Open AccessOn the diffusivity of cosmic ray transport
Author(s) -
Tautz R. C.,
Shalchi A.
Publication year - 2010
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2009ja014944
Subject(s) - physics , test particle , isotropy , cosmic ray , particle (ecology) , turbulence , mean squared displacement , diffusion , statistical physics , thermal diffusivity , classical mechanics , computational physics , mechanics , astrophysics , molecular dynamics , optics , geology , quantum mechanics , oceanography
A common assumption in particle transport theory is the assumption of diffusive propagation, corresponding to a linear increase of the mean square displacement of particle orbits with time. In recent years, however, several authors have discovered nondiffusive transport in observations and in test particle simulations. Some analytical theories also predict subdiffusion or superdiffusion of charged particles. In this article, a recently developed test particle code is employed to explore diffusive and nondiffusive transport regimes. For slab, two‐component, and isotropic turbulence the simulations are performed for different particle energies. It is demonstrated that, in most cases, cross‐field transport is indeed subdiffusive. The level of subdiffusivity is sensitively controlled by the turbulence geometry.