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Journal Articles

Magnetic structure of short-range ordering in intermetallic antiferromagnet Mn$$_3$$RhSi

Kodama, Katsuaki; Honda, Takashi*; Yamauchi, Hiroki; Shamoto, Shinichi*; Ikeda, Kazutaka*; Otomo, Toshiya*

Journal of the Physical Society of Japan, 90(7), p.074710_1 - 074710_7, 2021/07

 Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)

Journal Articles

Magnetic pair distribution function of spin-glass system Mn$$_{0.5}$$Fe$$_{0.5}$$TiO$$_3$$

Kodama, Katsuaki; Honda, Takashi*; Ikeda, Kazutaka*; Shamoto, Shinichi; Otomo, Toshiya*

JPS Conference Proceedings (Internet), 33, p.011059_1 - 011059_6, 2021/03

Journal Articles

Magnetic, thermal, and neutron diffraction studies of a coordination polymer; bis(glycolato)cobalt(II)

Nakane, Tomohiro*; Yoneyama, Shota*; Kodama, Takeshi*; Kikuchi, Koichi*; Nakao, Akiko*; Ohara, Takashi; Higashinaka, Ryuji*; Matsuda, Tatsuma*; Aoki, Yuji*; Fujita, Wataru*

Dalton Transactions (Internet), 48(1), p.333 - 338, 2019/01

 Times Cited Count:2 Percentile:18.04(Chemistry, Inorganic & Nuclear)

Journal Articles

Nanoscale ice-type structural fluctuation in spinel titanates

Torigoe, Shuhei*; Hattori, Takayuki*; Kodama, Katsuaki; Honda, Takashi*; Sagayama, Hajime*; Ikeda, Kazutaka*; Otomo, Toshiya*; Nitani, Hiroaki*; Abe, Hitoshi*; Murakawa, Hiroshi*; et al.

Physical Review B, 98(13), p.134443_1 - 134443_7, 2018/10

 Times Cited Count:5 Percentile:27.26(Materials Science, Multidisciplinary)

Journal Articles

Neutron scattering study of yttrium iron garnet

Shamoto, Shinichi; Ito, Takashi; Onishi, Hiroaki; Yamauchi, Hiroki; Inamura, Yasuhiro; Matsuura, Masato*; Akatsu, Mitsuhiro*; Kodama, Katsuaki; Nakao, Akiko*; Moyoshi, Taketo*; et al.

Physical Review B, 97(5), p.054429_1 - 054429_9, 2018/02

 Times Cited Count:14 Percentile:67.35(Materials Science, Multidisciplinary)

Nuclear and magnetic structure and full magnon dispersions of yttrium iron garnet Y$$_3$$Fe$$_5$$O$$_{12}$$ have been studied by neutron scattering. The lowest-energy dispersion below 14 meV exhibits a quadratic dispersion as expected from ferromagnetic magnons. The imaginary part of $$q$$-integrated dynamical spin susceptibility $$chi$$"($$E$$) exhibits a square-root energy-dependence in the low energies. The magnon density of state is estimated from the $$chi$$"($$E$$) obtained on an absolute scale. The value is consistent with a single chirality mode for the magnon branch expected theoretically.

Journal Articles

Study on the behavior of radiolytically produced hydrogen in a high-level liquid waste tank of a reprocessing plant; Comparison between actual and simulated solutions

Kinuhata, Hiroshi*; Yamamoto, Masahiko; Taguchi, Shigeo; Surugaya, Naoki; Sato, Soichi; Kodama, Takashi*; Tamauchi, Yoshikazu*; Shibata, Yuki*; Anzai, Kiyoshi*; Matsuoka, Shingo*

Nuclear Technology, 192(2), p.155 - 159, 2015/11

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Experiments using a small-scale apparatus with 30 ml actual high-level liquid waste from the Tokai Reprocessing Plant were carried out to show that the hydrogen concentration in the gas phase reaches a steady-state value of much less than 4% (lower explosive limit) in the absence of sweeping-air. The H$$_{2}$$ concentration reached a steady-state value as was expected and it was compared with a value predicted from an equation with parameters which had been obtained using the simulated solution. Satisfactory agreement showed that the Pd-ion catalytic H$$_{2}$$ consumption reaction previously found in the simulated solution proceeded equally well in the actual solution.

