Evolutionary sheath structure in magnetized collisionless plasma with electron inertia

Abstract

A classical hydrodynamic model is methodologically formulated to see the equilibrium properties of a planar plasma sheath in two-component magnetized bounded plasma. It incorporates the weak but finite electron inertia instead of asymptotically inertialess electrons. The effects of the externally applied oblique (relative to the bulk plasma flow) magnetic field are judiciously accented. It is, for the sake of simplicity, assumed that the relevant physical parameters (plasma density, electrostatic potential, and flow velocity) vary only in a direction normal to the confining wall boundary. It is noticed for the first time that the derived Bohm condition for sheath formation is modified conjointly by the electron inertia, magnetic field, and field orientation. It is manifested that the electron inertia in the presence of plasma gyrokinetic effects slightly enhances the ion Mach threshold value (typically, M_i0 ≥ 1.139) toward the sheath entrance. This flow supercriticality is in contrast with the heuristic formalism (M_i0 ≥ 1) for the zero-inertia electrons. A numerical illustrative scheme on the parametric sheath features on diverse nontrivial apposite arguments is constructed alongside ameliorative scope.