Microfield fluctuations and radiative transitions in laser-generated strongly coupled plasmas

Abstract.

Previously unaccessible plasma states of matter can be produced by irradiation with powerful lasers. The interactions within the plasma shift and distort the spectral lines corresponding to radiative transitions. The shape of the spectra is determined by two frequencies characterizing the fluctuations of the electric microfield in the plasma and the Stark splitting of the lines. Traditionally the fluctuations due to the motion of the ions are considered as sufficiently slow and weak to be treated in a linear quasi-static approximation, while the electrons are accounted for in an instantaneous impact approximation. Here also the intermediate regimes and strongly correlated ions are investigated. For that purpose the microfield fluctuations are calculated by molecular dynamics computer simulations. They are then used as input in a numerical solution of the time-dependent Schrödinger equation for the radiating electron. The shape of the Ly$_{\alpha}$-line in H and in Al is investigated in the intermediate regime. The calculations are in agreement with recent experiments on the Ly$_{\alpha}$ and Ly$_{\gamma}$ lines in Al.