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Kawachi, Tetsuya; Hasegawa, Noboru; Nishikino, Masaharu; Ishino, Masahiko; Imazono, Takashi; Oba, Toshiyuki; Kaihori, Takeshi; Kishimoto, Maki; Ochi, Yoshihiro; Tanaka, Momoko; et al.
X-Ray Lasers 2010; Springer Proceedings in Physics, Vol.136, p.15 - 24, 2011/12
This paper reviews recent improvement in the source development of laser-driven X-ray lasers and the applications in the research fields of material science, laser processing, X-ray imaging, and radiation damage in biological cells. In the application for material science, we have firstly observed temporal correlation between the domain structures of ferro-electric substance under the Curie temperature. In the laser processing, new X-ray laser interferometer reveals us the nano-scale surface distortion of substance pumped by a femto-second optical pulse. In the X-ray diffraction image, we have taken several static images of micro-structure of samples: now we are trying to extend the objective to nano-scale dynamics using pump and probe method. In the radiation damage of biological cells, we observed double strand break in DNA using X-ray laser exposure; this results are compared with the case using incoherent several KeV X-ray exposure.
Hasegawa, Noboru; Ochi, Yoshihiro; Kawachi, Tetsuya; Terakawa, Kota*; Tomita, Takuro*; Yamamoto, Minoru; Nishikino, Masaharu; Oba, Toshiyuki; Kaihori, Takeshi; Imazono, Takashi; et al.
X-Ray Lasers 2010; Springer Proceedings in Physics, Vol.136, p.353 - 358, 2011/12
The understanding of the dynamics of the initial process is important for the micro processing and welding by the ultra-short laser pulse. The X-ray laser is suitable for probing this initial process because it has short wavelength (Ni-like Ag, 13.9 nm) and short duration (7 ps). For this investigation, the origin of time of the pumping pulse is quite important. In this study, we used the scintillation plate and the plasma gate technique to realize the spatial and temporal synchronization of the pump and probe pulses. For the spatial alignment, a CsI scintillation plate that was set at the sample position was illuminated by both the X-ray laser pulse, and the fluorescence light were detected by the CCD camera. For the temporal synchronization, we set a thin foil at the sample position. We measured the transmission of the X-ray laser while changing a temporal delay of the pumping laser with respect to the time of X-ray laser pulse to obtain the origin of the irradiation time.
Nishikino, Masaharu; Tanaka, Momoko; Ochi, Yoshihiro; Kishimoto, Maki; Ishino, Masahiko; Hasegawa, Noboru; Kado, Masataka; Sukegawa, Kota*; Kawachi, Tetsuya; Nagashima, Keisuke
IEEE Journal of Selected Topics in Quantum Electronics, 10(6), p.1382 - 1387, 2004/11
Times Cited Count：9 Percentile：45.77(Engineering, Electrical & Electronic)no abstracts in English
Nagashima, Keisuke; Tanaka, Momoko; Nishikino, Masaharu; Kishimoto, Maki; Kado, Masataka; Kawachi, Tetsuya; Hasegawa, Noboru; Ochi, Yoshihiro; Sukegawa, Kota*; Tai, R.; et al.
Applied Physics B, 78(7), p.927 - 932, 2004/05
We have succeeded in developing a laser-pumped X-ray laser with full spatial coherence at 13.9 nm. A highly directed X-ray laser beam with the divergence of 0.2 mrad was generated from the double target experiment, where a seeding light from the first laser medium was amplified in the second medium. The observed divergence is close to the diffraction limit value within a factor of two. The seeding light was amplified in the second medium without refraction influence and the gain coefficient was about 8 cm-1. From the measurement of visibility, it was found that the spatial coherent length is longer than the beam diameter. As an application of this coherent X-ray laser, we observed a surface microstructure of ferroelectric material, BaTiO
and clarified a change of the microstructure near the Curie temperature.
Nagashima, Keisuke; Tanaka, Momoko; Nishikino, Masaharu; Kishimoto, Maki; Kado, Masataka; Kawachi, Tetsuya; Hasegawa, Noboru; Ochi, Yoshihiro; Sukegawa, Kota*; Tai, R.
Purazuma, Kaku Yugo Gakkai-Shi, 80(3), p.236 - 240, 2004/03
A laser-pumped X-ray laser with full spatial coherence has been developed for the first time. This X-ray laser has the wavelength of 13.9 nm and the beam divergence of 0.2 mrad. In the experiment, a seeding light from the first laser medium was amplified in the second medium, which worked as an active spatial filter. The observed beam divergence was close to the diffraction limited value within a factor of two. The seeding light was amplified in the second medium without refraction influence. The gain region of the second medium was far away from the target surface compared with that of the first medium and located in the considerably low density region. From the measurement of visibility, it was found that the spatial coherent length is longer than the beam diameter. It means that this X-ray laser beam is full spatial coherent.
Nishikino, Masaharu; Tanaka, Momoko; Nagashima, Keisuke; Kishimoto, Maki; Kado, Masataka; Kawachi, Tetsuya; Sukegawa, Kota*; Ochi, Yoshihiro; Hasegawa, Noboru; Kato, Yoshiaki
Physical Review A, 68(6), p.061802_1 - 061802_4, 2003/12
Times Cited Count：61 Percentile：89.32(Optics)We demonstrate a generation of highly coherent X-ray laser at 13.9 nm by oscillator-amplifier configuration with two targets. In the oscillator-amplifier configuration, the seeding X-ray laser beam from the first target is injected into the plasma amplifier at the second target. When the X-ray laser beam is not affected by refraction during propagation in the amplifier, the X-ray laser beam with small divergence and high coherence is generated. The observed X-ray laser beam has 0.2 mrad of the diffraction limited divergence and the full spatial coherence.
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.
Ochi, Yoshihiro; Hasegawa, Noboru; Nishikino, Masaharu; Tanaka, Momoko; Oba, Toshiyuki; Kaihori, Takeshi; Kishimoto, Maki; Kado, Masataka; Ishino, Masahiko; Imazono, Takashi; et al.
no journal, ,
Recent progress in the source development of laser-driven plasma soft-X-ray lasers and the applications in JAEA are presented. The fully spatial coherent soft-X-ray laser at a wavelength of 13.9 nm with the repetition-rate of 0.1 Hz is now routinely used for the applications in JAEA. In this paper, details of the driver laser system, soft-X-ray laser system, and some examples of its applications are described.
Kado, Masataka; Kawachi, Tetsuya; Ochi, Yoshihiro; Nishikino, Masaharu; Ishino, Masahiko; Imazono, Takashi; Sasaki, Akira; Hasegawa, Noboru; Kishimoto, Maki; Tanaka, Momoko; et al.
no journal, ,
Full coherent X-ray laser operating at 0.1 Hz are realized with originally developed high power laser system and double-target amplification scheme at JAEA. Utilizing the high spatial coherent several applications have been done recently such as study of temporal correlation of the domain fluctuation of BaTiO with X-ray speckle measurement and X-ray interferometric measurement of nano-scale dynamics of solid surface with X-ray interferometer. Irradiating the X-ray laser onto biological cells DNA radiation damages showed different features comparing ordinary X-ray sources. Recent progress of X-ray laser development at JAEA and its applications will be presented.
Sakurai, Takeru; Iguchi, Masahide; Nakahira, Masataka; Minemura, Toshiyuki*; Yanagi, Yutaka*; Osemochi, Koichi*
no journal, ,
no abstracts in English
