kato, Takako*
Journal of Plasma and Fusion Research SERIES, Vol.7, p.348 - 351, 2006/00
no abstracts in English
Sasaki, Akira; Murata, Masaki*; Kashiwagi, Hiroe*; Jo, Kazuki*; Lukas, P.*; Kato, Daiji*; Murakami, Izumi*
no journal, ,
no abstracts in English
Sasaki, Akira; Kimura, Mineo*; Kato, Daiji*
no journal, ,
no abstracts in English
Sasaki, Akira; Murakami, Izumi*; Kato, Daiji*; Kato, Takako*
no journal, ,
no abstracts in English
Watanabe, Yoshiyuki; Iwakiri, Hirotomo*; Murayoshi, Norihiko*; Kato, Daiji*; Tanigawa, Hiroyasu
no journal, ,
no abstracts in English
Sasaki, Akira; Murakami, Izumi*; Kato, Daiji*; Morita, Shigeru*
no journal, ,
The non-local thermodynamic equilibrium (nLTE) atomic kinetics in high-Z plasmas is investigated for Ag, Sn through W, which are used for X-ray lasers, EUV sources and fusion devices. We develop the atomic model based on nl configuration averaged levels structure, with atomic energy levels, radiative rates and autoionization rates calculated using the HULLAC code. The dielectronic recombination processes are included into the model by including autoionizing levels explicitly. We investigate the mean charge and radiative power loss with respect to the size of the model; by defining the groups of the levels, which consist of core a configuration and one excited electron, and by performing calculations increasing the number of groups. It is found that as a general trend, the mean charge decreases and the radiative power loss increases, until convergence is obtained when sufficiently large number of dielectronic recombination channels is included. The model is validated at code comparison workshops and also comparison with spectroscopic measurements, which are carried out using magnetic fusion devices.
