Studies of relativistic electron injection events in 1997 and 1998

The acceleration of magnetospheric electrons to multi-MeV energies has been a topic of much interest and study over the last several years. To further investigate this acceleration process, Polar and SAMPEX data from 1997 and 1998 were used to examine the general, repeating characteristics of the relativistic electron injection events that occurred over the 2-year period. Around the intensity peak, usually in the L range from 3.2 to 4.5, it was found that (1) during the main phase of the storm, there is a dropout of the relativistic electron fluxes; (2) fluxes increase as recovery begins; (3) the electrons are most sharply peaked in pitch angle at the beginning of the event and flatten with time; (4) the rate at which the flux increases slows with increasing energy; and (5) strong pitch angle scattering is intimately associated with relativistic electron injection events. A recirculation or resonant heating process coupled with rapid radial diffusion or a melding of both would be consistent with the observations.