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Yamazaki, Takumi*; Hirai, Takamasa*; Yagi, Takashi*; Yamashita, Yuichiro*; Uchida, Kenichi*; Seki, Takeshi*; Takanashi, Koki
Physical Review Applied (Internet), 21(2), p.024039_1 - 024039_11, 2024/02
Times Cited Count：0 Percentile：0.01(Physics, Applied)Masuda, Hiroto*; Yamane, Yuta*; Seki, Takeshi*; Raab, K.*; Dohi, Takaaki*; Modak, R.*; Uchida, Kenichi*; Ieda, Junichi; Kl
ui, M.*; Takanashi, Koki
Applied Physics Letters, 122(16), p.162402_1 - 162402_7, 2023/04
Times Cited Count：1 Percentile：49.29(Physics, Applied)Murase, Kiyoka*; Kataoka, Ryuho*; Nishiyama, Takanori*; Nishimura, Koji*; Hashimoto, Taishi*; Tanaka, Yoshimasa*; Kadokura, Akira*; Tomikawa, Yoshihiro*; Tsutsumi, Masaki*; Ogawa, Yasunobu*; et al.
Journal of Space Weather and Space Climate (Internet), 12, p.18_1 - 18_16, 2022/06
Times Cited Count：1 Percentile：20.65(Astronomy & Astrophysics)We identified two energetic electron precipitation (EEP) events during the growth phase of moderate substorms and estimated the mesospheric ionization rate for an EEP event for which the most comprehensive dataset from ground-based and space-born instruments was available. The mesospheric ionization signature reached below 70 km altitude and continued for ~15 min until the substorm onset, as observed by the PANSY radar and imaging riometer at Syowa Station in the Antarctic region. We also used energetic electron flux observed by the Arase and POES 15 satellites as the input for the air-shower simulation code PHITS to quantitatively estimate the mesospheric ionization rate. Combining the cutting-edge observations and simulations, we shed new light on the space weather impact of the EEP events during geomagnetically quiet times, which is important to understand the possible link between the space environment and climate.
Masuda, Hiroto*; Seki, Takeshi*; Yamane, Yuta*; Modak, R.*; Uchida, Kenichi*; Ieda, Junichi; Lau, Y.-C.*; Fukami, Shunsuke*; Takanashi, Koki
Physical Review Applied (Internet), 17(5), p.054036_1 - 054036_9, 2022/05
Times Cited Count：6 Percentile：70.93(Physics, Applied)The antisymmetric interlayer exchange coupling (AIEC) was recently discovered, playing pivotal roles in magnetization switching of a synthetic antiferromagnet (SAF) through inducing magnetization canting. Large AIEC is reported for perpendicularly magnetized Pt/Co/Ir/Co/Pt with wedge-shaped layers. The effective field of the AIEC is related with symmetric interlayer exchange coupling, providing guides to enhance the AIEC. We develop an extended Stoner-Wohlfarth model for a SAF, revealing key factors in its magnetization switching. Combining the theoretical knowledge and the experimental results, perpendicular magnetization switching is achieved solely by an in-plane magnetic field.
Kato, Atsushi; Kubo, Shigenobu; Chikazawa, Yoshitaka; Miyagawa, Takayuki*; Uchita, Masato*; Suzuno, Tetsuji*; Endo, Junji*; Kubo, Koji*; Murakami, Hisatomo*; Uzawa, Masayuki*; et al.
Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Sustainable Clean Energy for the Future (FR22) (Internet), 11 Pages, 2022/04
The authors are carrying out conceptual design studies for a pool-type sodium-cooled fast reactor. There are main challenges such as measures against severe earthquake in Japan, thermal hydraulic in a reactor vessel (RV), a decay heat removal system design. When the JP-pool SFR of 650 MWe is installed in Japan, it shall be designed against the severe seismic conditions. Additionally, a newly three-dimensional seismic isolation system is under development.
