CALCULATION OF THE EFFECTS OF VELOCITY-GRADIENTS AND OPACITY ON LINE TRANSFER IN LASER-PRODUCED PLASMAS

A method that allows the simulation of K-shell resonance line emission in low density as well as high density laser-produced plasmas is described. The effect of resonance line trapping on ionic populations is taken into account using escape probabilities. A multifrequency line transfer algorithm that allows for plasma flow velocity gradients, and includes a choice of Doppler, Voigt, or a convolution of Doppler and Stark profiles, is described. The application of the code is illustrated by a set of calculations for the Ly-alpha (AlXIII ls-2p) line in an aluminium plasma created with a nanosecond, 0.53 mum laser beam and for the Ly-beta (AlXIII 1s-3p) and He-beta (AlXII 1s2-1s3p) lines in a plasma created with a 12 psec, 0.268 mum laser beam. The effect of velocity gradients is found to be of critical importance in determining the line shapes and intensities.