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Araki, Yasufumi; Ieda, Junichi
Journal of the Physical Society of Japan, 92(7), p.074705_1 - 074705_9, 2023/06
Times Cited Count：0 Percentile：0(Physics, Multidisciplinary)Topological electromagnetism owing to nontrivial momentum-space topology of electrons in insulators gives rise to diverse anomalous magnetoelectric responses. While conventional inductors and capacitors are based on classical electromagnetism described by Maxwell's equations, here we show that topological electromagnetism in combination with spin dynamics in magnets also generates an inductance or a capacitance. We build a generic framework to extract the complex impedance on the basis of topological field theory, and demonstrate the emergence of an inductance or a capacitance in several heterostructure setups. In comparison with the previously-studied emergent inductances in metallic magnets, insulators highly suppress the power loss, because of the absence of Joule heating. We show that the inductance from topological electromagnetism is achieved at low current and high frequency, and is also advantageous in its power efficiency, as characterized by the high quality factor (Q-factor).
Yamanouchi, Michihiko*; Araki, Yasufumi; Sakai, Takaki*; Uemura, Tetsuya*; Ota, Hiromichi*; Ieda, Junichi
Science Advances (Internet), 8(15), p.eabl6192_1 - eabl6192_6, 2022/04
Times Cited Count：7 Percentile：73.76(Multidisciplinary Sciences)In a ferromagnetic Weyl metal SrRuO, a large effective magnetic field 
exerted on a magnetic domain wall (DW) by current has been reported. We show that the ratio of to current density exhibits nonmonotonic temperature dependence and surpasses those of conventional spin-transfer torques and spin-orbit torques. This enhancement is described well by topological Hall torque (THT), which is exerted on a DW by Weyl electrons emerging around Weyl points when an electric field is applied across the DW. The ratio of the arising from the THT to current density is over one order of magnitude higher than that originating from spin-transfer torques and spin-orbit torques reported in metallic systems, showing that the THT may provide a better way for energy-efficient manipulation of magnetization in spintronics devices.
Araki, Yasufumi; Ieda, Junichi
Physical Review Letters, 127(21), p.277205_1 - 277205_7, 2021/12
Times Cited Count：5 Percentile：41.09(Physics, Multidisciplinary)Momentum-space topology of electrons under strong spin-orbit coupling contributes to the electrically induced torques exerting on magnetic textures insensitively to disorder or thermal fluctuation. We present a direct connection between band topology and the torques by classifying the whole torques phenomenologically. As well as the intrinsic anomalous Hall effect, the torques also emerge intrinsically from the anomalous velocity of electrons regardless of a nonequilibrium transport current. We especially point out the intrinsic contribution arising exclusively in magnetic textures, which we call the "topological Hall torque (THT)". The THT emerges in bulk crystals without any interface or surface structures. We numerically demonstrate the enhancement of the THT in comparison with the conventional spin-transfer torque in the bulk metallic ferromagnet, which accounts for the giant current-induced torque measured in ferromagnetic 
.
Oto, Tsutomu; Asano, Norikazu; Kawamata, Takanori; Yanai, Tomohiro; Nishimura, Arashi; Araki, Daisuke; Otsuka, Kaoru; Takabe, Yugo; Otsuka, Noriaki; Kojima, Keidai; et al.
JAEA-Review 2020-018, 66 Pages, 2020/11
JAEA-Review-2020-018.pdf:8.87MB
A collapse event of the cooling tower of secondary cooling system in the JMTR (Japan Materials Testing Reactor) was caused by the strong wind of Typhoon No.15 on September 9, 2019. The cause of the collapse of the cooling tower was investigated and analyzed. As the result, it was identified that four causes occurred in combination. Thus, the soundness of the cooling tower of Utility Cooling Loop (UCL cooling tower), which is a wooden cooling tower installed at the same period as the cooling tower of secondary cooling system, was investigated. The items of soundness survey are to grasp the operation conditions of the UCL cooling tower, to confirm the degradation of structural materials, the inspection items and inspection status of the UCL cooling tower, and to investigate the past meteorological data. As the results of soundness survey of the UCL cooling tower, the improvement of inspection items of the UCL cooling tower was carried out and the replacement and repair of the structural materials of the UCL cooling tower were planned for safe maintenance and management of this facility. And the renewal plan of new cooling tower was created to replace the existing UCL cooling tower. This report is summarized the soundness survey of the UCL cooling tower.
