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Generation of particles and fragments by quasicontinuous wave fiber laser irradiation of stainless steel, alumina, and concrete materials

大道 博行*; 山田 知典; 古河 裕之*; 伊藤 主税; 宮部 昌文; 柴田 卓弥; 長谷川 秀一*

Journal of Laser Applications, 33(1), p.012001_1 -  012001_16, 2021/02

In order to preserve a safe working environment, in particular for nuclear decommissioning like the Fukushima Daiichi Nuclear Power Station, special care should be taken to confine and retrieve such particles during laser processing. In the experiments, particle production from the vapor, as well as the molten phase layer in the targeted material were observed with a high speed camera with fine particles collected and analyzed using an electron microscope. The observed results were qualitatively interpreted with the help of a simplified one-dimensional hydrodynamic code coupled with a stress computation code. Characterization and classification of the results are expected to provide a useful database which will contribute to the decommissioning of nuclear facilities as well as other industrial applications.


Development of a laser chipping technique combined with water jet for retrieval of fuel debris at Fukushima Daiichi Nuclear Power Station

山田 知典; 武部 俊彦*; 石塚 一平*; 大道 博行*; 羽成 敏秀; 柴田 卓弥; 大森 信哉*; 黒澤 孝一*; 佐々木 豪*; 中田 正宏*; et al.

Journal of Nuclear Science and Technology, 56(12), p.1171 - 1179, 2019/12

 被引用回数:0 パーセンタイル:100(Nuclear Science & Technology)



Study on optical properties of metallic sodium by vacuum ultra violet in UVSOR

河口 宗道; 斉藤 淳一; 大道 博行*; 末元 徹*

UVSOR-46, P. 89, 2019/08




大道 博行*; 山田 知典

オプトロニクス, 37(12), p.67 - 71, 2018/12

日本においては1960年代から70年代にわたる高度経済成長期に道路、トンネル, 橋梁等、公共インフラが集中的に建設された。現在、50年の年月を経て、その適切な保全・維持管理と更新が焦眉の課題になっている。このような焦眉の国家的課題の要請に呼応するかのように、新たなレーザー応用技術の開発が進んでいる。インフラの健全性を診断するための非破壊リモートセンシング技術、補修や更新に資する技術などが対象である。本稿では、これらの中で、補修や更新に貢献することが期待されるコンクリート構造物のレーザーによる切断技術に関し筆者らの研究を中心に紹介する。


Experimental characterization of concrete removal by high-power quasicontinuous wave fiber laser irradiation

Nguyen, P. L.; 大道 博行; 山田 知典; 西村 昭彦; 長谷川 登*; 河内 哲哉*

Journal of Laser Applications, 29(4), p.041501_1 - 041501_11, 2017/11

 被引用回数:4 パーセンタイル:58.5(Materials Science, Multidisciplinary)




大道 博行

レーザー研究, 45(7), p.397 - 398, 2017/07

本特集号ではレーザーのインフラ保全、交換へのレーザー技術の可能性を紹介する。例えばトンネル、電力施設、原子力施設、などが対象である。関連するレーザー技術としてはリモートセンシング、その中のLIBS, LIDAR、レーザーと結びついた遠隔技術、表面クリーニング技術を順次紹介する。


Demonstration of laser processing technique combined with water jet technique for retrieval of fuel debris at Fukushima Daiichi Nuclear Power Station

羽成 敏秀; 武部 俊彦*; 山田 知典; 大道 博行; 石塚 一平*; 大森 信哉*; 黒澤 孝一*; 佐々木 豪*; 中田 正宏*; 酒井 英明*

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 3 Pages, 2017/04




大道 博行

レーザー研究, 45(3), p.135 - 136, 2017/03



Type II shell evolution in $$A=70$$ isobars from the $$N geq 40$$ island of inversion

Morales, A. I.*; Benzoni, G.*; Watanabe, H.*; 角田 佑介*; Otsuka, T.*; 西村 俊二*; Browne, F.*; Daido, R.*; Doornenbal, P.*; Fang, Y.*; et al.

Physics Letters B, 765, p.328 - 333, 2017/02

 被引用回数:21 パーセンタイル:6.23(Astronomy & Astrophysics)

The level schemes of neutron-rich isotopes $$^{70}$$Co and $$^{70}$$Ni were populated in the $$beta$$ decay of $$^{70}$$Fe and studied using $$beta$$-delayed $$gamma$$-ray spectroscopy of the $$beta$$ decay, at the RIBF in RIKEN, Japan. The experimental results were compared to state-of-the-art shell-model calculations, and indicate a dominance of prolate deformation in the low-lying states, coexisting with spherical states. The $$beta$$ decay of the $$A=70$$ isobars is shown to progress in accordance to a new type of shell evolution, the so-called Type II, which involves many particle-hole excitations across energy gaps.


Contributions to the decommissioning of Fukushima Daiichi Nuclear Power Station by JAEA Naraha Remote Technology Development Center

大道 博行; 川妻 伸二; 小島 久幸; 石原 正博; 中山 真一

Proceedings of 54th Annual Meeting of Hot Laboratories and Remote Handling (HOTLAB 2017) (Internet), 8 Pages, 2017/00

Naraha Remote Technology Development Center of Japan Atomic Energy Agency has started full operation on April 1st 2016. We describe the role, details of the facility including mock-ups and virtual reality system coupled with the robot simulation techniques for mainly the decommissioning of Fukushima Daiichi Nuclear Power Station. We also emphasize our own research and development to encourage and to contribute to facility utilization. The facility is open for domestic as well as foreign users who wish to contribute to the decommissioning as well as revitalization of Fukushima.



