A Model of Near-Wall Conductivity and Its Application to Plasma Thrusters

We propose a macroscopic diffusion model to describe near-wall electron conduction in plasma thrusters. This model is obtained by a diffusion approximation technique from a collisionless electron-transport model in crossed electric and magnetic fields. It assumes that the transverse dimension of the thruster is small enough and that the scattering operator with the wall is randomizing. For isotropic scattering, analytic diffusion and conductivity coefficients are obtained, which are inversely proportional to the square of the magnetic field, as experimentally observed.