[en] We have been developing an x-ray laser with high brightness and high spatial coherence using double targets scheme. The x-ray laser is applied to an x-ray interference measurement, an x-ray speckle measurement, and so on. Accuracy of the target alignment is very important in order to lead the seed light generated from the first target to the second target. An auto alignment system has been developed to achieve the required accuracy and the target chamber has been designed and fabricated in the viewpoint of high precision and high stability. The stability of the target position has been examined and achieved target movement less than 4 μrad due to vibration of the pumping system and less than ±10 μm due to the deforming of the target chamber during evacuation. We have achieved the resolutions of the target alignment system as 6 μm in direction of perpendicular of the target, 20 μrad in rotation and the stability as ±12 μm and ±40 μrad, respectively. (author)

[en] We have been developing an x-ray laser with high brightness and high spatial coherence using double targets scheme. The x-ray laser is applied to an x-ray interference measurement, an x-ray speckle measurement, and so on. Accuracy of the target alignment is very important in order to lead the seed light generated from the first target to the second target. An auto alignment system has been developed to achieve the required accuracy and the target chamber has been designed and fabricated in the viewpoint of high precision and high stability. The stability of the target position has been examined and achieved target movement less than 4 μrad due to vibration of the pumping system and less than ±10 μm due to the deforming of the target chamber during evacuation. We have achieved the resolutions of the target alignment system as 6 μm in direction of perpendicular of the target, 20 μrad in rotation and the stability as ±12 μm and ±40 μrad, respectively. (author)

[en] Spatially full coherent x-ray lasers have been recently demonstrated by double target method at JAERI. The beam divergence of 0.2 mrad is achieved with the full coherent x-ray lasers, which is one order better than ordinary x-ray lasers. In is the problem that is unstable beam pointing occurred by the beam divergence. Beam pointing stability is very important for application research. Because it must align a target in every 1 shot in case as a solid target, it is difficult to generate an x-ray laser at high repetition rate. Low repetition rate limits the application of x-ray laser. To solve these problems, a high precision target alignment system is needed. Therefore, we have been developing an auto-alignment system for high repetition rate. (author)

[en] The soft x-ray laser, 13.9 nm in wavelength, with full spatial coherence has been focused with a Fresnel zoneplate (FZP). The soft x-ray laser is generated with two gain media. The energy of the soft x-ray laser is about 2 μJ and the beam divergences at vertical and horizontal direction are 0.4 mrad and 2.3 mrad, respectively. We calculate numerically a far field image of the diffraction at about 480 mm after the FZP. A good agreement is obtained in the comparison between measured and calculated images. From the calculation, the intensity and diameter of the focused beam are estimated to be 3x10¹⁰ W/cm² and 140 nm, respectively. (author)

[en] We have observed lasing on Ne-like 3s-3p line from titanium (32.4 nm), Ni-like 4p-4d line from silver (13.9 nm) and tin (11.9 nm) with the transient collisional excitation (TCE) scheme that uses combination of a long pre-pulse (∼ns) and a short main pulse (∼ps). A gain coefficient of 23 cm^-1 was measured for plasma length up to 4 mm with silver slab targets. We have also observed lasing on Ne-like and Ni-like lines with new TCE scheme that used pico-seconds laser pulse to generate plasma and observed strong improvement of x-ray laser gain coefficient. A gain coefficient of 14 cm^-1 was measured for plasma length up to 6 mm with tin targets. (author)

[en] We have designed a new chirp-pulse amplification (CPA) laser system as a driver laser for a 0.1 Hz repetition rate soft x-ray laser system. We adopted an optical parametric chirped pulse amplifier (OPCPA) for a pre-amplifier from the point of view of pulse contrast controllability. For a main-amplifier, we decided to use a zigzag-slab amplifier from the points of view of heat radiation ability and compactness. In order to obtain homogeneous spatial profile of amplified laser beam, the image of the incident laser light created by a serrated aperture is transferred by use of an image relay system. This paper reports the preliminary results of each amplifier characteristics in a prototype system and details of the final system design. (author)

[en] The spatial gain profile of the transient collisional excitation Ni-like silver x-ray laser in various plasma lengths was observed using the near field imaging method. The gain region was the size of 50 μm and 30-50 μm distant from the target surface. The gain region had two maxima which are separated by 50 μm in the direction parallel to the target surface. (author)

[en] We report the spatial coherence of a x-ray laser at 13.9 nm after double-target amplification. The spatial coherence of the x-ray laser beam is characterized with the Young's double slit interferometry. The experimental coherence lengths for horizontal and vertical directions were greater than the beam size of the x-ray laser after double-target amplification. This x-ray laser beam has full spatial coherence, and the divergence of the x-ray laser beam is very close to diffraction limit. (author)

[en] This paper gives an overview of recent progress of x-ray laser research in Japan Atomic Energy Agency (JAEA). The fully spatial coherent x-ray laser beam at a wavelength of 13.9 nm is used for the several applications such as the x-ray speckle measurement in ferroelectric substance. For the purpose of further application experiments, 0.1 Hz-repetition rate x-ray laser driver is being developed, which is based on a Nd:glass zigzag slab amplifier with two beam lines. 0.1 Hz operation of the driver laser and the generation of the x-ray laser at a wavelength of 13.9 nm was succeed. (author)

[en] We obtained the neon-like manganese x-ray laser with the injection of the high order harmonic light as the seed x-ray at the wavelength of 26.9 nm for the purpose of generation of the temporally coherent x-ray laser. The x-ray amplifier, which has quite narrow spectral width, selected and amplified the temporally coherent mode of the harmonic light. The temporal coherence of the mode selected harmonic light was nearly transform limited pulse, and the obtained x-ray laser with the seed x-ray expected to be nearly temporally coherent x-ray. (author)