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Journal Articles

Monte Carlo shell model studies with massively parallel supercomputers

Shimizu, Noritaka*; Abe, Takashi*; Homma, Michio*; Otsuka, Takaharu*; Togashi, Tomoaki*; Tsunoda, Yusuke*; Utsuno, Yutaka; Yoshida, Toru*

Physica Scripta, 92(6), p.063001_1 - 063001_19, 2017/06

 Times Cited Count:24 Percentile:80.78(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Effect of neutron energy and fluence on deuterium retention behaviour in neutron irradiated tungsten

Fujita, Hiroe*; Yuyama, Kenta*; Li, X.*; Hatano, Yuji*; Toyama, Takeshi*; Ota, Masayuki; Ochiai, Kentaro; Yoshida, Naoaki*; Chikada, Takumi*; Oya, Yasuhisa*

Physica Scripta, 2016(T167), p.014068_1 - 014068_5, 2016/02

 Times Cited Count:30 Percentile:83.05(Physics, Multidisciplinary)

The irradiation defects were introduced by Fe$$^{2+}$$ irradiation, fission neutron irradiation and D-T neutron irradiation. After the irradiation, the deuterium ions (D$$_{2}^{+}$$) implantation was performed and the D retention behavior was evaluated by thermal desorption spectroscopy. The experimental results indicated that dense vacancies and voids within the shallow region near the surface were introduced by Fe$$^{2+}$$ irradiation. The trapping state of D by vacancies and void were clearly controlled by the damage concentration and the voids would become the most stable D trapping site. For fission neutron irradiated W, most of the D was adsorbed on the surface and/or trapped by dislocation loops and no vacancies and voids for D trapping due to its lower damage concentration. D trapping by vacancies were found in the bulk of D-T neutron irradiated W, indicating that the neutron energy distribution could make a large impact on irradiation defect formation and the D retention behavior.

Journal Articles

Development of the radial dose distribution function relevant to the treatment planning system for heavy particle cancer therapy

Moribayashi, Kengo

Physica Scripta, 90(5), p.054013_1 - 054013_5, 2015/05

 Times Cited Count:5 Percentile:41.07(Physics, Multidisciplinary)

Journal Articles

Photoelectron spectra produced from the irradiation of X-ray free-electron laser light pulses onto non-spherically symmetric targets

Moribayashi, Kengo

Physica Scripta, T144, p.014049_1 - 014049_3, 2011/06

 Times Cited Count:2 Percentile:20.32(Physics, Multidisciplinary)

We will soon get new X-ray sources, that is, X-ray free electron lasers (XFELs) which will be developed in USE, EU, and Japan around 2010. If we can use them well, it will bring useful fruits for the man's future. We predict that these high-intensity short-wavelength X-ray sources provide new physical phenomena and that they give rise to new technologies. In this paper, we show the mechanism of the production of hollow atoms and the behavior of photo-electrons produced by high intensity X-rays irradiating a cluster or a bio-molecule. We have also proposed the X-ray flux by using them.

Journal Articles

Radiation damage of C$$_{1}$$H$$_{1}$$, N$$_{1}$$H$$_{1}$$ and O$$_{1}$$H$$_{1}$$ clusters induced by irradiation with X-ray free electron lasers

Kai, Takeshi

Physica Scripta, T144, p.014050_1 - 014050_4, 2011/06

 Times Cited Count:2 Percentile:20.32(Physics, Multidisciplinary)

Journal Articles

Surface morphology and deuterium retention in tungsten exposed to low-energy, high flux pure and helium-seeded deuterium plasmas

Alimov, V.; Shu, Wataru*; Roth, J.*; Sugiyama, Kazuyoshi*; Lindig, S.*; Balden, M.*; Isobe, Kanetsugu; Yamanishi, Toshihiko

Physica Scripta, T138, p.014048_1 - 014048_5, 2009/12

 Times Cited Count:121 Percentile:95.33(Physics, Multidisciplinary)

