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Ramadhan, R. S.*; Glaser, D.*; Soyama, Hitoshi*; Kockelmann, W.*; Shinohara, Takenao; Pirling, T.*; Fitzpatrick, M. E.*; Tremsin, A. S.*
Acta Materialia, 239, p.118259_1 - 118259_12, 2022/10
Times Cited Count：3 Percentile：45.58(Materials Science, Multidisciplinary)Nakajima, Kenji; Kawakita, Yukinobu; Ito, Shinichi*; Abe, Jun*; Aizawa, Kazuya; Aoki, Hiroyuki; Endo, Hitoshi*; Fujita, Masaki*; Funakoshi, Kenichi*; Gong, W.*; et al.
Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12
The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.
Soyama, Hitoshi*; Futakawa, Masatoshi; Naoe, Takashi*
Tabo Kikai, 34(6), p.336 - 342, 2006/06
no abstracts in English
Futakawa, Masatoshi; Naoe, Takashi; Tsai, C.-C.*; Kogawa, Hiroyuki; Ishikura, Shuichi*; Ikeda, Yujiro; Soyama, Hitoshi*; Date, Hidefumi*
Journal of Nuclear Materials, 343(1-3), p.70 - 80, 2005/08
Times Cited Count：57 Percentile：95.59(Materials Science, Multidisciplinary)no abstracts in English
Soyama, Hitoshi*; Futakawa, Masatoshi; Homma, Kana*
Journal of Nuclear Materials, 343(1-3), p.116 - 122, 2005/08
Times Cited Count：10 Percentile：56.74(Materials Science, Multidisciplinary)In order to estimate life time of the mercury target vessel of spallation neutron source which will be subjected to cavitation impacts, prediction methods of pitting damage induced by the cavitation impact were proposed. It is very important to estimate incubation time, in which plastic deformation occurs without mass loss, because the thickness of vessel is very thin. In the present paper, two estimation methods were proposed. One of them is estimatiion from erosion test of severely damaged specimen by plotting the mass loss as a function of exposure time to cavitation on the logarithmic scales. Another method is the observation method of plastic deformation pits on damaged surface at very early period in incubation stage.
Soyama, Hitoshi*; Futakawa, Masatoshi
Tribology Letters, 17(1), p.27 - 30, 2004/07
Times Cited Count：20 Percentile：58.64(Engineering, Chemical)Estimation have been made, resulting in a general method for the prediction of the incubation time for cavitation erosion using various cavitating conditions and materials. From a single erosion test, the incubation time can be estimated for various conditions and materials by plotting the mass loss as a function of exposure time to cavitation on a log-log scale.
Futakawa, Masatoshi; Kogawa, Hiroyuki; Ishikura, Shuichi*; Kudo, Hisaaki*; Soyama, Hitoshi*
Journal de Physique, IV, 110, p.583 - 588, 2003/09
A liquid-mercury target system for the MW-scale target is being developed in the world. The moment the proton beams bombard the target, pressure waves will be generated in the mercury by the thermally shocked heat deposition. Provided that the negative pressure generates through its propagation in the mercury target and causes cavitation in the mercury, there is the possibility for the cavitation bubbles collapse to form pits on the interface between the mercury and the target vessel wall. In order to estimate the cavitation erosion damage, Split Hopkinson Pressure Bar (SHPB) tests impact tests were performed to impose the impact pressure to the interface between mercury and solid metals. In particular, the surface hardening treated samples: Kolsterising, some coatings are investigated. As results, it is confirmed that the pitting damage is suppressed by surface hardening treatments and relative hardness appeared to be a good correlating parameter on impact erosion resistance.
Yamaguchi, Daisuke; Koizumi, Satoshi; Ojima, Hitoshi*; Isoyama, Ryo*; Ishiwatari, Yoshiyuki*; Kodama, Hiroto*; Takeda, Hisanori*; Fukita, Hitoshi*; Takashima, Yoshiyuki*
no journal, ,
Resin-filler composites were investigated by small-angle neutron scattering (SANS). Two types of fillers, talc and TiO
, were employed and compounded with polypropylene in this study. The dispersion state of the fillers was examined by SANS measurements. In addition, the size distribution of the fillers was separately measured through the laser right scattering and SEM. The calculated scattering function including the polydispersity of fillers whose size distribution reflects the results of laser right scattering and SEM consistently reproduced the experimental SANS scattering profiles.
Kogawa, Hiroyuki; Kawashima, Hiroyuki; Ariyoshi, Gen; Wakui, Takashi; Saruta, Koichi; Naoe, Takashi; Haga, Katsuhiro; Futakawa, Masatoshi; Soyama, Hitoshi*; Kuji, Chieko*; et al.
no journal, ,
In a mercury target system of the J-PARC, an operation injecting microbubbles of helium gas into mercury is carried out to reduce the pressure waves that cause cavitation damage. It was confirmed the damage was mitigated by increasing the injection amount of gas bubbles, while the damage considered to be caused by impact pressure from the gas bubbles was observed. To improve durability, it is necessary to find the optimum bubble condition, and those are also important to evaluate the radiation damage of the vessel material and to develop a diagnosis technology. In this report, as the first report of the series, the outline of the development to improve the durability will be reported with the damage observation results.
Kawashima, Hiroyuki; Kogawa, Hiroyuki; Futakawa, Masatoshi; Soyama, Hitoshi*; Kuji, Chieko*; Tanaka, Nobuatsu*
no journal, ,
In the J-PARC mercury target, helium gas bubbles are injected to mitigate cavitation damage. However, it was recently shown that this injected gas bubbles may cause the damage. In this study, we focused on the local impact force generated when the bubbles collapse, as the first step to propose the optimum condition of the injected gas bubbles. Bubble behavior generated by the underwater spark discharge method near a wall surface was taken by the high-speed camera. At the same time, the vibration on the wall surface due to local impact force was measured with a laser Doppler vibrometer. In addition, bubble behavior was calculated by Keller-Miksis equation. Relationship between local impact force and bubble behavior will be discussed.
