Interference of radiating states and ion dynamics in spectral line broadening

Abstract

The influence of the plasma coupling between the populations and the coherences on the lineshape is investigated. Ion dynamics is taken into account. The present research is performed within the atomic density matrix formalism. Ion microfield dynamics is simulated by the kangaroo - Poisson stochastic process (model microfield method). Numerical calculations of both lifetimes of radiating states and lineshapes are performed for the spectral doublet (1s - 2s) - (1s - 4p), (1s - 2) - (1s - 4d) of helium-like multicharged ions in hot dense plasmas. It is found that the ion microfield essentially influences the difference of populations of radiating states. Calculation of the lineshape of the doublet (1s - 2p) - (1s - 4d), (1s - 2p) - (1s - 4f) of neutral helium at astrophysical plasma conditions is also performed. The contribution of nonlinear interference effects (NIEF) in both allowed and forbidden components is calculated at various plasma conditions and a comparison with binary adiabatic theory is made. The results demonstrate that it is essential to take account of NIEF in the calculation of lineshapes of multicharged ions, but not essential in the case of neutral helium.