Perturbation analysis of sheath evolution, with application to plasma source ion implantation

A perturbation model has been developed to describe the evolution of an exp anding plasma sheath around a cathode after a high-voltage negative pulse i s applied to the cathode, simulating the conditions in devices such as thos e used for plasma source ion implantation. The set of governing equations c onsists of two coupled collisionless fluid equations for ions, and Poisson' s equation and Boltzmann's assumption for electrons. The time-dependent, se lf-consistent expressions for the potential, ion density and ion flux are o btained and compared successfully with experimental and simulation results.