Effects of amplitude modulation on nonlinear interactions between electrons and chorus waves

Abstract

The effects of amplitude modulation on nonlinear interactions between a parallel propagating chorus wave packet and electrons in a dipole field are investigated in this work using a test particle code. Previous research used a single wave to model a chorus wave element, leading to nonlinear processes such as phase trapping and bunching when the wave amplitude was large enough. However, high resolution observations of chorus wave packets show a modulation of the wave amplitude, forming the so-called chorus subpackets or subelements. Here we first extend a previous method to model a realistic chorus packet. Using the modeled chorus packet, we demonstrate directly that including the realistic amplitude modulation could significantly affect the behavior of resonant electrons. Our results suggest that the amplitude modulation should be considered in the quantitative treatment of interactions between electrons and chorus waves. Copyright 2012 by the American Geophysical Union.