A pulse-train yttrium aluminium garnet (YAG) laser was used with a shaped envelope, as well as a new lens system for producing a dotted-line irradiation pattern in X-ray laser experiments. Amplified spontaneous emission (ASE) signals of the two Li-like Al transitions (3d-4f, 15.47 nm and 3p-4d, 15.06 nm) were observed with a pumping energy of only 1.5–2 J. The gain coefficient were approximately 3 cm-1 for the 3d-4f line and was maintained for a period of about 1 ns. The double-pass amplification experiment was carried out using a plane multilayer mirror. A clear increase in the above two Li-like Al transition lines was observed. It is highly expected that a strong laser amplification could be achieved in an X-ray laser cavity with two multilayer X-ray mirrors.

The application of electrical fields of radio frequency by external electrodes to cells that contain mixtures of caesium with argon, krypton or xenon at low temperatures (<340 K) produces capacitative discharges in columns, that show discontinuities where the discharge is confined. In this work an explanation is given based on the propagation of two electrical waves in opposite directions that produce a quasi-potential.

An in situ calibration experiment of a soft x-ray spectrograph for x-ray laser research has been performed. The calibrated spectrograph was a flat-field grazing incidence spectrometer with an x-ray charge-coupled device camera. The absolute sensitivity of the spectrograph was obtained for the wavelength range from 2.6 to 4.0 nm using a transmission grating spectrograph as a reference spectrograph set along the axial direction of a line-focused laser-produced plasma. The absolute sensitivity determined in this work shows nearly the same value as that deduced from the calibration experiment using synchrotron radiation.

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