Title:NON-MARKOVIAN FOKKER-PLANCK EQUATIONS AND TURBULENT DIFFUSION IN PLASMAS
Authors:A.Zagorodny (Bogolyubov Institute for Theoretical Physics, 252143 Kyiv 143, Ukraine), J.Weiland (Institute for Electromagnetics, Chalmers University of Technology, S-41296 G\"oteborg, Sweden)

Non-Markovian generalization of the Fokker-Planck equation is proposed in attempt to describe the influence of memory effects on stochastic particle motion in both velocity and configuration spaces. General relations between the time-nonlocal diffusion coefficient, its conventional part and meansquare displacements are established. Application of the proposed non-Marcovian equation to the description of diffusive processes in the configurational space directly leads to a time-nonlocal diffusion equation. The results obtained are in agreement with the continuous time random walk theory. Microscopic derivation of the non-Markovian equation is given for the specific case of turbulent plasma using particle propagators renormalized with regard for the evolution of kinetic coefficients. The influence of memory effects on transport processes in plasmas with saturated turbulence is discussed.

Key words: Fokker-Planck equation, turbulence saturation, time-nonlocal diffusion
Comments: Figs. 0, Refs. 12, Tabs. 0.