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Teshigawara, Makoto; Ikeda, Yujiro*; Yan, M.*; Muramatsu, Kazuo*; Sutani, Koichi*; Fukuzumi, Masafumi*; Noda, Yohei*; Koizumi, Satoshi*; Saruta, Koichi; Otake, Yoshie*
Nanomaterials (Internet), 13(1), p.76_1 - 76_9, 2023/01
Times Cited Count：2 Percentile：66.71(Chemistry, Multidisciplinary)To enhance neutron intensity below cold neutrons, it is proposed that nanosized graphene aggregation could facilitate neutron coherent scattering under particle size conditions similar to nanodiamond. It might also be possible to use it in high neutron radiation conditions due to graphene's strong sp2 bonds. Using the RIKEN accelerator-driven compact neutron source and iMATERIA at J-PARC, we performed neutron measurement experiments, total neutron cross-section, and small-angle neutron scattering on nanosized graphene aggregation. The measured data revealed, for the first time, that nanosized graphene aggregation increased the total cross-sections and small-angle scattering in the cold neutron energy region, most likely due to coherent scattering, resulting in higher neutron intensities, similar to nanodiamond.
Kureta, Masatoshi; Yamagata, Yoji*; Miyakoshi, Ken*; Mashii, Tatsuya*; Miura, Yoshiaki*; Takahashi, Kazunori*
JAEA-Research 2022-007, 28 Pages, 2022/09
JAEA-Research-2022-007.pdf:8.17MB
To enhance energy separation in a counter-current Ranque-Hilsch vortex tube, a newly designed hollow helical fin was inserted into the hot tube of the vortex tube. In this study, the effect of the fin on the energy separation was investigated using three types of the vortex tube, and then computational fluid dynamics (CFD) simulation has been conducted to understand the experimental results and discuss the flow structure in the vortex tube with the hollow helical fin. As a result, it was found from the experimental data that the fin effectively enhanced energy separation, and that the tube length could be shorten. When the inlet air pressure was 0.5 MPa, the maximum temperature difference from the inlet to the cold exit was 62.2
C. The CFD code employing the Reynolds Stress Model (RSM) turbulence model was used to analyze the fluid dynamics in the vortex tube. As a result, it was confirmed that the temperature, velocity, and pressure distributions changed significantly at the stagnation point, and that the distributions in the tube with the fin were completely different from those without the fin. It was thought that a strong reversing helical vortex flow with small recirculating vortex structure formed between the fin end and the stagnation point on the cold exit side would enhance energy separation in the vortex tube with the hollow helical fin.
Teshigawara, Makoto; Tsuchikawa, Yusuke*; Ichikawa, Go*; Takata, Shinichi; Mishima, Kenji*; Harada, Masahide; Oi, Motoki; Kawamura, Yukihiko*; Kai, Tetsuya; Kawamura, Seiko; et al.
Nuclear Instruments and Methods in Physics Research A, 929, p.113 - 120, 2019/06
Times Cited Count：16 Percentile：86.84(Instruments & Instrumentation)A nano-diamond is an attractive neutron reflection material below cold neutron energy. The total neutron cross section of a nano-diamond was derived from a neutron transmission measurement over the neutron energy range of 0.2 meV to 100 meV because total neutron cross section data were not available. The total cross section of a nano-diamond with particle size of approximately 5 nm increased with a decrease in neutron energy to 0.2 meV. It was approximately two orders of magnitude larger than that of graphite at 0.2 meV. The contribution of inelastic scattering to the total cross section was to be shown negligible small at neutron energies of 1.2, 1.5, 1.9, 2.6, and 5.9 meV in the inelastic neutron scattering measurement. Moreover, small-angle neutron scattering measurements of the nano-diamond showed a large scattering cross section in the forward direction for low neutron energies.
Yoshida, Hajime; Yokoyama, Kenji; Suzuki, Satoshi; Enoeda, Mikio; Akiba, Masato
Review of Scientific Instruments, 77(4), p.043502_1 - 043502_4, 2006/04
Times Cited Count：0 Percentile：0.01(Instruments & Instrumentation)New beam extraction electrode has been developed for a 100 eV level, high-flux, large irradiation area, and steady-state ion beam source to study about plasma wall interaction in fusion reactors. This electrode has two specific features; one is the structure has sub-millimeter order of spherical multi-aperture triode electrodes and the other is to utilize the plasma sheath for ion acceleration. Obtained ion fluxes ware from 1.5
1020 H/m
s to 5.31020 H/ms with the energy from 28 eV/H to 102 eV/H. These values are comparable to those of conventional high flux ion source in spite of such an extremely low energy.
