Whistler anisotropy instability: Wave-particle scattering rate

[1] An electron temperature anisotropy T-perpendicular toe > T-parallel toe (where perpendicular to and parallel to refer to directions relative to the background magnetic field) can excite the whistler anisotropy instability in a collisionless plasma. The resulting enhanced fluctuating magnetic fields scatter the electrons and reduce the anisotropy. We use particle-in-cell simulations in a spatially homogeneous plasma model to compute the maximum values of the wave-particle scattering rate for electron anisotropy reduction. This rate scales as the electron cyclotron frequency but, for a fixed initial growth rate, is relatively independent of the electron temperature if k(B)T(e) less than or equal to 5 keV For larger electron temperatures, the scattering rate decreases with increasing T-e, suggesting that relativistic effects play a role.