Correlation Effects and their Impact on Line Broadening in Plasmas: Application to $H_\alpha$

In the last two decades, several computational approaches to the Stark broadening in plasma have been developed, where motion of both ions and electrons is simulated and their fields are calculated using an effective Debye-Yukawa potential. Such an approximation, in general, can be questioned in cases when the number of plasma particles in the Debye sphere is about unity or below. For testing the applicability of this approach, large-scale molecular-dynamics simulations were performed, with all plasma particles interacting by the Coulomb potential, and the correlations in the motion of the particles were analyzed. It was found that even for a moderately coupled plasma ($n_e = 10^{18}~\mbox{cm}^{-3}$, $T = 1~\mbox{eV}$), the collective effects play a major role in the statistical and dynamical properties of the micro-fields. Nevertheless, the corrections to the $H_\alpha$ profile are rather minor, for which an explanation is presented.