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Journal Articles

Development of flow-induced vibration evaluation methodology based on unsteady fluid flow analysis for large diameter pipe with elbow in JSFR

Hayakawa, Satoshi*; Ishikura, Shuichi*; Watanabe, Osamu*; Kaneko, Tetsuya*; Yamano, Hidemasa; Tanaka, Masaaki

Proceedings of 8th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-8) (USB Flash Drive), 10 Pages, 2012/12

The present methodology was applied to the analysis for the 1/3-scale experiment of the hot-leg pipe of JSFR, and the predicted stress values were compared with the measured stress values. The predicted stress values were underestimated in the case of using the intact pressure fluctuations obtained by the unsteady fluid flow analysis. Therefore, the improvement of the prediction accuracy of the pressure fluctuations on the pipe wall was attempted.

Journal Articles

Neutron scattering studies of the spin-5/2 antiferromagnetic linear trimer substance SrMn$$_3$$P$$_4$$O$$_{14}$$

Hase, Masashi*; D$"o$nni, A.*; Ozawa, Kiyoshi*; Kitazawa, Hideaki*; Sakai, Osamu*; Pomjakushin, V. Y.*; Keller, L.*; Kaneko, Koji; Metoki, Naoto; Kakurai, Kazuhisa; et al.

Journal of Physics; Conference Series, 340, p.012066_1 - 012066_7, 2012/00

 Times Cited Count:1 Percentile:52.44

We determined the magnetic structure below $$T_{rm N1}=2.2(1)$$ K of the spin-5/2 antiferromagnetic (AF) trimer substance SrMn$$_3$$P$$_4$$O$$_{14}$$ using neutron powder diffraction experiments. The incommensurate propagation vector is expressed as [0, $$k_y$$, 0], due to competition between the nearest-neighbor and next-nearest-neighbor interactions in trimerized chains. The value of $$k_y$$ is 0.316 to 0.331, changing rapidly at $$T_{rm N2}= 1.75(5)$$ K. We confirmed that the intra-trimer $$J_1$$ interaction is AF. The magnetic excitation peaks were obsereved at 0.46, 0.68, and 1.02 meV. The weak Q dependence indicates the discrete energy levels, which do not contradict the AF trimer model with the intra-trimer interaction value of 0.29 meV (3.4 K).

Journal Articles

Development of a negative hydrogen ion source for spatial beam profile measurement of a high intensity positive ion beam

Shinto, Katsuhiro; Wada, Motoi*; Nishida, Tomoaki*; Demura, Yasuhiro*; Sasaki, Daichi*; Tsumori, Katsuyoshi*; Nishiura, Masaki*; Kaneko, Osamu*; Kisaki, Masashi*; Sasao, Mamiko*

AIP Conference Proceedings 1390, p.675 - 683, 2011/09

 Times Cited Count:0 Percentile:100

Journal Articles

A Negative ion beam probe for diagnostics of a high intensity ion beam

Shinto, Katsuhiro; Wada, Motoi*; Kaneko, Osamu*; Tsumori, Katsuyoshi*; Nishiura, Masaki*; Sasao, Mamiko*; Kisaki, Masashi*

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.999 - 1001, 2010/05

We propose a negative ion beam probe system as a new scheme to diagnose beam profile of high power positive ion beams. Two RF linacs of IFMIF have to drive the neutron source by providing continuous-wave (CW) positive deuterium ion beams with the intensity of 125 mA each at the beam energy of 40 MeV. During the CW beam operations, the extreme intensity of the beam and the severe radiation levels make the beam diagnostics with conventional techniques in the transport lines terribly difficult. A beam of negative ions liable to lose the additional electron at the occasion of impact with a high energy particle can work as a probe to measure the positive ion beam profile. On possible configuration to achieve high intensity beam profile measurement is to inject a negative ion probe beam into the target beam perpendicularly, and measure the attenuation of the negative ion beam by beam-beam interaction at each position. We have started an experimental study for the proof-of-principle of the new beam profile monitoring system. The paper presents the status quo of this beam profile monitor system development and the prospects to apply the system to the IFMIF beam line controls.

Journal Articles

Dynamics of ion internal transport barrier in LHD heliotron and JT-60U tokamak plasmas

Ida, Katsumi*; Sakamoto, Yoshiteru; Yoshinuma, Mikiro*; Takenaga, Hidenobu; Nagaoka, Kenichi*; Hayashi, Nobuhiko; Oyama, Naoyuki; Osakabe, Masaki*; Yokoyama, Masayuki*; Funaba, Hisamichi*; et al.

