MHD Study of Kelvin-Helmholtz Instability at Mars

The Kelvin-Helmholtz (K-H) instability is a fundamental fluid instability developing when there is a velocity shear in a fluid or along the interface of two fluids. At unmagnetized planets such as Venus and Mars, K-H instability is commonly observed at the induced magnetic boundary, where there is a velocity shear between the shocked magnetosheath plasma and the ionospheric plasma. Compared with Venus, the Martian plasma environment is more complex because of the crustal magnetic field, making it harder to understand the evolution of K-H instability at Mars. K-H instability can contribute to the Martian ion loss significantly due to the detachment of plasma clouds during its late stage. With a high-resolution global multi-species magnetohydrodynamic (MHD) model, the structure and development of K-H instability at Mars are studied. The influence of solar wind upstream conditions on the growth of K-H instability will be discussed. The ion escape caused by K-H instability will be quantified.