Evolution of Kelvin-Helmholtz Instability on the Venusian Ionopause with the Influence of Hall Effect

It has been demonstrated that Kelvin-Helmholtz (KH) instability is an essential large-scale mechanism to generate plasma waves along the boundary layers of Venus. In this paper, evolution of KH instability on the Venusian ionopause with the influence of the Hall effect was investigated under Hall magnetohydrodynamic (MHD) simulations. Linear and nonlinear physical behaviors of KH instability with different wavelengths of perturbation, magnetic field configurations, and ion inertial lengths were studied. Numerical results indicate that, for perturbation with short wavelength, the circulation area of matter becomes small and the driving force is weakened. The combined effect of short wavelength and the antiparallel magnetic field leads to longer linear growth time, while the antiparallel magnetic field tends to enlarge the pressure gradient. As for the moderate wavelength of perturbation, the growth rate reaches its peak value, whereas the maximal y component of total kinetic energy increases significantly with the wavelength. Hall MHD simulations indicate that the Hall effect does not change the growth rates for different ion inertial lengths at all. However, the Hall effect has a depression effect on small structures at the nonlinear stage of KH instability.