Identifying the Source and Loss Regions for Radiation Belt Electrons

The radiation belt electrons are maintained through a competition of multiple source and loss processes occurring within the magnetosphere. Although many different possible source and loss processes have been identified, a quantitative understanding does not yet exist of which processes dominate under various solar wind driving conditions. This research focuses on identifying the location of source and loss processes in order to constrain the possible mechanisms that are acting on the radiation belt electrons. We have used multiple GOES satellites at geosynchronous orbit to determine the radial gradient of electron phase space density. Our initial effort has concentrated on a few time periods of low geomagnetic activity when there were elevated electron flux levels. We find that during these times the radial gradient was predominantly positive, indicating a source location outside of geosynchronous orbit. As the radiation belts decayed, the loss occurred initially at the lower L values, suggesting that the dominant loss mechanism was operating inside geosynchronous orbit. Variations in the measured radial gradient of phase space density with geomagnetic activity and the implications for radiation belt source and loss processes will be discussed.