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SbLechner, S.*; Miyagi, Takayuki*; Xu, Z. Y.*; Bissell, M. L.*; Blaum, K.*; Cheal, B.*; Devlin, C. S.*; Garcia Ruiz, R. F.*; Ginges, J. S. M.*; Heylen, H.*; et al.
Physics Letters B, 847, p.138278_1 - 138278_9, 2023/12
Times Cited Count：0 Percentile：0.02(Astronomy & Astrophysics)no abstracts in English
10
W/cm
Skobelev, I. Yu.*; Ryazantsev, S. N.*; Kulikov, R. K.*; Sedov, M. V.*; Filippov, E. D.*; Pikuz, S. A.*; Asai, Takafumi*; Kanasaki, Masato*; Yamauchi, Tomoya*; Jinno, Satoshi; et al.
Photonics (Internet), 10(11), p.1250_1 - 1250_11, 2023/11
Times Cited Count：0 Percentile：0(Optics)It is challenging to clearly distinguish the impacts of the optical field and collisional ionization in the evolution of the charge state of a plasma produced when matter interacts with high-intensity laser pulses. In this work, time-dependent calculations of plasma kinetics are used to show that it is possible only when low-density gaseous targets with sufficiently small clusters are used. In the case of Ar plasma, the upper limit of the cluster radius was estimated to be 
m.
Kawabori, Tatsuru*; Watanabe, Masashi; Imai, Yoshiyuki; Ueta, Shohei; Yan, X.; Mizoshiri, Mizue*
Applied Physics A, 129(7), p.498_1 - 498_9, 2023/07
Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)We investigated a potential of femtosecond laser sintering of silicon carbide (SiC) using the nanoparticles in air. A SiC nanoparticle ink including polyvinylpyrrolidone and ethylene glycol exhibited intense absorption by SiC nanoparticles at the wavelength of 780 nm. The whole of the sintered film patterns from the surface to the bottom underwent significant oxidation at a scanning speed of 1 mm/s, suggesting that the excessive energy irradiation generated silicon oxides. In contrast, the patterns fabricated by laser scanning at a raster pitch of 30 
m at which a sintered area was observed at a scanning speed of 5 mm/s, exhibited no significant difference in oxidation of the raw SiC nanoparticles except for the surfaces from 1.72 m. These results indicate that the irradiation of femtosecond laser pulses generated the sintered SiC patterns without additional atmospheric oxidation of the raw materials because of its low heat accumulation. In additions, the dispersant of polyvinylpyrrolidone and ethylene glycol did not affect the sintering by an X-ray photoelectron spectroscopy. This vacuum-free direct printing technique has the potential for additive manufacturing.
Daido, Hiroyuki*; Yamada, Tomonori
ILT-APR-34; ILT 2023 Nempo (Internet), p.1 - 5, 2023/07
The decommissioning of Fukushima and the contribution to reconstruction have become national issues. The authors participated in the "Analysis of fine particles generated by laser processing and development of nuclide identification method" (represented by Professor Shuichi Hasegawa of the University of Tokyo), which was adopted as one of the JAEA's publicly solicited projects for this purpose, from FY 2018 to FY 2021 as a subcontractor, The authors conducted research on the observation, evaluation and analysis of the interaction between lasers and various laser-irradiated targets. This report outlines the results of the research in which the authors took part. In the experiments, laser irradiation was carried out on test specimens set up in an irradiation chamber, and shadowgraphs were taken using a high-speed camera and a He-Ne laser. As an example of the experimental results, shadowgraphs of metal (stainless steel) and metal oxide (zirconia), irradiation traces after laser irradiation, and the relationship between laser irradiation power and jet mass are shown, and the interaction between the laser and the metal or metal oxide is discussed. The results will not only contribute to the decommissioning technology of the Fukushima Daiichi NPP, but also to laser processing technology and laser interaction research.