Journal Articles

Ion acceleration in subcritical density plasma via interaction of intense laser pulse with cluster-gas target

Fukuda, Yuji; Faenov, A.*; Tampo, Motonobu; Pikuz, T.*; Nakamura, Tatsufumi; Kando, Masaki; Hayashi, Yukio; Yogo, Akifumi; Sakaki, Hironao; Kameshima, Takashi*; et al.

Progress in Ultrafast Intense Laser Science VII, p.225 - 240, 2011/05

We present substantial enhancement of the accelerated ion energies up to 10-20 MeV per nucleon by utilizing the unique properties of the cluster-gas target irradiated with 40-fs laser pulses of only 150 mJ energy, corresponding to approximately tenfold increase in the ion energies compared to previous experiments using thin foil targets. A particle-in-cell simulation infers that the high energy ions are generated at the rear side of the target due to the formation of a strong dipole vortex structure in sub-critical density plasmas. The demonstrated method can be important in the development of efficient laser ion accelerators for hadron therapy and other applications.

Journal Articles

Characterization of electron self-injection in laser wake field acceleration due to the parametric resonance

Zhidkov, A.*; Koga, J. K.; Hosokai, Tomonao*; Fujii, Takashi*; Oishi, Yuji*; Nemoto, Koshichi*; Kodama, Ryosuke*

Physics of Plasmas, 17(8), p.083101_1 - 083101_6, 2010/08

 Times Cited Count:11 Percentile:42.17(Physics, Fluids & Plasmas)

Journal Articles

Energy increase in multi-MeV ion acceleration in the interaction of a short pulse laser with a cluster-gas target

Fukuda, Yuji; Faenov, A. Y.; Tampo, Motonobu; Pikuz, T. A.*; Nakamura, Tatsufumi; Kando, Masaki; Hayashi, Yukio; Yogo, Akifumi; Sakaki, Hironao; Kameshima, Takashi*; et al.

Physical Review Letters, 103(16), p.165002_1 - 165002_4, 2009/10

 Times Cited Count:152 Percentile:96.74(Physics, Multidisciplinary)

A new approach for accelerating ions, based on the use of a cluster-gas target and a compact ultrashort pulse laser, is presented. It is shown that ions with energy 10-20 MeV per nucleon having a small divergence (full angle) of 3.4$$^{circ}$$ are generated, corresponding to an approximately tenfold increase in the ion energies compared to previous experiments using solid targets. It is inferred from a particle-in-cell code simulation that the high energy ions are generated at the rear side of the target due to the formation of a strong dipole vortex structure in near-critical density plasmas.

Journal Articles

Ion acceleration in the interaction of short pulse laser radiation with the cluster-gas target

Fukuda, Yuji; Faenov, A. Y.; Tampo, Motonobu; Pikuz, T. A.*; Nakamura, Tatsufumi; Kando, Masaki; Hayashi, Yukio; Yogo, Akifumi; Sakaki, Hironao; Kameshima, Takashi; et al.

AIP Conference Proceedings 1153, p.85 - 93, 2009/07

When the target consists of solid-density clusters embedded in the background gas, its irradiation by high intensity laser light renders ion acceleration a truly unique property. We present that the cluster-gas target, which consists of submicron-sized clusters and background gases, irradiated by a few TW laser pulse produces high energy ions upward of the order of 10-20 MeV/n in the forward direction.

Journal Articles

Front lines of structural analyses by pulsed neutron diffraction

Shamoto, Shinichi; Suzuya, Kentaro; Kamiyama, Takashi*; Kodama, Katsuaki; Otomo, Toshiya*; Fukunaga, Toshiharu*

Purazuma, Kaku Yugo Gakkai-Shi, 84(6), p.323 - 332, 2008/06

Pulsed neutron powder diffraction methods are reviewed, including the prospects at MLF facility in J-PARC center by top level scientists in Japan.

Journal Articles

Introduction to plasma fusion energy

Takamura, Shuichi*; Kado, Shinichiro*; Fujii, Takashi*; Fujiyama, Hiroshi*; Takabe, Hideaki*; Adachi, Kazuo*; Morimiya, Osamu*; Fujimori, Naoji*; Watanabe, Takayuki*; Hayashi, Yasuaki*; et al.

