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Journal Articles

Full-coherent free electron laser seeded by 13th- and 15th-order harmonics of near-infrared femtosecond laser pulses

Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Yamanouchi, Kaoru*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Togashi, Tadashi*; Fukami, Kenji*; et al.

Journal of Physics B; Atomic, Molecular and Optical Physics, 46(16), p.164006_1 - 164006_6, 2013/08

 Times Cited Count:3 Percentile:21.46(Optics)

By introducing 13th- (61.7 nm) and 15th-order harmonics (53.4 nm) of femtosecond laser pulses at 800 nm into an undulator of SCSS (SPring-8 Compact SASE Source) test accelerator at RIKEN, these harmonic pulses were amplified by a factor of more than 10$$^{2}$$ with a high contrast ratio through the interaction between accelerated electron bunches and the harmonic pulses. From numerical simulations of the amplification processes of high-order harmonic pulses in the undulator, optimum conditions of the electron bunch duration interacting with the high-order harmonic pulses were investigated for generating full-coherent and intense pulses in the extreme ultraviolet wavelength region.

Journal Articles

Performance upgrade in the JAEA actinide science beamline BL23SU at SPring-8 with a new twin-helical undulator

Saito, Yuji; Fukuda, Yoshihiro; Takeda, Yukiharu; Yamagami, Hiroshi; Takahashi, Sunao*; Asano, Yoshihiro*; Hara, Toru*; Shirasawa, Katsutoshi*; Takeuchi, Masao*; Tanaka, Takashi*; et al.

Journal of Synchrotron Radiation, 19(3), p.388 - 393, 2012/05

 Times Cited Count:77 Percentile:96.46(Instruments & Instrumentation)

The soft X-ray beamline BL23SU at SPring-8 has undergone an upgrade with a twin-helical undulator of in-vacuum type to enhance the experimental capabilities of the end stations. The new light source with a fast helicity-switching operation allows not only the data throughput but also the sensitivity in X-ray magnetic circular dichroism (XMCD) to be improved. The operational performance and potential are described by presenting XMCD results of paramagnetic $$beta$$-US$$_{2}$$ measured with a 10 T superconducting magnet.

Journal Articles

Extreme ultraviolet free electron laser seeded with high-order harmonic of Ti:sapphore laser

Togashi, Tadashi*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Okino, Tomoya*; Yamanouchi, Kaoru*; et al.

Optics Express (Internet), 19(1), p.317 - 324, 2011/01

 Times Cited Count:88 Percentile:96.89(Optics)

The 13th harmonic of a Ti:sapphire (Ti:S) laser in the plateau region was injected as a seeding source to a 250-MeV free-electron-laser (FEL) amplifier. When the amplification conditions were fulfilled, strong enhancement of the radiation intensity by a factor of 650 was observed. The random and uncontrollable spikes, which appeared in the spectra of the Self-Amplified Spontaneous Emission (SASE) based FEL radiation without the seeding source, were found to be suppressed drastically to form to a narrow-band, single peak profile at 61.2 nm. The properties of the seeded FEL radiation were well reproduced by numerical simulations. We discuss the future precept of the seeded FEL scheme to the shorter wavelength region.

Journal Articles

Technology development for the construction of the ITER superconducting magnet system

Okuno, Kiyoshi; Nakajima, Hideo; Sugimoto, Makoto; Isono, Takaaki; Kawano, Katsumi; Koizumi, Norikiyo; Hamada, Kazuya; Nunoya, Yoshihiko; Matsui, Kunihiro; Nabara, Yoshihiro; et al.

Nuclear Fusion, 47(5), p.456 - 462, 2007/05

 Times Cited Count:7 Percentile:27.89(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Technology development for the construction of ITER superconducting magnet system

Okuno, Kiyoshi; Nakajima, Hideo; Sugimoto, Makoto; Isono, Takaaki; Kawano, Katsumi; Koizumi, Norikiyo; Hamada, Kazuya; Nunoya, Yoshihiko; Nabara, Yoshihiro; Kitamura, Kazunori; et al.

Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03

The ITER superconducting magnet system consists of 18 TF coils, one CS and six Poloidal Field (PF) coils. Among six PTs, Japan, EU and US will be responsible for major part of the superconducting magnets, and Japanese contribution will be the largest, including the following four areas: part of TF conductors, about half (9 out of 19) of TF coil winding packs, most of TF coil structures and part of CS conductor. Since 2004, Japan Atomic Energy Agency (JAEA) started preparation activities for procurement, including manufacturing studies to identify detailed fabrication processes and tools for critical components, such as TF coil winding and case, and manufacturing demonstrations at full scale level on Nb$$_{3}$$Sn strands and conductors and cryogenic structural materials, such as coil case segments and radial plates. Details are described in the following sections.

