Ionization layer at the edge of the accelerating plasma in a pulsed plasma thruster

Summary form only given. There are different characteristic sub-regions near the surface namely space-charge sheath, Knudsen layer, presheath and ionization layer, where transition to ionization equilibrium occurs. We describe the phenomena associated with a contact wall surface-plasma under conditions of strong plasma acceleration. Such a case is realized in pulsed plasma thrusters. There are two specific problems that we address in this work, namely plasma generation phenomena (ablation) and formation of the ionization layer. Considering ablation phenomena we couple the non-equilibrium, Knudsen layer, with the hydrodynamic layer, that provides solution for the ablation rate. The ablation rate is determined by the flow velocity at the edge of the Knudsen layer. Considering an electromagnetic pulsed plasma thruster we found that, depending on the current density in the hydrodynamic layer, this velocity varies from very small (compared to the sound speed) up to the sound speed with current density increase. It was shown how plasma acceleration under external forces affects the boundary condition at the edge of the Knudsen layer.