Subdiffusive transport of charged particles perpendicular to the large scale magnetic field

Transport of charged particles across the mean magnetic field due to broad band, powerlaw-distributed magnetic fluctuations is examined by direct computation of a large number of charged test particle trajectories. Fluctuations consist of a one dimensional slab spectrum with an additional 0.01 percent level of two dimensional fluctuations; the net field has no ignorable directions. We find that, at long times (t), the mean square displacements subdiffusively scale as ~t^1/2. This confirms that perpendicular diffusion is suppressed when turbulence lacks strong three dimensional structure, in agreement with theories of Urch and of Kóta and Jokipii.