We present observations from the Van Allen Probes spacecraft that identify a region of intense whistler mode activity within a large density enhancement outside of the plasmasphere. We speculate that this density enhancement is part of a remnant plasmaspheric plume, with the observed wave being driven by a weakly anisotropic electron injection that drifted into the plume and became nonlinearly unstable to whistler emission. Particle measurements indicate that a significant fraction of thermal (<100 eV) electrons within the plume were subject to Landau acceleration by these waves, an effect that is naturally explained by whistler emission within a gradient and high-density ducting inside a density enhancement.
Bibliographical noteFunding Information:
This research was funded by NASA contract NNG-13PJ05I, NSF award AGS-1141676 and the SHIELDS Project, a LANL/Laboratory Directed Research and Development (LDRD) Program funded by the U.S. Department of Energy. This research was also funded in part by the Office of Undergraduate Research at Embry-Riddle Aeronautical University. ECT and EMFISIS data for this study were obtained from the respective instruments web portals, and EFW burst data was provided by the EFW team. Geomagnetic indices were obtained from the Kyoto WDC for Geomagnetism. Data and programs used to obtain the results presented in this study can be obtained from email@example.com.
- wave-particle interactions