Over-the-barrier ionization of multielectron atoms by intense VUV free-electron laser

摘要: Free-electron laser sources now under construction are intended to attain radiative intensities higher than at photon energies up 30 eV. We investigate the over-the-barrier mechanism of ionization heavy atoms by such a source. find that, for valence electrons, this mode is suppressed in regime where electric field and energy comparable, respectively, atomic fields binding energies. Ionization inner-shell electrons still possible, but some kind `two-fluid' model necessary describe phenomenon.