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Tajima, Yoshihiro; Kuwabara, Jun; Oyokawa, Atsushi; Kabuto, Shoji; Araya, Naoyuki; Kikuchi, Kaoru; Miyamoto, Shingo; Nemoto, Hideyuki; Oe, Osamu
JAEA-Review 2016-003, 56 Pages, 2016/05
JAEA-Review-2016-003.pdf:7.16MB
Nuclear Facilities Management Section implements the operation, maintenance and decommissioning of the first nuclear ship "MUTSU" and the operation and maintenance of the liquid waste facility and the solid waste facility where a small amount of nuclear fuel is used. This is the report on the operations of the Nuclear Facilities Management Section for FY 2012 and FY 2013.
Kiriyama, Hiromitsu; Suzuki, Masayuki*; Daito, Izuru; Okada, Hajime; Ochi, Yoshihiro; Sato, Masatoshi*; Tamaoki, Yoshinori*; Yoshii, Takehiro*; Maeda, Junya*; Matsuoka, Shinichi*; et al.
Reza Kenkyu, 40(2), p.143 - 145, 2012/02
We demonstrate a compact, high-spatiotemporal-quality, high-intensity diode-pumped Yb:YAG thin-disk chirped-pulse amplification (CPA) laser system that incorporates a nonlinear preamplifier based on optical parametric chirped-pulse amplification (OPCPA). The stretched pulses are amplified in the OPCPA preamplifier and the following Yb:YAG main amplifier to 
100 mJ at 10 Hz. The broadband amplified beam quality of 1.1 (horizontal direction) and 1.4 (vertical direction) times diffraction limited and pulse compression down to 470 fs with contrast of better than 10
have been achieved successfully.
Numakura, Masahiko*; Sato, Nobuaki*; Bessada, C.*; Okamoto, Yoshihiro; Akatsuka, Hiroshi*; Nezu, Atsushi*; Shimohara, Yasuaki*; Tajima, Keisuke*; Kawano, Hirokazu*; Nakahagi, Takeshi*; et al.
Progress in Nuclear Energy, 53(7), p.994 - 998, 2011/11
Times Cited Count：13 Percentile：69.55(Nuclear Science & Technology)X-ray absorption fine structure (XAFS) measurements on thorium fluoride in molten lithium-calcium fluoride mixtures and molecular dynamics (MD) simulation of zirconium and yttrium fluoride in molten lithium-calcium fluoride mixtures have been carried out. In the molten state, coordination number of thorium and inter ionic distances between thorium and fluorine in the first neighbor are nearly constant in all mixtures. However the fluctuation factors (Debye-Waller factor and C
cumulant) increase until 
CaF
= 0.17 and decrease by addition of excess CaF. It means that the local structure around Th
is disordered until CaF=0.17 and stabilized over CaF = 0.17. The variation of fluctuation factors is related to the number density of F
in ThF
mixtures and the stability of local structure around Th increases with decreasing the number density of F in ThF mixtures. This tendency is common to those in the ZrF and YF mixtures.
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki*; Shimomura, Takuya; Sasao, Hajime*; Tanaka, Momoko; Ochi, Yoshihiro; Tanoue, Manabu*; Kondo, Shuji; Kanazawa, Shuhei; et al.
Reza Kenkyu, 38(9), p.669 - 675, 2010/09
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 a low gain optical parametric chirped-pulse amplification (OPCPA) preamplifier that uses high energy, clean pulse seeding and is shown to significantly improve the contrast to better than 10
-10
relative to the peak of the main femtosecond pulse. We also report the use of a diffractive optical element for beam homogenization of a 100 J level Nd:glass green pump laser, achieving a flat-topped spatial profile with a filling factor near 80 %.
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.
Asano, Yoshihiro; Matsumura, Toru; Chiba, R.*; Hashimoto, Tomoyuki*; Miura, Akio*; Shimizu, Hajime*; Tajima, Yasuhisa*; Yoshida, H.*
Nuclear Instruments and Methods in Physics Research A, 451(2), p.658 - 696, 2000/11
no abstracts in English
Esirkepov, T. Z.; Bulanov, S. V.; Miyajima, Satoshi*; Ito, Yoshihiro*; Koga, J. K.; Yamagiwa, Mitsuru; Tajima, Toshiki
no journal, ,
no abstracts in English
Kawachi, Tetsuya; Kishimoto, Maki; Kado, Masataka; Tanaka, Momoko; Hasegawa, Noboru; Ochi, Yoshihiro; Nishikino, Masaharu; Ishino, Masahiko; Imazono, Takashi; Kunieda, Yuichi; et al.
