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.

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A comparative experimental study of soft x-ray emission from laser-irradiated Au–Cu mix-Z targets of different atomic compositions has been performed. Plasma was produced from planar targets using second-harmonic laser pulses from an Nd:glass laser at a focused intensity of ∼1013 W cm−2. Radiation intensity in the spectral region ∼15–150 Å and integrated x-ray yield for mix-Z target were observed to be higher than those for individual elements. The maximum conversion occurred for an atomic composition of Au 0.43–Cu 0.57. These observations are consistent with the variation of Rosseland mean opacity with atomic composition calculated using a screened hydrogenic average atom model.

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