SIMULATIONS OF COSMIC-RAY CROSS-FIELD DIFFUSION IN HIGHLY PERTURBED MAGNETIC-FIELDS

The process of particle cross-field diffusion in high amplitude Alfven ic turbulence is considered using the method of the Monte Carlo partic le simulations. We derive the cross-field diffusion coefficient kappa( perpendicular to) and the parallel diffusion coefficient kappa(paralle l to) in the presence of different 1-D, 2-D and 3-D turbulent wave fie ld models and discuss the kappa(perpendicular to),kappa(parallel to) a nd kappa(perpendicular to)kappa(parallel to) variations with the wave amplitude. kappa(perpendicular to) is compared also to the respective derived values of the magnetic field diffusion coefficient. We note su bstantial differences in the cross-field diffusion efficiency at the s ame perturbation amplitude, depending on the detailed form of the turb ulent field considered. Vanishing of kappa(perpendicular to) at 1-D an d 2-D turbulent fields is confirmed. For some types of the turbulent m agnetic field an initial regime of sub-diffusive transport appears in the simulations. The derived values of kappa(parallel to) are weakly d ependent on the wave form and scale as the inverse of the squared pert urbation amplitude up to our highest non-linear amplitudes.