The magnetic presheath boundary condition with E×B drifts

It is demonstrated rigorously that the effects on a one-dimensional, collisionless, magnetic presheath with oblique magnetic field B of a uniform tangential electric field, causing a drift vD=E×B/B2, are equivalent to a transformation to a frame moving tangential to the surface. Therefore, in particular, the Chodura solution with parallel velocity v∥=cs (the sound speed) is transformed into a solution with v∥=cs+vD/tan α, where α is the field angle to the surface.