Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Teshigawara, Makoto; Ikeda, Yujiro*; Muramatsu, Kazuo*; Sutani, Koichi*; Fukuzumi, Masafumi*; Noda, Yohei*; Koizumi, Satoshi*; Saruta, Koichi; Otake, Yoshie*
Journal of Neutron Research, 26(2-3), p.69 - 74, 2024/09
Slow neutrons, such as cold neutrons, are important non-destructive probes not only for basic physics but also for the structural genomics advancements in the life sciences and the battery technology advancements needed for the transition to a hydrogen society. Neutron-based science is also known as high-neutron-intensity-dependent science. A new unique method focusing on nanosized particle aggregation has been proposed to increase neutron intensity in that energy region. The method is based on intensity enhancement by multiple coherent scatterings with nanosized particle aggregation. The aggregation of nanosized particles matches the wavelength of below cold neutrons, causing a similar effect to coherent scattering, so-called Bragg scattering, leading to neutron intensity enhancement by several orders of magnitude. Nanodiamonds and magnesium hydride have recently been studied numerically and experimentally. The major challenge with nanodiamonds in practical applications is the molding method. Another carbon structure, graphene is focused on to find a solution to this problem. It is hypothesized that nanosized graphene could aid coherent neutron scattering under particle size conditions similar to nanodiamonds. We report the potential of nanosized graphene as a reflector material below cold neutrons, together with experimental results.
Kusumoto, Toshiyuki*; Saruta, Koichi; Naoe, Takashi; Teshigawara, Makoto; Futakawa, Masatoshi; Hasegawa, Kazuo*; Tsuboi, Akihiko
Jikken Rikigaku, 23(4), p.310 - 315, 2023/12
Reducing spatter, i.e., melt droplets flown out of the melt pool, is one of the critical issues when laser cutting is employed as a machining tool for radioactive wastes because the ejected droplets can lead to radioactive contamination with potential human exposure. The spattering phenomena are complicated processes that involve multiple physical phenomena, causing difficulty in the determination of laser parameters to minimize the amount of spatter. Here we observe the spatter ejected from 316L stainless steel plates using a high-speed camera and apply a machine learning technique to these captured images on the basis of three distinctive behaviors appeared at specific time intervals of the process of spattering phenomena: (I) a vapor, (II) a liquid film and breakup into droplets, and (III) a liquid capillary. The numerical model established through the machine learning technique predicts the spattering phenomena with an accuracy of 89% and can be used to determine the laser power and beam diameter that reduce the spatter eruption during laser irradiation.
Ariyoshi, Gen; Saruta, Koichi; Kogawa, Hiroyuki; Futakawa, Masatoshi; Maeno, Koki*; Li, Y.*; Tsutsui, Kihei*
Proceedings of 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20) (Internet), p.1407 - 1420, 2023/08
Cavitation damage on a target vessel due to proton beam-induced pressure waves is one of the crucial issues for the pulsed neutron source using a mercury spallation target. As a mitigation technique for the damage, the helium microbubble injection into the mercury has been carried out by using a swirl bubbler in order to utilize compressibility of bubbles. Moreover, double-walled structure, which consists of an outer wall and an inner wall, has been applied as the target head structure. In this study, we aim to develop an abnormality diagnostic technology to detect the inner wall cracking, which is caused by such cavitation damage, from the outside of the target vessel. The mercury flow fields in the case with the cracking are evaluated by computational fluid dynamics analysis based on finite element method. And then, effect of the cracking on the flow field is discussed from the point of view of the flow-induced vibration and the acoustic vibration.
