Kinetic Alfven double layer formed by electron viscosity

Abstract

The effect of the electron viscosity on the kinetic Alfven solitary wave is investigated. It is found that small electron viscosity changes the electron motion along the magnetic field producing a boundary layer, and thus that in a low beta electron-ion plasma(β≪me/mi), an obliquely propagating kinetic solitary Alfven wave can become a double layer. This double layer can exist in the sub-Alfvenic and super-Alfvenic regimes. The length scale of density drop for this double layer is on the order of that of the conventional kinetic solitary Alfven wave, and thus this double layer can accelerate electrons on a very short length scale.