On X-ray spectral diagnostics of laser plasma with external photon pumping

The development of diagnostic methods for dense high-temperature plasma exposed to powerful streams of short-wave radiation is of particular relevance in connection with the planned construction in Russia of the SYLA, a MegaScience facility, which is an acceleration-storage complex that combines a fourth-generation synchrotron source and an X-ray free-electron laser, and with laser plasma experiments intensively conducted using hohlraum-type targets. The possibility is considered of this plasma diagnostics by one of the X-ray spectral techniques, namely by relative intensities of the resonant and intercombination lines of multicharged He-like ions. Based on detailed kinetic calculations, conditions are defined under which this technique can be applied to this plasma without any modification and relative intensities of these lines are calculated for cases when external effects significantly change the kinetics of their excitation.