Density dependence of the atomic transition probabilities in hot, dense plasmas.

Abstract

The atomic properties and transition probabilities of highly ionized aluminum in hot, dense plasmas were studied. In particular, we present computational results of the variations with density of the following atomic parameters: atomic potential and screening factor (due to both bound and free electrons), free-electron distribution, atomic wave functions, binding energies, line shifts, and, finally, transition probabilities and oscillator strengths. The calculations were carried out using the ion-sphere model (ISM) which treats the bound and free electrons in the atom self-consistently in a central potential. This potential is produced by the combination of the nuclear Coulomb field together with contributions by the bound- and free-electron charge distributions. The results indicate an increasing effect of the plasma on the atomic properties with increasing plasma density. Particularly, the free-electron screening reduces the atomic potential, pushes the atomic wave functions away from the nucleus, and reduces the binding energy of the bound electrons. The transition probability also decreases monotonically with density up to the ionization limit of the upper state beyond which it drops to zero. The computational results are compared to those expected from a homogeneous free-electron spatial distribution.