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Journal Articles

Clinical significance of L-type amino acid transporter 1 expression as a prognostic marker and potential of new targeting therapy in biliary tract cancer

Kaira, Kyoichi*; Sunose, Yutaka*; Ohshima, Yasuhiro; Ishioka, Noriko; Arakawa, Kazuhisa*; Ogawa, Tetsushi*; Sunaga, Noriaki*; Shimizu, Kimihiro*; Tominaga, Hideyuki*; Oriuchi, Noboru*; et al.

BMC Cancer, 13, p.482_1 - 482_12, 2013/10

 Times Cited Count:51 Percentile:85.76(Oncology)

Journal Articles

Mechanical properties of full austenitic welding joint at cryogenic temperature for the ITER toroidal field coil structure

Iguchi, Masahide; Saito, Toru; Kawano, Katsumi; Chida, Yutaka; Nakajima, Hideo; Ogawa, Tsuyoshi*; Katayama, Yoshinori*; Ogata, Hiroshige*; Minemura, Toshiyuki*; Tokai, Daisuke*; et al.

Fusion Engineering and Design, 88(9-10), p.2520 - 2524, 2013/10

 Times Cited Count:8 Percentile:59.34(Nuclear Science & Technology)

ITER TFC structures are large welding structures made of heavy thick stainless steels. JAEA plans to apply narrow gap TIG welding with FMYJJ1 which is full austenitic stainless filler material to manufacture TFC structure. FMYJJ1 is specified in "Codes for Fusion Facilities -Rules on Superconducting Magnet Structure (2008)". In order to evaluate effect of base material combinations and thickness of welded joint on tensile properties at 4 K, tensile tests were conducted at 4 K by using tensile specimens taken from 40 mm thickness weld joints of four combinations and 200 mm thickness ones of two combinations of base materials. These weld joints were manufactured by one side narrow gap TIG welding with FMYJJ1. As the results, it was confirmed that yield and tensile strengths of welded joint at 4K were decreased with decreasing of nitrogen of base material, and there were no large distribution of strengths at 4 K along the thickness of welded joints of 200 mm thickness.

Journal Articles

Mechanical properties of friction stir welded 11Cr-ferritic/martensitic steel

Yano, Yasuhide; Sato, Yutaka*; Sekio, Yoshihiro; Otsuka, Satoshi; Kaito, Takeji; Ogawa, Ryuichiro; Kokawa, Hiroyuki*

Journal of Nuclear Materials, 442(1-3), p.S524 - S528, 2013/09

 Times Cited Count:12 Percentile:73.42(Materials Science, Multidisciplinary)

Friction stir welding was applied to the wrapper tube materials, 11Cr-ferritic/martensitic steel, intended for fast reactors and defect-free welds were successfully produced. Then, the mechanical and microstructural properties of the friction stir welded steel were investigated. The hardness values of the stir zone were about 550 Hv, and they had hardly any dependence on the rotational speed, although they were much higher than that of the base material. However, tensile strengths and elongations of the stir zones were better at 298 K, compared to those of the base material. These excellent tensile properties were attributable to the fine grain formation during friction stir welding. A part of this study is the result of "Friction stir welding of the wrapper tube materials for Na fast reactors" carried out under the Strategic Promotion Program for Basic Nuclear Research by the Ministry of Education, Culture, Sports, Science and Technology of Japan.

Journal Articles

Development of structures for ITER toroidal field coil in Japan

Iguchi, Masahide; Chida, Yutaka; Takano, Katsutoshi; Kawano, Katsumi; Saito, Toru; Nakajima, Hideo; Koizumi, Norikiyo; Minemura, Toshiyuki*; Ogata, Hiroshige*; Ogawa, Tsuyoshi*; et al.

IEEE Transactions on Applied Superconductivity, 22(3), p.4203305_1 - 4203305_5, 2012/06

 Times Cited Count:8 Percentile:47.85(Engineering, Electrical & Electronic)

Japan Atomic Energy Agency (JAEA) has responsibility to procure 19 structures for ITER toroidal field (TF) coils as in-kind components. JAEA plans to use materials specified in the material section of "Codes for Fusion Facilities; Rules on Superconducting Magnet Structure (2008)" issued by the Japan Society of Mechanical Engineers (JSME) in 2008. Large forged products were produced and their mechanical properties at 4K were evaluated. In addition, the following activities have been performed; (1) to optimize the design of each weld type identified in the manufacturing sequence, (2) to qualify typical welding procedure including repair, (3) to establish welding techniques other than narrow gap TIG welding with FMYJJ1, (4) to demonstrate the manufacturing procedures through manufacture of 1-m mockups and full-scale segments of TFC structure. This paper describes the results of material qualification and industrialization activities of manufacturing processes of ITER TFC structure.

