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Iwamoto, Osamu; Iwamoto, Nobuyuki; Kunieda, Satoshi; Minato, Futoshi; Nakayama, Shinsuke; Kimura, Atsushi; Nakamura, Shoji; Endo, Shunsuke; Nagaya, Yasunobu; Tada, Kenichi; et al.
EPJ Web of Conferences, 284, p.14001_1 - 14001_7, 2023/05
Times Cited Count:0 Percentile:0.21(Nuclear Science & Technology)Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Faenov, A. Y.*; Pikuz, T. A.*; Kawachi, Tetsuya; Sagisaka, Akito; Koga, J. K.; Mori, Michiaki; Kawase, Keigo*; et al.
RAL-TR-2015-025, P. 22, 2015/00
Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A. Ya.*; Pikuz, T. A.*; Kawachi, Tetsuya; Sagisaka, Akito; et al.
New Journal of Physics (Internet), 16(9), p.093003_1 - 093003_30, 2014/09
Times Cited Count:30 Percentile:80.96(Physics, Multidisciplinary)Ideguchi, Eiji*; Ota, Shinsuke*; Morikawa, Tsuneyasu*; Oshima, Masumi; Koizumi, Mitsuo; Toh, Yosuke; Kimura, Atsushi; Harada, Hideo; Furutaka, Kazuyoshi; Nakamura, Shoji; et al.
Progress of Theoretical Physics Supplement, (196), p.427 - 432, 2012/10
Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A. Ya.*; Pikuz, T.; Kawachi, Tetsuya; Sagisaka, Akito; et al.
AIP Conference Proceedings 1465, p.167 - 171, 2012/07
Times Cited Count:1 Percentile:46.41(Physics, Applied)Esirkepov, T. Z.; Pirozhkov, A. S.; Kando, Masaki; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A.*; Pikuz, T.; Kawachi, Tetsuya; Sagisaka, Akito; et al.
AIP Conference Proceedings 1465, p.172 - 180, 2012/07
Times Cited Count:0 Percentile:0.13(Physics, Applied)The bow wave induced mechanism of high-order harmonics generation was discovered using simulations and catastrophe theory. This mechanism feasibility was successfully demonstrated in 3D and 2D PIC simulations. The mechanism and the simulations explained high-order harmonics in the XUV spectral region seen in recent experiments with terawatt lasers. Development of new XUV light and X-ray source based on the high-order harmonics generation mechanism is proposed.
Ogura, Koichi; Shizuma, Toshiyuki; Hayakawa, Takehito; Yogo, Akifumi; Nishiuchi, Mamiko; Orimo, Satoshi; Sagisaka, Akito; Pirozhkov, A. S.; Mori, Michiaki; Kiriyama, Hiromitsu; et al.
Japanese Journal of Applied Physics, 51(4), p.048003_1 - 048003_2, 2012/04
Times Cited Count:2 Percentile:8.9(Physics, Applied)A proton beam driven by a repetitive high-intensity-laser is utilized to induce a Li(p,n)Be nuclear reaction. The total activity of Be are evaluated by two different methods. The activity obtained measuring the decay -rays after 1912 shots at 1 Hz is 1.70.2 Bq. This is in good agreement with 1.60.3 Bq evaluated from the proton energy distribution measured using a time-of-flight detector and the nuclear reaction cross-sections. We conclude that the production of activity can be monitored in real time using the time-of-flight-detector placed inside a diverging proton beam coupled with a high-speed signal processing system.
Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A. Ya.*; Pikuz, T.; Kawachi, Tetsuya; Sagisaka, Akito; et al.
Physical Review Letters, 108(13), p.135004_1 - 135004_5, 2012/03
Times Cited Count:69 Percentile:90.68(Physics, Multidisciplinary)We demonstrate a new high-order harmonic generation mechanism reaching the "water window" spectral region in experiments with multi-terawatt femtosecond lasers irradiating gas jets. A few hundred harmonic orders are resolved, giving J/sr pulses. Harmonics are collectively emitted by an oscillating electron spike formed at the joint of the boundaries of a cavity and bow wave created by a relativistically self-focusing laser in underdense plasma. The spike sharpness and stability are explained by catastrophe theory. The mechanism is corroborated by particle-in-cell simulations.
Oto, Tsutomu; Kimura, Tadashi; Fukasaku, Akitomi; Kusunoki, Tsuyoshi
JAEA-Review 2010-066, 22 Pages, 2011/01
The refurbishment of JMTR is scheduled from the beginning of FY 2007 to the end of FY 2010. An integrity investigation for concrete structures of the JMTR buildings was carried out in early phase of the refurbishment. This paper describes investigated results and repair work of the vent stack, trenches, canal building and the filter bank. Investigated items were the concrete surface deterioration, rebound number (nondestructive estimation of strength), comprehensive strength using drilled concrete core test piece, carbonation depth, reinforced bar corrosion and chloride ion content. The integrity of these concrete structures was confirmed by these investigations. Based on the investigation results, repair works such as re-painting were carried out from the viewpoint of preventive maintenance for the vent stack, trenches and canal building.