no journal, ,
Recent progress in X-ray laser research in Japan Atomic Energy Agency is reviewed. Using the nickel-like silver soft X-ray laser at the wavelength of 13.9 nm, the application experiments have been conducted in the research fields such as material science, high-density plasma diagnostics, XRL ablation, XRL imaging using single-shot holography and atomic physics. The repetition rate of the XRL beam has been improved from each 10-20 minutes to 0.1 Hz by using new driver laser system with Nd: glass zigzag slab amplifier, and we are now constructing new beam line for the pump-probe measurement of the surface phase-transition by the method of X-ray laser interferometer. In the research activity on the extension of the wavelength region of the X-ray lasers, firstly, the demonstration of novel coherent X-ray generation by "flying mirror" technique is reported. The second is theoretical investigation of the resonance photo-pumping scheme toward water-window region.
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki; Shimomura, Takuya; Sasao, Hajime; Tanaka, Momoko; Ochi, Yoshihiro; Tanoue, Manabu*; Okada, Hajime; Kondo, Shuji; et al.
no journal, ,
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 final compressed pulse we found that the temporal contrast in this system exceeds 10 on the sub-nanosecond timescale before 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 near-perfect top-hat intensity distributions.
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki*; Shimomura, Takuya; Sasao, Hajime; Tanaka, Momoko; Ochi, Yoshihiro; Tanoue, Manabu*; Okada, Hajime; Kanazawa, Shuhei; et al.
no journal, ,
We report the demonstration of over 30-J of uncompressed broadband energy, indicating the potential peak power in excess of 500-TW with high temporal-contrast around 10
and a flat-toped spatial-profile with an 80 percent filling factor.
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki*; Shimomura, Takuya; Sasao, Hajime*; Tanaka, Momoko; Ochi, Yoshihiro; Tanoue, Manabu*; Okada, Hajime; Kanazawa, Shuhei; et al.
no journal, ,
OPCPA (Optical parametric chirped-pulse amplification) operation with low gain by seeding with high energy, clean pulses is shown to significantly improve the contrast to better than 10-10 in a high intensity Ti:sapphire laser system that is based on chirped pulse amplification. In addition to the high contrast broadband high energy output from the final amplifier is achieved with a flat-topped spatial profile of filling factor near 77 %. This is the result of pump beam spatial profile homogenization with diffractive optical elements. Final pulse energies exceed 30 Joules indicating capability for reaching peak powers in excess of 500-TW.
Kiriyama, Hiromitsu; Nagashima, Keisuke; Ochi, Yoshihiro; Mori, Michiaki; Tanaka, Momoko; Sasao, Fumitaka; Kosuge, Atsushi; Okada, Hajime; Kondo, Kiminori; Sagisaka, Akito; et al.
no journal, ,
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 final compressed pulse we found that the temporal contrast in this system exceeds 10 on the sub-nanosecond timescale before 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 near-perfect top-hat intensity distributions.
Kiriyama, Hiromitsu; Mori, Michiaki; Shimomura, Takuya; Nakai, Yoshiki*; Tanoue, Manabu*; Sasao, Hajime*; Kondo, Shuji; Kanazawa, Shuhei; Ochi, Yoshihiro; Tanaka, Momoko; et al.
no journal, ,
We report on a femtosecond high-intensity OPCPA/Ti:sapphire hybrid laser system that produces more than 30 J broadband output energy, indicating the potential for achieving petawatt-class peak powers. High temporal-contrast of 10 to 10 has been obtained with a near-perfect flat-topped spatial-profile of filling factor 80%. We also present a compact, high-intensity OPCPA/Yb:YAG hybrid laser system that generates 100 mJ output energy with a temporal contrast of better than 10 and good spatial beam quality.
Kiriyama, Hiromitsu; Mori, Michiaki; Shimomura, Takuya; Tanoue, Manabu; Kondo, Shuji; Kanazawa, Shuhei; Daito, Izuru; Suzuki, Masayuki*; Okada, Hajime; Ochi, Yoshihiro; et al.
no journal, ,
We describe two specific high intensity laser systems that are being developed in our laboratory for many applications such as high field science, nonlinear optics. We report on an ultra-high intensity petawatt-class Ti:sapphire chirped-pulse amplification laser system that can produce a pulse energy of 18 J with 30 fs pulse duration for studying extremely high intensity laser matter interaction process and a small-scaled Yb:YAG chirped-pulse amplification laser system that can generate a pulse energy of 100 m J of 500 fs pulse duration for compact, high efficiency, high repetition system. We discuss the basic design aspects and present the results from our experimental investigations of these laser systems.
