Field-aligned electric field accompanied by drift Alfven waves in an inhomogeneous plasma

One of the most important questions in the dynamics of the magnetosphere and the coupling between the magnetosphere and the ionosphere is the mechanics of the generation of field-aligned (or parallel) electric fields. Since ideal magnetohydrodynamics do not allow a parallel electric field, non-ideal mechanisms must be introduced to account for its generation. Nonlinear effects such as anomalous resistivity or double layers which induce an electric field by interruption of a field aligned current could be responsible. A field-aligned electric field, δEparallel, which is accompanied by drift Alfven wave perturbations in an inhomogeneous plasma, can be expressed in simple terms as δEparallel = Tee k2perpendicularρ21∂δψ∂ell∂ellnn∂ψ where ψ and δψ are the magnetic flux function and its perturbation, Te is the electron temperature, n(ψ) is the plasma density, kperpendicular is the perpendicular wave number, ρi is the ion Larmor radius and ell is the coordinate along a magnetic line of force