Ultrafast nonequilibrium electron dynamics in a solid-density aluminium interacting with an ultra-intense ultrafast x-ray pulse

Ultrafast nonequilibrium dynamics of free electrons in a solid-density aluminium produced by an ultra-intense ultrafast x-ray pulse is investigated by solving Fokker-Planck equation. Electron energy distribution function (EEDF) contains two parts: a lower energy part at nearly equilibrium and a higher energy part at evident nonequilibrium. The former part accounts for the most population of the total electron number. X-ray transmission and bound-bound emissivity show little difference between the results with EEDF obtained by solving Fokker-Planck equation and by Maxwellian distribution assumption. Yet the bremsstrahlung emissivity shows great difference.