Kara Zukai, Purazuma Enerugi No Subete, P. 164, 2007/03

no abstracts in English

JAEA Reports

2005 Annual report of MEXT specially promoted research, "Development of the 4D space access neutron spectrometer (4SEASONS) and elucidation of the mechanism of oxide high-$$T_c$$ superconductivity"

Arai, Masatoshi; Yokoo, Tetsuya*; Kajimoto, Ryoichi; Nakajima, Kenji; Shamoto, Shinichi; Yamada, Kazuyoshi*; Fujita, Masaki*; Ino, Takashi*; Soyama, Kazuhiko; Nakamura, Mitsutaka; et al.

JAEA-Review 2006-033, 58 Pages, 2006/11

JAEA-Review-2006-033.pdf:17.22MB

A research project entitled "Development of the 4D Space Access Neutron Spectrometer (4SEASONS) and Elucidation of the Mechanism of Oxide High-$$T_c$$ Superconductivity" has started in 2005 (repr. by M. Arai). It is supported by MEXT, Grant-in-Aid for Specially Promoted Research and is going to last until fiscal 2009. The goal of the project is to elucidate the mechanism of oxide high-$$T_c$$ superconductivity by neutron scattering technique. For this purpose, we will develop an inelastic neutron scattering instrument 4SEASONS (4d SpacE AccesS neutrON Spectrometer) for the spallation neutron source in Japan Proton Accelerator Research Complex (J-PARC). The instrument will have 100 times higher performance than existing world-class instruments, and will enable detailed observation of anomalous magnetic excitations and phonons in a four-dimensional momentum-energy space. This report summarizes the progress in the research project in fiscal 2007.

Journal Articles

In-out asymmetry of low-$$Z$$ impurity deposition on the JT-60 divertor tiles

Masaki, Kei; Yagyu, Junichi; Miyo, Yasuhiko; Goto, Yoshitaka*; Arai, Takashi; Hayashi, Takao; Kodama, Kozo; Sasajima, Tadayuki; Kaminaga, Atsushi; Tanabe, Tetsuo*; et al.

Journal of Nuclear Materials, 329-333(Part1), p.845 - 848, 2004/08

 Times Cited Count:0 Percentile:0.01(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Transmission electron microscopy of redeposition layers on graphite tiles used for open divertor armor of JT-60

Goto, Yoshitaka*; Arai, Takashi; Yagyu, Junichi; Masaki, Kei; Kodama, Kozo; Miya, Naoyuki

Journal of Nuclear Materials, 329-333(1), p.840 - 844, 2004/08

 Times Cited Count:15 Percentile:69.87(Materials Science, Multidisciplinary)

TEM and Selected Area Diffraction (SAD) were made on nm-structures of redeposition layers on graphite tiles used in the lower-X-point divertor of JT-60. The tiles were used in the 1988 experimental campaign in which 300 divertor discharges and 1500 limiter discharges were made. TEM observations were made at poloidal and/or toroidal sections at two positions on the inboard side of the inner-separatrix strike point. Layer structures in 0-6micron depths were correlated to the last 40-shots in the campaign. Columnar structures corresponded to divertor discharges of additional heating power below 10MW. Lamellar structures were due to limiter discharges or to the higher power divertor discharges. Carbon-Mo, Ti or carbon-Ni, Fe, Cr, Ti codeposition layers were ascribed to disruptive shots. From analyses on poloidal orientation of the column axes and graphene sheets composing columns, the observed columnar structures were ascribed to both low adatom-migration due to the low deposition temperatures and also to self-shadowing effects due to inclined incidence of carbon impurity ions.

Journal Articles

Tritium distribution in the first wall of JT-60U

Masaki, Kei; Sugiyama, Kazuyoshi*; Tanabe, Tetsuo*; Goto, Yoshitaka*; Tobita, Kenji; Miyo, Yasuhiko; Kaminaga, Atsushi; Kodama, Kozo; Arai, Takashi; Miya, Naoyuki

Nihon Genshiryoku Gakkai Wabun Rombunshi, 2(2), p.130 - 139, 2003/06

no abstracts in English

Journal Articles

Tritium distribution in JT-60U W-shaped divertor

Masaki, Kei; Sugiyama, Kazuyoshi*; Tanabe, Tetsuo*; Goto, Yoshitaka*; Miyasaka, Kazutaka*; Tobita, Kenji; Miyo, Yasuhiko; Kaminaga, Atsushi; Kodama, Kozo; Arai, Takashi; et al.

