Simulation of auroral double layers

Abstract

The plasma double layer is a possible mechanism for the acceleration of high‐energy auroral electrons. Some of the basic properties of double layers are deduced from particle‐in‐cell computer simulations and are related to parallel electric field structures above the auroral regions. We conclude that a large potential difference applied to a finite length plasma will be concentrated in a shocklike localized region instead of occurring over the entire length of the system. The initial stage of the formation of the double layer is dominated by a large‐potential pulse. Once the double layer is formed, the entire potential φ 0 is dropped over a distance L DL ≃6( eφ 0 /kT e ) 1/2 λ D . For the parameters above the auroral region this distance is about 1 km.