Recently, cosmic ray albedo neutron decay (CRAND) has been identified as the main source of relativistic electrons measured at the inner edge of inner radiation belt. Here we introduce a drift‐source model that includes azimuthal drift and a CRAND electron source to simulate the quasi‐trapped electron distribution measured by the DEMETER satellite during 20–30 April 2010. The simulated longitude distribution of quasi‐trapped electron fluxes at the inner edge of inner radiation belt successfully reproduces the DEMETER observations, confirming CRAND as the main source for these electrons. Furthermore, a comparison of the energy spectrum and the L distribution of the quasi‐trapped relativistic electrons between simulations and observations further suggests that CRAND is likely the dominant source for 300–700‐keV quasi‐trapped electrons at L < 2 and L ≈ 3.

Using Van Allen Probes' observations and established plasmapause location (Lpp) models, we investigate the relationship between the location of the initial enhancement (IE) of energetic electrons and the innermost (among all magnetic local time sectors) Lpp over five intense storm periods. Our study reveals that the IE events for~30-keV to~2-MeV electrons always occurred outside of the innermost Lpp. On average, the inner extent of the IE events (L IE ) for <800-keV electrons was closer to the innermost Lpp when compared to the L IE for >800-keV electrons that was found consistently at~1.5 R E outside of the innermost Lpp. The IE of tens of kiloelectron volts electrons was observed before the IE of hundreds of kiloelectron volt electrons, and the IE of >800-keV electrons was observed on average 12.6 ± 2.3 hr after the occurrence of the earliest IE event. In addition, we report an overall electron (~30 keV to~2 MeV) flux increase outside the plasmasphere during the selected storm periods, in contrast to the little change of energy spectrum evolution inside the plasmasphere; this demonstrates the important role of the plasmasphere in shaping energetic electron dynamics. Our investigation of the L IE -Lpp relationship also provides insights into the underlying physical processes responsible for the dynamics of~30-keV to~2-MeV electrons. KHOO ET AL. 9252Key Points:• The initial enhancements of~30-keV to 2-MeV electrons are always located outside of the innermost plasmapause locations • The initial enhancement of >800-keV electrons always occurs at~1.5 R E away from the 12-hr innermost plasmapause locations • A drastic difference of the energy spectrum evolution between inside and outside of the plasmasphere is observed during storm periods Supporting Information:• Supporting Information S1

Cosmic Ray Albedo Neutron Decay (CRAND) has been recently confirmed as a source of energetic electrons at the inner edge of the inner belt by the Colorado Student Space Weather Experiment (CSSWE) mission. Here we use observations from the Detection of Electro‐Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) mission, to investigate the CRAND contribution to inner belt electrons quantitatively over a broad energy range (~100–800 keV). Spectral fitting analysis supports the conclusion that CRAND is the most important electron source at the inner edge of the inner belt. For the first time, we show that CRAND is the dominant source of >250‐keV quasitrapped electrons throughout the inner belt and slot region during quiet times. We suggest that additional sources for <250‐keV electrons exist, perhaps from inward transport. In contrast, dynamics of electrons in the inner belt and slot region is dominated by injections during active times.