Charge loss of proton flux as an additional source of plasma in F 2 region

Abstract

Ion and electron production rates are analysed by the Monte-Carlo model of proton flux transport in the atmosphere. It was found that a flux of protons with initial energies from 0.2 to 16 keV loses the greater part of its charge at the altitudes of 300–400 km. This additional positive charge is mainly neutralised by upward electron flux from lower altitudes or by downward magnetospheric electron flux. Our results for initial proton energies <16 keV show that the rate of ion-electron production occurring in this way is greater than the ionisation rate produced by direct collisional ionisation at this altitude region. Therefore, the charge loss of proton fluxes is an additional reason for plasma accumulation in the F 2 region. This mechanism seems to be particularly important in the evening sector of the diffuse aurora zone.