Journal Articles

Development in fabrication structures for the ITER toroidal field coils

Iguchi, Masahide; Chida, Yutaka; Nakajima, Hideo; Ogawa, Tsuyoshi*; Katayama, Yoshinori*; Ogata, Hiroshige*; Minemura, Toshiyuki*; Miyabe, Keisuke*; Tokai, Daisuke*; Niimi, Kenichiro*

Teion Kogaku, 47(3), p.193 - 199, 2012/03

Japan Atomic Energy Agency (JAEA) has conducted qualification and rationalization activities in Japan in order to rationalize manufacturing procedure of ITER Toroidal Field (TF) coil structures. The activities included qualification of structural materials and qualification of welding procedure according to Japan Society of Mechanical Engineers (JSME) code constituted for fusion devices, demonstration of the manufacturing method and procedures through full-scale segments of TF coil structure. From results of these activities, JAEA confirmed applicability of JSME code to actual series TF coil structures as quality control method hence the quality of structural materials and weld joints of Gas Tungsten Arc Welding (GTAW) were satisfied ITER requirement. In addition, JAEA obtained knowledge of welding deformation of actual TF coil structures. This paper describes results of these qualification and development activities for TF coil structure.

Journal Articles

Compensation of residual third-order dispersion in a fiber stretched, chirped-pulse amplification system using a grism pair

Ogawa, Kanade; Akahane, Yutaka; Tsuji, Koichi; Yamakawa, Koichi

Reza Kenkyu, 38(10), p.779 - 783, 2010/10

We have newly designed a grism pair compensator for third-order dispersion in a fiber stretched chirped-pulse amplification system. In a numerical calculation, we have obtained a pedestal-free re-compressed pulse close to the transform-limited pulse using the grism pair. We have experimentally demonstrated a two-fold enhancement of peak intensity and pulse shortening of the compressed pulse with this device.

Journal Articles

Compression of idler pulses with an identical positive dispersive media to signal pulse stretcher in ultrafast optical-parametric chirped-pulse amplification

Akahane, Yutaka; Ogawa, Kanade; Tsuji, Koichi; Aoyama, Makoto; Yamakawa, Koichi

Proceedings of SPIE, Vol.7589, p.75890L_1 - 75890L_8, 2010/02

 Times Cited Count:0 Percentile:0.01

We have proposed and demonstrated a very simple and robust femtosecond optical-parametric chirped-pulse amplification scheme in which an even order dispersion of an idler pulse is compensated by passing through an identical positive dispersive material used for temporal stretching a signal pulse. By compressing the idler pulses having a negatively chirp in this manner, high power sub-100 fs pulses were successfully obtained with only a transparent glass block used for the stretcher and compressor.

Journal Articles

Optical-parametric chirped-pulse amplification using a positive dispersive material for pulse stretching and compression

Yamakawa, Koichi; Akahane, Yutaka; Ogawa, Kanade; Aoyama, Makoto

Denki Gakkai Hikari, Ryoshi Debaisu Kenkyukai Shiryo OQD-09-61, p.13 - 16, 2009/09

We have proposed and demonstrated a novel optical-parametric chirped-pulse amplification scheme in which an even order dispersion of an idler pulse is compensated by passing through an identical positive dispersive material used for temporal stretching a signal pulse. By compressing the idler pulses having a negatively chirp in this manner, high power sub-100 fs pulses were successfully obtained with only a transparent glass block used for the stretcher and compressor. A feasible design of real world femtosecond laser systems employing this scheme is also discussed.

Journal Articles

Idler pulse compression using an identical positive stretcher/compressor combination in optical-parametric chirped-pulse amplification

Akahane, Yutaka; Ogawa, Kanade; Tsuji, Koichi; Aoyama, Makoto; Yamakawa, Koichi

Applied Physics Express, 2(7), p.072503_1 - 072503_3, 2009/07

 Times Cited Count:4 Percentile:19.88(Physics, Applied)

We have proposed and demonstrated a very simple and robust femtosecond optical-parametric chirped-pulse amplification scheme in which an even order dispersion of an idler pulse is compensated by passing through an identical positive dispersive material used for temporal stretching a signal pulse. By compressing the idler pulses having a negatively chirp in this manner, high power sub-100 fs pulses were successfully obtained with only a transparent glass block used for the stretcher and compressor. A feasible design of real world femtosecond laser systems employing this scheme is also discussed.