Daido, Hiroyuki*; Yamada, Tomonori; Saruta, Koichi; Miyabe, Masabumi; Ito, Chikara; Shibata, Takuya; Inoue, Kaoru*; Terabayashi, Ryohei*; Hasegawa, Shuichi*
Physica Scripta, 98(3), p.035112_1 - 035112_22, 2023/02
Times Cited Count：1 Percentile：23.32(Physics, Multidisciplinary)Characterization of kW class quasi-continuous wave (a pulse duration of 10 ms) laser interaction with metal targets and those with metal oxide targets are presented in respect to the laser induced breakdown and the successive laser induced melting and evaporation coupled with a mechanical response followed by ejection of various kinds of particles and fragments. An experiment was performed using fiber lasers coupled with a high-speed camera to observe dynamics of the interaction. Ejected fine particles were collected using a cascade impactor and a home-made collector and were observed with electron microscopes. Shapes of irradiation marks were observed with a digital optical microscope. We also measured total ejected mass from a target. The experimental results reveal that firstly the laser threshold intensity of the interaction with the metal target was lower and more stable than those with the metal oxide targets. Secondly, in the stainless steel targets, the dynamics of molten layer created by thermal conduction from the laser heated thin layer and successive particle ejection with less mechanical response by the adjacent solid layer are dominant processes, while in the metal oxide targets, the fracturing in the relatively deeper interaction region coupled with brittle material response having relatively large laser shot to shot fluctuation appears to play a significant role in addition to the laser induced melting.
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：4 Percentile：50.15(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.
Saruta, Koichi; Shirahama, Takuma*; Yamaguchi, Toshihiko; Ueda, Masashi
E-Journal of Advanced Maintenance (Internet), 10(2), p.1 - 8, 2018/08
Saruta, Koichi; Yamaguchi, Toshihiko; Ueda, Masashi
E-Journal of Advanced Maintenance (Internet), 7(4), p.NT75_1 - NT75_8, 2016/02
Saruta, Koichi; Yamaguchi, Toshihiko; Ueda, Masashi
EUR-27790-EN, p.209 - 214, 2016/00
Saruta, Koichi; Kobayashi, Takao*
EUR-26577-EN, p.490 - 496, 2014/07
Saruta, Koichi; Tsukimori, Kazuyuki; Shimada, Yukihiro; Nishimura, Akihiko; Kobayashi, Takao*
Nihon Hozen Gakkai Dai-6-Kai Gakujutsu Koenkai Yoshishu, p.219 - 222, 2009/08
A thermal-resistant fiber Bragg grating (FBG) fabricated by femtosecond laser processing was examined to evaluate the performance as a strain sensor, compared with a conventional FBG sensor. Each FBG was affixed on a stainless-steel beam along with a strain gauge to measure the Bragg wavelength shift as a function of strain. We used the intensity of the reflection spectra from the FBGs as a weighting factor to determine the Bragg wavelengths. Although the strain sensitivity for the thermal-resistant FBG was found to be 0.34 pm/
, a measurement accuracy of 
3 was able to be achieved by employing the Bragg wavelength determination algorithm, which was comparable to a measurement accuracy of 2 for the conventional FBG sensor.