Nagai, Ryoji; Hajima, Ryoichi; Shizuma, Toshiyuki; Mori, Michiaki; Akagi, Tomoya*; Kosuge, Atsushi*; Honda, Yosuke*; Araki, Sakae*; Terunuma, Nobuhiro*; Urakawa, Junji*
Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1328 - 1330, 2015/09
Accelerator and laser technologies required for laser Compton scattering (LCS) photon source based on an energy-recovery linac (ERL) have been developed at the Compact ERL (cERL) facility. A high-flux, energy tunable, and monochromatic photon source such as the ERL-based LCS photon source is necessary for nondestructive assay of nuclear materials. For the demonstration of the ERL-based LCS photon generation, a laser enhancement cavity was installed at the recirculation loop of the cERL. The electron beam energy, the laser wavelength, and the collision angle are 20 MeV, 1064 nm, and 18 
, respectively. The calculated maximum energy of the LCS photons is about 7 keV. A silicon drift detector (SDD) with active area of 17 mm
placed 16.6 m from the collision point was used for observation of the LCS photons. As a result of the measurement, the flux on the detector, central energy, and energy width of the LCS photons were obtained as 1200/s, 6.91 keV, and 81 eV, respectively.
Nagai, Ryoji; Hajima, Ryoichi; Mori, Michiaki; Shizuma, Toshiyuki; Akagi, Tomoya*; Araki, Sakae*; Honda, Yosuke*; Kosuge, Atsushi*; Terunuma, Nobuhiro*; Urakawa, Junji*
Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.1607 - 1609, 2015/06
Accelerator and laser technologies required for laser Compton scattering (LCS) photon source based on an energy-recovery linac (ERL) have been developed at the Compact ERL (cERL) facility. A high-flux, energy tunable, and monochromatic photon source such as the ERL-based LCS photon source is necessary for nondestructive assay of nuclear materials. For the demonstration of the ERL-based LCS photon generation, a laser enhancement cavity was installed at the recirculation loop of the cERL. The electron beam energy, the laser wavelength, and the collision angle are 20 MeV, 1064 nm, and 18 deg., respectively. The calculated maximum energy of the LCS photons is about 7 keV. A silicon drift detector (SDD) with active area of 17 mm placed 16.6 m from the collision point was used for observation of the LCS photons. As a result of the measurement, the flux on the detector, central energy, and energy width of the LCS photons were obtained as 1200 /s, 6.91 keV, and 81 eV, respectively.
Yamazaki, Yoshio; Hirano, Koichiro*; Fukuda, Satoshi*; Takano, Mikio*; Araki, Sakae*; Terunuma, Nobuhiro*; Urakawa, Junji*
Proceedings of 9th European Particle Accelerator Conference (EPAC 2004), 0 Pages, 2004/07
Focusing on the cover layer materials (as the Radon Barrier Materials), which could have the effect to restrain the radon from scattering into the air and the effect of the radiation shielding, we produced the radon barrier materials with crude bentonite on an experimental basis, using the rotary type comprehensive unit for grinding and mixing, through which we carried out the evaluation of the characteristics thereof.
Sato, Shinichi*; Araki, Masanori; Omori, Junji*; Oono, Isamu*; Sato, Satoshi; Yamauchi, Michinori*; Nishitani, Takeo
JAERI-Tech 2002-083, 126 Pages, 2002/10
JAERI-Tech-2002-083.pdf:4.07MB
It is one of the foremost goals for ITER to demonstrate the attractiveness with regard to safety and environmental potential. This implies that the radioactive materials and waste at decommissioning phase should carefully be treated with prescribed regulations. As possible activities during the Coordinated Technical Activity (CTA), Japanese Participant Team (JA-PT) has proposed a study for searching the possibility of more reduction in the activated level by taking account of minimum material changes while keeping original design concept and structure. Based on it, reassessment of the activation level and the amount of activation volumes will give us positive aspects for public acceptance.
Omori, Junji*; Kitamura, Kazunori*; Araki, Masanori; Oono, Isamu*; Shoji, Teruaki
JAERI-Tech 2002-053, 86 Pages, 2002/07
JAERI-Tech-2002-053.pdf:3.81MB
no abstracts in English
Mori, Masahiro; Shoji, Teruaki; Araki, Masanori; Saito, Keiji*; Senda, Ikuo; Omori, Junji*; Sato, Shinichi*; Inoue, Takashi; Ono, Isamu*; Kataoka, Takahiro*; et al.
