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Hasegawa, Noboru; Kawachi, Tetsuya; Kishimoto, Maki; Sukegawa, Kota*; Tanaka, Momoko; Tai, R. Z.*; Ochi, Yoshihiro; Nishikino, Masaharu; Nagashima, Keisuke; Kato, Yoshiaki*
Japanese Journal of Applied Physics, 48(1), p.012503_1 - 012503_6, 2009/01
Times Cited Count:6 Percentile:26.26(Physics, Applied)We evaluate the characteristics of a higher-order harmonics light as a seed X-ray amplified through the laser-produced X-ray amplifier. Narrow spectral bandwidth of the X-ray amplifier works as the frequency filter of the seed X-ray, resulting in that only the temporally coherent X-ray is amplified. Experimental investigation using the 29th-order harmonic light of the Ti:sapphire laser at a wavelength of 26.9 nm together with the neon-like manganese X-ray laser medium shows obvious spectral narrowing of the seed X-ray and amplification without serious diffraction effects on the propagation of the amplified X-ray beam. This implies that the present combination is potential to realize temporally coherent X-ray lasers, with the expected duration of several 100 fs.
Nishikino, Masaharu; Hasegawa, Noboru; Kawachi, Tetsuya; Yamatani, Hiroshi; Sukegawa, Kota; Nagashima, Keisuke
Applied Optics, 47(8), p.1129 - 1134, 2008/03
Times Cited Count:43 Percentile:86.01(Optics)Hasegawa, Noboru; Kawachi, Tetsuya; Sasaki, Akira; Kishimoto, Maki; Sukegawa, Kota; Tanaka, Momoko; Tai, R. Z.*; Ochi, Yoshihiro; Nishikino, Masaharu; Nagashima, Keisuke; et al.
Physical Review A, 76(4), p.043805_1 - 043805_5, 2007/10
Times Cited Count:20 Percentile:66.75(Optics)We firstly demonstrated the measurement of temporal profile of the amplification gain of the transient collisional excitation (TCE) X-ray laser with the solid target by use of X-ray diagnostic beam injection technique. In this experiment, higher-order harmonic light at a wavelength of 26.9 nm was injected into the neon-like manganese plasma as X-ray laser medium, and the amplified signal was observed. The obtained buildup time of the amplification gain was 23 ps measured from the time of the main pumping laser pulse, and the lifetime of the amplification gain was 27 ps. This result was in good agreement with the theoretical simulation by using an atomic kinetics code.
Namba, Shinichi*; Hasegawa, Noboru; Nishikino, Masaharu; Kawachi, Tetsuya; Kishimoto, Maki; Sukegawa, Kota; Tanaka, Momoko; Ochi, Yoshihiro; Takiyama, Ken*; Nagashima, Keisuke
Physical Review Letters, 99(4), p.043004_1 - 043004_4, 2007/07
Times Cited Count:32 Percentile:77.84(Physics, Multidisciplinary)The interaction of large Xe clusters with a soft X-ray laser pulse having a wavelength of 13.9 nm and an intensity of up to 210
W/cm
was investigated using a time-of-flight ion mass spectrometer. It was found that Xe
ions (which result from double Auger decay of 4d vacancies) became the dominant final ionic product with increasing cluster size and X-ray intensity. This is in contrast to the results of synchrotron radiation experiments involving free Xe atoms, in which Xe
is the dominant resultant ion species. Possible mechanisms responsible for the enhancement of the double Auger transition probability in X-ray laser and cluster interaction are discussed.
Sukegawa, Kota*; Kishimoto, Maki; Kado, Masataka
JAERI-Tech 2004-077, 21 Pages, 2005/01
no abstracts in English
Ochi, Yoshihiro; Hasegawa, Noboru; Suzuki, Yoji; Sukegawa, Kota*; Kawachi, Tetsuya; Kishimoto, Maki; Nagashima, Keisuke
JAERI-Tech 2004-062, 32 Pages, 2004/11
We have designed new chirp-pulse amplification (CPA) laser system for 0.1 Hz repetition rate soft X-ray laser system. We adopted the optical parametric chirped pulse amplifier (OPCPA) for a pre-amplifier because of its pulse controllability. For a main-amplifier, we decided to use a zigzag-slab amplifier because of its thermal radiation ability. In order to avoid the inhomogeneous spatial profile of the amplified laser beam, the image of the incident laser light created by a serrated aperture is transferred by use of an image relay system. In this report, we will show the preliminary test of each amplifier using a prototype system and the details of the final system design.
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:45.75(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.
Hasegawa, Noboru; Kawachi, Tetsuya; Utsumi, Takayuki*; Sasaki, Akira; Tanaka, Momoko; Kado, Masataka; Sukegawa, Kota*; Lu, P.; Kishimoto, Maki; Tai, R.; et al.
Japanese Journal of Applied Physics, Part 1, 43(5A), p.2519 - 2522, 2004/05
Times Cited Count:12 Percentile:44.98(Physics, Applied)We conducted high-precision measurements of the wavelength of the nickel-like silver X-ray laser in order to compare it with a theoretical wavelength. The reasons for using this laser are as follows: First, this laser line is in the wavelength region of Mo/Si multi-layer mirrors; therefore, this laser line is important for applications. Second, the strongamplification of this laser line has been obtained in our previous work, and the higher order line in the spectra obtained by our spectrometer can be used. Third, since silver is arelatively low-z material (z = 47), this wavelength is a ideal benchmark of atomic structural codes such as the Multiconfiguration Dirac-Fock (MCDF) code. The wavelength of the nickel-like silver X-ray laser was determined to be 13.887 nm. The comparison with MCDF codes shows that the present experimental result can work as a good benchmark of the accuracy of the codes.
