Anomalous diffusion of energetic particles in MHD turbulence

Diffusive transport of charged particles in a collisionless plasma is one of the central issues in space plasma research. Most of the conventional arguments are based on a classical diffusion model, a second order linear diffusion equation with a prescribed diffusion coefficient. Underlying assumptions are the low turbulence level and the lack of phase coherence among the waves. In real MHD turbulence in space, however, both of these assumptions are likely to be violated in many circumstances. We introduce a simple mathematical model to describe particles trajectories in the turbulence field, where the turbulence is assumed to be composed of multi-scale eddies. Details of the model as well as comparison of the results with test particle simulations will be presented.