On the propagation of electrostatic wave modes in the inhomogeneous ionospheric plasma of Venus

Abstract

The influence of gradients of number density, magnetic field, and flow velocity in a plasma on the propagation of low-frequency electrostatic waves is investigated in plasma conditions relevant for the Venusian ionosphere (vicinity of Venus terminator). For this purpose, we assume a collisionless inhomogeneous plasma model consisting of two positive ion species, hydrogen H+ and oxygen O+, as well as neutralizing electrons. Linear dispersion relations predict two types of plasma modes, namely, ion-acoustic mode and drift mode. It is found that these modes have relatively long wavelengths, extending to 10 km and frequencies on the order of ∼10−3−10−2 Hz. The characteristics of these modes show a strong dependence on the gradients of plasma parameters, and numerical analysis reveals that the coupling of these modes may lead to nonlinear instabilities. However, unstable modes occur only when the field-aligned shear flows are introduced. These results help explain the presence of low-frequency electrostatic modes and their basic features in the Venusian ionosphere, and will allow future studies to extend modeling to other planetary or even cometary conditions.

Role of solar wind on the ionic escaping from Venus upper ionosphere via plasma wakefield

“…On the other hand, the role of the plasmas in Venus's ionosphere is studied by many authors [17][18][19][20][21]. The basic properties of the propagation of the nonlinear and fully nonlinear IAWs in the Venusian ionosphere are studied by Sayed et al [17].…”

“…Fayad et al [19] proposed a theoretical model to examine the effect of magnetic field strength, ions' streaming velocity and higher order nonlinearity on the properties of the solitary structure in Venus' ionosphere. Also, Fayad et al [20] investigated the effect of the gradients of the number density, the flow velocity and the magnetic field on the basic features of the propagated low-frequency electrostatic waves in the vicinity of Venus' terminator. Recently, Salem et al [21] investigated the effect of SW plasma parameters on the conditions of the propagated nonlinear IAWs in Venus' mantle region.…”