Boundary region analysis in collisional plasmas

Summary form only given. The boundary region in a plasma is characterized by large gradients in density, velocity, and electric potential. These large gradients strongly influence the erosion of surfaces in contact with the plasma. Analysis of the boundary region in a plasma using perturbation techniques is presented. The boundary region is shown to consist of three nested layers on three disparate physical length scales. The equations governing the behavior of the plasma are derived by scale analysis based on the leading order physical phenomena in each of the layers. These equations are examined considering previously published models of the boundary region. The equations governing each layer are solved and the method of matched asymptotic expansions is employed to construct a composite solution valid throughout the boundary region. The results are used to analyze the boundary region in relatively dense plasmas such as those found in electromagnetic and electrothermal launcher applications.