Stochastic properties of equilibrium strongly coupled plasmas are investigated by a molecular dynamics method. The Krylov-Kolmogorov entropy K and the dynamical memory time t(m) are calculated both for electrons and ions with mass ratios 10-10(5). Two values of K entropy for ions are discovered corresponding to electron and ion time scales. The dependence of the K entropy on the number of particles, the nonideality parameter, and the form of the interaction potential is investigated. The problem of the accuracy of molecular dynamics simulations is discussed. A universal relation between Kt(m) and the fluctuation of the total energy of the system is obtained. The relation does not depend on the numerical integration scheme, temperature, density, and the interparticle interaction potential, so that it may be applied to arbitrary dynamic systems. Transition from dynamic to stochastic correlation is treated for both electron and ion velocity autocorrelation functions, for Langmuir and ion-sound plasma wave dynamic structure factors. We point to quantum uncertainty as a physical reason which limits dynamic (Newton) correlation for times greater than t(m).

A b s t r a c t I n t r o d u c t i o nIn nearly all cases gaseous plasmas behave classically and the largest part of plasma physics is based on classical theory. However strictly speaking classical theory cannot provide the full truth since the Coulomb singularity does not admit a classical treatment. It was first Planck in the twenthies who reckognized this principal difficulty and made a first approach how to develop a consequent semi-classical theory. Planck's basic idea was to split the pair states into bound states which have to be treated by quantum theory and free states which admit a semi-classical tratment. This idea was developed by Brillouin and treated in recent time with modern quantum statistical methods by Larkin and others [l, 21. Here MD-calculations are performed and compared with theoretical expressions. Our main interest is devoted to the semi-classical theory of the free charges in plasmas consisting of electrons and ions in the range of large nonideality (coupling) parameter r = ez/kTd, where d = ( 3 / 4~n , ) ' /~ is the average distance between the ions. Berlin and Montroll, Unsold, Ecker and Weizel, Kaklyugin and others [3, 4, 5, 61 predicted that in the region of large r the thermodynamic functions, e.g. the mean Coulomb energy U,, should observe a linear scaling with r. Method of effective potentialsThe idea of effective potentials is to incorporate classical as well as quantum-mechanical effects by appropriate potentials. Such a quasi-classical approach has of course several limits which are basically connected with the trajectory concept. We mention for example the principal difficulty to describe microspic quantum effects as tunneling, and macroscopic quantum effects as superfluidity and superconductance. Our aim is only the calculation of standard macroscopic properties which have a well defined classical limit. Since bound states cannot be described classically our method is restricted to the subsystem of free charges. However this is not a very serious restriction since most properties of the plasma are determined by the subsystem of the free charges. In the following we shall use the BPL-convention for the bound states and quasi-classical approximations for the effective potential [l, 2, 7, 81 The most easy way to arrive at potentials including quantum effects is through the so-called Slater sums. The Slater sum is an analogue of the classical Boltzmann factor and allows to define effective potentials [l, 2, 7, 81 62 Contrib. Plapma Phys. 39 (1999) where with 5 = r/&b. The effective potentials derived from perturbation theory (Kelbg-like potentials) do not include bound state effects and give the constant A = 0. They may be used only in the region of high temperaturesIn the region of inter,mediate temperatures 0.1 < T < 0.3 we may use the Kelbg-potential with a temperature-dependent correction A(T) which is adapted in such away that Sob(r = 0) has the exact value corresponding to the two-particle wave functions [l]. At lower temperatures T < 0.1 we may perform the limit li + 0...

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The conception is developed which distinguishes initial stages of the fast (nanosecond) electric explosion of wires: the superheating of the solid conductor, its spontaneous (spinodal) decay and the successive formation of the nonideal plasma column. The molecular dynamics simulation approach is used to simulate homogeneous nucleation at a constant heating rate. The subsequent evolution of the fluid column and the axial plasma uniformity are considered. The results are compared with the experimental data on nanosecond wire explosions.

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