Matsuda, Shohei; Yokoyama, Keiichi
Isotope News, (786), p.6 - 9, 2023/04
no abstracts in English
Miyabe, Masabumi; Kato, Masaaki*; Hasegawa, Shuichi*
Journal of Analytical Atomic Spectrometry, 38(2), p.347 - 358, 2023/02
Times Cited Count：0 Percentile：0.02(Chemistry, Analytical)To develop remote isotopic analysis for the nuclids with small isotope shifts, Doppler-free fluorescence spectroscopy of Ca was performed using laser ablation plume. Counter-propagating laser beams from two external cavity diode lasers were used to irradiate the plume in order to excite the ground-state Ca atoms to the 
D
state through a double resonance scheme of S
P
D. Subsequently, we measured fluorescence spectra associated with the relaxation from the D to P states. The linewidth measured at 1 ms delay after ablation under helium gas pressure of 70 Pa was found to be less than 70 MHz, which was about 1/30 of the linewidth of the Doppler-limited fluorescence spectrum. A broad Gaussian pedestal was observed at less than 600 micro-second delay in the temporal variation in fluorescence spectra, and it was most likely due to the velocity-changing collision. Additionally, the pressure broadening rate coefficient for the second-step P D transition was determined to be 46.0 MHz/torr from the spectra measured under various gas pressures. We evaluated analytical performances such as linearity of the calibration curve, limit of detection, and measurement accuracy using fluorescence signals of three naturally occurring Ca isotopes (i.e., 
Ca, 
Ca, and 
Ca). The limit of detection of isotopic abundance was estimated to be 0.09% from the 3-sigma criteria of the background. These results suggest that this spectroscopic technique is promising for remote isotopic analysis of nuclides with small isotope shifts.
O-BO
-SiO glass plate with bearing NiO for heat center and structural probeTomita, Kana*; Kishi, Tetsuo*; Matsumura, Daiju; Yano, Tetsuji*
Journal of Non-Crystalline Solids, 597, p.121891_1 - 121891_10, 2022/12
Times Cited Count：1 Percentile：14.66(Materials Science, Ceramics)Miyagawa, Reina*; Kamibayashi, Daisuke*; Nakamura, Hirotaka*; Hashida, Masaki*; Zen, H.*; Somekawa, Toshihiro*; Matsuoka, Takeshi*; Ogura, Hiroyuki*; Sagae, Daisuke*; Seto, Yusuke*; et al.
Scientific Reports (Internet), 12, p.20955_1 - 20955_8, 2022/12
Times Cited Count：0 Percentile：0(Multidisciplinary Sciences)We evaluated Laser-Induced Periodic Surface Structure (LIPSS) crystal structures using the stress imaging station at BL22XU of JAEA-BL on SPring-8. Crystallization of LIPPS was used different two types laser these are Ti:Sapphire laser (wavelength: 800 nm) and MIR-FEL (mid-infrared free electron laser, wavelength 11.4 m). These lasers are different in the laser pulse structure and the wavelength. We investigated on the effects of formed LIPSS crystallization using different kind of laser. Measured synchrotron X-ray energy is 30 keV and beam size is 20 m. Detector of diffracted X-ray is two-dimensional detector (PILATUS300K, DECTRIS). LIPSS formed using Ti:Sapphire laser has deformed structure with good crystallinity. LIPSS formed using MIR-FEL has dislocation or fault without structural stress. These results show depending on select of laser forming LIPPS structure. These information becomes important a point of the functional application of LIPSS.
Wada, Yoriko*; Akagi, Hiroshi*; Kumada, Takayuki; Itakura, Ryuji*; Wakabayashi, Tomonari*
Photochem (Internet), 2(3), p.798 - 809, 2022/09
Coulomb explosion experiments using 60 fs laser pulses were conducted for structural characterization of three dichloroethylene isomers. Under laser intensity at 1.8 10
W/cm
, mass-resolved momentum imaging (MRMI) for selected fragment ions of 
Cl
and C
revealed different patterns for the three isomers. The C
ion fragmented from multiply charged trans-1,2-DCE was forced to leave perpendicularly to the direction of the laser polarization, due to recoil forces from adjacent cations. In contrast, the fast ions of C from cis-1,2-DCE exhibited an isotropic distribution, whereas the fast ions of C from 1,1-DCE recoiled along the laser polarization together with the slow C ions, and thereby distinction of the three isomers was demonstrated. Coulomb explosion occurs predominantly at specific orientation, which is useful for potential applications of MRMI analysis to molecular structure assays.
Wakui, Takashi; Yamasaki, Kazuhiko*; Futakawa, Masatoshi
Advanced Experimental Mechanics, 7, p.103 - 109, 2022/08
As part of the development of technique to cut and reduce the volume of highly radioactive components in the closed space, pulsed Nd:YAG laser was irradiated to radiation shielding glasses with the different lead content in the different irradiation condition; power and number of irradiation. The large black irradiated area with concave shape and cracks around it occurred with an increase of the lead content, power and number of irradiation. General mechanical properties in unirradiated and irradiated area were investigated to investigate the influence of mechanical properties on the irradiation damage. The thermal impact fracture toughness calculated based on the estimated mechanical properties decreased with increasing the lead content. The micro hardness in black irradiated area was 10% smaller than that in the unirradiated area. The change of the mechanical property due to the laser irradiation was confirmed.