Blistering and deuterium retention in re-crystallized tungsten exposed to low-energy, high flux (10$$^{22}$$ D/m$$^{2}$$s) pure and helium-seeded D plasmas to a fluence of 10$$^{27}$$ D/m$$^{2}$$ have been examined with scanning electron microscopy, thermal desorption spectroscopy (TDS), and the D($$^{3}$$He,p)$$^{4}$$He nuclear reaction at a $$^{3}$$He energy varied from 0.69 to 4.0 MeV. In the case of exposure to pure D plasma (38 eV/D), blisters with various shapes and sizes depending on the exposure temperature are found on the W surface. No blisters appear at temperatures above 700 K. The deuterium retention increases with the exposure temperature, reaching a maximum value of about 10$$^{22}$$ D/m$$^{2}$$ at 480 K, and then decreases as the temperature rises further. Seeding of helium into the D plasma to the He ion concentration of 0.2 and 5% significantly reduces the D retention at elevated temperatures and prevents formation of the blisters.

Journal Articles

Recent activities related to the development of the plasma facing components for the ITER and fusion DEMO plant

Suzuki, Satoshi; Ezato, Koichiro; Seki, Yohji; Yokoyama, Kenji; Hirose, Takanori; Mori, Seiji; Enoeda, Mikio

Physica Scripta, T138, p.014003_1 - 014003_5, 2009/12

 Times Cited Count:3 Percentile:26.46(Physics, Multidisciplinary)

JAEA is going to procure the whole ITER divertor outer vertical target. The qualification of the ITER divertor components has been started to validate the technical capability of the domestic agencies. JAEA has developed vertical target qualification prototypes which cover most of the critical technical issues toward the series of production. The prototypes have been high heat flux tested in Efremov institute, and showed sufficient durability at 20 MW/m$$^{2}$$. JAEA has successfully obtained the certification from ITER organization. Development of a breeding blanket is one of the most important issues to realize DEMO plant. The engineering testing of the Test Blanket Module (TBM) in ITER is a key milestone toward the DEMO blanket. R&D's on the water-cooled solid breeder blanket has been performed in JAEA. A full-scale length TBM first wall mock-up made of F82H, has been developed by using HIP bonding technique. This mock-up showed sound thermal performance in the high heat flux test.

Journal Articles

MUTA calculations of a laser-produced Mg hollow atom spectrum

Colgan, J.*; Abdallah, J. Jr.*; Faenov, A. Y.; Pikuz, T. A.*; Skobelev, I. Yu.*

Physica Scripta, 78(1), p.015302_1 - 015302_6, 2008/07

 Times Cited Count:10 Percentile:55.62(Physics, Multidisciplinary)

Journal Articles

Microstructure dependence of deuterium retention and blistering in the near-surface region of tungsten exposed to high flux deuterium plasmas of 38 eV at 315 K

Shu, Wataru; Kawasuso, Atsuo; Miwa, Yukio; Wakai, Eiichi; Luo, G.-N.*; Yamanishi, Toshihiko

Physica Scripta, T128, p.96 - 99, 2007/03

 Times Cited Count:86 Percentile:91.94(Physics, Multidisciplinary)

The dependence of deuterium retention and blistering upon the microstructures of tungsten exposed to 38 eV plasma were studied with TDS, PA and SEM. For samples exposed to higher fluences (up to 10$$^{27}$$ D/m$$^{-2}$$), a peculiar phenomenon of bursting release of deuterium was found obviously in TDS spectra, where sudden spikes appeared. SEM observations also confirmed the phenomenon of bursting of blisters, even for the single crystal tungsten (111) exposed to 10$$^{26}$$ D/m$$^{-2}$$ at room temperature. The preliminary PA measurements suggested that the vacancy concentration in the near-surface region of the partially-recrystallized tungsten increased after the exposure, and electron back-scattering diffraction (EBSD) results showed that blisters appeared predominantly on the grains with nearly (111) surface orientation.

