Acceleration in the earth's auroral magnetosphere below 1 R/sub E/

Particle acceleration in the auroral magnetosphere is treated as a combination of DC electric field acceleration and wave heating in order to explain observed oblique pitch angle distributions of ions. Coherent electrostatic ion cyclotron waves which have been observed in the acceleration region saturate by ion trapping and thereby heat ions from the initial ionospheric temperatures of <1 eV to keV in perpendicular energy. Some of this is converted to parallel energy by the dipole mirror force and mixed with parallel acceleration in DC electric fields to produce the observed upstreaming conical pitch angle distributions of ions