Nuclear Fusion, 49(9), p.095024_1 - 095024_9, 2009/09

 Times Cited Count:26 Percentile:26.42(Physics, Fluids & Plasmas)

Dynamics of ion internal transport barrier (ITB) formation and impurity transport both in the Large Helical Device (LHD) heliotron and JT-60U tokamak are described. Significant differences between heliotron and tokamak plasmas are observed. The location of the ITB moves outward during the ITB formation regardless of the sign of magnetic shear in JT-60U and the ITB becomes more localized in the plasma with negative magnetic shear. In LHD, the low Te/Ti ratio ($$<$$ 1) of the target plasma for the high power heating is found to be necessary condition to achieve the ITB plasma and the ITB location tends to expand outward or inward depending on the condition of the target plasmas. Associated with the formation of ITB, the carbon density tends to be peaked due to inward convection in JT-60U, while the carbon density becomes hollow due to outward convection in LHD. The outward convection observed in LHD contradicts the prediction by neoclassical theory.

Journal Articles

Spectroscopic observations of beam and source plasma light and testing Cs-deposition monitor in the large area negative ion source for LHD-NBI

Oka, Yoshihide*; Tsumori, Katsuyoshi*; Ikeda, Katsunori*; Kaneko, Osamu*; Nagaoka, Kenichi*; Osakabe, Masaki*; Takeiri, Yasuhiko*; Asano, Eiji*; Komada, Seiji*; Kondo, Tomoki*; et al.

Review of Scientific Instruments, 79(2), p.02C105_1 - 02C105_4, 2008/02

 Times Cited Count:0 Percentile:100(Instruments & Instrumentation)

In the present studies, we studied the cesium lines in the source plasma during beam shots on the LND MN-NBI system. It was found for the first time in the LHD-source 2, that both the amount of Cs I (neutral Cs) and Cs II (Cs$$^{+}$$) in the source plasma light rose sharply when beam acceleration began, and continued rising during a 10 s pulse. We think that this was because the cesium was evaporated/sputtered from the source backplate by the back-streaming positive ions.

Journal Articles

The H-Invitational Database (H-InvDB); A Comprehensive annotation resource for human genes and transcripts

Yamasaki, Chisato*; Murakami, Katsuhiko*; Fujii, Yasuyuki*; Sato, Yoshiharu*; Harada, Erimi*; Takeda, Junichi*; Taniya, Takayuki*; Sakate, Ryuichi*; Kikugawa, Shingo*; Shimada, Makoto*; et al.

Nucleic Acids Research, 36(Database), p.D793 - D799, 2008/01

 Times Cited Count:50 Percentile:25.11(Biochemistry & Molecular Biology)

Here we report the new features and improvements in our latest release of the H-Invitational Database, a comprehensive annotation resource for human genes and transcripts. H-InvDB, originally developed as an integrated database of the human transcriptome based on extensive annotation of large sets of fulllength cDNA (FLcDNA) clones, now provides annotation for 120 558 human mRNAs extracted from the International Nucleotide Sequence Databases (INSD), in addition to 54 978 human FLcDNAs, in the latest release H-InvDB. We mapped those human transcripts onto the human genome sequences (NCBI build 36.1) and determined 34 699 human gene clusters, which could define 34 057 protein-coding and 642 non-protein-coding loci; 858 transcribed loci overlapped with predicted pseudogenes.

Journal Articles

Extended steady-state and high-beta regimes of net-current free heliotron plasmas in the Large Helical Device

Motojima, Osamu*; Yamada, Hiroshi*; Komori, Akio*; Oyabu, Nobuyoshi*; Muto, Takashi*; Kaneko, Osamu*; Kawahata, Kazuo*; Mito, Toshiyuki*; Ida, Katsumi*; Imagawa, Shinsaku*; et al.

Nuclear Fusion, 47(10), p.S668 - S676, 2007/10

 Times Cited Count:34 Percentile:22.29(Physics, Fluids & Plasmas)

The performance of net-current free heliotron plasmas has been developed by findings of innovative operational scenarios in conjunction with an upgrade of the heating power and the pumping/fuelling capability in the Large Helical Device (LHD). Consequently, the operational regime has been extended, in particular, with regard to high density, long pulse length and high beta. Diversified studies in LHD have elucidated the advantages of net-current free heliotron plasmas. In particular, an internal diffusion barrier (IDB) by a combination of efficient pumping of the local island divertor function and core fuelling by pellet injection has realized a super dense core as high as 5$$times$$10$$^{20}$$ m$$^{-3}$$, which stimulates an attractive super dense core reactor. Achievements of a volume averaged beta of 4.5% and a discharge duration of 54 min with a total input energy of 1.6 GJ (490 kW on average) are also highlighted. The progress of LHD experiments in these two years is overviewed by highlighting IDB, high-beta and long pulse.

