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A simple XUV transmission grating spectrograph operating in the wavelength range 3-90 Å with sub-ångström resolution without using any XUV imaging optics is described. This is based on a free-standing gold microstructure grating of 2000 Å period in normal incidence geometry. A spectral resolution of 0.6 Å is obtained by optimizing the slit aperture, the source-to-grating distance and the grating-to-detector distance. Electron temperatures deduced from analysis of the spectrum of a laser-produced magnesium plasma using a plasma spectroscopic code are consistent with theoretical considerations. The spectral range can be extended to higher wavelengths by using a larger detector. The simple geometry and ease of operation of the spectrograph should make it useful in many experiments such as those involving plasma-based XUV lasers and odd-harmonic generation in the XUV spectral region using ultra-short laser pulses.

The report presents the results from experimental investigation of micropinch formation in the plasma of a vacuum discharge induced by a 6 ns laser pulse of energy J = 0.5–200 mJ (at a storage voltage from 4 to 15 kV and the discharge current range of 6–26 kA, respectively). The discharge gap images were obtained using a pinhole camera in the EUV and soft X-ray ranges of 15–73 eV and 80–284 eV energy. It is shown that micropinch formation in the plasma cathode jet occurs, mainly, in the matter evaporated by the laser pulse at the discharge ignition near the moment when the current derivative reaches the maximum. It is found that the cathode jet may consist of several pinched areas, and each of them has its own structure, and the improvement of the discharge and laser radiation parameters allows us to reach a stable single pinching of plasma. The parameters of the micropinch (the plasma compression ratio, size, and position of the emitting area in the interelectrode gap) as well as the current flow through the interelectrode gap, at the given storage voltage, are completely governed by the laser radiation characteristics.

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