Journal Articles

Solubility Measurement of Iron-Selenium Compounds under Reducing Conditions

Kitamura, Akira; Shibata, Masahiro; Kitao, Hideo*

Materials Research Society Symposium Proceedings, Vol.807, p.609 - 614, 2004/00

None

JAEA Reports

Solubility measurement of iron-selenium compounds under reducing conditions

Kitamura, Akira; Shibata, Masahiro; Kitao, Hideo*

JNC TN8400 2003-004, 76 Pages, 2003/03

JNC-TN8400-2003-004.pdf:1.81MB

Chemical behavior of selenium(Se), which was one of the important elements for performance assessment of geological disposal of high-level radioactive waste, was investigated under reducing and iron-containing conditions. A washing method for an iron diselenide(FeSe$$_{2}$$(cr)) reagent with acidic and basic solutions (0.1 and 1 M HCl and 1 M NaOH) was carried out for the purification of FeSe$$_{2}$$ reagent, which was considered to be a solubility limiting solid for Se under the geological disposal conditions. Furthermore, solubility of FeSe$$_{2}$$(cr) was measured in alkaline solution (pH: 11 - 13) under reducing conditions (E$$_{h}$$ vs SHE: -0.4 - O V), and thermodynamic data on equilibrium reactions between Se in solution and Se precipitate were obtained. The dependencies of solubility values on pH and redox potential (Eh: vs. standard hydrogen electrode) were best interpreted that the solubility limiting solid was not FeSe$$_{2}$$(cr) but Se(cr) and the aqueous species was SeO$$_{3}$$$$^{2-}$$ in the present experimental conditions. The equilibrium constant between Se(cr) and SeO$$_{3}$$$$^{2-}$$ at zero ionic strength was determined and compared with literature values. The chemical behavior of Se under geological disposal conditions was discussed.

Journal Articles

Helicity switching of circularly polarized undulator radiation by local orbit bumps

Hara, Toru*; Shirasawa, Katsutoshi*; Takeuchi, Masao*; Seike, Takamitsu*; Saito, Yuji; Muro, Takayuki*; Kitamura, Hideo*

Nuclear Instruments and Methods in Physics Research A, 498(1-3), p.496 - 502, 2003/02

 Times Cited Count:56 Percentile:95.51(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Demagnetization of undulator magnets irradiated high energy electrons

Bizen, Teruhiko*; Tanaka, Takashi*; Asano, Yoshihiro; Kim, D. E.*; Bak, J. S.*; Lee, H. S.*; Kitamura, Hideo*

Nuclear Instruments and Methods in Physics Research A, 467-468(Part1), p.185 - 189, 2001/07

 Times Cited Count:39 Percentile:92.78(Instruments & Instrumentation)

no abstracts in English

Oral presentation

Preparation of procurement for ITER TF coil

Sugimoto, Makoto; Kitamura, Kazunori; Hamada, Kazuya; Nakajima, Hideo; Okuno, Kiyoshi

no journal, , 

no abstracts in English

Oral presentation

Fracture mechanics analysis of ITER toroidal field coil

Onodera, Osamu*; Iguchi, Masahide*; Saito, Masakatsu*; Hamada, Kazuya; Nakajima, Hideo; Okuno, Kiyoshi; Sugimoto, Makoto; Nakahira, Masataka; Kitamura, Kazunori; Takayanagi, Tadatoshi*; et al.

no journal, , 

no abstracts in English

Oral presentation

XMCD spectroscopy using a twin helical undulator

Saito, Yuji; Fukuda, Yoshihiro; Takeda, Yukiharu; Hara, Toru*; Shirasawa, Katsutoshi*; Takeuchi, Masao*; Kitamura, Hideo*

no journal, , 

The SPring-8 BL23SU (JAEA Actinide Science beamline) has been upgraded by the replacement of the original APPLE-2 type undulator with a twin helical undulator using in-vacuum devices. Recently, polarization switching between beams of opposite helicity at 1 Hz has reached operational status. The test results clearly show that the new light source is very well suited for the measurement of precision X-ray absorption, magnetic circular dichroism, spectra, as well as element-specifc hysteresis loops.

Oral presentation

Strain evaluation of GlidCop for materials of the high-heat-road components

Sano, Mutsumi*; Takahashi, Sunao*; Watanabe, Atsuo*; Kitamura, Hideo*; Shiro, Ayumi; Shobu, Takahisa

no journal, , 

no abstracts in English

13 (Records 1-13 displayed on this page)
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