Dynamic theory of relativistic electrons stochastic heating by whistler mode waves with application to the Earth magnetosphere

Abstract

In the Hamiltonian approach, electron motion in a coherent packet of the whistler mode waves propagating along the direction of an ambient magnetic field is studied. The physical processes by which these particles are accelerated to high energy are established. Equations governing particle motion are transformed into a closed pair of nonlinear difference equations. The solutions of these equations show there exists a threshold in initial electron energy, below which electron motion is regular and above which electron motion is stochastic. Particle energy spectra and pitch angle electron scattering are described by the Fokker-Planck-Kolmogorov equations. A calculation of the stochastic diffusion of electrons due to a spectrum of whistler modes is presented. The parametric dependence of the diffusion coefficients on the plasma particle density, magnitude of wave field, and the strength of magnetic field is studied. It is shown that significant pitch angle diffusion occurs for the Earth radiation belt electrons with energies from a few keV up to a few MeV. Copyright 2008 by the American Geophysical Union.