A unified particle diffusion theory for cross-field scattering: Subdiffusion, recovery of diffusion, and diffusion in three-dimensional turbulence

Abstract

A new nonlinear theory for cosmic-ray scattering across the mean magnetic field is derived. This theory can be applied for arbitrary turbulence geometry. Previous theories such as the extended nonlinear guiding center theory are deduced as special limits. Furthermore, the new theory can explain subdiffusive transport for slab turbulence and the recovery of diffusion for slab/two-dimensional and three-dimensional turbulence. The nonlinear standard theory for field line wandering can be obtained as a special limit. © 2010. The American Astronomical Society. All rights reserved.