Journal Articles

Sub-millimeter synchrotron X-ray focusing by crystal bender

Yoneda, Yasuhiro; Matsumoto, Norimasa; Furukawa, Yukito*; Ishikawa, Tetsuya*

Physica Scripta, T115, p.995 - 997, 2005/00

Sagittal focusing is known as one of the most efficient focusing methods for synchrotron X-rays which increases the photon density at the sample position. Results are reported on the performance of a fixed height exit bender with an unribbed silicon (311) crystal. The fixed height exit was achieved by using a 4-point bending mechanism. This bending mechanism is designed for the SPring-8 standard double crystal monochromator (DCM) of bending-magnet beamlines and the bender is installed as a second crystal of the DCM. By using unribbed crystal, the focusing beam size was kept 0.5 mm in the energy ranges from 35 - 60 keV. Since mirrors for high-energy X-rays are still under development at the moment, focusing techniques by crystal bender are demanded for many practical applications.

Journal Articles

XAFS and spectroscopic characterization for the structure and electronic structure of Ce-DMDPhPDA complexes in methanol

Yaita, Tsuyoshi; Shiwaku, Hideaki; Suzuki, Shinichi; Okamoto, Yoshihiro; Shimada, Asako*; Assefa, Z.*; Haire, R. G.*

Physica Scripta, T115, p.302 - 305, 2005/00

The structural parameter and the electronic structure of the complex between cerium and N,N'-dimethyl-N,N'-diphenylpyridine-2,6-carboxyamide(DMDPhPDA) was investigated by XAFS, photo luminescence and excitation spectra. The DMDPhPDA is one of the promising ligands for separation of trivalent actinides from lanthanides. The Ce-K XAFS spectra were measured at BL11XU of SPring-8. The bond distances between the carbonyl oxygens and cerium, and between the pyridyl nitrogen and cerium are 253pm and 264pm, respectively. The bond angle of the plane consisting of the two carbonyl oxygens and nitrogen with cerium was about 180 degree. This complex was a yellow color unique for the DMDPhPDA-lanthanide complexes. The photo absorption peak for the complex was extremely broad, and the peak position was at a higher wavenumber as compared with those for the other lanthanide complexes. The peak in the highest wavenumber of this band may be attributed to the transition between f and d orbitals, which are greatly influenced by the ligand field of the DMDPhPDA. The XANES spectrum of the cerium complex clearly showed that cerium was trivalent.

Journal Articles

Structural analysis of Co-extracted heptavalent technetium and rhenium complexes by EXAFS

Suzuki, Shinichi; Yaita, Tsuyoshi; Okamoto, Yoshihiro; Shiwaku, Hideaki; Motohashi, Haruhiko*

Physica Scripta, T115, p.306 - 307, 2005/00

In spent fuel reprocessing, distribution behavior of technetium in tri- butyl phosphate (TBP) extraction system is a very complicated. Especially, in the presence of metallic ions, i.e., U(VI), Pu(IV)and Zr(IV)in the TBP extraction system, the extraction of technetium is enhanced by the co- extraction with U, Pu and Zr. The mechanism of co-extraction mechanism of technetium is performed by exchange with nitric acid ion and per-technetate ion. In this research, we perform the structural analysis of technetium complexes in ethanol solution compared with rhenium and manganese complexes by EXAFS. Furthermore we measured some organic complexes and co-extracted complexes of technetium with uranium and zirconium extracted by TBP as compared with those of rhenium.

Journal Articles

Direct observation of the Fe substitution effect on the MCD spectra of the dysprosium iron garnet family

Agui, Akane; Mizumaki, Masaichiro*; Matsushita, Tomohiro*; Kawamura, Naomi*; Nakatani, Takeshi

Physica Scripta, T115, p.611 - 613, 2005/00

no abstracts in English

Journal Articles

First observation of natural circular dichroism for biomolecules in soft X-ray region studied with a polarizing undulator

Tanaka, Masahito*; Nakagawa, Kazumichi*; Agui, Akane; Fujii, Kentaro; Yokoya, Akinari

