Acceleration Mechanism of Auroral Particles: A Review (a. Precipitating Particles and Auroras) (Proceedings of the First Symposium on Coordinated Observations of the Ionosphere and the Magnetosphere in the Polar Regions (Part I))

A review of recent observational and theoretical results on the problem of auroral particle acceleration is given. First, evidences of the existence of field-aligned potential drops as an agent of particle acceleration are summarized. Second, the necessity of external electric generators is shown, and several models of electric generator are reviewed. Third, the structure of the particle acceleration region is considered; Chiu-Schulz magnetic-mirror theory of the structure of electric potential is criticized, and recent evidences of the double-layer formation in laboratory and computer experiments are reviewed briefly