Coupling Between Dispersive Alfvén Wave and Modified Electron Acoustic Wave in Downward Current Region: Parallel Potential Drop and Upgoing Ionospheric Electrons
Abstract
Abstract Results from a 1D kinetic simulation, for the first time, unveil the generation and time evolution of the downward parallel electric fields stemming from the coupling between modified electron acoustic waves (MEAWs) and dispersive Alfvén waves (DAWs). Under the incidence of long‐period Alfvén waves carrying downward field‐aligned currents, a parallel potential drop forms in the transition region between magnetospheric hot electrons and ionospheric cold electrons, accelerating cold electrons upward. These accelerated electrons progressively replace hot electrons as the main current carrier. Parametric investigations show that the ratio of potential drop to downward field‐aligned current increases with hot‐electron temperature and decreases with hot electron density, and is several (7–8) times smaller than that for upward currents because less potential drop is required for more abundant cold electrons to reach the same current magnitude. These results unify the generation of E || in both current polarities in the same DAW‐MEAW coupling framework.
Key Points
Objective
To investigate the coupling between modified electron acoustic waves and dispersive Alfvén waves and its effects on parallel electric fields.
Methods
- Conducted a 1D kinetic simulation to analyze wave interactions.
- Examined the effects of hot-electron temperature and density on the potential drop and electric fields.
- Performed parametric investigations to study the relationship between potential drop and field-aligned currents.
Results
- Identified the generation of downward parallel electric fields from wave coupling.
- Found that the ratio of potential drop to downward currents increases with hot-electron temperature.
- Determined that the potential drop for downward currents is significantly smaller than for upward currents, due to the abundance of cold electrons.