Numerically simulated two‐dimensional auroral double layers

Electrostatic plasma double layers are numerically simulated by using a magnetized 2½ dimensional particle‐in‐cell system, periodic in one direction and bounded by reservoirs of Maxwellian plasma in the other. The simulations of both oblique and two‐dimensional double layers show periodic instability, indicate Debye length rather than gyroradii scaling, and reveal low‐frequency electrostatic turbulence and electron beam excited electrostatic electron‐cyclotron waves. Simulated electric field and electron beam data resemble referenced satellite measurements of oppositely directed electric fields within auroral regions and of precipitating electrons in inverted ν events. Estimates are given for the thicknesses of auroral double layers and for the separations within multiple auroral arcs. The temporal modulation of accelerated beams is investigated; the possibilities of the double‐layer production of ion conies and of ion precipitation are hypothesized; and the consequences of electrostatic plasma wave excitement are discussed. Simulations including the atmospheric backscattering of electrons predict the presence of an ionospheric sheath that acts to accelerate ionospheric ions upward.