Transverse Kelvin-Helmholtz Instability with Parallel Electron Dynamics and Coulomb Collisions.

Electron parallel dynamics and Coulomb collisions are included in the analysis of the transverse Kelvin-Helmholtz instability. The electrons are treated kinetically while the ions are treated in the fluid limit. It is shown that, in the collisionless case, for an in homogeneous velocity profile vxv sub tanh xL the kelvin-Helmholtz instability is stable for k sub zk sub y v sub 0L omega sub lh k u L1-k y sq rt in the limit w-ky v sub 0 k sube x V sube e. Here V sub o is the flow velocity, L is the scale length of the velocity shear layer, k sub z v sube k sube are the parallel and perpendicular wavenumbers, respectively, omega sub l h sq. rt.Omega sub e Omega sub i, and v sube is the compressional energy given to the electrons parallel to B. In the collisional limit, Coulomb collisions are shown to increase the unstable kz domain because they inhibit the electron motion parallel to B. Applications to the high latitude ionosphere are discussed. Keywords Kelvin Helmholtz instability High latitude ionosphere Velocity shears.