Characteristics of monotonic sheaths near a wall with grazing magnetic incidence

Abstract

Abstract We consider a magnetised plasma in contact with an absorbing planar wall, where the angle α between the magnetic field and the wall is small, α ≪ 1 (in radians), and the plasma is uniform in the directions tangential to the wall. The finite ratio γ of the characteristic electron gyroradius ρ e to the Debye length λ D , γ = ρ e /λ D, is retained via a grazing-incidence (α ≪ 1) gyrokinetic treatment [1,2]. Building on a previously developed iterative scheme [2,3] to solve for the steady-state electrostatic potential in the quasineutral magnetic presheath of width ∼ ρ S , we developed a scheme that simultaneously solves for both the presheath and the non-neutral Debye sheath of width ∼ λ D in the limit λ D /ρ S → 0, provided that the electrostatic potential solution is monotonic. The code, called GYRAZE, thus provides the energy-angle distribution of ions at the wall and the velocity distributions of electrons reflected by the wall for different values of wall potential.