Yoshida, Hajime; Yokoyama, Kenji; Taniguchi, Masaki; Ezato, Koichiro; Suzuki, Satoshi; Akiba, Masato
Fusion Engineering and Design, 81(1-7), p.361 - 366, 2006/02
Times Cited Count：2 Percentile：17.06(Nuclear Science & Technology)A 100 V level, high-flux, large area and steady-state ion beam acceleration has been developed for the investigation of the interactions between fusion edge plasmas and plasma facing materials. We have developed the new electrodes and installed them in the Super Low Energy Ion Source (SLEIS). Obtained hydrogen ion flux is comparable to those of conventional high-flux ion source (
1020 H/ms), though the accelerated voltage is extremely low (60-200 eV). This 100 V level ion beam acceleration will be useful to investigate the plasma wall interaction in divertor.
-ray detectionYamasoto, Kotaro; Tsutsumi, Masahiro; Oishi, Tetsuya*; Yoshizawa, Michio; Yoshida, Makoto
Nuclear Instruments and Methods in Physics Research A, 550(3), p.609 - 615, 2005/09
Times Cited Count：5 Percentile：40.98(Instruments & Instrumentation)A phoswich detector composed of a thin plate CsI(Tl) scintillator and a plastic scintillator (BC-400) has been designed and evaluated to improve the sensitivity in the low-energy region of large-area plastic scintillation detector. Applicability of the CsI(Tl)/Plastic phoswich detector was examined on radioactivity measurement of massive and large-area materials. The rise-time discrimination technique was applied in order to further improve the minimum detectable activity in the low-energy region. On the basis of the estimation of minimum detectable activity, it was made clear that the energy range of large-area plastic scintillation detector can be expanded down to a few tens of keV by adding a thin plate CsI(Tl) scintillator.
Iijima, Hokuto; Hajima, Ryoichi; Uesaka, Mitsuru*; Sakumi, Akira*; Sakamoto, Fumito*; Ueda, Toru*
Proceedings of 2nd Annual Meeting of Particle Accelerator Society of Japan and 30th Linear Accelerator Meeting in Japan, p.501 - 503, 2005/07
We report the availability of velocity bunching in an energy recovery linac (ERL) by a numerical analysis, and the plan of precise measurement of bunching emittance via a double-slit-scan method. The simulation performed for eight TESLA-type cavities reveals successful bunch compression from 3.2 ps to 0.17 ps. Since the residual energy spread after velocity bunching is considerably smaller than the correlated energy spread required for magnetic compression through a recirculation loop, velocity bunching is useful to realized short-pulse and high-brightness X-rays by ERL. The emittance of velocity bunching was calculated to be 1.5 
mm.mrad for the bunch charge of 77pC without the emittance compensation by an external solenoid field. Although the emittance growth due to the space-charge effect was small in the simulation, it is necessary to evaluate the emittance-growth mechanism under velocity bunching. Therefore, the emittance measurement via double-slit-scan method is carrying out in the UTNL-18L.
Iijima, Hokuto; Uesaka, Mitsuru*; Sakamoto, Fumito*; Ueda, Toru*; Kumagai, Noritaka*; Serafini, L.*
Japanese Journal of Applied Physics, Part 1, 44(7A), p.5249 - 5253, 2005/01
Times Cited Count：8 Percentile：32.12(Physics, Applied)We represent an experimental verification of a bunch compression method named "velocity bunching". The velocity bunching based on the rectilinear compression uses a traveling wave accelerating tube as a compressor. The experiment was performed by an S-band photoinjector and a linac at Nuclear Engineering Research Laboratory, University of Tokyo. The shot-by-shot bunch length was measured to be 0.5 
0.1 ps (rms) in average by the femtosecond streak camera for a bunch charge of 1 nC. The experimental result is in good agreement with PARMELA simulations.