Physica Scripta, T115, p.873 - 876, 2005/00

no abstracts in English

Journal Articles

Investigation of structural and electronic properties in Ru perovskite oxides by XAFS measurements

Mizumaki, Masaichiro*; Yoshii, Kenji; Hinatsu, Yukio*; Doi, Yoshihiro*; Uruga, Tomoya*

Physica Scripta, T115, p.513 - 515, 2005/00

The electronic and structural properties of Ru oxides were investigated by utilizing X-ray absorption spectroscopy (XAS). We estimate the valence of Ru in perovskite ruthenium oxides by XAS measurements. XAS measurements were carried out at room temperature around Ru K-edge. The valence of Ru in $$A$$$$_{2}$$ ($$A$$ = Ba, Sr)LnRuO$$_{6}$$ and $$A$$ ($$A$$ = Ca, Ba, Sr)RuO$$_{3}$$ was 4+. The valence of Ru in Ln$$_{3}$$RuO$$_{7}$$ was 5+. The valence of Ru in PbRuO$$_{3}$$ showed an intermediate value between 4+ and 5+. Theoretical calculation reproduced the experimental spectra. We analyzed XAS spectra and obtained information of local structure. The bond length between Ru and O was consistent with the results of neutron diffraction.

Journal Articles

Analyses of hydrogen isotope distributions in the outer target tile used in the W-shaped divertor of JT-60U

Oya, Yasuhisa*; Morimoto, Yasutomi*; Oyaizu, Makoto*; Hirohata, Yuko*; Yagyu, Junichi; Miyo, Yasuhiko; Goto, Yoshitaka*; Sugiyama, Kazuyoshi*; Okuno, Kenji*; Miya, Naoyuki; et al.

Physica Scripta, T108, p.57 - 62, 2004/00

no abstracts in English

Journal Articles

Tritium profiles on the surface of graphite tiles used in JT-60U

Sugiyama, Kazuyoshi*; Miyasaka, Kazutaka*; Tanabe, Tetsuo*; Masaki, Kei; Goto, Yoshitaka*; Tobita, Kenji; Kodama, Kozo; Miya, Naoyuki

Physica Scripta, T103, p.56 - 58, 2003/00

 Times Cited Count:14 Percentile:62.9(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Modelling for near-surface transport dynamics of hydrogen of plasma facing materials by use of cellular automaton

Shimura, Kenichiro*; Yamaguchi, Kenji; Terai, Takayuki*; Yamawaki, Michio*

Physica Scripta, T103, p.101 - 104, 2003/00

 Times Cited Count:2 Percentile:21.48(Physics, Multidisciplinary)

In this study, the kinetics of desorption of adsorbed hydrogen from an ideal metallic surface is modeled in Cellular Automaton (CA). The modeling is achieved by downgrading the surface to one dimension. The model consists of two parts that are, surface migration and desorption. The former is attained by randomly sorting the particles at each time, the latter is realized by modeling the thermally-activated process. For the verification of this model, thermal desorption is simulated and then the comparison with the chemical kinetics is carried out. Excellent agreement is observed from the result. The overall results show that this model is reasonable to express the recombinative desorption of two chemisorbed adatoms. Although the application of this model is limited to second-order reaction case, it can be believed that the groundwork of modeling the transport dynamics of hydrogen through the surface under complex conditions is established.

Journal Articles

Application of surface-sensitive techniques to the study of hydrogen behavior in solids

Luo, G.*; Yamaguchi, Kenji; Terai, Takayuki*; Yamawaki, Michio*

Physica Scripta, T94, p.21 - 27, 2001/10

 Times Cited Count:3 Percentile:27.59(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Atom-driven permeation of deuterium through Nb

Okoshi, K.*; Toda, S.*; Shimura, Kenichiro*; Yamaguchi, Kenji; Terai, Takayuki*; Yamawaki, Michio*

Physica Scripta, T94, p.16 - 20, 2001/10

 Times Cited Count:2 Percentile:20.81(Physics, Multidisciplinary)

no abstracts in English

26 (Records 1-20 displayed on this page)