Tachibana, Yukio; Hontani, Koji*; Kojima, Takao; Takeda, Takeshi; Emori, Koichi; Saruta, Toru; Iyoku, Tatsuo; Kunitomi, Kazuhiko
JAERI-Tech 2000-026, p.61 - 0, 2000/03
JAERI-Tech-2000-026.pdf:2.18MB
no abstracts in English
Sakaba, Nariaki; Emori, Koichi; Saruta, Toru
JAERI-Tech 99-072, p.125 - 0, 1999/10
no abstracts in English
猿田 晃一; 直江 崇; 勅使河原 誠; 二川 正敏; 梁 輝
Erkan Nejdet*
JP, 2021-188317 Patent licensing information
【課題】加工により発生するヒュームの大気中への拡散防止およご前記ヒュームを回収可能な加工装置を提供すること。 【解決手段】 加工対象物10の局所部16を溶融するために、前記局所部16を加熱する加熱ヘッド122を備えた加熱装置120と、前記局所部16と前記加熱ヘッド122とを繋ぐ加熱エリア20の外側にミストカバー層40を形成するミスト層形成装置140と、液体からミスト41を生成して前記ミスト層形成装置140に供給するミスト生成装置130と、前記加熱ヘッド122により加熱されて溶融する前記局所部16を前記加工対象物10の加工場所12に沿って移動させる加工位置移動機構30と、を備え、前記ミスト層形成装置140から噴霧された前記ミスト41により、前記加熱エリア20の外周を覆う前記ミストカバー層40を形成した、ことを特徴とする加工装置。
勅使河原 誠; 猿田 晃一
村松 一生*; 池田 裕二郎*; 大竹 淑恵*; 岩田 英里*; 高橋 一馬*; 須谷 康一*
JP, 2022-161968 Patent licensing information
【課題】賦形性がよく、高い放射線場での耐久性にも優れ、さらに、干渉性散乱によって冷中性子や極冷中性子を高強度化することができる、冷中性子や極冷中性子の反射材を提供する。 【解決手段】ナノ炭素構造体を含んでなる三次元形状の炭素構造体であって、前記ナノ炭素構造体はグラフェン骨格を有する20NM未満の厚さの薄片状炭素が花弁状に固定された花弁状構造、および、1~100NMの大きさのシード状構造体が集まって形成された凸凹状構造の少なくとも一つの構造を有するものである、炭素構造体。
勅使河原 誠; 猿田 晃一
村松 一生*; 池田 裕二郎*; 大竹 淑恵*; 岩田 英里*; 高橋 一馬*; 須谷 康一*
JP, 23874741.4 Patent licensing information
Provided is a carbon structure having a three-dimensional shape containing nano-carbon structures, wherein the nano-carbon structures have at least one structure from among a petal-like structure, in which flaky carbon having a graphene framework and a thickness of less than 20 nm is fixed in a petal-like shape, and an uneven structure formed by a collection of seed-like structures having a size of 1 to 100 nm. The carbon structure has favorable shapability and excellent durability in high radiation fields, and is effective as a reflective material for cold neutrons and very cold neutrons, the reflective material being capable of increasing the strength of the cold neutrons and very cold neutrons by coherent scattering.
勅使河原 誠; 猿田 晃一
村松 一生*; 池田 裕二郎*; 大竹 淑恵*; 岩田 英里*; 高橋 一馬*; 須谷 康一*
JP, 19/115,022 Patent licensing information
Provided is a carbon structure having a three-dimensional shape containing nano-carbon structures, wherein the nano-carbon structures have at least one structure from among a petal-like structure, in which flaky carbon having a graphene framework and a thickness of less than 20 nm is fixed in a petal-like shape, and an uneven structure formed by a collection of seed-like structures having a size of 1 to 100 nm. The carbon structure has favorable shapability and excellent durability in high radiation fields, and is effective as a reflective material for cold neutrons and very cold neutrons, the reflective material being capable of increasing the strength of the cold neutrons and very cold neutrons by coherent scattering.
勅使河原 誠; 猿田 晃一
村松 一生*; 池田 裕二郎*; 大竹 淑恵*; 岩田 英里*; 高橋 一馬*; 須谷 康一*
JP, 202380067536.2 Patent licensing information
Provided is a carbon structure having a three-dimensional shape containing nano-carbon structures, wherein the nano-carbon structures have at least one structure from among a petal-like structure, in which flaky carbon having a graphene framework and a thickness of less than 20 nm is fixed in a petal-like shape, and an uneven structure formed by a collection of seed-like structures having a size of 1 to 100 nm. The carbon structure has favorable shapability and excellent durability in high radiation fields, and is effective as a reflective material for cold neutrons and very cold neutrons, the reflective material being capable of increasing the strength of the cold neutrons and very cold neutrons by coherent scattering.
Saruta, Koichi
no journal, ,
no abstracts in English
Ota, Yasufumi; Saruta, Koichi; Noguchi, Shotaro; Ueda, Masashi
no journal, ,
no abstracts in English
