Substorm-injected protons and electrons and the injection boundary model

Analysis of observations of substorm-associated enhancements of proton and electron fluxes: (1) makes a strong case for the existence of a boundary limiting the regional particle injection associated with substorms, (2) supports the hypothesis that the injection process is almost instantaneous (less than approximately 5 min), and (3) indicates that the injection takes place within a large region extending at least several earth radii tailward of the injection boundary. The injection boundary model is superior to others in that it simultaneously explains: (1) the drift and energy dispersion of substorm-injected protons between 1 and 30 keV, (2) the relative behavior of protons with 81 deg and 27 deg pitch angles, (3) the absence of observed electrons below 30 keV, and (4) the time dispersion of impulsively injected electrons seen outside the plasmapause.