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Iwasa, Naohito*; Ishikawa, Shunki*; Kubono, Shigeru*; Sakakibara, T.*; Kominato, Kazuya*; Nishio, Katsuhisa; Matsuda, Makoto; Hirose, Kentaro; Makii, Hiroyuki; Orlandi, R.; et al.
Physical Review C, 103(1), p.015801_1 - 015801_5, 2021/01
Times Cited Count:1 Percentile:19.67(Physics, Nuclear)Toda, Hiroyuki*; Yamaguchi, Masatake; Matsuda, Kenji*; Shimizu, Kazuyuki*; Hirayama, Kyosuke*; Su, H.*; Fujihara, Hiro*; Ebihara, Kenichi; Itakura, Mitsuhiro; Tsuru, Tomohito; et al.
Tetsu To Hagane, 105(2), p.240 - 253, 2019/02
Times Cited Count:0 Percentile:0(Metallurgy & Metallurgical Engineering)no abstracts in English
Yoshida, Kensuke*; Fujioka, Shinsuke*; Higashiguchi, Takeshi*; Ugomori, Teruyuki*; Tanaka, Nozomi*; Kawasaki, Masato*; Suzuki, Yuhei*; Suzuki, Chihiro*; Tomita, Kentaro*; Hirose, Ryoichi*; et al.
Applied Physics Letters, 106(12), p.121109_1 - 121109_5, 2015/03
Times Cited Count:8 Percentile:34.82(Physics, Applied)Yoshida, Kensuke*; Fujioka, Shinsuke*; Higashiguchi, Takeshi*; Ugomori, Teruyuki*; Tanaka, Nozomi*; Ohashi, Hayato*; Kawasaki, Masato*; Suzuki, Yuhei*; Suzuki, Chihiro*; Tomita, Kentaro*; et al.
Applied Physics Express, 7(8), p.086202_1 - 086202_4, 2014/08
Times Cited Count:28 Percentile:73.87(Physics, Applied)We demonstrate high conversion efficiency for extreme ultraviolet (EUV) emission at 6.5-6.7 nm from multiple laser beam-produced one-dimensional spherical plasmas. Multiply charged-state ions produce strong resonance emission lines, which combine to yield intense unresolved transition arrays in Gd, Tb, and Mo. The maximum in-band EUV conversion efficiency was observed to be 0.8%, which is one of the highest values ever reported due to the reduction of plasma expansion loss.
Hirose, Yusuke*; Yoshiuchi, Shingo*; Nishimura, Naoto*; Sakaguchi, Junya*; Enoki, Kentaro*; Iwakawa, Ken*; Miura, Yasunao*; Sugiyama, Kiyohiro*; Onuki, Yoshichika; Settai, Rikio*; et al.
Journal of the Korean Physical Society, 62(12), p.1858 - 1861, 2013/06
Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)Maeda, Yoshihito; Nishimura, Kentaro*; Nakajima, Takahito*; Matsukura, Bui*; Narumi, Kazumasa; Sakai, Seiji
Physica Status Solidi (C), 9(10-11), p.1884 - 1887, 2012/10
Times Cited Count:4 Percentile:88.56We report enhancement of intrinsic photoluminescence (PL) from -FeSi nanocrystals by doping carbon. In the appropriate dose of C ion implantation into the average nanocrystal size of 14 nm, the PL intensity was enhanced by 260% and increase of the exciton binding energy of 1.8 meV in comparison with that of the non-doped nanocrystal. Furthermore, we found that there was a clear correlation between the PL enhancement and increase of the exciton binding energy. This important result suggests that carbon atoms doped in the silicide lattice may play as an isoelectronic trap and probably form bound excitons with stable states as predicted theoretically. We found a new mechanism of the PL enhancement for -FeSi nanocrystals.
