Using the Helium Oxygen Proton Electron (HOPE) and Electric Field and Waves (EFW) instruments from the Van Allen Probes, we explored the relationship between electron energy fluxes in the eV and keV ranges and spacecraft surface charging. We present statistical results on spacecraft charging within geosynchronous orbit by L and MLT. An algorithm to extract the H+ charging line in the HOPE instrument data was developed to better explore intense charging events. Also, this study explored how spacecraft potential relates to electron number density, electron pressure, electron temperature, thermal electron current, and low-energy ion density between 1 and 210 eV. It is demonstrated that it is imperative to use both EFW potential measurements and the HOPE instrument ion charging line for examining times of extreme spacecraft charging of the Van Allen Probes. The results of this study show that elevated electron energy fluxes and high-electron pressures are present during times of spacecraft charging but these same conditions may also occur during noncharging times. We also show noneclipse significant negative charging events on the Van Allen Probes.
Bibliographical noteFunding Information:
The University of Michigan co-authors would like to thank the University of Michigan Rackham Graduate school, NASA, and the NSF for sponsoring this work under grants NWX11AO60G, NWX144AC02G, and AGS-1102863. Work at Los Alamos National Laboratory was performed under the auspices of the U.S. Department of Energy, LA-UR-15-27864. This work was supported by Van Allen Probes-ECT funding provided by JHU/APL contract 967399 under NASA''s Prime contract NAS5-01072. Data used to generate figures for this project came from the Van Allen Probes data center at http://www.vanallenprobes-ect.lanl.gov/data_pub/. We would also like to thank Brian Walsh for his useful science direction.
©2016. The Authors.
- Van Allen Probes
- spacecraft charging
- surface charging