A “Trap‐Release‐Amplify” Model of Chorus Waves

Whistler mode chorus waves are quasi-coherent electromagnetic emissions with frequency chirping. Various models have been proposed to understand the chirping mechanism, which is a long-standing problem in space plasmas. Based on analysis of effective wave growth rate and electron phase dynamics self-consistent particle simulation, we propose phenomenological model called “Trap-Release-Amplify” (TaRA) for chorus. In this model, structures correlated electrons formed by nonlinear interactions, mainly occur downstream equator. When released from packet upstream, these lead selective amplification new satisfy phase-locking condition maximize power transfer, resulting The at release point gives that is, fully consistent one Helliwell case nonuniform background magnetic field. interaction part TaRA results proportional amplitude, conclusion originally reached Vomvoridis et al. Therefore, unifies two different seemingly unrelated studies. Furthermore, naturally explains fine waves, including subpackets bandwidth, their evolution through phase-trapped electrons. Finally, suggest could be applied explain other related phenomena, uniform field ion cyclotron magnetosphere.