Quasilinear diffusion in stochastic magnetic fields: Reconciliation of drift-orbit modification calculations

An apparent difference between two calculations of drift-orbit modifications to the spatial diffusion rate of particles in stochastic magnetic fields is addressed [H. E. Mynick and J. A. Krommes, Phys. Rev. Lett. 43, 1506 (1979); J. R. Myra and P. J. Catto, Phys. Fluids B 4, 176 (1992)]. The calculations are reconciled by noting the relevance of an inequality which was not discussed in these studies. It is shown, both analytically and by Monte Carlo simulation, that the diffusion coefficient can be sensitive to the spectral width of the magnetic turbulence relative to a finite Larmor radius parameter.