Nonlinear Diffusion of the Magnetic Field in Weakly Ionized Plasmas

Enhanced nonlinear penetration of the external periodic magnetic field into a weakly ionized plasma is investigated. The penetration is enhanced by the convection of the magnetic field due to the Lorentz force. The nonlinearity leads to the wavelike propagation of the magnetic field or to the nonlinear diffusion similar to the diffusion in porous medium depending on plasma collisionality. It is shown that the periodic magnetic field experiences much slower decay inside the plasma compared to that of the standard skin effect.