Diffuse Auroral Precipitation

Abstract

In this review, we summarize one at least plausibly coherent view of the self-consistent coupling of convection in the plasma sheet to particle precipitation and the ionosphere. We focus upon our understanding of the plasma instabilities responsible for diffuse auroral precipitation. At present, the electrostatic ion and electron cyclotron harmonic loss-cone instabilities seem to be the best candidates. However, they depend sensitively upon the cold electron density and temperature deep in space on auroral field lines, parameters about which we have little or no experimental or theoretical information.