Journal Articles

Controlling the phase matching conditions of optical parametric chirped-pulse amplification using partially deuterated KDP

Ogawa, Kanade; Sueda, Keiichi*; Akahane, Yutaka; Aoyama, Makoto; Tsuji, Koichi; Fujioka, Kana*; Kanabe, Tadashi*; Yamakawa, Koichi; Miyanaga, Noriaki*

Optics Express (Internet), 17(10), p.7744 - 7749, 2009/05

 Times Cited Count:12 Percentile:54.45(Optics)

Using a partially deuterated KDP crystal for an optical parametric amplifier, we demonstrated ultrabroadband optical parametric chirped-pulse amplification of more than 250 nm bandwidth at a center wavelength of 1050 nm. We numerically show how to control the broadband phase matching conditions at different wavelengths to match center wavelengths of suitable broadband seed sources by adjusting the deuteration level in partially deuterated KDP.

Journal Articles

Ultrahigh intensity few-cycle lasers

Yamakawa, Koichi; Aoyama, Makoto; Akahane, Yutaka; Ogawa, Kanade; Tsuji, Koichi

Reza Kenkyu, 36(9), p.555 - 561, 2008/09

We review progress in the generation of ultrahigh-intensity optical pulses in a few-cycle regime. A design of a Generation of ENergetic Beam Ultimate (GENBU) laser based on optical parametric chirped-pulse amplification, which will be produced a peak power of up to 6-PW with a variable pulse durations ranging from 5-fs to 8-ps is described. Ultra-broadband optical parametric chirped-pulse amplification pumped by a picosecond laser pulse delivered from a diode-pumped, cryogenically-cooled Yb:YLF chirped-pulse amplification laser is also reported.

Journal Articles

Report on ITPA (International Tokamak Physics Activity) meeting, 22

Takenaga, Hidenobu; Ogawa, Yuichi*; Takizuka, Tomonori; Yagi, Masatoshi*; Yamada, Hiroshi*; Sakamoto, Yoshiteru; Toi, Kazuo*; Fukuda, Takeshi*; Fukuyama, Atsushi*; Fujita, Takaaki; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 84(7), p.465 - 467, 2008/07

no abstracts in English

Journal Articles

Bandwidth enhancement of optical parametric chirped pulse amplification by temporally delayed two pump beams

Ogawa, Kanade; Aoyama, Makoto; Akahane, Yutaka; Tsuji, Koichi; Kawanaka, Junji*; Harimoto, Tetsuo*; Nishioka, Hajime*; Fujita, Masayuki*; Yamakawa, Koichi

Japanese Journal of Applied Physics, 47(6), p.4592 - 4594, 2008/06

 Times Cited Count:7 Percentile:31.85(Physics, Applied)

We have demonstrated ultra-broadband optical parametric chirped-pulse amplification of more than 350 nm bandwidth in a near infrared region. We have observed a substantial enhancement (nearly 2-fold) of the parametric amplification bandwidth by using time delayed two broadband pump pulses at degeneracy.

Journal Articles

High-energy diode-pumped picosecond regenerative amplification at 999 nm in wavelength with a cryogenically cooled Yb:LuLiF$$_{4}$$ crystal

Akahane, Yutaka; Aoyama, Makoto; Sugiyama, Akira; Kubo, Ryoichi; Ogawa, Kanade; Tsuji, Koichi; Yamakawa, Koichi

Optics Letters, 33(5), p.494 - 496, 2008/03

 Times Cited Count:2 Percentile:15.43(Optics)

A diode-pumped, cryogenically-cooled Yb:LuLiF$$_{4}$$ regenerative amplifier has been developed for the first time to our knowledge. A chirped-seed pulse was amplified and compressed in the regenerative amplifier, simultaneously, which generated $$sim$$6-mJ, 13-ps pulses at 999 nm wavelength without a pulse compressor. Simultaneous lasing at 999 nm and 1024 nm, respectively, was demonstrated, which could be used for different frequency generation in the THz region.

Journal Articles

Report on ITPA (International Tokamak Physics Activity) meeting, 20

Fujita, Takaaki; Fukuda, Takeshi*; Fukuyama, Atsushi*; Sakamoto, Yoshiteru; Toi, Kazuo*; Ogawa, Yuichi*; Takenaga, Hidenobu; Takizuka, Tomonori; Yagi, Masatoshi*; Yamada, Hiroshi*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 84(1), p.70 - 72, 2008/01

no abstracts in English

Journal Articles

Report of meetings of ITPA (International Tokamak Physics Activity), 19

Sasao, Mamiko*; Kusama, Yoshinori; Kawano, Yasunori; Kawahata, Kazuo*; Mase, Atsushi*; Sugie, Tatsuo; Fujita, Takaaki; Fukuda, Takeshi*; Fukuyama, Atsushi*; Sakamoto, Yoshiteru; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 83(9), p.779 - 782, 2007/09

