Formation of correlations in strongly coupled plasmas

The formation of binary correlations in plasma is studied from the quantum kinetic equation. It is shown that this formation is much faster than dissipation due to collisions. In a hot (dense) plasma the correlations are formed on the scale of inverse plasma frequency (Fermi energy). We derive analytical formulae for the time dependency of the potential energy which measures the extent of correlations. We discuss the dynamical formation of screening and compare with the statical screened result. Comparisons are made with molecular dynamic simulations. Recent lasers allow to create a high density plasma within few femto seconds and observe its time evolution on a comparable scale [1,2]. In this paper we discuss the very first time regime, the transient regime, in terms of the energy balance. Let us assume a typically set up of molecular dynamics. One takes N particles, distributes them randomly into a box and let them classically move under Coulomb forces due to their own charges. Their first movement thus forms correlations which lower the Coulomb energy VC = e /r. This build up of screening stops when the effective Debye potential VD = e 2e−κr/r is reached. We will discuss the formation of correlations in terms of correlation energy. To this end we can use a kinetic equation, which leads to the total energy conservation. It is immediately obvious that the ordinary Boltzmann equation cannot be used because the kinetic energy is an invariant of its collision integral. We have to consider non-Markovian kinetic equations of Levinson type [1]