Ionization kinetics in non-ideal dense plasmas: Ionization fronts

The ionization kinetics in non-ideal plasmas is described by reaction diffusion equations which follow from the non-ideal quantum kinetic theory. In the approximation of ambipolar diffusion the mathematical description reduces to only one equation which is investigated with respect to front solutions. It has been shown that in particular cases there exist two different types of travelling fronts: (i) a front connecting the homogeneous atomic phase and some ionized state and (ii) a front connecting two homogeneous ionized stable states differing in the degree of ionization. The fronts are considered with respect to their profile and their velocity. The relation of this dynamic phase transition to the plasma phase transition well known in the theory of thermodynamic equilibrium of the non-ideal plasma is discussed.