Modulation of electron precipitation regulated by electron injection: PIC simulations

It is widely accepted that repetitive chorus waves are responsible for the internal modulation of pulsating auroras. Recent studies have indicated that the repetitive nature of chorus waves stems from continuous electron injection. By employing a one-dimensional general curvilinear plasma simulation code, we introduce periodic electron injection into the simulation system. This generates repetitive rising-tone chorus waves, subsequently resulting in periodic electron precipitation, which potentially contributes to the formation of pulsating auroras. There is a distinct one-to-one correlation between each chorus element and the prompt electron precipitation. Moreover, we find that such electron precipitations are primarily driven by nonlinear interactions with chorus elements via nonlinear interactions, specifically phase bunching. Our work suggests that electron injection can modulate the electron precipitation by controlling the repetition period of chorus waves, thereby potentially influencing the period of internal modulation of pulsating auroras.