Kinetic study of ion acoustic waves in Venusian ionosphere

Abstract

Kinetic dispersion of the ion acoustic waves has been explored for an unmagnetized five component plasma system comprising of Venusian protons, Venusian oxygen ions, Venusian electrons, solar wind protons, and kappa electrons. The solar wind protons and electrons are assumed to be streaming along the ambient magnetic field. The plasma parameters for this study have been obtained from Lundin et al. [Icarus 215(2), 751–758 (2011)] for the dawn dusk meridian of Venus Express with the data from the ASPERA-4 ion mass analyzer. Our analysis revealed that two modes, viz., ion acoustic mode and beam driven mode, are excited for the considered plasma parameters. The ion acoustic mode exists due to the Venusian ions, and its growth rate is influenced by the solar wind beam electrons. The beam driven mode's existence and its growth rate depend on the solar wind beam protons. We conjecture that the ion acoustic mode and the beam driven mode could be useful in explaining the electrostatic noise in the Venusian ionosphere in the range of several hundreds Hz to 1 kHz and several tens kHz, respectively.