Journal of Nuclear Materials, 313-316, p.514 - 518, 2003/03

 Times Cited Count:54 Percentile:95.06(Materials Science, Multidisciplinary)

Detailed tritium profiles on the JT-60U W-shaped divertor and first wall tiles were examined by Tritium Imaging Plate Technique (TIPT) and full combustion method. The tritium deposition image obtained by TIPT was consistent with the distribution measured by combustion method. The highest tritium concentration was 60 kBq/cm$$^{2}$$ at the dome top tile. However, deposition layer was not obviously observed on the dome top tile. The tritium concentration in the inner divertor target tile was lower (2 kBq/cm$$^{2}$$) even with the thick deposition layer of $$sim$$60 $$mu$$m. This tritium distribution can be explained by energetic triton particle loss due to ripple loss. According to the simulation using the OFMC code, 31% of the triton particles produced by D-D nuclear reaction is implanted deeply to the wall without fully losing the initial energy of 1 MeV.

Journal Articles

Analyses of erosion and re-deposition layers on graphite tiles used in the W-shaped divertor region of JT-60U

Goto, Yoshitaka*; Yagyu, Junichi; Masaki, Kei; Kizu, Kaname; Kaminaga, Atsushi; Kodama, Kozo; Arai, Takashi; Tanabe, Tetsuo*; Miya, Naoyuki

Journal of Nuclear Materials, 313-316, p.370 - 376, 2003/03

 Times Cited Count:45 Percentile:93.38(Materials Science, Multidisciplinary)

Erosion and re-deposition were studied for graphite tiles from W-shaped divertor region of JT-60U in Jun. 1997 - Oct. 1998 periods in which more than 3000 D-D discharges were made with all-carbon wall with boronizations and inner-private flux pumping. On the outer divertor targets, erosion was dominant: maximum erosion depth of around 20 micrometers was measured, while on the inner targets, re-deposition was dominant: columnar structure layers and laminar/columnar-layered structures of maximum thickness around 60 micrometers were found. Through XPS analysis, compositions of the re-deposition layers at a around mid point on the inner target were 94 - 95 at% C, 3 - 4 at% B, and less than 0.6 at% O, Fe, Cr, and Ni. Boron is mainly bound to Carbon. No continuous deposition layers on the dome top/outer wing, while deposition layers were found on the inner wing. Observed in/out asymmetry is attributable to in/out asymmetry of plasma particle conditions in the divertor region.

Journal Articles

Wall conditioning and experience of the carbon-based first wall in JT-60U

Masaki, Kei; Yagyu, Junichi; Arai, Takashi; Kaminaga, Atsushi; Kodama, Kozo; Miya, Naoyuki; Ando, Toshiro; Hiratsuka, Hajime; Saido, Masahiro

Fusion Science and Technology (JT-60 Special Issue), 42(2-3), p.386 - 395, 2002/09

 Times Cited Count:9 Percentile:52.78(Nuclear Science & Technology)

The wall conditioning of JT-60U consists of the 300$$^{circ}$$C baking, He-TDC, He-GDC, tokamak discharge cleaning and boronization. Using these methods, total pressure of the vacuum vessel reached finally 10$$^{-6}$$ $$sim$$ 10$$^{-5}$$ Pa. The oxygen impurity was decreased to $$sim$$0.5%. The experience with the carbon-based first wall showed that taper shaping is effective to reduce the local heat concentration to the tile edges. The observed poloidal asymmetric deposition of carbon on the divertor region implies that the carbon impurity produced in the outer divertor contributes to the deposition on the inner divertor. In 1992 and 1993, the B$$_{4}$$C converted CFC tiles were installed in the outer divertor to reduce chemical sputtering of CFC tiles and oxygen impurity. The reduction was successfully demonstrated with the B$$_{4}$$C converted CFC tiles. In order to understand the tritium behavior in JT-60U, tritium in the first wall and the exhaust gas were measured. The estimated tritium inventory in the first wall was $$sim$$50% of the generated tritium.

Journal Articles

Quality evaluation of graphites and carbon/carbon composites during production of JT-60U plasma facing materials

Ando, Toshiro; Kodama, Kozo; Yamamoto, Masahiro; Arai, Takashi; Kaminaga, Atsushi; Horiike, Hiroshi; Eto, Motokuni; Fukaya, Kiyoshi; Kiuchi, Teruo*; Teruyama, Kazuhiro*; et al.

Journal of Nuclear Materials, 191-194(2), p.1423 - 1427, 1992/09

no abstracts in English

53 (Records 1-20 displayed on this page)