Comment on "New probing techniques of radiative shocks, by C.Stehle et   al"
  In this comment, we discuss the possibility of imaging the radiative precursor of a strong shock with a 21.2 nm soft x-ray laser probe and we analyze the data presented in C.Stehle et al "New probing techniques of radiative shocks", (Optics Communications 285, 64, 2012) in order to derive some estimation of the achieved resolution. We show that the presented results are inconclusive for the existence of a radiative precursor. Furthermore, our best estimation of cold and warm Xenon VUV opacities tells that 21.2 nm backlighting would not be able to probe this radiative precursor. 
Michel Busquet
astro-ph.IM astro-ph.SR physics.plasm-ph