Nihon Genshiryoku Gakkai-Shi, 44(1), p.16 - 89, 2002/01
no abstracts in English
Araki, Masanori; Sato, Shinichi*; Senda, Ikuo; Omori, Junji*; Shoji, Teruaki
Fusion Engineering and Design, 58-59, p.887 - 892, 2001/11
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)no abstracts in English
Omori, Junji*; Araki, Masanori
JAERI-Tech 2000-006, p.15 - 0, 2000/02
JAERI-Tech-2000-006.pdf:0.66MB
no abstracts in English
Morota, Hidetsugu*; Yamada, Masao*; Nasif, H.*; Masuda, Fukuzo*; Iida, Hiromasa; Sato, Satoshi; Nishitani, Takeo; Tamamizu, Shigeyuki*; Karaki, Junichi*
no journal, ,
Development of CAD preprocessing tool "CrtVoid" is reported. The code extracts surface element information and re-arrange them as input data for CAD/MCNP automatic conversion cord "GEOMIT". Reports includes detail of the development and test results of confirmation of its functions.
Ejiri, Mitsuru*; Kitamura, Kazunori*; Araki, Takao*; Omori, Junji*; Asano, Shiro*; Hayakawa, Atsuro*; Shibama, Yusuke; Masaki, Kei; Sakasai, Akira
no journal, ,
In the operation of tokamak, such loads as electromagnetic and seismic are assumed to be imposed on the vacuum vessel (VV), and not a little thermal expansion takes place when VV is baked. The gravity support leg (GS) has to support the loads described above in addition to the dead weight of VV including in-vessel components and compensate deformation. The GS is equipped with plate spring (PS) to have both stiffness and flexibility. In this study, the buckling strength of the PSs was evaluated. The effect of the initial imperfection of the PSs which is assumed to result from machining or welding process on the buckling strength was also studied. It is concluded that GS has sufficient buckling strength against assumed initial imperfections.
Ejiri, Mitsuru*; Asano, Shiro*; Omori, Junji*; Okuyama, Toshihisa*; Takahashi, Nobuji*; Yamada, Masahiro*; Araki, Takao*; Kai, Toshiya*; Shibama, Yusuke; Masaki, Kei; et al.
no journal, ,
In the operation of Tokamak device, such loads as electromagnetic and seismic are assumed to be imposed on the vacuum vessel (VV), and not a little thermal expansion takes place when VV is baked. The gravity support (GS) has to support the loads described above in addition to the dead weight of VV including in-vessel components and compensate deformation. The GS is equipped with leaf spring that has both stiffness and flexibility. In this study, the FEM analysis-based design and assembly procedure of the GS is reported. The manufacturing process of GS components is also reported with trial manufacturing results.
Kano, Keisuke*; Saruya, Ryota*; Kawabata, Shunsuke*; Araki, Jun*; Noguchi, Katsuya*; Kada, Wataru*; Miura, Kenta*; Kato, Hijiri*; Sato, Takahiro; Koka, Masashi; et al.
no journal, ,
Kawabata, Shunsuke*; Saruya, Ryota*; Kato, Hijiri*; Araki, Jun*; Miura, Kenta*; Kada, Wataru*; Sato, Takahiro; Koka, Masashi; Ishii, Yasuyuki; Kamiya, Tomihiro; et al.
no journal, ,
no abstracts in English
Araki, Shohei; Izawa, Kazuhiko; Gunji, Satoshi; Suyama, Kenya; Ishii, Junichi; Seki, Masakazu; Kobayashi, Fuyumi; Fukaya, Hiroyuki
no journal, ,
To measure critical characteristics of fuel debris, the Static Experiment Critical Facility (STACY) is being converted to the heterogeneous thermal system using fuel rods and light water moderator from the homogeneous system using solution fuel. This report presents an overview and progress of the modified STACY.
Araki, Yasufumi; Ieda, Junichi
no journal, ,
no abstracts in English
Sakai, Takaki*; Yamanouchi, Michihiko*; Araki, Yasufumi; Uemura, Tetsuya*; Ota, Hiromichi*; Ieda, Junichi
no journal, ,
