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Ikeda, Yuji*; Soriano, J. K.*; Oba, Hironori; Wakaida, Ikuo
Applied Optics, 62(31), p.8434 - 8441, 2023/10
Times Cited Count：4 Percentile：39.40(Optics)Utilizing micro-lasers and microwaves, the impact of microwaves on the expansion of air plasma was examined. Microwaves was applied to the air plasma generated by a micro-laser, the plasma growth image was visualized and emissions spectra using by a high-resolution spectrometer was observed, and temperature changes and electron density was analyzed. A 400-fold increase in plasma volume due to microwave enhancement, even though the micro-laser operated at a modest energy level of 1 mJ was observed. Although a slight change in electron temperature was observed during microwave irradiation, it was pointed towards the ability of microwaves to sustain plasma characteristics over time. These will be suggested that the microwave application potentially improves the analytical performance of laser-induced breakdown spectroscopy (LIBS).
Ikeda, Yuji*; Soriano, J. K.*; Oba, Hironori; Wakaida, Ikuo
Scientific Reports (Internet), 13, p.4828_1 - 4828_9, 2023/03
Times Cited Count：16 Percentile：90.53(Multidisciplinary Sciences)Collaborative Laboratories for Advanced Decommissioning Science; i-Lab*
JAEA-Review 2021-027, 62 Pages, 2021/11
JAEA-Review-2021-027.pdf:3.06MB
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2020. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2020, this report summarizes the research results of the "Challenge to advancement of debris composition and direct isotope measurement by microwave-enhanced LIBS" conducted in FY2020. Although LIBS (laser-induced breakdown spectroscopy) is commercially available for application to remote composition measurement, it is not suitable for high radiation environment due to loss in optical fibers derived from the influence of radiation, reduction in laser transmission output, and nuclear fuel debris properties. There are general concerns of the signal strength decrease. In addition, since LIBS is generally considered to be unsuitable for isotope measurement, there are problems to be improved.
Oba, Masaki; Miyabe, Masabumi; Akaoka, Katsuaki; Wakaida, Ikuo
Japanese Journal of Applied Physics, 59(6), p.062001_1 - 062001_6, 2020/06
Times Cited Count：9 Percentile：37.68(Physics, Applied)Using a semiconductor microwave source and a coaxial cable for microwave transmission, a compact microwave-assisted, laser-induced breakdown spectroscopy system without a microwave cavity or waveguide was developed. Several types of electrode heads were tested, so that the emission intensity was 50 times larger than without microwave. The limit of the enhancement effect was also found.
Ishiguro, Masazumi; Aratono, Yasuyuki
Review of Scientific Instruments, 76(2), p.026106_1 - 026106_4, 2005/02
Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)Simple and widely applicable microwave spectroscopy system for the low temperature condensed media has been developed. We applied the technique of opto-thermal detection with superconducting thin-film sensor (STS) for the detection of very weak absorption signal of molecules trapped in quantum solid and liquid such as solid para-hydrogen (
-H
) and bulk liquid helium. For the test of the system, the microwave transition of ortho-hydrogen (
-H) pair in solid -H was observed. The S/N ratio of the observed spectrum of the G
transition at 1.4 K was approximately 8. Ultra high sensitivity of STS makes it possible not only to obtain sufficient sensitivity but also to make the apparatus very simple especially around the sample cell.
Wakaida, Ikuo; Oba, Hironori; Akaoka, Katsuaki; Miyabe, Masabumi; Oba, Masaki; Ito, Chikara; Saeki, Morihisa; Kato, Masaaki
no journal, ,
In nuclear engineering, especially for the decommissioning of severe accident atomic power plant, development of quick, easy, non-contact, no-preparation, direct, remote, onsite and in-situ analysis of nuclear fuel materials which has very complex and large amount of optical emission lines will be indispensable. In these R&D, it may be important how we realize high sensitivity and high resolution spectroscopy and perform the identification of the specific element among a large number of emission spectra. Various kind of technique, such as Double-pulse LIBS and Microwave assisted LIBS for multiply the emission intensity, high resolution LIBS by ultra-high resolution spectrometer or Laser Ablation Resonance Absorption Spectroscopy for isotope analysis, Ultra-thin Liquid flow LIBS for liquid phase application and LIBS based on radiation resistant optical fiber for onsite/in-situ monitoring of melt downed nuclear fuel debris, will have been under investigation. Japan Atomic Energy Agency has opened the new research center "Collaborative Laboratories for Advanced Decommissioning Science", and laser based spectroscopy will be restarted as one of the basic projects.
Khumaeni, A.; Miyabe, Masabumi; Akaoka, Katsuaki; Wakaida, Ikuo
no journal, ,
Wakaida, Ikuo; Oba, Hironori; Oba, Masaki; Matsumoto, Ayumu; Ruas, A.; Toshimitsu, Masaaki; Akaoka, Katsuaki; Miyabe, Masabumi
no journal, ,
For the decommissioning of "Fukushima Daiichi Nuclear Power Station", Optical Fiber based LIBS probe is constructed, and under water condition, we have successfully observed some specific spectra from the simulated sample of molten debris made by sintered oxide of Zr and U. For the use of more longer optical fiber, long-pulse laser with the pulse duration about 100 ns will be introduced to compensate the delivery power loss and/or to enhance the emission signal to be about several times by the time integration of emission signal. As for the signal enhancement technique, microwave assisted LIBS technique coupled with simple antenna for the combination use with fiber LIBS will be under developing, and about ten times enhancement was observed under the atmosphere condition. For the application to the liquid phase sample, especially for the analysis of the polluted cooling water, the thin-sheet liquid jets will be also introduced as the convenience and high sensitive monitoring for dissolved elements of nuclear fuel debris.
Wakaida, Ikuo; Oba, Hironori; Miyabe, Masabumi; Akaoka, Katsuaki; Tamura, Koji; Saeki, Morihisa; Oba, Masaki; Shibata, Takuya; Ikeda, Yuji*; Sakka, Tetsuo*; et al.
no journal, ,
Wakaida, Ikuo; Oba, Hironori; Akaoka, Katsuaki; Karino, Takahiro; Sakamoto, Kan*; Nakanishi, Ryuzo*; Kashiwakura, Shunsuke*; Taira, Takunori*; Ikeda, Yuji*; Deguchi, Yoshihiro*
no journal, ,
We are developing remote in-situ analysis by laser induced breakdown spectroscopy (LIBS) for simple in-situ screening analysis of fuel debris in the decommissioning of the Fukushima Daiichi Nuclear Power Station. For various application scenarios, microchip laser based LIBS for ultra-long distance analysis, microwave assisted LIBS for signal enhancement, and long/short double pulse laser LIBS for water-containing samples are developing as the fiber-optic LIBS system. To have the reliability, valuation with nuclear fuel materials and spent fuel, and radiation resistance test by 
Co irradiation will be planed. As a challenging trial, a development of Machine learning technique has introduced for automatically analysis of LIBS spectra.
