Abstract Dust-impact-induced plasma oscillations (dust ringing) detected in Saturn’s Enceladus plume provide a novel method for measuring electron density. However, since S. Ye et al. discovered such events, their underlying mechanisms remain unclear. In this study, linear instability analysis and particle-in-cell (PIC) simulations are employed to demonstrate that the beam–plasma instability mechanism is the more probable cause of dust-ringing events. Dust-ringing events were first observed in a pristine environment within the Enceladus plume, with a characteristic duration of approximately 1 ms under negative spacecraft potential. Our linear analysis demonstrates significant wave growth at a high beam density of 0.1 times the background electron density, occurring when the beam electron velocity surpasses the ambient electron thermal velocity by a factor of 4. Additionally, the PIC simulations confirm Langmuir wave excitation at kλ De ≈ 0–0.3, manifested as enhanced electric field oscillations and electron velocity scattering. These results suggest that when the plasma cloud generated by the dust impact maintains a relatively high density during initial diffusion and forms a rapid beam relative to the background plasma, it triggers beam–plasma instability, resulting in dust-ringing effects.
Wu et al. (Wed,) studied this question.