X‐ray spectromicroscopy of clusters heated by fs laser radiation

The review of systematic investigations of X‐ray radiation properties of different clusters heated by short‐pulse (35–1100 fs) high‐intensive (1016– 1018 W/cm2) Ti:Sa laser radiation is presented. The cluster targets were formed by the adiabatic expansion in vacuum of an Kr or Ar gas jets produced by a pulsed valve with Laval or conical nozzles. The gas pressure is varied from 15 up to 100 bar. High spectrally (λ/δλ=4000–5000) and spatially (40–80 μm) resolved X‐Ray spectra near resonance lines (4‐2 transitions) of Ne‐like ions of Kr, H‐ and He‐like ions of Ar have been obtained and detailed spectroscopic analysis was consistent with a theoretical two‐temperature collisional‐radiative model of irradiated atomic clusters incorporating with an effects of highly energetic electrons. The role of laser prepulse for X‐ray intensity emission investigated in details. X‐ray spectra radiation from plasma with electron density more than 2×1022 cm−3 was observed. Big effect of fast electrons influence on the X‐ray em...