Yoshida, Masayuki*; Nishihata, Itsuki*; Matsuda, Tomoki*; Ito, Yusuke*; Sugita, Naohiko*; Shiro, Ayumi*; Shobu, Takahisa; Arakawa, Kazuto*; Hirose, Akio*; Sano, Tomokazu*
Journal of Applied Physics, 132(7), p.075101_1 - 075101_9, 2022/08
Times Cited Count：5 Percentile：67.2(Physics, Applied)Wakui, Takashi; Yamasaki, Kazuhiko*; Futakawa, Masatoshi
Jikken Rikigaku, 22(2), p.96 - 104, 2022/06
Pulsed laser irradiation and indentation tests on radiation shielding glasses and a lead-free glass were carried out. The size of irradiation damage of the glass with high lead content was larger than that with low content. The micro plastic behavior of glasses was quantitatively determined using the inverse analyses based on indentation results. Flow stress decreased with an increase of lead content and that in irradiated area was lower than that in unirradiated area. On the other hand, plastic flow resistance increased with an increase of the lead content and that in irradiated area was higher than that in unirradiated area. Fracture energy and critical size of plastic zone around tip of crack in unirradiated and irradiated areas were calculated based on experimental results including constants evaluated using the inverse analysis. These values decreased with an increase of the lead content and these values in irradiated area were lower than that in unirradiated area.
Iwasa, Toma; Arima, Tatsumi*
JAEA-Technology 2021-036, 23 Pages, 2022/03
JAEA-Technology-2021-036.pdf:1.35MB
Knowledge on the liquefaction (thermal decomposition and melting) temperatures of MA-bearing nitride fuels for transmutation by accelerator-driven system is essential for elucidation of the fuel behaviors under abnormal condition and for the safety analysis. A melting temperature measurement system for refractory materials was developed based on a laser spot heating method, which is expected to measure in a very short time with a small amount of sample, and demonstration tests using refractory metals and zirconium nitride were performed. As the results, it was found that this melting temperature measurement system can be applicable up to the temperatures around 3000 K which is close to the thermal decomposition temperature of nitride fuels and we confirmed the technical feasibility of this system for future application to small specimens of transuranium nitrides.
ion complex; Presence of a Rh
Intermediate in Direct PhotoreductionSaeki, Morihisa*; Matsumura, Daiju; Nakanishi, Ryuzo*; Yomogida, Takumi; Tsuji, Takuya; Saito, Hiroyuki*; Oba, Hironori*
Journal of Physical Chemistry C, 126(12), p.5607 - 5616, 2022/03
Times Cited Count：1 Percentile：14.66(Chemistry, Physical)The reaction mechanism of the direct photoreduction of a Rh ion complex to a Rh
species induced by pulsed ultraviolet laser irradiation was studied using dispersive X-ray absorption fine structure (DXAFS) spectroscopy. The time-resolved X-ray absorption near edge structure (XANES) showed the absence of isosbestic points and suggested that more than two Rh
species contribute toward the direct photoreduction of Rh. Analysis of the time-resolved XANES data by singular value deposition showed that the direct photoreduction involves three Rh species. Multivariate curve resolution by alternating least-squares analysis (MCR-ALS) of the time-resolved XANES data gave pure spectra and concentration profiles of the three Rh species. The Rh species were assigned to Rh, Rh, and Rh species based on the features of the pure XANES spectra. The concentration profiles suggested that the direct photoreduction proceeds in the order of Rh Rh Rh. A reaction mechanism, which was proposed involving photoreductions of Rh and Rh, photoinduced autocatalytic reductions of Rh and Rh, and photooxidation of Rh, well reproduced the concentration profiles of three Rh species.
Yamane, Ikumi; Takahashi, Nobuo; Sawayama, Kengo; Nishiwaki, Hiroki; Matsumoto, Takashi; Ogawa, Jumpei; Nomura, Mitsuo; Arima, Tatsumi*
JAEA-Technology 2021-038, 18 Pages, 2022/02
JAEA-Technology-2021-038.pdf:1.61MB
We have dismantled uranium enrichment facilities in Ningyo-toge Environmental Engineering Center since their operation finished in 2001, and the total amount of metallic wastes is estimated to be about 130 thousand tons. Eighty percent of them can be disposed as nonradioactive waste (NR), but there are some steel parts possibly uranium-contaminated. We need removing painted surface of such steels and radiologically surveying to dispose them as NRs. Though painted surfaces have been conventionally removed through hand working with grinders, this manual work requires installation of green house, protective clothing, and full-face mask, in order to prevent dispersion and inhalation of airborne dusts. We desire further developments of surface cleaning techniques to reduce time, cost, workload, and secondary waste generation caused by excessive grinding. Therefore, in this study, we focused on the laser cleaning technology used for the separation and removal of paint films at construction sites. In order to improve the coating separation and removal technology for NR objects, we evaluated the coating separation and removal performance of NR steel surface by laser cleaning system, observed the coating scattering behavior by high-speed camera and investigated the coating recovery method, evaluated the laser separation and removal performance of steel surface powder, and thermodynamically evaluated the uranium compounds on steel surface. We additionally evaluated the feasibility of laser cleaning techniques in our works basing on these results, and discussed future work plans for further developments of laser cleaning techniques.
