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Journal Articles

Full-$$f$$ gyrokinetic simulations of ohmic L-mode plasmas in linear and saturated ohmic confinement regimes

Idomura, Yasuhiro; Dif-Pradalier, G.*; Garbet, X.*; Sarazin, Y.*; Tore Supra Teams*

Physics of Plasmas, 30(4), p.042508_1 - 042508_18, 2023/04

 Times Cited Count:1 Percentile:56.19(Physics, Fluids & Plasmas)

Two time slices in linear and saturated ohmic confinement (LOC and SOC) regimes in a Tore Supra ohmic L-mode discharge are analyzed using nonlinear global full-$$f$$ gyrokinetic simulations, and qualitative features of the LOC-SOC transition are reproduced. The exhaust of carbon impurity ions is caused by fast ion mixing, which is driven by the toroidal field stress. The intrinsic rotation develops in the opposite direction between the LOC and SOC phases, which is characterized by the different features of the mode asymmetry between trapped electron modes in the LOC phase and ion temperature gradient driven modes in the SOC phase, leading to the change of the profile shear stress. The energy fluxes of electrons and deuterium ions are dominant in the LOC and SOC phases, respectively, and the ratio of the energy confinement time between two phases agree with the experimental value.

Journal Articles

Calcium silicate hydrate (C-S-H) gel solubility data and a discrete solid phase model at 25$$^{circ}$$C based on two binary non-ideal solid solutions

Walker, C.; Suto, Shunkichi; Oda, Chie; Mihara, Morihiro; Honda, Akira

Cement and Concrete Research, 79, p.1 - 30, 2016/01

 Times Cited Count:69 Percentile:90.65(Construction & Building Technology)

Modeling the solubility behavior of calcium silicate hydrate (C-S-H) gel is important to make quantitative predictions of the degradation of hydrated ordinary Portland cement (OPC) based materials. Experimental C-S-H gel solubility data have been compiled from the literature, critically evaluated and supplemented with new data from the current study for molar Ca/Si ratios = 0.2-0.83. All these data have been used to derive a discrete solid phase (DSP) type C-S-H gel solubility model based on two binary non-ideal solid solutions in aqueous solution(SSAS). Features of the DSP type C-S-H gel solubility model include satisfactory predictions of pH values and Ca and Si concentrations for all molar Ca/Si ratios = 2.7 $$rightarrow$$ 0 in the C-S-H system, portlandite (CH) for Ca/Si ratios $$>$$ 1.65, congruent dissolution at Ca/Si ratios = 0.85, and amorphous silica (SiO$$_{2 (rm am)}$$) for Ca/Si ratios $$<$$ 0.55 as identified in the current study by IR spectroscopy.

Journal Articles

Dissolution behavior of slag in cement-equilibrated aqueous solutions

Maeda, Toshikatsu; Bamba, Tsunetaka*; Mizuno, Tsuyoshi*; Terakado, Shogo; Kitagawa, Isamu; Numata, Masami

Haikibutsu Gakkai Rombunshi, 17(4), p.271 - 281, 2006/07

no abstracts in English

Journal Articles

Use of GAF-film and PC-scanner for easy high-resolution measurement of ion beam fluence distribution

Agematsu, Takashi; Hanaya, Hiroaki

JAEA-Review 2005-001, TIARA Annual Report 2004, p.355 - 357, 2006/01

We examined a combination of Gaf-chromic film dosimeter HD-810 and an image scanner for a personal computer as two-dimensional densitometer which is cheap, easy to use and allows speedy measurement with high spatial resolution. Linearity of dose response was mesured with RGB component up to 500Gy. The cause of low uniformity in ion beam fluense distribution at the JAERI AVF cyclotron raster beam scanning system was clarified by this method, which was a very sharp concentration of fluence in a beam spot.

Journal Articles

Preparation and characterization of single-phase SiC nanotubes and C-SiC coaxial nanotubes

Taguchi, Tomitsugu; Igawa, Naoki; Yamamoto, Hiroyuki; Shamoto, Shinichi; Jitsukawa, Shiro

Physica E, 28(4), p.431 - 438, 2005/09

 Times Cited Count:83 Percentile:91.14(Nanoscience & Nanotechnology)

Preparation conditions of single-phase SiC nanotubes and C-SiC coaxial nanotubes were investigated. The characterization of single-phase SiC nanotubes and C-SiC coaxial nanotubes were carried out. The SiC nanowires, which were made of the catenated SiC grains of 50-200 nm in diameter, were obtained in carbon nanotubes reacted at 1450 $$^{circ}$$C. The only C-SiC coaxial nanotubes were formed at 1300 $$^{circ}$$C. A few single-phase SiC nantoubes were synthesized at 1200 $$^{circ}$$C for 100 h. More than half number of nanotubes reacted at 1200 $$^{circ}$$C for 100 h were altered to single-phase SiC nantoubes by heat treatment of 600 $$^{circ}$$C for 1h in air since the remained carbon was removed. The energy dispersive X-ray spectroscopy analysis revealed that the atomic ratio of Si to C in single-phase SiC nanotubes was almost 1; these single-phase SiC nanotubes consisted of near-stoichiometric SiC grains.

