The thickness of target for X-ray sources with approximate Planck's spectral distribution from laser-produced plasmas is optimized using a one-dimensional radiation hydrodynamics code MULTI. The effect of X-ray radiation field with Planck's distribution on the processes of excitation and ionization in a plasma is stadied using a non-LTE ionized material package NIMP. These results are very important in the future experimental design to study the influence of X-ray emission from accretion disks on interstellar matter.