COLLECTIVE COORDINATES FOR ION DYNAMICS

Utilising a link between microfield smoothness and ion dynamics, a method for calculating the autocorrelation function of spectral line shapes in a plasma, including ion dynamics, is presented. The method is based on a time-independent simulation, in that the dynamics are handled semi-analytically via a separable kernel approximation in Dyson's equation. For each perturber configuration this reduces to the solution of a linear algebraic system. In addition this method naturally leads to a set of (approximate) relevant collective coordinates. It is shown that the microfield must be smooth and this implies the existence of new collective coordinates, namely the microfield values at a few time points. Nonsmooth components are separated out and treated analytically by the ion impact theory. This approach is valid for all parameter ranges and may be utilized either as an alternative to solving the Schrodinger equation in a simulation-like manner, or by using the collective coordinate approach. In the later case, knowledge of the many-times joint probability density is desirable.