Jay M. Albert ^1* William J. Longley ² Anthony Chan ³

• ¹ Air Force Research Lab, Kirtland AFB, NM, United States
• ² New Jersey Institute of Technology, Newark, New Jersey, United States
• ³ Rice University, Houston, Texas, United States

We consider a method for estimating bounce-averaged quasi-linear diffusion coefficients due to whistler-mode waves for a specified ratio of plasma frequency to gyrofrequency, ω p /Ω e , using values precomputed for a different value of that ratio. This approach was recently introduced to facilitate calculations associated with the "POES technique," generalized to infer both wave intensity and cold plasma density from measurements of particle fluxes near the loss cone.The original derivation was justified on the basis of parallel-propagating waves, but applied to calculations with much more general models of the waves. Here, we justify the estimates, which are based on equating resonant frequencies for differing values of ω p /Ω e and energy, for wide ranges of wave normal angle, resonance number, energy, and equatorial pitch angle.Refinements of the original estimates are obtained and tested numerically against full calculations of the diffusion coefficients for representative wave models. The estimated diffusion coefficients are fast to calculate and generally give useful estimates for energies in the 30 keV to 300 keV range, especially when both relevant values of the ratio ω p /Ω e are large.