Maeda, Yoshihito; Nishimura, Kentaro*; Nakajima, Takahito*; Matsukura, Bui*; Narumi, Kazumasa; Sakai, Seiji
Physica Status Solidi (C), 9(10-11), p.1888 - 1891, 2012/10
Times Cited Count:3 Percentile:83.37We have systematically investigated photoluminescence (PL) properties of -phase nanocrystals which are formed by a phase transition from metastable -FeSi with a Fluorite structure to -FeSi, and succeeded in enhancement of the PL intensity in the optimum conditions of double annealing process. For the PL enhancement, the time of postannealing at 800C is dominated by the time of the preannealing at 400 or 500C which is related to amount of the -phase. After discussing some possible factors, we speculate that the PL enhancement observed in this study may be attributed mainly to improvement of the interface condition between the nanocrystal and Si, because the crystallographic epitaxial relationship among the phases, Si(111)//(111)//(202)/(220) can be maintained during precipitation of the nanocrystal on Si(111).
Shibano, Junichi*; Kajiwara, Kentaro*; Kiriyama, Koji*; Shobu, Takahisa; Suzuki, Kenji*; Nishimura, Suguru*; Miura, Setsuo*; Kobayashi, Michiaki*
Materials Science Forum, 638-642, p.2476 - 2481, 2010/01
Shibano, Junichi*; Kajiwara, Kentaro*; Kiriyama, Koji; Shobu, Takahisa; Suzuki, Kenji*; Nishimura, Suguru*; Miura, Setsuo*; Kobayashi, Michiaki*
Zairyo, 57(7), p.667 - 673, 2008/07
Nishimura, Arata*; Hishinuma, Yoshimitsu*; Seo, Kazutaka*; Tanaka, Teruya*; Muroga, Takeo*; Nishijima, Shigehiro*; Katagiri, Kazumune*; Takeuchi, Takao*; Shindo, Yasuhide*; Ochiai, Kentaro; et al.
AIP Conference Proceedings 824, p.241 - 248, 2005/09
Design activity of International Thermonuclear Experimental Reactor clarifies intense neutron streaming from ports for neutral beam injectors. Energy spectrum of the streaming is very wide and 14 MeV neutron and ray are the typical radiations. Large amount of glass fiber reinforced plastics will be used in a superconducting magnet system as an electric insulation material and a support structure, for such organic material is easy to manufacture, and light and cheap. In this report, effects of 14 MeV neutron and ray irradiation on interlaminar shear strength and fracture mode are investigated using G-10CR small specimen of which configuration was proposed as a standard for evaluation of the interlaminar shear strength.
Ochiai, Kentaro; Nishimura, Arata*; Nishitani, Takeo; Nishijima, Shigehiro*
no journal, ,
NbSn, NbTi wires and glass fiber reinforced plastics (GFRP) are prospective candidate materials of the superconducting coil assembly for fusion reactors. These materials are activated by D-T neutrons penetrating through the reactor core. From the radioactive waste point of view, it is important to investigate the activation properties for these candidate materials. However, no experiment has been done to investigate the activation properties for these materials. Therefore, we have carried out the experimental investigation of the activation properties of NbSn, NbTi wires and GFRP materials. The neutron irradiation experiment has been done by the FNS D-T neutron source of JAEA. We used complex multi-filaments wires of NbSn and NbTi produced by FURUKAWA-electric Ltd. and a commercial GFRP (G10CR) plate. These samples were irradiated up to the neutron fluence of 410n/m corresponding to about one twentieth neutron fluence expected for ITER life time. After the cooling time, the dose rates and the emitted -ray spectra were measured with a survey meter and a Ge detector, respectively. Induced major radioactive nuclides are Nb-92m, Sn-117m, Sn-113 and Co-60 for NbSn, and Nb-92m, Sc-46 and Co-60 for NbTi. Also Na-24, Na-22, Sc-47, Co-57, As-74, Rb-83, Mn-54 and some unknown radioactive nuclides were observed from the irradiated GFRP. It is considered that those radioactive elements are due to the activation of the additive compounds in GFRP. The initial dose rates of the irradiated NbSn, NbTi and GFRP samples were 160Sv/h, 120Sv/h and 20Sv/h, respectively. After 5 months from the irradiation, these dose rates were reduced to 2-4Sv/h. Also, from the measured -ray spectra, it was found that the final dose rates of NbSn and NbTi wires were dominated by Co-60 (5.27y) and the that of GFRP was dominated by Na-22 (2.60y).
