Periodic low-frequency electric field structures in a magnetized non-thermal auroral plasma

Abstract

The theoretical explanation of electric field structures associated with density depletion in the Earth’s upper ionosphere is presented. Using the quasi-neutrality hypothesis, the effect of excess energetic electron species is studied on the evolution of nonlinear low-frequency ion-cyclotron and ion-acoustic waves in a magnetized auroral plasma. The dynamics of the cold ion beam is governed by the fluid equations and the electron is treated as energetic species with non-thermal density distribution. Numerical computations appear in a series of periodic oscillations, such as spiky, sawtooth and sinusoidal waveforms. The present model can generate up to 18 mV/m electric field amplitude, which is in the range of the FREJA satellite measurements in the auroral acceleration region.