Multi-Period ULF Modulation of Energetic Electron Flux Observed by BD-IES

Abstract:

We present multi-period modulation of energetic electron fluxes observed by BD-IES instrument onboard an inclined geosynchronous orbit (IGSO) satellite on October 13, 2015. Electron flux oscillations (~50 to 200 keV) were observed at the dominant period of ~200s. Despite the lack of in-situ electric and magnetic field observation, poloidal ULF waves at the same period were identified with ground-based magnetometer measurements. Interestingly, electron flux modulations at an energy-dependent secondary period were also observed at each energy channel. We speculate that these secondary modulations are caused by the non-linear effect at the damping stage of the localized poloidal ULF waves. Other possible scenarios including the distortion of the electron trajectory and the simultaneous interaction between energetic electrons and both poloidal and compressional ULF wave are also discussed.