  The diffusion approximation to the Fokker-Planck equation is commonly used to
model the transport of solar energetic particles in interplanetary space. In
this study, we present exact analytical predictions of a higher order telegraph
approximation for particle transport and compare them with the corresponding
predictions of the diffusion approximation and numerical solutions of the full
Fokker-Planck equation. We specifically investigate the role of the adiabatic
focusing effect of a spatially varying magnetic field on an evolving particle
distribution. Comparison of the analytical and numerical results shows that the
telegraph approximation reproduces the particle intensity profiles much more
accurately than does the diffusion approximation, especially when the focusing
is strong. However, the telegraph approximation appears to offer no significant
advantage over the diffusion approximation for calculating the particle
anisotropy. The telegraph approximation can be a useful tool for describing
both diffusive and wavelike aspects of the cosmic-ray transport.
