Synergistic effects of hot plasma‐driven potentials and wave‐driven ion heating on auroral ionospheric plasma transport

Abstract

Transverse acceleration by waves and parallel acceleration by field‐aligned electric fields are important processes in the transport of ionospheric ions along auroral field lines. In order to study the transport of ionospheric plasma in this environment we have developed a generalized semikinetic model which combines the tracking of ionospheric ion gyrocenters with a generalized fluid treatment of ionospheric electrons. Large‐scale upward and downward directed electric fields are generated within the model by introducing magnetospheric plasma whose components have differing temperature anisotropies. We study the effects of such potentials when combined with the effect of ion heating by a distribution of waves along the flux tube. We find that the combination of wave heating and an upward electric field results in an order of magnitude increase in O+ outflow (compared to a case with an upward electric field and no wave heating). Under these conditions we observe the formation of bimodal conics. When a downward electric field is added to a case with wave heating, the energy gained by the ions from the waves increases by a factor of 2 or 3 (over the scenario with wave heating and no hot plasma‐driven electric field) owing to their slower transit of the heating region. Typically, the velocity distributions under these conditions are toroids and counterstreaming conics. We also find that the upflowing, dense, heated ionospheric plasma acts to reduce the potential set up by the anisotropies in the magnetospheric components.