Electron–ion hybrid mode due to transverse velocity shear

Abstract

It has been established that electrostatic ion‐cyclotron‐like and Kelvin–Helmholtz modes can be sustained by a transverse velocity shear for L>ρ_i, where L is the velocity shear scale length and ρ_i is the ion gyroradius. Here it is shown that if ρ_e<L≪ρ_i, where ρ_e is the electron gyroradius, then a short wavelength electron–ion hybrid mode can be excited around the lower hybrid frequency. Like the Kelvin–Helmholtz instability, an explicit dependence on the second derivative of the dc electric field is essential for the growth of this mode.