## Cosmic Ray Pitch Angle Scattering in Isotropic TurbulenceJ. W. Bieber, C. W. Smith and W. H. Matthaeus
## Abstract:The divergent conclusions emerging from previous investigations of cosmic-ray pitch-angle scattering in isotropic magnetic turbulence can be reconciled by incorporating a dissipation range in the turbulence model. Such a dissipation range, where the omnidirectional energy spectrum falls off faster than k(exp-3) (k is the magnitude of the wavevector), can be expected to occur at scales smaller than some finite value, which we denote the ``dissipation scale.'' Utilizing an isotropic turbulence model that includes dissipation, we calculate the Fokker-Planck coefficient for pitch-angle scattering and find that the ``slab'' form of the Fokker-Planck coefficient favored by Jokipii is valid at very low energies. A smooth, gradual transition between the two forms occurs at energies such that the particle Larmor radius is of the order of the dissipation scale. Return to Charles W. Smith's Publication Page Return to Charles W. Smith Home Page |