Nonlinear triggering process of whistler mode emissions in a homogeneous magnetic field

Abstract:

We perform a one-dimensional electromagnetic particle simulation in a uniform magnetic field to study the initial stage of the generation process of whistler-mode triggered emissions at the equatorial magnetosphere. To find the generation of whistler-mode waves by triggering waves in the simulation system, we drive two orthogonally aligned antennas by right-handed polarized external currents oscillating with frequencies below the electron cyclotron frequency. During the propagation of triggering whistler-mode waves, we inject energetic electrons into the simulation system. After the injection, we find the generation of new emissions as the result of the interaction between the triggering waves and the injected energetic electrons. The triggered emissions have both rising-tone and falling-tone structures. We report characteristics of the nonlinear wave growth and its threshold condition in the homogeneous magnetic field, and present analyses of particle dynamics in the velocity phase space based on the nonlinear wave growth theory.