Anomalous test particle transport in turbulent MHD fields

Anisotropic stochastic magnetic fields lead to significant changes in the test particle transport as compared to isotropic cases. The analysis of the Langevin equations for the test particles, when considering both the magnetic anisotropy and the collisions, lead to anisotropic transport ranging from subdiffusion to diffusion. In absence of collisions, the transport is diffusive in all directions but with different diffusion coefficients. In the case of MHD produced fields, the transport in the plane perpendicular to the main magnetic field is strongly reduced, and appears to be almost diffusive while the parallel transport is still in the ballistic regime. (authors)