Rufai O R
University of the Western Cape, Robert Sobukwe Rd, Bellville 7535, Cape Town, South Africa.
Heliyon. 2019 Jul 8;5(7):e01976. doi: 10.1016/j.heliyon.2019.e01976. eCollection 2019 Jul.
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.
本文给出了与地球高层电离层密度损耗相关的电场结构的理论解释。利用准中性假设，研究了过量高能电子种类对磁化极光等离子体中非线性低频离子回旋波和离子声波演化的影响。冷离子束的动力学由流体方程控制，电子被视为具有非热密度分布的高能粒子。数值计算呈现出一系列周期性振荡，如尖峰、锯齿和正弦波形。本模型可产生高达18 mV/m的电场振幅，这在极光加速区域的FREJA卫星测量范围内。
