On the Gradient-Current Mechanism of Formation of the Irregular Structure of the High-Latitude Upper Ionosphere

We consider the gradient-current instability of an inhomogeneous magnetoactive plasma in the approximation of double-fluid magnetohydrodynamics. Unlike the known gradient-drift and current-convective instabilities, the gradient-current instability is related to generation of nonpotential quasistatic electric fields polarized orthogonal to the external magnetic field B ₀ and excited by eddy currents whose density vector lies in the plane passing through the vectors of the magnetic field B ₀ and large-scale electron-density gradient. It is shown that in the high-latitude upper ionosphere, in the regions containing large-scale currents flowing in and out of the ionosphere along the magnetic field, the gradient-current instability can lead to the appearance of sheet-like irregularities extended predominantly in the plane passing through the geomagnetic-field and regular plasma-drift velocity vectors. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 7, pp. 574–587, August 2005.