Abstract
The mechanism for omega bands and torch structures as observed on the poleward boundary of the postmidnight diffuse aurora is studied by a two-dimensional electrostatic particle simulation for the motion of magnetospheric plasma perpendicular to the geomagnetic field. This type of diffuse aurora is caused by precipitation of energetic electrons with energies in excess of a few keV. In the model, the diffuse aurora (which may be identified with the central plasmasheet) is embedded within a less energetic but hot plasma which extends to higher latitudes. The temporal evolution of the diffuse auroral pattern can be visualized by following the cluster of the energetic electrons. Electric dipoles can grow on the poleward boundary of the hot plasma, due to charge separation induced by magnetic drifts. As a result of these dipoles, there is a spatial modulation of the energetic electrons, which leads to the formation of omega bands and the subsequent evolution into torch structures. The magnetospheric (or ionospheric) potential distribution obtained in the simulation is consistent with observed distribution of ionospheric electric fields and field-aligned currents in events of torches/omega bands.
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call