Journal Articles

Effects of ultrastrong gravitational field on the crystalline state of a Bi-Sb alloy

Huang, X.*; Mashimo, Tsutomu; Ono, Masao; Tomita, Takeshi; Sawai, Tomotsugu; Osakabe, Toyotaka; Mori, Nobuo*

Journal of Applied Physics, 96(3), p.1336 - 1340, 2004/08

 Times Cited Count:11 Percentile:42.77(Physics, Applied)

Mega-gravity field experiments were performed on the Bi$$_{70}$$Sb$$_{30}$$(atomic percent) alloy and pure Bi below their melting points, to investigate the change in crystalline state. For the alloy centrifuged at 191-205 $$^{circ}$$C, no change in composition was observed, and the grain sizes of the crystals decreased from several mm to tens of $$mu$$m, while no distinct change in grain size was observed for the centrifuged pure Bi. The alloy centrifuged at 220-240 $$^{circ}$$C consisted of two regions with different morphologies-fine-grained crystals with grain sizes around tens of $$mu$$m in the low gravity region, and large crystals with grain sizes several mm long and hundreds of $$mu$$m wide along the direction of gravity in the high gravity region, where sedimentation of atoms was confirmed. The large crystals with hexagonal structures were formed by preferential crystal growth roughly along the c axes, and a large strain that increased as the gravitational field increased existed inside these crystals. Formation of this anomalous crystal state might be correlated with the sedimentation of atoms.

Journal Articles

Relationship between the current direction in the inversion layer and the electrical characteristics of metal-oxide-semiconductor field effect transistors on 3C-SiC

Oshima, Takeshi; Lee, K. K.; Ishida, Yuki*; Kojima, Kazutoshi*; Tanaka, Yasunori*; Takahashi, Tetsuo*; Yoshikawa, Masahito; Okumura, Hajime*; Arai, Kazuo*; Kamiya, Tomihiro

Materials Science Forum, 457-460(Part2), p.1405 - 1408, 2004/06

The electrical characteristics of cubic silicon carbide (3C-SiC) Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) with the current direction in the inversion layer perpendicular to [-110] ([-110]-perpendicular MOSFETs) were compared to those of 3C-SiC MOSFETs with the current direction in the inversion layer parallel to [-110] ([-110]-parallel MOSFETs). The threshold voltage (V$$_{T}$$) for both MOSFETs shows -0.5 V although enhancement type MOSFETs were designed. The values of channel mobility which was estimated from linear region of drain current (I$$_{D}$$) - drain voltage (V$$_{D}$$) curves are 230 cm$$^{2}$$/Vs for [-110]-perpendicular MOSFETs and 215 cm$$^{2}$$/Vs for [-110]-parallel MOSFETs, indicating no significant difference between both MOSFETs. The value of I$$_{D}$$ for [-110]-perpendicular MOSFETs is of order of 10-8 A at V$$_{D}$$ = 10V and gate voltage (V$$_{G}$$) of -2V. However, for [-110]-parallel MOSFETs, I$$_{D}$$ shows of order of -10-6 A at V$$_{D}$$ = 10V and V$$_{G}$$ = -2V.

JAEA Reports

Investigation of automatic shutdown of HTTR on May 21st, 2003

Hirato, Yoji; Saito, Kenji; Kondo, Makoto; Sawahata, Hiroaki; Motegi, Toshihiro; Tsuchiyama, Masaru*; Ando, Toshio*; Mizushima, Toshihiko; Nakazawa, Toshio

JAERI-Tech 2004-037, 33 Pages, 2004/04

JAERI-Tech-2004-037.pdf:4.08MB

HTTR (High Temperature Engineering Test Reactor) was operated from May 6th, 2003 to June 18th, 2003 to obtain operation data in parallel loaded operation mode and in safety demonstration tests. Operated with the reactor power at 60% of the rated power on May 21st, HTTR was automatically scrammed by a signalof "Primary coolant flow rate of the Primary Pressurized Water Cooler (PPWC): Low". The cause of the shutdown was the primary gas circulator (A) automatically stopped. The primary coolant flow rate of the PPWC decresed and reached the scram set value due to the gas circulator stop. As a result of investigation, it became clear that the cause of the gas circulator stop was malfunction of an auxiliary relay which monitored electric power of a circuit breaker in power line of the gas circulator. The cause of malfunction was deterioration of the relay under high temperature condition because the relay was installed beside an electric part which was heated up by electricity.

