Correlation of Slow and Fast Electron Holes With Local Ion Distribution Minimum

Abstract

Although the theory of electron holes has a 60-year history, whether fast and slow electron holes may share a common origin remains enigmatic. Here, with observations of Magnetospheric Multiscale spacecraft, we report that slow electron holes are accompanied with ion beams while fast electron holes are not. The velocity of slow holes is observed to vary with the local ion beam intensity and have the potential to be accelerated. Simulations demonstrate that ion distribution with a distinct beam constrains the velocity of electron holes into slow holes with stable electric field amplitudes while a weak beam fails to confine the hole's velocity but accelerates them through ion repulsion into fast holes with amplitude decay. Therefore, we speculate that the fast and slow electron holes may share a common origin and their subsequent behavior is determined by different ion distributions.