The inapplicability of spatial diffusion models for solar cosmic rays
Abstract
It is noted that because of the rapid temporal evolution of the particle density, the interplanetary propagation of solar cosmic rays cannot be accurately described by a spatial diffusion equation. Using a simple numerical integration scheme, it is shown that the pitchangle scattering equation gives intensitytime profiles and anisotropies very different from the spatial diffusion results in many cases. Reasons are given for the failure of the diffusion limit, and an explanation is offered for the fact that some temporal profiles of solar particle events look diffusive.
 Publication:

The Astrophysical Journal
 Pub Date:
 April 1981
 DOI:
 10.1086/158812
 Bibcode:
 1981ApJ...245..328O
 Keywords:

 Cosmic Rays;
 Interplanetary Medium;
 Particle Diffusion;
 Solar Corpuscular Radiation;
 Anisotropic Media;
 Numerical Integration;
 Solar Flares;
 Time Response;
 Solar Physics