A model for opacity measurements across expanding X-ray laser media

Abstract
A theoretical model has been developed for opacity calculations across an expanding laser produced plasma used as an x-ray laser medium. The assumptions of planar geometry, exponentially decreasing emissivity and absorption coefficient with distance with a step rise at a particular point and a linear with distance plasma bulk velocity profile have been made. The hydrodynamic coupled to the atomic 'EHYBRID' code has been modified to take into account the radiation trapping across the plasma using the net radiative bracket predicted by the above model. The result of the theoretical model as well as the output of the modified EHYBRID code have been employed to solve the radiation transfer equation and to simulate 123 Ne-like and 399 F-like Germanium resonance lines both in time resolved and time integrated modes. We obtain agreement between the simulated spectra and experimental spectra measured during x-ray laser experiments.