Mesospheric ionization during substorm growth phase

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

https://doi.org/10.1051/swsc/2022012

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.

Distinct variation of electronic states due to annealing in -type LaEuCuO and NdCuO

Asano, Shun*; Ishii, Kenji*; Matsumura, Daiju; Tsuji, Takuya; Kudo, Kota*; Taniguchi, Takanori*; Saito, Shin*; Sunohara, Toshiki*; Kawamata, Takayuki*; Koike, Yoji*; et al.

Physical Review B, 104(21), p.214504_1 - 214504_7, 2021/12

https://doi.org/10.1103/PhysRevB.104.214504

MnVAl Heusler alloy thin films; Appearance of antiferromagnetism and exchange bias in a layered structure with Fe

Tsuchiya, Tomoki*; Kobayashi, Ryota*; Kubota, Takahide*; Saito, Kotaro*; Ono, Kanta*; Ohara, Takashi; Nakao, Akiko*; Takanashi, Koki*

Journal of Physics D; Applied Physics, 51(6), p.065001_1 - 065001_7, 2018/02

https://doi.org/10.1088/1361-6463/aaa41a

Final design of the energy-resolved neutron imaging system "RADEN" at J-PARC

Shinohara, Takenao; Kai, Tetsuya; Oikawa, Kenichi; Segawa, Mariko; Harada, Masahide; Nakatani, Takeshi; Oi, Motoki; Aizawa, Kazuya; Sato, Hirotaka*; Kamiyama, Takashi*; et al.

Journal of Physics; Conference Series, 746, p.012007_1 - 012007_6, 2016/00

https://doi.org/10.1088/1742-6596/746/1/012007

no abstracts in English

Preliminary conceptual design of the secondary sodium circuit-eliminated JSFR (Japan Sodium Fast Reactor) adopting a supercritical CO turbine system, 1; Sodium/CO heat exchanger

Kisohara, Naoyuki; Sakamoto, Yoshihiko; Kotake, Shoji*

JAEA-Research 2014-015, 33 Pages, 2014/09

JAEA-Research-2014-015.pdf:27.33MB

JAEA has performed a design study of an S-CO gas turbine system applied to the JSFR. In this study, the S-CO cycle turbine system was directly connected to the primary sodium system of the JSFR to eliminate the secondary sodium circuit, aiming for further economical improvement. The Na/CO heat exchanger is one of the key components, and this report describes its structure and the safety in case of CO leak. A Printed Circuit Heat Exchanger (PCHE) is employed to the heat exchanger. A SiC/SiC ceramic composite material is used for the PCHE to prevent crack growth and to reduce thermal stress. The Na/CO heat exchanger has been designed in such a way that a number of small heat transfer modules are combined in the vessel in consideration of manufacture and repair. CO leak events in the heat exchanger have been also evaluated, and it revealed that no significant effect has arisen on the core or the primary sodium boundary.

Horonobe Underground Research Laboratory Project; Research and development plan (H22-H26)

Iwatsuki, Teruki; Sato, Haruo; Nohara, Tsuyoshi; Tanai, Kenji; Sugita, Yutaka; Amano, Kenji; Yabuuchi, Satoshi; Oyama, Takuya; Amano, Yuki; Yokota, Hideharu; et al.

JAEA-Research 2011-009, 73 Pages, 2011/06

JAEA-Research-2011-009.pdf:4.41MB

The research and development plan in Horonobe Underground Research Laboratory are summarized according to the 2nd Midterm Plan till 2014 fiscal year of JAEA. In this midterm, galleries and the infrastructures for the research and development up to the depth of 350 m are constructed by Private Financial Initiative (PFI). Additionally Phase 3: Operation phase at the galleries begins in parallel to Phase 2: Construction phase. In these phases various research and development including collaboration with other institutes are conducted at the galleries. Generallic applicable techniques on the subject of the investigation of geological environment, facility construction in deep underground and the reliability of geological deposal are developed during the phase. The feasibility and reliance of various technologies concerning geological disposal is demonstrated by widely opening the outcome to the public in the society.

