Expected electron microburst energy dispersion caused by chorus wave interaction

Abstract:

Electron microbursts in space physics are defined by strong electron precipitation having duration less than 1 sec. Since the first observations with X-ray detectors onboard balloon in 1960s, many experiments have revealed the detail characteristics of the microbursts. The microbursts have minimum duration of 250 msec and the coincidence of chorus and microburst occurrence supports the origin of wave-particle interaction. In addition, recent measurements revealed the microburst does not fill the loss cone and shows less e-folding energy in parallel component than perpendicular one. However, several characteristics are remained unsolved. For example, the relationship between ~100 keV and MeV microburst is still unknown. If the energy dispersion of microbursts could be measured, we might understand how the microbursts are produced by wave-particle interaction. Because the microburst duration is less than the electron bouncing period, the energy dispersion should be identified if the detectors have enough fast time resolution. During chorus waves propagate along magnetic field, the resonance condition should be satisfied at different magnetic latitude for different energy electrons because chorus have narrow frequency band. If we observed electron microbursts at low altitude, the arrival time of different energy electrons should make unique energy dispersion structures. In this study, we tried to show the expected microburst energy dispersion with simple test particle simulation. These results may provide useful information in designing electron detectors for the future mission.