Takei, Hayanori
Isotope News, (779), p.11 - 15, 2022/02
The Japan Atomic Energy Agency (JAEA) has designed a Transmutation Physics Experimental Facility (TEF-P) as an experimental facility in the Japan Proton Accelerator Research Complex (J-PARC). The TEF-P is a critical assembly driven by a low-power proton beam, a maximum of 10 W, which is extracted from a high-power beam source, such as 250 kW of 400 MeV proton beam of the J-PARC Linac. To extract such a low-power proton beam from the high-power proton beam, we developed a laser charge exchange (LCE) device and employed its technique, which is one of the non-contact beam extraction techniques. For the proof of performance of the LCE device to the TEF-P, a low-power proton beam was extracted using a negative-hydrogen Linac having an energy of 3 MeV, and a bright laser. This paper summarizes the experimental results.
Kitagawa, Yoshihiro; Shirahama, Takuma*; Kisohara, Naoyuki; Tsuboi, Akihiko
Dai-96-Kai Reza Kako Gakkai Koen Rombunshu (Internet), p.91 - 96, 2022/01
Laser scanning quenching is a locally and rapidly heat-treated process and has an advantage of no coolant required. Compared with conventional technique such as induction quenching, the region of laser quenching is about 0.5
0.7mm in depth and it needs to be expanded for more applications or durability. For this purpose, the temperature distributions and transitions in materials during laser irradiation have been revealed by using a 3D heat transfer computer code, micro-structural observation and hardness transitions in depth direction. The results indicate the laser irradiation with low power and low scan speed condition allows deeper quenching area, but it also suggests the hardness of the deepest quenching area is degraded due to slow temperature decreasing rate after laser heat scanning. Multiple times continuous irradiation have been proposed and studied to resolve this hardness degradation, and maximum quenching depth of 1.4mm is obtained under three times irradiation and controlling its power and scan speed properly.
Haraga, Tomoko; Saito, Shingo*
Bunseki Kagaku, 70(12), p.671 - 679, 2021/12
We developed highly sensitive capillary electrophoresis-laser-induced fluorescence detection methods for lanthanide (Ln) and actinide (An) ions with small sample volume and low emission of waste, by which the radiation risk can be minimized. Specifically, determination of Nd ion in spent nuclear fuel, effective separation between Am and Cm ion, and specific detection of UO in real radioactive samples were achieved by molecular design of fluorescence probes composed of an aminocarboxylate chelating moiety, a fluorophore and a spacer, and unique separation mode based on dynamic ternary complexation. We found that there are appropriate combination of probe and ternary complexation for detection and separation of each Ln and An ions. For example, acyclic and macrocyclic hexadentate is suitable for Ln, Am and Cm, and planer tetradentate with 
electron system is specific for UO, with ppt-sub ppt level detection.
Hironaka, Kota; Ito, Fumiaki*; Lee, J.; Koizumi, Mitsuo; Takahashi, Tone; Suzuki, Satoshi*; Yogo, Akifumi*; Arikawa, Yasunobu*; Abe, Yuki*
Dai-42-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2021/11
Neutron resonance transmission analysis (NRTA) is a method for non-destructive measurement of nuclear material by using a time-of-flight (TOF) technique with a pulsed neutron source. For NRTA system to carry out the short-distance TOF measurements with high resolutions, a short-pulsed neutron source is required. Laser-driven neutron sources (LDNSs) is very suitable as such a neutron source because of its short pulse width. Moreover, the compactness of the laser system is also expected due to the remarkable development of laser technology in recent years. In the present study, we have developed a technology for applying LDNS to the NRTA system and conducted the demonstration experiment using the LFEX laser at Osaka University to investigate the feasibility of the system. In this experiment, we successfully observed the neutron resonance peaks of indium and silver samples.
Nakata, Koki
Kotai Butsuri, 56(8), p.429 - 439, 2021/08
We review the thermomagnetic relation of bosons, the Wiedemann-Franz law for magnon transport, and discuss the universality.
