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M
ri, A.*; Mazurek, M.*; Ota, Kunio; Siitari-Kauppi, M.*; Eichinger, F.*; Leuenberger, M.*
Minerals (Internet), 11(10), p.1072_1 - 1072_17, 2021/10
Times Cited Count：4 Percentile：34.69(Geochemistry & Geophysics)Tachi, Yukio; Ito, Tsuyoshi*; Akagi, Yosuke*; Sato, Hisao*; Martin, A. J.*
Water Resources Research, 54(11), p.9287 - 9305, 2018/11
Times Cited Count：5 Percentile：26.57(Environmental Sciences)Effects of fine-scale surface alterations on radionuclide migration in fractured crystalline rocks were investigated by a comprehensive approach coupling a series of laboratory tests, microscopic observations and modelling, using a single fractured granodiorite sample from the Grimsel Test Site, Switzerland. Laboratory tests including through-diffusion, batch sorption and flow-through tests using five tracers indicated that tracer retention was consistently in the sequence of HDO, Se, Cs, Ni, Eu, and as well as showing the existence of a diffusion-resistance layer near the fracture surface, cation excess and anion exclusion effects for diffusion. Microscale heterogeneities in structural properties around the fracture were clarified quantitatively by coupling X-ray CT and EPMA. A three layer model including weathered vermiculite, foliated mica and undisturbed matrix layers, and their properties such as porosity, sorption and diffusion parameters, could provide a reasonable interpretation for breakthrough curves and concentration distributions near fracture surface of all tracers, measured in flow-through tests.
-permselective silica membrane for the separation of H from the hydrogen iodide decomposition reaction in the iodine-sulfur processMyagmarjav, O.; Ikeda, Ayumi*; Tanaka, Nobuyuki; Kubo, Shinji; Nomura, Mikihiro*
International Journal of Hydrogen Energy, 42(9), p.6012 - 6023, 2017/03
Times Cited Count：19 Percentile：49.58(Chemistry, Physical)Soler, J. M.*; Landa, J.*; Havlov
, V.*; Tachi, Yukio; Ebina, Takanori*; Sardini, P.*; Siitari-Kauppi, M.*; Eikenberg, J.*; Martin, A. J.*
Journal of Contaminant Hydrology, 179, p.89 - 101, 2015/08
Times Cited Count：39 Percentile：81.5(Environmental Sciences)Matrix diffusion is a key process for radionuclide retention in crystalline rocks. An in-situ diffusion experiment in granite matrix was performed at the Grimsel Test Site (Switzerland). Several tracers (HTO, Na
, Cs) were circulated through a borehole and the decrease in tracer concentrations was monitored for 2.5 years. Then, the borehole section was overcored and the tracer profiles in the rock were analyzed. Transport distances in the rock were 20 cm for HTO, 10 cm for Na and 1 cm for Cs. The dataset was analyzed with diffusion-sorption models by different teams using different codes, with the goal of obtaining effective diffusivities (De) and rock capacity factors. There was a rather good agreement between the values from different teams, implied that De and capacity factors in the borehole damaged zone are larger than those in the bulk rock. However, HTO seems to display large discrepancies between measured and modeled results.
Yonekawa, Izuru; Sueoka, Michiharu; Hosoyama, Hiroki*; Kawamata, Yoichi; Suzuki, Takahiro; Kurihara, Kenichi
Fusion Engineering and Design, 81(15-17), p.1897 - 1903, 2006/07
Times Cited Count：2 Percentile：17.18(Nuclear Science & Technology)Recent years, plasma current profile (j-profile) control has been newly proposed to avoid instabilities in the high normalized-beta plasma. In particular, for the real-time profile feedback control, the control period should be roughly less than several tens of ms, including data communication among relating systems. In order to minimize data transfer time,the profile data being a function of time and position is required to decrease its data size for efficient data handling. A profile data,defined as 3-dimension time series data (q,R,Z,t), was reduced by introducing normalized minor radius rho in place of (R,Z). Data handling for profile control will be presented with their technical issues, together with computing hardware engineering.
Kasai, Satoshi*; Kamiya, Kensaku; Shinohara, Koji; Kawashima, Hisato; Ogawa, Hiroaki; Uehara, Kazuya; Miura, Yukitoshi; Okano, Fuminori; Suzuki, Sadaaki; Hoshino, Katsumichi; et al.
Fusion Science and Technology, 49(2), p.225 - 240, 2006/02
Times Cited Count：3 Percentile：24.11(Nuclear Science & Technology)The diagnostic system of JFT-2M has consisted of about 30 individual diagnostic instruments,which were used to study the plasma production, control, equilibrium, stability, confinement, plasma heating by NBI and/or RF (LH, ICRF, ECH) and current drive by RF. In these instruments, the motional Stark effect (MSE) polarimeter, charge exchanged recombination spectroscopy (CXRS), heavy-ion beam probe (HIBP), time of flight (TOF) neutral particle analyzer, etc. have contributed to make clear the improved mechanism of confinement such as H-mode and High Recycling Steady (HRS) H-mode, and to search the operational region of these modes.The infrared TV camera system and lost ion probe have played a very important role to investigate the heat load onto the walls due to ripple loss particles and escaping ions from core plasma, respectively.