JAEA Reports

Findings of the reactor automatic shutdown caused by a signal of a primary coolant flow rate of the PPWC:Low in the HTTR

Takamatsu, Kuniyoshi; Nakazawa, Toshio; Furusawa, Takayuki; Homma, Fumitaka; Saito, Kenji; Kokusen, Shigeru; Kamata, Takashi; Ota, Yukimaru; Ishii, Yoshiki; Emori, Koichi

JAERI-Tech 2003-062, 94 Pages, 2003/06

JAERI-Tech-2003-062.pdf:26.47MB

no abstracts in English

Journal Articles

The Electrical characteristics of metal-oxide-semiconductor field effect transistors fabricated on cubic silicon carbide

Oshima, Takeshi; Lee, K. K.; Ishida, Yuki*; Kojima, Kazutoshi*; Tanaka, Yasunori*; Takahashi, Tetsuo*; Yoshikawa, Masahito; Okumura, Hajime*; Arai, Kazuo*; Kamiya, Tomihiro

Japanese Journal of Applied Physics, Part 2, 42(6B), p.L625 - L627, 2003/06

 Times Cited Count:39 Percentile:77.43(Physics, Applied)

The n-channel Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) were fabricated on cubic silicon carbide (3C-SiC) epitaxial layers grown on 3C-SiC substrates. The gate oxide of the MOSFETs was formed using pyrogenic oxidation at 1100$$^{circ}$$C. The 3C-SiC MOSFETs showed enhancement type behaviors after annealing at 200$$^{circ}$$C for 30 min in argon atmosphere. The maximum value of the effective channel mobility of the 3C-SiC MOSFETs was 260 cm$$^{2}$$/Vs. The leakage current of gate oxide was of a few tens of nA/cm$$^{2}$$ at an electric field range below 8.5 MV/cm, and breakdown began around 8.5 MV/cm.

JAEA Reports

Lessons learned from remote dismantling activities of JPDR (Contract research)

Tachibana, Mitsuo; Shiraishi, Kunio; Yanagihara, Satoshi

JAERI-Tech 2001-014, 42 Pages, 2001/03

JAERI-Tech-2001-014.pdf:2.4MB

In the JPDR dismantling demonstration project, the dismantling activities were conducted for the purpose of verification of remote dismantling machines and collection of various kinds of data on work activities. These lessons were categorized into safety consideration, waste treatment and work efficiency by analyzing the data on work activities. Exemplified are necessities of facility information, efficiency of mock-up tests for evaluation of remote dismantling procedures. There will be useful for implementing other decommissioning projects in safe and efficiency. This report describes the measure taken for remote dismantling activities and the lessons learned from the dismantling activities.

Journal Articles

Composition adjustment of low activation materials for shallow land burial

Seki, Yasushi; Tabara, Takashi*; Aoki, Isao; Ueda, Shuzo; Nishio, Satoshi; Kurihara, Ryoichi

Fusion Engineering and Design, 48(3-4), p.435 - 441, 2000/09

 Times Cited Count:1 Percentile:12.1(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Effects of steam annealing on electrical characteristics of 3C-SiC metal-oxide-semiconductor structures

Yoshikawa, Masahito; Kojima, Kazutoshi; Oshima, Takeshi; Ito, Hisayoshi; Okada, Sohei; Ishida, Yuki*

Materials Science Forum, 338-342, p.1129 - 1132, 2000/00

no abstracts in English

Journal Articles

Characterizatin of Au Schottky contacts on p-type 3C-SiC grown by low pressure chemical vapor deposition

Kojima, Kazutoshi; Yoshikawa, Masahito; Oshima, Takeshi; Ito, Hisayoshi; Okada, Sohei

Materials Science Forum, 338-342, p.1239 - 1242, 2000/00

no abstracts in English

JAEA Reports

JAEA Reports

Development of compact surveillance and monitoring system, COSMOS

Ogawa, Hironobu; Mukaiyama, Takehiko

JAERI-Tech 99-035, 106 Pages, 1999/03

JAERI-Tech-99-035.pdf:5.11MB

no abstracts in English

Journal Articles

Study of residual defects in ion-implanted and subsequently annealed 3C-SiC

Oshima, Takeshi; Ito, Hisayoshi; Uedono, Akira*; Suzuki, Ryoichi*; Ishida, Yuki*; Takahashi, Tetsuo*; Yoshikawa, Masahito; Kojima, Kazutoshi; Odaira, Toshiyuki*; Nashiyama, Isamu; et al.

Denshi Gijutsu Sogo Kenkyujo Iho, 62(10-11), p.469 - 476, 1999/00

no abstracts in English

Journal Articles

Discrete-variational Dirac-Slater calculation on valence band XPS for UC

Kurihara, Masayoshi*; Hirata, Masaru; Sekine, Rika*; Onoe, Jun*; Nakamatsu, Hirohide*; Mukoyama, Takeshi*; *

Journal of Alloys and Compounds, 283, p.128 - 132, 1999/00

 Times Cited Count:10 Percentile:59.64(Chemistry, Physical)

no abstracts in English

Journal Articles

Development of SiC fiber-reinforced SiC composites by radiation-cured preceramic polymer

Sugimoto, Masaki; Morita, Yosuke; Seguchi, Tadao; *

Key Engineering Materials, 164-165, p.11 - 14, 1999/00

no abstracts in English

80 (Records 1-20 displayed on this page)