Uchida, Mao*; Alzahrani, H.*; Shiono, Mikihito*; Sakai, Takaaki*; Matsushita, Kentaro; Ezure, Toshiki; Tanaka, Masaaki
Proceedings of 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19) (Internet), 16 Pages, 2022/03
Gas entrainment from cover gas is one of key issues for sodium-cooled fast reactors design to prevent unexpected effects to core reactivity. A vortex model based evaluation method has been developed to evaluate the surface vortex gas core growth at the free surface in the reactor vessel. In this study, water experiments were performed to clarify the prediction accuracy for the vortex gas core growth during the vortex drift motion using a circulating water tunnel with an open flow channel test section. Gas core growth were predicted by applying the evaluation method to the numerical analyses performed in the same geometry of the experiments, and compared with the experimental results. It was observed the gas core growth became large at downstream region where downward velocity became large in experiment. However, the gas core length which were predicted from numerical result showed a discrepancy with the experimental result on the peak position and an overestimation of peak value.
layers in the triple-layer cuprate BiSrCaCu
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studied by angle-resolved photoemission spectroscopyIdeta, Shinichiro*; Johnston, S.*; Yoshida, Teppei*; Tanaka, Kiyohisa*; Mori, Michiyasu; Anzai, Hiroaki*; Ino, Akihiro*; Arita, Masashi*; Namatame, Hirofumi*; Taniguchi, Masaki*; et al.
Physical Review Letters, 127(21), p.217004_1 - 217004_6, 2021/11
Times Cited Count：6 Percentile：60.19(Physics, Multidisciplinary)Matsushita, Kentaro; Fujisaki, Tatsuya*; Ezure, Toshiki; Tanaka, Masaaki; Uchida, Mao*; Sakai, Takaaki*
Keisan Kogaku Koenkai Rombunshu (CD-ROM), 26, 6 Pages, 2021/05
For the gas entrainment vortex at the free surface in sodium-cooled fast reactors, development of the numerical analysis method to evaluate amount of the gas entrainment from the free surface has been developing. In this paper, the automatic creation of analysis meshes which can suppress the calculation cost while maintaining the prediction accuracy of the vortex shape is investigated, and the adaptive mesh refinement (AMR) method is examined to the creation of analysis mesh applying to the unsteady vortex system. The refined mesh based on the criterion evaluated by vorticity, Q-value as second invariant of the velocity and the discriminant for the eigen equation of the velocity gradient tensor is considered, and it found that the AMR method based on Q-value can refine the analysis meshes most efficiently.
Daimon, Shunsuke*; Uchida, Kenichi*; Ujiie, Naomi*; Hattori, Yasuyuki*; Tsuboi, Rei*; Saito, Eiji
Applied Physics Express, 13(10), p.103001_1 - 103001_4, 2020/10
Times Cited Count：7 Percentile：43.4(Physics, Applied)Kataoka, Ryuho*; Nishiyama, Takanori*; Tanaka, Yoshimasa*; Kadokura, Akira*; Uchida, Herbert Akihito*; Ebihara, Yusuke*; Ejiri, Mitsumu*; Tomikawa, Yoshihiro*; Tsutsumi, Masaki*; Sato, Kaoru*; et al.
Earth, Planets and Space (Internet), 71(1), p.9_1 - 9_10, 2019/12
Times Cited Count：8 Percentile：39.55(Geosciences, Multidisciplinary)Transient ionization of the mesosphere was detected at around 65 km altitude during the isolated auroral expansion occurred at 2221-2226 UT on June 30, 2017. A general-purpose Monte Carlo particle transport code PHITS suggested that significant ionization is possible in the middle atmosphere due to auroral X-rays from the auroral electrons of 
10 keV.
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/Pt/FeO epitaxial trilayersKikkawa, Takashi*; Suzuki, Motohiro*; Ramos, R.*; Aguirre, M. H.*; Okabayashi, Jun*; Uchida, Kenichi*; Lucas, I.*; Anad
n, A.*; Kikuchi, Daisuke*; Algarabel, P. A.*; et al.