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:89.28(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.
Kim, J.*; Kim, D. E.*; Kawachi, Tetsuya; Hasegawa, Noboru; Sukegawa, Kota*; Iwamae, Atsushi*; Fujimoto, Takashi*
Journal of the Optical Society of Korea, 7(3), p.145 - 149, 2003/09
The anistropy of electron energy distribution in oxygen plasmas produced by a high intensinty laser was investigated by using polarization spectroscopy. An ultra-short pulsed laser with a pulse duration of 66.5 fs and a power density of 110
W/cm
was used. At this power density and pulse duration, the plasma was generated predominantly by optical field ionization. The degree of polarization of OVI 1s
2p
P
-1s
4d
D
(J=1/2-3/2 and J=3/2-5/2) transition line at 129.92
の1s
2p
P
-1s
4s
S
(J=1/2-1/2 and J=3/2-1/2) transition line at 132.26 AA was used to calibrate the sensitivity of the optical system. The dependencies of the degree of polarization on the initial gas density and on the laser polarization were investigated. When the laser polarization was changed from a linear to a circlar polarization was decreased. When the initial gas density was increased, the degree of polarization was decreased.
Kawachi, Tetsuya; Kado, Masataka; Tanaka, Momoko; Hasegawa, Noboru; Nagashima, Keisuke; Sukegawa, Kota*; Lu, P.; Takahashi, Kenjiro; Namba, Shinichi; Koike, Masato; et al.
Applied Optics, 42(12), p.2198 - 2205, 2003/04
Times Cited Count:27 Percentile:72.16(Optics)no abstracts in English
Tang, H.; Daido, Hiroyuki; Kishimoto, Maki; Sukegawa, Kota*; Tai, R.; Mesesson, S.*; Tanaka, Momoko; Lu, P.; Kawachi, Tetsuya; Nagashima, Keisuke; et al.
Japanese Journal of Applied Physics, 42(2A), p.443 - 448, 2003/02
Times Cited Count:14 Percentile:50.29(Physics, Applied)no abstracts in English
Tai, R.; Namikawa, Kazumichi*; Kishimoto, Maki; Tanaka, Momoko; Sukegawa, Kota*; Hasegawa, Noboru; Kawachi, Tetsuya; Kado, Masataka; Lu, P.; Nagashima, Keisuke; et al.
Physical Review Letters, 89(25), p.257602_1 - 267602_4, 2002/12
Times Cited Count:40 Percentile:81.07(Physics, Multidisciplinary)no abstracts in English
Lu, P.; Kawachi, Tetsuya; Kishimoto, Maki; Sukegawa, Kota*; Tanaka, Momoko; Hasegawa, Noboru; Suzuki, Masayuki; Tai, R.; Kado, Masataka; Nagashima, Keisuke; et al.
Optics Letters, 27(21), p.1911 - 1913, 2002/11
Times Cited Count:8 Percentile:39.76(Optics)We demonstrate a high gain nickel-like xenon ion x-ray laser using a gas puff target. The elongated x-ray laser plasma column was produced by irradiating the gas puff target with line-focused double picosecond laser pulses with a total energy of 18 J in a travelling-wave excitation scheme. Strong lasing at 9.98 nm was observed, and a high gain coefficient of 17.4 1/cm was measured on the transient collisionally excited 4d ミ 4p, J=0-1 transition for nickel-like xenon ion with target lengths up to 0.45 cm long. A weak nickel-like lasing line at a shorter wavelength of 9.64 nm was also observed with a gain coefficient of 5.9 1/cm.
Nagashima, Keisuke; Kawachi, Tetsuya; Kado, Masataka; Tanaka, Momoko; Hasegawa, Noboru; Sukegawa, Kota*; Namba, Shinichi; Tang, H.; Daido, Hiroyuki; Kato, Yoshiaki
Purazuma, Kaku Yugo Gakkai-Shi, 78(3), p.248 - 255, 2002/03
no abstracts in English
Lu, P.; Kawachi, Tetsuya; Suzuki, M.*; Sukegawa, Kota*; Namba, Shinichi; Tanaka, Momoko; Hasegawa, Noboru; Nagashima, Keisuke; Daido, Hiroyuki; Arisawa, Takashi; et al.
Japanese Journal of Applied Physics, Part 2, 41(2A), p.L133 - L135, 2002/02
Times Cited Count:9 Percentile:37.96(Physics, Applied)no abstracts in English
Tanaka, Momoko; Kawachi, Tetsuya; Kado, Masataka; Hasegawa, Noboru; Sukegawa, Kota*; Lu, P.; Nagashima, Keisuke; Kato, Yoshiaki; Takenaka, Hisataka*
Surface Review and Letters, 9(1), p.641 - 644, 2002/02
Times Cited Count:12 Percentile:53.13(Chemistry, Physical)no abstracts in English
Kato, Yoshiaki; Daido, Hiroyuki; Nagashima, Keisuke; Kawachi, Tetsuya; Hasegawa, Noboru; Tanaka, Momoko; Tang, H.; Tai, R.; Lu, P.; Kishimoto, Maki; et al.
AIP Conference Proceedings 641, p.31 - 39, 2002/00
no abstracts in English