Latitudinal and longitudinal dispersion of energetic auroral protons

Using a collision by collision model from Lorentzen et al., the latitudinal and longitudinal dispersion of single auroral protons are calculated. The proton energies varies from 1 to 50 keV, and are released into the atmosphe re at 700 km altitude. The dipole magnetic field has a dip-angle of 8 degre es. Results show that the main dispersion region is at high altitudes (300- 350 km) and occurs during the first few charge exchange collisions. As the proton travels further down the atmosphere the mean free path becomes small er, and as a result the spreading effect will not be as pronounced. This me ans that the first few charge exchange collisions fully determines the widt h of both the latitudinal and longitudinal dispersion. The volume emission rate was calculated for energies between 1 and 50 keV, and it was found tha t dayside auroral hydrogen emissions rates were approximately 10 times weak er than nightside emission rates. Simulations were also performed to obtain the dependence of the particle dispersion as a function of initial pitch-a ngle. It was found that the dispersion varies greatly with initial pitch-an gle, and the results are summarized in two tables; a main and an extreme di spersion region.