Influence of Amplitude and Frequency Modulation of the Whistler Wave Packet on Cyclotron Interaction With Energetic Electrons in the Earth's Magnetosphere

We consider the resonant interaction of a whistler-mode wave packet with energetic electrons. The wave packet parameters are based on Cluster spacecraft data. Both model profiles of the packet amplitude and frequency (Gaussian and linear, respectively) and profiles taking into account variations in amplitude and frequency, directly based on spacecraft data, are used. The effect of the wave packet amplitude and frequency modulation on the acceleration of electrons and their precipitation into the loss cone as a result of the interaction is analyzed by using test particle simulations. It is shown that both modulations have a similar effect on the interaction characteristics: the presence of modulation (amplitude and/or frequency) generally significantly increases the probability of particle trapping by the wave field, but the maximum energy gain for trapped particles decreases. However, there are regions of the initial electron parameters in which, even in the presence of modulation, significant acceleration of individual groups of particles is possible. As a result of the interaction considered, electrons with energies of 20 to 200 keV can effectively precipitate into the loss cone. As the packet propagates away from the equator, less effective precipitation of particles with energies of 200 to 600 keV is possible. The precipitation characteristics depend only weakly on the presence of amplitude and/or frequency modulation of the wave packet.