Anneal temperature effect on crystallite size and electric conductivity of LiMnO

Basar, K.*; Xianglian*; Siagian, S.*; Ohara, Kota*; Sakuma, Takashi*; Takahashi, Haruyuki*; Abe, Osami*; Igawa, Naoki; Ishii, Yoshinobu*

Indonesian Journal of Physics, 20(1), p.9 - 11, 2009/01

Nanosized LiMnO has been successfully prepared by solid state reaction of LiOH and MnO. Neutron scattering experiments at room temperature and conductivity measurement have been performed on the samples. Anneal temperature effect on the crystallite size and electric conductivity of LiMnO is analyzed. The average crystallite size is obtained from the full width at half maximum (FWHM) of Bragg lines using Scherrer equation. The average crystallite size increases with the increase of anneal temperature. Activation energy and conductivity prefactor increase with anneal temperature.

Studies of super-critical CO gas turbine power generation fast reactor(Contract research, Translated document)

Kisohara, Naoyuki; Kotake, Shoji; Sakamoto, Yoshihiko

JAEA-Review 2008-040, 67 Pages, 2008/08

JAEA-Review-2008-040.pdf:3.93MB

(1) Preliminary design of an SFR that adopts a super-critical CO turbine has been made. This SFR system eliminates secondary sodium circuits. The power generation efficiency of the SFR is 42%. Compared to a SFR that adopts a steam cycle with secondary sodium circuits, the reactor building volume of the SC-CO SFR is reduced by 20%. (2) A super-critical CO cycle test loop was fabricated. The high efficiency of a compressor is confirmed near the super-critical region. The temperature efficiencies of PCHE recuperators are 98-99% (hot leg). No flow instability is observed in the loop operation. (3) Na/CO Reaction tests were executed. Continuous reaction occurs more than 570-580C. Reaction products are NaCO and CO. The reaction heat is 50-75kJ/Na-mol. (4) Safety calculation was done for 1 DEG tube failure in Na/CO heat exchanger. The maximum pressure in the primary circuit is below the allowed level. The void reactivity of the reactor core also has no affect. The reaction product brought no sodium flow blockage in fuel assemblies. (5) After an exposure of 600C-5000 hours in super-critical CO environment, the corrosion of 12Cr steel and 316FR were 170g/m and 5g/m, respectively. 316 FR shows a good corrosion proof property.

Microbeam system for heavy ions from cyclotron to irradiate living cells

Yokota, Wataru; Ohara, Yoshihiro; Arakawa, Kazuo

Proceedings of 36th ICFA Advanced Beam Dynamics Workshop (NANOBEAM 2005) (CD-ROM), 6 Pages, 2005/10

no abstracts in English

Effect of hyperthermal atomic oxygen exposures on hydrogenated diamond-like carbon films

Yokota, Kumiko*; Asada, Hidetoshi*; Tagawa, Masahito*; Ohara, Hisanori*; Nakahigashi, Takahiro*; Yoshigoe, Akitaka; Teraoka, Yuden; Martin, J. M.*; Belin, M.*

no journal, , 

Hydrogenated diamond-like carbon (DLC) is expected as a lubricant for space uses because of its ultra low friction charactor in vacuum. Thus, DLC films were exposed to atomic oxygens which were generated by a laser detonation method simulating a low orbit space environment. The DLC surfaces were analysed and the results are reported in this talk. The hydrogenated amorphous DLC was fabricated by a RF-CVD method on Si substrates. Relative collision energy of space planes against atomic oxygens can be simulated with the space environment experimental apparatus. The DLC films exposed to atomic oxygens were analysed by an SR-PES method etc. The SR-PES was performed at the surface chemical reaction analysis station installed in the BL23SU of SPring-8. It was suggested that some volatile oxides were formed and desorbed from the DLC surface when DLC surface was irradiated by atomic oxygens with an incident energy of 4.2 eV and fluence of 510atoms/cm.