Oikawa, Toshihiro; Suzuki, Takahiro; Isayama, Akihiko; Hayashi, Nobuhiko; Fujita, Takaaki; Naito, Osamu; Tsuda, Takashi; Kurita, Genichi; JT-60 Team
Nuclear Fusion, 45(9), p.1101 - 1108, 2005/09
Times Cited Count：4 Percentile：14.24(Physics, Fluids & Plasmas)Evolution of the current density profile associated with magnetic island formation in a neoclassical tearing mode plasma was measured for the first time in JT-60U by. As the island grew, the current density profile turned flat at the radial region of the island, followed by an appearance of a hollow structure. As the island shrank, the deformed region became narrower, and it finally diminished after the disappearance of the island. In an MHD-quiescent plasma, on the other hand, no deformation was observed. The observed deformation in the current density profile associated with the tearing mode is reproduced in a time dependent transport simulation assuming reduction of the bootstrap current in the radial region of the island. Comparison of the measurement with a calculated steady-state solution also explains the temporal behaviors of the current density and safety factor profiles with reduction and recovery of the bootstrap current. From the experimental observation and simulations, we reach conclusion that the bootstrap current decreases within the island O-point.
n eigenmodes in reversed shear plasmas in JT-60U negative-ion-based neutral beam injection dischargesTakechi, Manabu; Fukuyama, Atsushi*; Ishikawa, Masao; Cheng, C. Z.*; Shinohara, Koji; Ozeki, Takahisa; Kusama, Yoshinori; Takeji, Satoru*; Fujita, Takaaki; Oikawa, Toshihiro; et al.
Physics of Plasmas, 12(8), p.082509_1 - 082509_7, 2005/08
Times Cited Count：34 Percentile：71.2(Physics, Fluids & Plasmas)Rapid frequency sweeping modes observed in reversed magnetic shear (RS) plasmas on the Japan Atomic Energy Research Institute Tokamak 60 Upgrade (JT-60U) have been identified as Reversed-Shear-induced Alfvn Eigenmodes (RSAEs), which are ideal MHD Alfvn eigenmodes (AEs) localized to the region of minimum safety factor, 
, and are excited by negative-ion-based neutral beam injection. The chirping and subsequent saturation of the mode frequency are consistent with theoretical predictions for the transition from RSAEs to Toroidal Alfv
n eigenmodes (TAEs). The previously observed rapid frequency sweeping modes in ion cyclotron wave heated plasmas in JT-60U can also be similarly explained. The observed AE amplitude is largest during the transition from RSAEs to TAEs, and fast ion loss is observed when the AE amplitude is largest at this transition. It is preferable to operate outside the transition range of 
, e.g., 2.4 
2.7 for the n = 1 AE to avoid substantial fast ion loss in RS plasmas.
Ohashi, Hirofumi; Nishihara, Tetsuo; Takeda, Tetsuaki; Inagaki, Yoshiyuki
Proceedings of 13th International Conference on Nuclear Engineering (ICONE-13) (CD-ROM), 8 Pages, 2005/05
A hydrogen production system connected to the High-Temperature Engineering Test Reactor (HTTR) is being designed to be able to produce hydrogen using a nuclear heat of 10 MW supplied by the HTTR. The HTTR hydrogen production system is first connected to a nuclear reactor in the world, hence an mock-up model test is planned to carry out prior to the demonstration test of the HTTR hydrogen production system. In parallel to the mock-up model test, the following tests as an essential problem, a corrosion test of a reforming tube, a permeation test of hydrogen isotopes through a heat exchanger tube, an integrity test of a high-temperature isolation valve, and a performance test of a hydrogen permselective membrane are carried out to obtain detailed data for a safety review and development of analytical codes. This paper describes the present status of the component tests on the R&D of the HTTR hydrogen production system.
Oikawa, Toshihiro; Isayama, Akihiko; Fujita, Takaaki; Suzuki, Takahiro; Tsuda, Takashi; Kurita, Genichi
Physical Review Letters, 94(12), p.125003_1 - 125003_4, 2005/04
Times Cited Count：10 Percentile：53.46(Physics, Multidisciplinary)Evolution of the current density profile associated with the magnetic island formation during a tearing mode was measured for the first time in the JT-60U tokamak. With the island growth, the current density profile turned flat at the radial region of the island, followed by appearance of a hollow structure. As the island shrank, the flat region became narrower, and it finally diminished after disappearance of the island. It was also observed that the local poloidal magnetic field fluctuated in correlation with the island rotation. This indicates that the observed deformation in the current density profile is localized in the O-point of the island. The result is the first experimental demonstration of theoretical predictions on the current density evolution in tearing modes.
