A large-scale instability competing with Kelvin-Helmholtz at Mercury’s boundary layer

Magnetic reconnexion and Kelvin-Helmholtz (KH) instability are usually recognized as the two main mixing processes along magnetopauses. However, a recent work [Dargent et al., 2019] showed that in Mercury’s conditions, another instability can grow faster than the KH instability along the magnetopause. This instability seems to rely on gradients of density and/or magnetic field and develops large-scales finger-like structures that prevents the growth of the KH vortices. In this work, I will characterize this instability and try to identify it. In particular, I will look at the dependance of the growth rate of this instability to the different parameters of the plasma and compare it to the growth rate of the Kelvin-Helmholtz instability.