Non-Markovian relative diffusion of stochastic magnetic lines

摘要

In this paper, we study some aspects related to the spatial relative diffusion of the magnetic-field lines. The nonlinear integral equation for the Lagrangian correlation is transformed into a system of two ordinary differential equations and solved numerically. The system of linear integral- differential equations for the moments is analyzed numerically for different values of the alpha-parameter (which is proportional to the ratio of parallel and perpendicular correlation lengths). A critical value for alpha (alpha (sub crit) = 0.3251) is obtained in a shearless stochastic magnetic-field model. For alpha > alpha(sub crit) the rate of damping of the anisotropy becomes complex, that means an oscillatory behavior for the correlations and anisotropies. For alpha (alpha)(sub crit) we find the well known behavior described in the literature for alpha << 1. 19 refs.