Suzuki, Takahiro; Ide, Shunsuke; Hamamatsu, Kiyotaka; Petty, C. C.*; Lao, L. L.*; Isayama, Akihiko; Fujita, Takaaki; Ikeda, Yoshitaka; Seki, Masami; Moriyama, Shinichi; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 80(6), p.511 - 515, 2004/06
no abstracts in English
Suzuki, Takahiro; Ide, Shunsuke; Hamamatsu, Kiyotaka; Isayama, Akihiko; Fujita, Takaaki; Petty, C. C.*; Ikeda, Yoshitaka; Kajiwara, Ken*; Naito, Osamu; Seki, Masami; et al.
Nuclear Fusion, 44(7), p.699 - 708, 2004/05
Times Cited Count：31 Percentile：69.25(Physics, Fluids & Plasmas)no abstracts in English
Suzuki, Takahiro; Oikawa, Toshihiro; Isayama, Akihiko; Fujita, Takaaki
Purazuma, Kaku Yugo Gakkai-Shi, 80(5), p.362 - 363, 2004/05
An analytical method to evaluate spatio-temporal change in current density profile directly from the motional Stark effect (MSE) diagnostic is applied to a discharge, where a neo-classical tearing mode (NTM) appeared and was stabilized by electron cyclotron current drive (ECCD). The analysis clearly shows spatially localized decrease in current density at the magnetic island location, implying decrease in bootstrap current due to flattening of pressure profile within the island. When the NTM is stabilized after the start of the ECCD application, increase in current density at the island location is observed.
Sugie, Tatsuo; Costley, A. E.*; Malaquias, A.*; Walker, C.*
Purazuma, Kaku Yugo Gakkai-Shi, 79(10), p.1051 - 1061, 2003/10
The main regions - the core, the edge, the scrape-off layer, and the divertor - will be probed by an extensive array of spectroscopic instrumentation covering the visible to X-ray wavelength range. Plasma parameters will be determined including impurity species/density/input-flux, ion temperature, He density, fueling ratio, plasma rotation, effective ionic charge and safety factor q. The measurements will be used for plasma control and in studies to understand and improve the performance of ITER. A diagnostic neutral beam (~100 keV) will be installed for Charge Exchange Recombination Spectroscopy. Motional Stark Effect measurements (for q profile) will be made using the heating beam (1 MeV). Diagnostic components, such as mirrors, windows, and optical fibers etc, mounted close to the plasma will experience higher levels of radiation due to neutron, gamma ray and particle irradiations than in present devices. Potentially their performance characteristics can be degraded and so the materials of the components have to be carefully selected and mitigating methods adopted where possible.
- and 
-alumina tube as the support tube in the Hi-HO gaseous mixtureHwang, G.*; Kim, J.*; Choi, H.*; Onuki, Kaoru
Journal of Membrane Science, 215(1-2), p.293 - 302, 2003/04
Times Cited Count：16 Percentile：56.33(Engineering, Chemical)no abstracts in English
Kamiya, Kensaku; Kimura, Haruyuki; Ogawa, Hiroaki; Kawashima, Hisato; Tsuzuki, Kazuhiro; Isei, Nobuaki; Sato, Masayasu; Shinohara, Koji
Purazuma, Kaku Yugo Gakkai-Shi, 78(12), p.1361 - 1367, 2002/12
no abstracts in English
Suzuki, Takahiro; Sugie, Tatsuo
Purazuma, Kaku Yugo Gakkai-Shi, 78(5), p.411 - 416, 2002/05
no abstracts in English
Ikeda, Yoshitaka; Ide, Shunsuke; Suzuki, Takahiro; Kasugai, Atsushi; Takahashi, Koji; Kajiwara, Ken; Isayama, Akihiko; Oikawa, Toshihiro; Hamamatsu, Kiyotaka; Kamada, Yutaka; et al.
Nuclear Fusion, 42(4), p.375 - 382, 2002/04
Times Cited Count：28 Percentile：65.15(Physics, Fluids & Plasmas)no abstracts in English
Suzuki, Takahiro; Ide, Shunsuke; Oikawa, Toshihiro; Ikeda, Yoshitaka; Kajiwara, Ken; Isayama, Akihiko; Fujita, Takaaki; Hamamatsu, Kiyotaka; JT-60 Team
Plasma Physics and Controlled Fusion, 44(1), p.1 - 9, 2002/01
Times Cited Count：18 Percentile：50.83(Physics, Fluids & Plasmas)no abstracts in English
Miura, Yukitoshi; Fujita, Takaaki; Oikawa, Toshihiro; Suzuki, Takahiro; Ide, Shunsuke; Sakamoto, Yoshiteru; Koide, Yoshihiko; Hatae, Takaki; Naito, Osamu; Isayama, Akihiko; et al.
IAEA-CN-94/EX/C3-1Ra (CD-ROM), 5 Pages, 2002/00
no abstracts in English