Journal Articles

Magnetic fusion energy studies in Japan

Ogawa, Masao*; Iio, Shunji*; Komori, Akio*; Kawahata, Kazuo*; Kaneko, Osamu*; Inoue, Takashi; Kamada, Yutaka

Nuclear Instruments and Methods in Physics Research A, 577(1-2), p.30 - 36, 2007/07

 Times Cited Count:4 Percentile:62.62(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Extended steady-state and high-beta regimes of net-current free heliotron plasmas in the large helical device

Motojima, Osamu*; Yamada, Hiroshi*; Komori, Akio*; Oyabu, Nobuyoshi*; Kaneko, Osamu*; Kawahata, Kazuo*; Mito, Toshiyuki*; Muto, Takashi*; Ida, Katsumi*; Imagawa, Shinsaku*; et al.

Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 12 Pages, 2007/03

The performance of net-current free Heliotron plasmas has been developed by findings of innovative operational scenarios in conjunction with an upgrade of the heating power and the pumping/fueling capability in the Large Helical Device (LHD). Consequently, the operational regime has been extended, in particular, with regard to high density, long pulse length and high beta. Diversified studies in LHD have elucidated the advantages of net-current free heliotron plasmas. In particular, an Internal Diffusion Barrier (IDB) by combination of efficient pumping of the local island divertor function and core fueling by pellet injection has realized a super dense core as high as 5$$times$$10$$^{20}$$m$$^{-3}$$, which stimulates an attractive super dense core reactor. Achievements of a volume averaged beta of 4.5 % and a discharge duration of 54-min. with a total input energy of 1.6 GJ (490 kW in average) are also highlighted. The progress of LHD experiments in these two years is overviewed with highlighting IDB, high $$beta$$ and long pulse.

Journal Articles

Kinetics of the graphite-diamond transformation in aqueous fluid determined by in-situ X-ray diffractions at high pressures and temperatures

Okada, Taku; Utsumi, Wataru; Kaneko, Hiroshi*; Turkevich, V.*; Hamaya, Nozomu; Shimomura, Osamu*

Physics and Chemistry of Minerals, 31(4), p.261 - 268, 2004/05

 Times Cited Count:11 Percentile:56.51(Materials Science, Multidisciplinary)

The graphite-diamond transformation was investigated by in situ time-resolved X-ray diffraction experiments using aqueous fluid containing dissolved MgO as the diamond forming catalyst under conditions of 6.6-8.9 GPa and 1400-1835 $$^{circ}$$C. The transformed volume fractions of diamond as a function of time under various pressure-temperature conditions were obtained and analyzed using the JMAK rate equation. Variations in the nucleation and growth processes during diamond formation as a function of pressure and temperature were clarified.

Journal Articles

X-ray diffraction and absorbtion experiment using large volume high pressure apparatus

Utsumi, Wataru; Katayama, Yoshinori; Saito, Hiroyuki; Kaneko, Hiroshi*; Okada, Taku*; Otaka, Osamu*

Mirai O Hiraku Koatsuryoku Kagaku Gijutsu Semina Shirizu, 28, p.14 - 20, 2004/01

no abstracts in English

Journal Articles

Congruent melting of gallium nitride at 6 GPa and its application to single-crystal growth

Utsumi, Wataru; Saito, Hiroyuki; Kaneko, Hiroshi*; Watanuki, Tetsu; Aoki, Katsutoshi; Shimomura, Osamu

Nature Materials, 2(11), p.735 - 738, 2003/11

 Times Cited Count:125 Percentile:3.84(Chemistry, Physical)

Synthesis of large single crystal GaN (gallium nitride) is a matter of great importance in optoelectronic devices for blue light-emitting diodes and lasers. Although high quality bulk single crystals of GaN suitable for substrates are desired, the standard method of cooling its stoichiometric melt has been unsuccessful for GaN because it decomposes into Ga and N$$_{2}$$ at high temperatures before its melting point. Here we report that applying high pressure completely prevents the decomposition and allows the stoichiometric melt of GaN. At pressures above 6.0 GPa, congruent melting of GaN occurred around 2220$$^{circ}$$C, and decreasing the temperature allowed the GaN melt to reversibly back-transform into the original crystal structure, which was confirmed by in situ X-ray diffraction. Single crystals of GaN were formed by cooling the melt slowly under high pressures and were recovered at ambient conditions.

Journal Articles

Heating and current drive by N-NBI in JT-60U and LHD

Kaneko, Osamu*; Yamamoto, Takumi; Akiba, Masato; Hanada, Masaya; Ikeda, Katsunori*; Inoue, Takashi; Nagaoka, Kenichi*; Oka, Yoshihide*; Osakabe, Masaki*; Takeiri, Yasuhiko*; et al.

