SIMULATION OF X-RAY-LINE TRANSFER IN A CYLINDRICALLY EXPANDING PLASMA

A method for calculating the X-ray resonance line emission from a cyli ndrically expanding laser-produced plasma is presented. A multi-freque ncy line transfer algorithm, incorporated as a post-processor to a tim e-dependent 1-D hydrodynamics and non-LTE atomic physics calculation, is used to compute spatially-resolved spectral profiles of the line em ission. Coupling of photon re-absorption to ionic state populations is achieved by use of the escape probability method. We use the code to investigate the effects of high expansion velocities, and the influenc e of neighbouring lines, on the opacity and detailed shape of opticall y thick lines. As an example we consider the profile of the Lyman-alph a (1s-2p) resonance line of hydrogenic aluminium. (C) 1997 Elsevier Sc ience Ltd.