Diodelike response of high‐latitude plasma in magnetosphere‐ionosphere coupling in the presence of field‐aligned currents

Abstract

The dynamic processes in the plasma along high‐latitude field lines plays an important role in ionosphere‐magnetosphere coupling process. We have created a time‐dependent, large‐scale simulation of these dynamics parallel to the geomagnetic field lines from the ionosphere well into the magnetosphere. The plasma consists of hot e − and H+ of magnetospheric origin and low‐energy e −, H+, and O+ of ionospheric origin. Including multiple electron species, a major improvement to the model, has allowed us for the first time to simulate the upward current region properly and to dynamically simulate the diodelike response of the field‐line plasma to the parallel currents coupling the ionosphere and magnetosphere. It is shown that return currents flow with small resistance, while upward currents produce kilovolt‐sized potential drops along the field, as concluded from satellite observations. The kilovolt potential drops are due to the effect of the converging magnetic field on the high‐energy magnetospheric electrons.