Fusion Science and Technology, 44(2), p.503 - 507, 2003/09

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

High energy negative-ion-based neutral beam injection (N-NBI) is expected as an efficient and reliable tool of heating and current driving for reactor plasmas such as ITER. A world wide activity on developing technology of negative ion production and beam formation started in 1980ユs and the great progress has been achieved up to now. In particular, Japan has two large projects that planned adopting N-NBI for real plasma experiments; the JT-60U tokamak and the LHD heliotron, which further motivated the R&D activity. These R&D programs were carried out at JAERI and NIFS separately in Japan, and both were successfully done. The first beam injection experiment was made on the JT-60U in 1996, followed by the LHD in 1998. They were the first experiments on heating plasma by high energy beam in tokamaks and in stellerators, and the obtained results were very promising.

Journal Articles

In situ X-ray observations of the decomposition of brucite and the graphite-diamond conversion in aqueous fluid at high pressure and temperature

Okada, Taku; Utsumi, Wataru; Kaneko, Hiroshi*; Yamakata, Masaaki*; Shimomura, Osamu

Physics and Chemistry of Minerals, 29(7), p.439 - 445, 2002/08

 Times Cited Count:14 Percentile:49.56(Materials Science, Multidisciplinary)

An experimental technique to make real-time observations at high pressure and temperature of the diamond forming process in candidate material of mantle fluids as a catalyst has been established for the first time. In situ X-ray diffraction experiments using synchrotron radiation have been performed upon a mixture of brucite (Mg(OH)$$_{2}$$) and graphite as starting material. Brucite decomposes into periclase (MgO) and H$$_{2}$$O at 3.6 GPa and 1050$$^{circ}$$C while no periclase is formed after the decomposition of brucite at 6.2 GPa and 1150$$^{circ}$$C, indicating that the solubility of the MgO component in H$$_{2}$$O greatly increases with increasing pressure. The conversion of graphite to diamond in aqueous fluid has been observed at 7.7 GPa and 1835$$^{circ}$$C. Time-dependent X-ray diffraction profiles for this transformation have been successfully obtained.

Journal Articles

Report of 16th Symposium on Fusion Engineering (SOFE '95)

Ueda, Shuzo; Kikuchi, Mitsuru; Kimura, Toyoaki; Kunugi, Tomoaki; Kuriyama, Masaaki; Tsuchiya, Kunihiko; Masaki, Kei; Kaneko, Osamu*; Sudo, Shigeru*; Muto, Kei*

Purazuma, Kaku Yugo Gakkai-Shi, 72(2), p.163 - 165, 1996/02

no abstracts in English

Oral presentation

Application of film dosimeter calibrated for cobalt 60 $$gamma$$-ray to low energy electron beam dosimetry

Nakai, Koji*; Sakamoto, Osamu*; Seito, Hajime; Haruyama, Yasuyuki; Kaneko, Hirohisa; Kojima, Takuji

no journal, , 

no abstracts in English

Oral presentation

Development of a beam monitor for high intensity positive ion beams using negative ion beam injection

Shinto, Katsuhiro; Wada, Motoi*; Imakita, Shinsuke*; Kaneko, Osamu*; Tsumori, Katsuyoshi*

no journal, , 

no abstracts in English

Oral presentation

High energy beam profile diagnostics by using a negative ion probe beam, 2

Shinto, Katsuhiro; Wada, Motoi*; Nishida, Tomoaki*; Demura, Yasuhiro*; Sasaki, Daichi*; Tsumori, Katsuyoshi*; Kisaki, Masashi*; Nishiura, Masaki*; Kaneko, Osamu*; Sasao, Mamiko*

no journal, , 

no abstracts in English

Oral presentation

Development of a beam profile monitor using a negative ion probe beam for high intensity positive ion beams

Shinto, Katsuhiro; Wada, Motoi*; Nishida, Tomoaki*; Kisaki, Masashi*; Tsumori, Katsuyoshi*; Nishiura, Masaki*; Kaneko, Osamu*; Sasao, Mamiko*

no journal, , 

We have proposed a negative ion beam probe system as a new scheme to diagnose beam profiles of high power positive ion beams. We show the present status of the proof-of-principle experiment for the negative ion beam probe system performed at NIFS NBI test stand. A negative hydrogen ion source which produces a rectangular shape beam was installed at the diagnostic chamber in the NBI test stand and the total current of H$$^-$$ beam extracted from the ion source was measured. We obtained the total H$$^-$$ beam current of 10 $$mu$$A with the beam energy of 3 kV.

Oral presentation

Study on flow-induced-vibration evaluation of large-diameter pipings in a sodium-cooled fast reactor, 38; Development of fluid-structure coupling analysis methodology based on unsteady fluid flow analysis

Hayakawa, Satoshi*; Ishikura, Shuichi*; Watanabe, Osamu*; Kaneko, Tetsuya; Yamano, Hidemasa; Tanaka, Masaaki

no journal, , 

no abstracts in English

21 (Records 1-20 displayed on this page)