Journal of Applied Physics, 126(14), p.143903_1 - 143903_11, 2019/10
Times Cited Count：10 Percentile：49.16(Physics, Applied)Isozaki, Naohiko; Morimoto, Kenji; Furukawa, Ryuichi; Tsuboi, Masatoshi; Yada, Yuji; Miyoshi, Ryuta; Uchida, Toyomi; Ikezawa, Kazumi*; Kurosawa, Kenji*
Nihon Hozen Gakkai Dai-16-Kai Gakujutsu Koenkai Yoshishu, p.225 - 228, 2019/07
Highly active liquid waste, which is generated by the reprocessing of spent nuclear fuel, is stored in storage tank of Tokai Reprocessing Plant until it is vitrified. The waste solution in the tank is periodically agitated to avoid the precipitation of insoluble residues during the storage. Three way valves and ball valves have been located at the tank for agitation. Radiation dose rate at the valve location is high and operator's radiation exposure become a problem. Therefore, measures to reduce radiation exposure are performed and reported in this presentation.
Fe
/YIG magnetic junctionsWongjom, P.*; Ramos, R.*; Pinitsoontorn, S.*; Uchida, Kenichi*; Saito, Eiji
Journal of Magnetism and Magnetic Materials, 471, p.439 - 443, 2019/02
Times Cited Count：5 Percentile：26.93(Materials Science, Multidisciplinary)Iwasaki, Yuma*; Takeuchi, Ichiro*; Stanev, V.*; Gilad Kusne, A.*; Ishida, Masahiko*; Kirihara, Akihiro*; Ihara, Kazuki*; Sawada, Ryoto*; Terashima, Koichi*; Someya, Hiroko*; et al.
Scientific Reports (Internet), 9, p.2751_1 - 2751_7, 2019/02
Times Cited Count：61 Percentile：93.15(Multidisciplinary Sciences)Uchida, Kenichi*; Daimon, Shunsuke*; Iguchi, Ryo*; Saito, Eiji
Nature, 558(7708), p.95 - 99, 2018/06
Times Cited Count：63 Percentile：91.61(Multidisciplinary Sciences)Daimon, Shunsuke*; Uchida, Kenichi*; Iguchi, Ryo*; Hioki, Tomosato*; Saito, Eiji
Physical Review B, 96(2), p.024424_1 - 024424_12, 2017/07
Times Cited Count：35 Percentile：81.94(Materials Science, Multidisciplinary)Hioki, Tomosato*; Iguchi, Ryo*; Qiu, Z.*; Hou, D.*; Uchida, Kenichi*; Saito, Eiji
Applied Physics Express, 10(7), p.073002_1 - 073002_4, 2017/06
Times Cited Count：14 Percentile：55.62(Physics, Applied)
Fe
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via X-ray magnetic circular dichroismKikkawa, Takashi*; Suzuki, Motohiro*; Okabayashi, Jun*; Uchida, Kenichi*; Kikuchi, Daisuke*; Qiu, Z.*; Saito, Eiji
Physical Review B, 95(21), p.214416_1 - 214416_7, 2017/06
Times Cited Count：16 Percentile：60.08(Materials Science, Multidisciplinary)O
/Pt]n multilayersRamos, R.*; Kikkawa, Takashi*; Anadn, A.*; Lucas, I.*; Uchida, Kenichi*; Algarabel, P. A.*; Morelln, L.*; Aguirre, M. H.*; Saito, Eiji; Ibarra, M. R.*
AIP Advances (Internet), 7(5), p.055915_1 - 055915_7, 2017/05
Times Cited Count：19 Percentile：65.47(Nanoscience & Nanotechnology)Iguchi, Ryo*; Uchida, Kenichi*; Daimon, Shunsuke*; Saito, Eiji
Physical Review B, 95(17), p.174401_1 - 174401_7, 2017/05
Times Cited Count：48 Percentile：88.01(Materials Science, Multidisciplinary)