Oto, Tsutomu; Kimura, Tadashi; Miyauchi, Masaru; Nemoto, Nobuaki; Tobita, Kenji; Fukasaku, Akitomi; Takahashi, Kunihiro
JAEA-Review 2010-017, 21 Pages, 2010/07
An integrity investigation of a Canal Expanded Joint was carried out as one of the integrity investigation of the JMTR reactor building related facilities and components, before the repair or replacement work of the JMTR related facilities that had begun in FY2007. The Canal Expanded Joint will be used for long-term after the JMTR restart. In the integrity investigation, the visual inspection, the performance test (Surface observations, Durometer hardness test) were investigated respectively and the integrity of the Canal Expanded Joint was confirmed. In order to use the Canal Expanded Joint continuously for long-term, it is important for maintaining the integrity of the Canal Expanded Joint by the periodical maintenance and the repairing work including that has been conducted up to now.
Miyauchi, Masaru; Kimura, Tadashi; Oto, Tsutomu; Nemoto, Nobuaki; Tobita, Kenji; Fukasaku, Akitomi; Takahashi, Kunihiro
JAEA-Review 2010-008, 106 Pages, 2010/06
An integrity investigation was carried out for the JMTR Concrete Structure (Vent Stack, Trench, Canal Building, Filter Bank), which was the concrete structure and would be used for the long-term after JMTR restart, before the repair or replacement work of the JMTR related facilities that had begun in FY2007. In the integrity investigation, the concrete surface deterioration, the rebound number (nondestructive strength test), compressive strength using drilled concrete core test piece, the static modules of elasticity, the carbonation depth, the reinforced bar corrosion and the chloride ion content were investigated respectively and the integrity of concrete was confirmed. After the investigation, repair works such as re-painting of the Vent Stack and Trench were carried out from the viewpoint of prevention of flaking off, floating of the painting and the thinning due to the investigation results. In order to use the JMTR concrete structure continuously for long-term, it is important for maintaining the integrity of a concrete structure by the periodical maintenance and the repairing work including the building outer-wall surface painting that has been conducted up to now.
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki; Shimomura, Takuya; Sasao, Hajime; Tanaka, Momoko; Ochi, Yoshihiro; Tanoue, Manabu*; Okada, Hajime; Kondo, Shuji; et al.
Applied Optics, 49(11), p.2105 - 2115, 2010/04
Times Cited Count:39 Percentile:83.63(Optics)We have developed a femtosecond high intensity laser system, which combines both Ti:sapphire chirped-pulse amplification (CPA) and optical parametric chirped-pulse amplification (OPCPA) techniques, that produces more than 30-J broadband output energy, indicating the potential for achieving peak powers in excess of 500-TW. With a cleaned high-energy seeded OPCPA preamplifier as a front-end in the system, for the compressed pulse without pumping the final amplifier we found that the temporal contrast in this system exceeds 10 on the sub-nanosecond timescales, and is near 10 on the nanosecond timescale prior to the peak of the main femtosecond pulse. Using diffractive optical elements for beam homogenization of 100-J level high-energy Nd:glass green pump laser in a Ti:sapphire final amplifier, we have successfully generated broadband high-energy output with a near-perfect top-hat-like intensity distribution.
Kimura, Tadashi; Oto, Tsutomu; Miyauchi, Masaru; Nemoto, Nobuaki; Tobita, Kenji; Fukasaku, Akitomi; Takahashi, Kunihiro
JAEA-Review 2010-001, 27 Pages, 2010/03
In order to investigate an integrity of the UCL (Utility Cooling Line) elevated water tank to be used for a long term after the JMTR restart, investigation on the base of the UCL elevated tank, especially for the part which had a significant aged effect, was carried out before the refurbishment work of the JMTR related facilities which had begun in FY2007. In the integrity investigation, it was confirmed that some part of the base bolts had significant aged effects, there were no evidence of crack and false indication in the welding region though thinning were observed in some parts of the base plate and the surrounding plate. After the investigation, repair works such as re-painting of the UCL elevated water tank were carried out from the viewpoint of prevention of flaking off, floating of the painting and the thinning due to corrosion based on the investigation results. In order to maintain the integrity of the UCL elevated tank, the periodical maintenance and the repair works of the base of the UCL elevated tank are important for continuous use of it in future.
