Simulations of Cosmic Ray Cross Field Diffusion in Highly Perturbed Magnetic Fields

The process of particle cross-field diffusion in high amplitude Alfvénic turbulence is considered using the method of the Monte Carlo particle simulations. We derive the cross-field diffusion coefficient κ⊥ and the parallel diffusion coefficient κ‖ in the presence of different 1-D, 2-D and 3-D turbulent wave field models and discuss the κ⊥, κ‖ and κ⊥κ‖ variations with the wave amplitude. κ⊥ is compared also to the respective derived values of the magnetic field diffusion coefficient. We note substantial differences in the cross-field diffusion efficiency at the same perturbation amplitude, depending on the detailed form of the turbulent field considered. Vanishing of κ⊥ at 1-D and 2-D turbulent fields is confirmed. For some types of the turbulent magnetic field an initial regime of subdiffusive transport appears in the simulations. The derived values of κ‖ are weakly dependent on the wave form and scale as the inverse of the squared perturbation amplitude up to our highest non-linear amplitudes.