Intensity correlation measurement system by picosecond single shot soft X-ray laser

Kishimoto, Maki; Namikawa, Kazumichi*; Sukegawa, Kota*; Yamatani, Hiroshi*; Hasegawa, Noboru; Tanaka, Momoko

Review of Scientific Instruments, 81(1), p.013905_1 - 013905_5, 2010/01

AA2009-0790.pdf:0.78MB

https://doi.org/10.1063/1.3280173

We developed a new soft X-ray speckle intensity correlation spectroscopy system by use of a single shot high brilliant plasma soft X-ray laser. The plasma soft X-ray laser is characterized by several picoseconds in pulse width, more than 90% special coherence, and 10 soft X-ray photons within a single pulse. We developed a Michelson type delay pulse generator using a soft X-ray beam splitter to measure the intensity correlation of X-ray speckles from materials and succeeded in generating double coherent X-ray pulses with picosecond delay times. Moreover, we employed a high-speed soft X-ray streak camera for the picosecond time-resolved measurement of X-ray speckles. We performed the X-ray speckle intensity correlation measurements for probing the relaxation phenomena of polarizations in polarization clusters in the paraelectric phase of the ferroelectric material BaTiO near its Curie temperature and verified its performance.

Characterization of a high-brilliance soft X-ray laser at 13.9 nm by use of an oscillator-amplifier configuration

Nishikino, Masaharu; Hasegawa, Noboru; Kawachi, Tetsuya; Yamatani, Hiroshi; Sukegawa, Kota; Nagashima, Keisuke

Applied Optics, 47(8), p.1129 - 1134, 2008/03

https://doi.org/10.1364/AO.47.001129

Enhancement of double auger decay probability in xenon clusters irradiated with a soft-X-ray laser pulse

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

https://doi.org/10.1103/PhysRevLett.99.043004

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 210W/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.

Design of chirp-pulse amplification laser system and test results of key elements for high-repetition rate soft X-ray lasers

Ochi, Yoshihiro; Hasegawa, Noboru; Suzuki, Yoji; Sukegawa, Kota*; Kawachi, Tetsuya; Kishimoto, Maki; Nagashima, Keisuke

JAERI-Tech 2004-062, 32 Pages, 2004/11

JAERI-Tech-2004-062.pdf:1.84MB

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.

Development of a full spatial coherent X-ray laser at 13.9 nm and its applications

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.

Development of a laser-pumped X-ray laser with full spatial coherence

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

http://ci.nii.ac.jp/naid/110003827831

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.

Study of the anisotropy of electron energy distribution of optical-field ionized oxygen plasma by using polarization spectroscopy

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

https://doi.org/10.3807/JOSK.2003.7.3.145

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 1s2p P-1s4d D (J=1/2-3/2 and J=3/2-5/2) transition line at 129.92 の1s 2pP-1s4sS (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.

Spatial coherence measurement of the 13.9nm Ni-like Ag soft X-ray laser pumped by a 1.5ps, 20J laser

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

https://doi.org/10.1143/JJAP.42.443

no abstracts in English

Demonstration of a transient-gain nickel-like xenon-ion X-ray laser

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

https://doi.org/10.1364/OL.27.001911

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.

Demonstration of a transient high gain soft X-ray laser for neon-like Argon

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

https://doi.org/10.1143/JJAP.41.L133

no abstracts in English