Kimura, Tadashi; Oto, Tsutomu; Miyauchi, Masaru; Nemoto, Nobuaki; Tobita, Kenji; Fukasaku, Akitomi; Takahashi, Kunihiro
JAEA-Review 2009-054, 73 Pages, 2010/03
An integrity investigation was carried out for the JMTR reactor building, which was the concrete structure and would be used for the long-term after JMTR restart, before the repair or replacement work of the JMTR related facilities that had begun in FY2007. In the integrity investigation, the concrete surface deterioration, the rebound number (nondestructive strength test), compressive strength using drilled concrete core test piece, the static modules of elasticity, the carbonation depth, the reinforced bar corrosion and the chloride ion content were investigated respectively and the integrity of concrete was confirmed. In order to use the JMTR reactor building continuously for long-term, it is important for maintaining the integrity of a concrete structure by the periodical maintenance and the repairing work including the building outer-wall surface painting that has been conducted up to now.
Ideguchi, Eiji*; Ota, Shinsuke*; Morikawa, Tsuneyasu*; Oshima, Masumi; Koizumi, Mitsuo; Toh, Yosuke; Kimura, Atsushi; Harada, Hideo; Furutaka, Kazuyoshi; Nakamura, Shoji; et al.
Physics Letters B, 686(1), p.18 - 22, 2010/03
Times Cited Count:37 Percentile:87.09(Astronomy & Astrophysics)A rotational band with five -ray transitions ranging from 2 to 12 states was identified in Ar. The deduced transition quadrupole moment of 1.45 0.15 eb indicates that the band has a superdeformed shape. The nature of the band is revealed by cranked Hartee Fock Bogoliubov calculations and a multiparticle-multihole configuration is assigned to the band.
Koga, J. K.; Moribayashi, Kengo; Fukuda, Yuji; Bulanov, S. V.; Sagisaka, Akito; Ogura, Koichi; Daido, Hiroyuki; Yamagiwa, Mitsuru; Kimura, Toyoaki*; Fujikawa, Taketoshi*; et al.
Journal of Physics D; Applied Physics, 43(2), p.025204_1 - 025204_15, 2010/01
Times Cited Count:17 Percentile:56.44(Physics, Applied)Kando, Masaki; Pirozhkov, A. S.; Fukuda, Yuji; Esirkepov, T. Z.; Daito, Izuru; Kawase, Keigo; Ma, J. L.*; Chen, L. M.*; Hayashi, Yukio; Mori, Michiaki; et al.
European Physical Journal D, 55(2), p.465 - 474, 2009/09
Times Cited Count:18 Percentile:63.89(Optics)Nonlinear interaction of intense laser beams with plasma causes a number of different regimes of generation of high energy particle beams and of strong radiation with the emitted photon energy from the X-ray to THz frequency range. The review of the first proof-of-principle experiment and the latest progress on the flying mirror is presented. A low frequency EM radiation emission has also been observed in our experiments. The interpretation invokes the relativistic electromagnetic solitons. The solitons are formed in an underdense plasma in the process of the laser pulse frequency downshift. They store a portion of EM wave energy with the polarization inherited from the laser and emit it at the plasma-vacuum interface in a form of the low frequency EM bursts. We present the results of the polarization-resolved measurements.
Ebisawa, Hiroyuki; Hanakawa, Hiroki; Asano, Norikazu; Kusunoki, Hidehiko; Yanai, Tomohiro; Sato, Shinichi; Miyauchi, Masaru; Oto, Tsutomu; Kimura, Tadashi; Kawamata, Takanori; et al.
JAEA-Technology 2009-030, 165 Pages, 2009/07
The condition of facilities and machinery used continuously were investigated before the renewal work of JMTR on FY 2007. The subjects of investigation were reactor building, primary cooling system tanks, secondary cooling system piping and tower, emergency generator and so on. As the result, it was confirmed that some facilities and machinery were necessary to repair and others were used continuously for long term by maintaining on the long-term maintenance plan. JMTR is planed to renew by the result of this investigation.
Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Fukuda, Yuji; Chen, L.-M.*; Daito, Izuru; Ogura, Koichi; Homma, Takayuki; Hayashi, Yukio; Kotaki, Hideyuki; et al.
AIP Conference Proceedings 1153, p.274 - 284, 2009/07
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki; Shimomura, Takuya; Tanoue, Manabu*; Akutsu, Atsushi; Okada, Hajime; Motomura, Tomohiro*; Kondo, Shuji; Kanazawa, Shuhei; et al.
Reza Kenkyu, 37(6), p.425 - 430, 2009/06
This paper reviews the temporal contrast and spatial beam quality improvement techniques in a high intensity Ti:sapphire laser system that is based on chirped-pulse amplification (CPA). We describe an optical parametric chirped-pulse amplification (OPCPA) preamplifier that is seeded by a cleaned high-energy pulse. It demonstrates a background amplified spontaneous emission (ASE) level of 10 relative to the peak main femtosecond pulse on the picosecond timescale. We also report a cryogenically-cooled Ti:sapphire final amplifier which generates focused peak intensity in excess of 10 W/cm at a 10 Hz repetition rate.