Evaluation of quasilinear diffusion coefficients for whistler mode waves in a plasma with arbitrary density ratio
Author  
Keywords  
Abstract 
Techniques are presented for efficiently evaluating quasilinear diffusion coefficients for whistler mode waves propagating according to the full cold plasma index of refraction. In particular, the density ratio ωpe/Ωe can be small, which favors energy diffusion. This generalizes an approach, previously used for highdensity hiss and electromagnetic ion cyclotron waves, of identifying (and omitting) ranges of wavenormal angle θ that are incompatible with cyclotron resonant frequencies ω occurring between sharp cutoffs of the modeled wave frequency spectrum. This requires a detailed analysis of the maximum and minimum values of the refractive index as a function of ω and θ, as has previously been performed in the highdensity approximation. Sample calculations show the effect of lowdensity ratio on the pitch angle and energy diffusion coefficients modeling the effect of chorus waves on radiation belt electrons. The highdensity approximation turns out to be quite robust, especially when the upper frequency cutoff is small compared with Ωe. The techniques greatly reduce the amount of computation needed for a sample calculation, while taking into account all resonant harmonic numbers n up to \textpm$\infty$.

Year of Publication 
2005

Journal 
Journal of Geophysical Research

Volume 
110

Date Published 
03/2005

ISSN Number 
01480227

URL 
http://onlinelibrary.wiley.com/doi/10.1029/2004JA010844/abstract

DOI 
10.1029/2004JA010844