Saegusa, Jun; Kawasaki, Katsuya; Mihara, Akira; Ito, Mitsuo; Yoshida, Makoto
Applied Radiation and Isotopes, 61(6), p.1383 - 1390, 2004/12
Times Cited Count：29 Percentile：85.14(Chemistry, Inorganic & Nuclear)no abstracts in English
Matsukawa, Makoto; Tobita, Kenji; Chikaraishi, Hirotaka*; Sagara, Akio*; Norimatsu, Takayoshi*
Purazuma, Kaku Yugo Gakkai-Shi, 80(7), p.559 - 562, 2004/07
Final purpose of the fusion energy development is to utilize the produced fusion power mainly as electric power for the easiness of transmission and conversion. In spite of the type of fusion power plant, large circulating electric power should exist in the plant for the plasma heating, current drive. This paper describes the electric power flow in the nuclear fusion power plants to be built as the DEMO reactor beyond ITER. Here, the necessity of the local energy storage and high efficient converter will be also discussed.
Taniguchi, Masaki; Sato, Kazuyoshi; Ezato, Koichiro; Yokoyama, Kenji; Dairaku, Masayuki; Akiba, Masato
Journal of Nuclear Materials, 313-316(1-3), p.360 - 363, 2003/03
Times Cited Count：10 Percentile：56.31(Materials Science, Multidisciplinary)no abstracts in English
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：55 Percentile：94.89(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 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) even with the thick deposition layer of 
60 
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.
Kume, Tamikazu
Proceedings of 9th International Conference on Radiation Curing (RadTech Asia '03) (CD-ROM), 4 Pages, 2003/00
Utilization of bio-resources by radiation has been investigated for recycling the natural resources and reducing the environmental pollution. Polysaccharides such as chitosan and sodium alginate were easily degraded by irradiation and induced various kinds of biological activities, i.g. anti-microbial activity, promotion of plant growth, suppression of heavy metal stress, phytoalexins induction. Radiation degraded chitosan was effective to enhance the growth of plants in tissue culture. It was demonstrated that the liquid sample irradiation system using low energy EB was effective for the preparation of degraded polysaccharides. Methylcellulose (MC) can be crosslinked under certain radiation condition as same as carboxymethylcellulose (CMC) and produced the biodegradable hydrogel for medical and agricultural use. Treatment of soybean seeds by low energy EB enhanced the growth and the number of rhizobia on the root.
Konno, Chikara; Maekawa, Fujio; Kasugai, Yoshimi; Uno, Yoshitomo; Kaneko, Junichi; Nishitani, Takeo; Wada, Masayuki*; Ikeda, Yujiro; Takeuchi, Hiroshi
Nuclear Fusion, 41(3), p.333 - 337, 2001/03
Times Cited Count：3 Percentile：10.92(Physics, Fluids & Plasmas)no abstracts in English
Kawabata, Yuji*; Ebisawa, Toru*; Tasaki, Seiji*; Suzuki, Masatoshi; Soyama, Kazuhiko
JAERI-Research 2000-019, p.20 - 0, 2000/03
JAERI-Research-2000-019.pdf:0.83MB
no abstracts in English
Miyamoto, Yukihiro; ; Harada, Yasunori
JAERI-Tech 98-039, 44 Pages, 1998/09
no abstracts in English
states in neutron-deficient Ba nucleiAsai, Masato*; Sekine, Toshiaki; Osa, Akihiko; Koizumi, Mitsuo; Kojima, Yasuaki*; Shibata, M.*; *; Kawade, Kiyoshi*
Physical Review C, 56(6), p.3045 - 3053, 1997/12
Times Cited Count：22 Percentile：74.51(Physics, Nuclear)no abstracts in English
Iwata, Tadao*; Iwase, Akihiro
JAERI-Research 97-073, 45 Pages, 1997/10
JAERI-Research-97-073.pdf:1.55MB
no abstracts in English
Tanaka, Atsushi; Shimizu, Takashi*; Kikuchi, Masahiro; Kobayashi, Yasuhiko; Yamashita, Takao*; Watanabe, Hiroshi
JAERI-Conf 97-003, p.323 - 326, 1997/03
no abstracts in English
; Kumamaru, Hiroshige; Murata, Hideo; Kukita, Yutaka
JAERI-Research 96-038, 55 Pages, 1996/07
JAERI-Research-96-038.pdf:1.63MB
no abstracts in English
