They are observed in association with nearly every substorm identified by other means. When enhanced fluxes at all energies are observed simultaneously, injection is referred to as a dispersionless injection. The region of space where dispersionless injections are seen is called the injection region.
Injections are more typical in the premidnight sector.
Outside the injection region one observes particles that have drifted out of it, and which thus show energy dispersion due to different magnetic drift speed of particles of different energy. Injections are often related to local magnetic field dipolarizations, especially when the injections are dispersionless. The main questions relating to the injections are the location and means of particle acceleration. Also the inward, adiabatic drift may play role in some injection events. Also induced electric field related to magnetic field dipolarization can accelerate particles locally.