Nishimura, Arata*; Hishinuma, Yoshimitsu*; Seo, Kazutaka*; Tanaka, Teruya*; Muroga, Takeo*; Nishijima, Shigehiro*; Katagiri, Kazumune*; Takeuchi, Takao*; Shindo, Yasuhide*; Ochiai, Kentaro; et al.
no journal, ,
A fusion device which creates burning plasma will be equipped with a superconducting magnet system to provide strong magnetic field and maintain the burning plasma. The fusion device also will have plasma heating devices such as neutral beam injectors and electron cyclotron systems. Since these systems need several ports to carry in the energy into plasma, the fusion device has large ports connecting to the systems locates in outside of cryostat. Through these ports, D-T neutron will come out of the burning plasma and damage the surrounding materials. The superconducting magnets also will be irradiated by the streaming neutron. To investigate mechanisms of degradation of superconducting properties, and to construct database of irradiation effect on superconducting magnet materials, a cryogenic target system has been install in Fusion Neutronics Source (FNS) at Japan Atomic Energy Agency (JAEA). The irradiation tests with D-T neutron have been carried out three times and some irradiation effects on superconducting magnet materials are clarified. In this paper, the present status of the cryogenic target system and some irradiation test results will be summarized and presented.
Kiriyama, Koji; Shibano, Junichi*; Nishimura, Suguru*; Shobu, Takahisa; Kaneko, Hiroshi; Kajiwara, Kentaro*; Suzuki, Kenji*
no journal, ,
no abstracts in English
Kiriyama, Koji; Shibano, Junichi*; Kajiwara, Kentaro*; Shobu, Takahisa; Suzuki, Kenji*; Kaneko, Hiroshi; Nishimura, Suguru*; Arai, Takayuki*
no journal, ,
Residual stress measurement is important to understand SCC (Stress Corrosion Cracking) process. In this study, CT (Computed Tomography) imaging and inner strain mapping of steel material (alpha-Fe) have performed at BL28B2 at SPring-8. The result showed that artificial cracking in the sample was clearly measured by CT and that strain maps quite correspond to CT image. Therefore, these methods are very effective tool to measure an inner state of steel material.
Kiriyama, Koji; Shibano, Junichi*; Kajiwara, Kentaro*; Shobu, Takahisa; Suzuki, Kenji*; Kaneko, Hiroshi; Nishimura, Suguru*; Arai, Takayuki*; Miura, Setsuo*; Kobayashi, Michiaki*
no journal, ,
Residual stress measurement is important to understand Stress Corrosion Cracking process. In this study, measurements of imaging and inner stress mapping around a crack-tip in steel material (alpha-Fe) have performed at beam-line BL14B1 and BL28B2 at SPring-8. The results showed that artificial cracking in the sample was clearly measured by imaging and that stress maps quite correspond to the result of imaging. Therefore, these methods are very effective tool for measurement of inner state of steel material.
Nishimura, Arata*; Takeuchi, Takao*; Nishijima, Shigehiro*; Ochiai, Kentaro; Takakura, Kosuke; Shikama, Tatsuo*; Sato, Isamu*; Watanabe, Kazuo*; Nishijima, Gen*
no journal, ,
no abstracts in English
Matsukura, Bui*; Nakajima, Takahito*; Nishimura, Kentaro*; Narumi, Kazumasa; Sakai, Seiji; Maeda, Yoshihito
no journal, ,
no abstracts in English
Nakajima, Takahito*; Nishimura, Kentaro*; Matsukura, Bui*; Narumi, Kazumasa; Sakai, Seiji; Maeda, Yoshihito
no journal, ,
no abstracts in English
Nishimura, Akihiko; Ito, Fuyumi; Terada, Takaya; Tomiyoshi, Kentaro; Oka, Kiyoshi
no journal, ,
no abstracts in English
Maeda, Yoshihito; Nishimura, Kentaro*; Nagasawa, Yoshiyuki*; Narumi, Kazumasa; Sakai, Seiji
no journal, ,
no abstracts in English