This is a report of highlights from 2007 spring meetings of seven Topical Groups (TG) of International Tokamak Physics Activity (ITPA). In each meeting, high priority issues in physics of International Thermonuclear Experimental Reactor (ITER) and other burning plasma experiments have been discussed and investigated. Twenty-seven scientists from Japan have participated in those meetings. Dates and places of the meetings are shown below. (1) Diagnostics TG: 26-30 March, Princeton (USA), (2) Transport Physics TG: 7-10 May, Lausanne (Switzerland), (3) Confinement Database and Modeling TG: 7-10 May, Lausanne (Switzerland), (4) Edge Pedestal Physics TG: 7-10 May, Garching (Germany) (5) Steady State Operation TG: 9-11 May, Daejeon (South Korea), (6)MHD TG: 21-24 May, San Diego (USA), (7) Scrape-off-layer and Divertor Physics TG: 7-10 May, Garching (Germany).

Journal Articles

Ultra-broadband optical parametric chirped-pulse amplification with a diverged pump beam

Ogawa, Kanade; Akahane, Yutaka; Harimoto, Tetsuo*; Aoyama, Makoto; Tsuji, Koichi; Kawanaka, Junji*; Nishioka, Hajime*; Fujita, Masayuki*; Yamakawa, Koichi

Reza Kenkyu, 35(9), p.596 - 598, 2007/09

no abstracts in English

Journal Articles

Magnetic fusion energy studies in Japan

Ogawa, Masao*; Iio, Shunji*; Komori, Akio*; Kawahata, Kazuo*; Kaneko, Osamu*; Inoue, Takashi; Kamada, Yutaka

Nuclear Instruments and Methods in Physics Research A, 577(1-2), p.30 - 36, 2007/07

 Times Cited Count:4 Percentile:36.92(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Multi-millijoule, diode-pumped, cryogenically-cooled Yb:KY(WO$$_{4}$$)$$_{2}$$ chirped-pulse regenerative amplifier

Ogawa, Kanade; Akahane, Yutaka; Aoyama, Makoto; Tsuji, Koichi; Tokita, Shigeki*; Kawanaka, Junji*; Nishioka, Hajime*; Yamakawa, Koichi

Optics Express (Internet), 15(14), p.8598 - 8602, 2007/07

 Times Cited Count:21 Percentile:70.17(Optics)

Ytterbium (Yb$$^{3+}$$) doped gain media are one of promising laser materials for the next generation of diode-pumped high-power lasers. Yb-doped media have several advantages. It has wide absorption bandwidth, the low quantum defect, and the simple electronic structure. Yb:KY(WO$$_{4}$$)$$_{2}$$ (Yb:KYW) and Yb:KG(WO$$_{4}$$)$$_{2}$$ (Yb:KGW) have a large absorption and wide emission cross section, broad emission spectral range, and high thermal conductivity, yielding a high repetition-rate, high-energy, sub-picosecond pulses. However, multi-millijoule-class Yb:KYW or Yb:KGW lasers have not yet been reported so far, excepting a massive, joule-class Ti:sapphire laser pumped Yb:KGW regenerative amplifier. So, We developed a compact diode-pumped, cryogenically-cooled chirped-pulse Yb:KYW regenerative amplifier. An amplified pulse with an energy of 5.5 mJ and a high optical conversion efficiency of $$sim$$14% is achieved. Regenerative pulse shaping is also used to counter gain narrowing during amplification.

Journal Articles

High-energy, diode-pumped, picosecond Yb:YAG chirped-pulse regenerative amplifier for pumping optical parametric chirped-pulse amplification

Akahane, Yutaka; Aoyama, Makoto; Ogawa, Kanade; Tsuji, Koichi; Tokita, Shigeki*; Kawanaka, Junji*; Nishioka, Hajime*; Yamakawa, Koichi

Optics Letters, 32(13), p.1899 - 1901, 2007/07

 Times Cited Count:38 Percentile:84.44(Optics)

A diode-pumped, cryogenic-cooled Yb:YAG regenerative amplifier utilizing gain-narrowing has been developed. A 1.2-ns chirped-seed pulse was amplified and compressed in the regenerative amplifier, simultaneously, which generated a 35-ps pulse with $$sim$$8-mJ of energy without a pulse compressor. Second-harmonics of the amplified pulse was used to pump picosecond two-color optical parametric amplification.

141 (Records 1-20 displayed on this page)