Kinetic theory of magnetohydrodynamic Kelvin–Helmholtz instability

Abstract

The magnetohydrodynamic Kelvin–Helmholtz instability in a low β collisionless plasma with smooth variations in plasma parameters across the boundary is studied. The surface Alfvén wave which is excited by the Kelvin–Helmholtz instability is shown to be mode-converted to the kinetic Alfvén wave (Alfvén wave with finite ion Larmor radius and electron inertia correction). Linear and nonlinear effects of this kinetic Alfvén wave on the Kelvin–Helmholtz instability are discussed. Because the resonant mode conversion enhances the wave amplitude, the nonlinear effect is manifested. In particular, the magnetic field pressure of the kinetic Alfvén wave exerts acceleration on the plasma at the higher density side toward the lower density side and may cause the Rayleigh–Taylor instability at the boundary layer.