大道 博行

保全学, 15(3), p.20 - 25, 2016/10



レーザーを活用した国土強靭化と廃炉技術への展開; レーザーの過酷環境下での利用・モバイル化を目指して

大道 博行

建設機械, 52(10), p.53 - 58, 2016/10

廃炉から国土強靭化に向けたレーザー利用 原子炉の廃炉において優れた特長を有するレーザー技術に対して期待が寄せられている。一方インフラの診断・補修に向けた技術と廃炉技術は持続可能社会に向けた共通の技術的基盤を有し、連携を取って進めるべき技術であることが明らかになってきた。この具体的内容を図を交えて解説した。


レーザ加工技術,1; 原子力分野への新展開

大道 博行

電気学会誌, 136(7), p.422 - 425, 2016/07




大道 博行

Isotope News, (743), p.7 - 11, 2016/03



Low-lying excitations in $$^{72}$$Ni

Morales, A. I.*; Benzoni, G.*; Watanabe, H.*; 西村 俊二*; Browne, F.*; Daido, R.*; Doornenbal, P.*; Fang, Y.*; Lorusso, G.*; Patel, Z.*; et al.

Physical Review C, 93(3), p.034328_1 - 034328_14, 2016/03

 被引用回数:16 パーセンタイル:16.06(Physics, Nuclear)

Low-lying excited states in $$^{72}$$Ni have been investigated at RIKEN by studying the $$beta$$ decay of $$^{72}$$Co to $$^{72}$$Ni. $$^{72}$$Co was separated with BigRIPS, implanted into the WaS3ABi Silicon array, and the $$gamma$$ ray measured using the EURICA $$gamma$$ spectrometer. From the analysis, 60 new $$gamma$$-ray transitions and 21 new levels in $$^{72}$$Ni were observed. The new experimental information is compared to shell-model calculations which include neutron excitation across the $$fpg$$ shell. The calculations reproduce rather well the observed states, implying that a clear understanding of these low-lying excitations has been achieved.


Decay properties of $$^{68,69,70}$$Mn; Probing collectivity up to N=44 in Fe isotopic chain

Benzoni, G.*; Morales, A. I.*; Watanabe, H.*; 西村 俊二*; Coraggio, L.*; Itaco, N.*; Gargano, A.*; Browne, F.*; Daido, R.*; Doornenbal, P.*; et al.

Physics Letters B, 751, p.107 - 112, 2015/12

 被引用回数:14 パーセンタイル:21.8(Astronomy & Astrophysics)

The $$beta$$ decays of $$^{68,69,70}$$Mn have been measured at the RIBF facility at RIKEN using the EURICA $$gamma$$ spectrometer combined with an active stopper consisting of a stack of Si detectors. Half-lives and $$beta$$-delayed neutron emission probabilities have been extracted for these decays, together with first experimental information on excited states populated in $$^{69,70}$$Fe. The data indicate a continuously increasing deformation for Fe isotopes up to A=70, and interpreted to be due to the interplay between quadrupole correlation of specific neutron orbitals and the monopole component of the proton-neutron interaction.


Surface modification effects on hydrogen absorption property of a hydrogen storage alloy by short pulse laser irradiation

阿部 浩之; 下村 拓也; 徳平 真之介*; 島田 幸洋*; 竹仲 佑介*; 古山 雄太*; 西村 昭彦; 内田 裕久*; 大道 博行; 大島 武

Proceedings of 7th International Congress on Laser Advanced Materials Processing (LAMP 2015) (Internet), 4 Pages, 2015/08



High order harmonics from relativistic electron spikes

Pirozhkov, A. S.; 神門 正城; Esirkepov, T. Z.; Faenov, A. Y.*; Pikuz, T. A.*; 河内 哲哉; 匂坂 明人; Koga, J. K.; 森 道昭; 川瀬 啓悟*; et al.

RAL-TR-2015-025, P. 22, 2015/00

We provide a description of experiments performed with the J-KAREN and Astra Gemini lasers where we discovered a new regime of relativistic high-order harmonic generation by multi-terawatt femtosecond lasers in gas targets. The results were explained using particle-in-cell simulations and catastrophe theory. Our work paves the way towards a bright coherent X-ray source based on compact lasers and accessible, repetitive, and debris-free gas jet targets. Such a source will be crucial for fundamental research and numerous applications requiring pumping, probing, imaging of microscopic objects and for attosecond science.


Demonstration of heat resistant fiber Bragg grating sensors based on femtosecond laser processing for vibration monitoring and temperature change

西村 昭彦; 竹仲 佑介*; 古山 雄大*; 下村 拓也; 寺田 隆哉; 大道 博行

Journal of Laser Micro/Nanoengineering, 9(3), p.221 - 224, 2014/11

 被引用回数:0 パーセンタイル:100(Nanoscience & Nanotechnology)



High order harmonics from relativistic electron spikes

Pirozhkov, A. S.; 神門 正城; Esirkepov, T. Z.; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A. Ya.*; Pikuz, T. A.*; 河内 哲哉; 匂坂 明人; et al.

New Journal of Physics (Internet), 16(9), p.093003_1 - 093003_30, 2014/09

 被引用回数:24 パーセンタイル:18.59(Physics, Multidisciplinary)

We present a detailed description of our discovery of a new regime of high-order harmonic generation, including experimental data, simulations, and description of new harmonic generation mechanism. The harmonics are generated by multi-terawatt relativistic-irradiance ($$>$$ 10$$^{18}$$ W/cm$$^2$$) femtosecond ($$approx$$ 30-50 fs) lasers focused to gas jet targets. According to our model, the harmonics are produced by sharp, structurally stable, oscillating electron spikes at the joint of boundaries of wake and bow waves excited by the laser pulse.

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