title: Plasma-wall boundary layers.
abstract: According to a well established result, boundary layers develop in plasmas near solid surfaces. By means of a one-dimensional two-fluid model, we analyze the influence of charge separation and ion viscosity upon the layer structure. This leads to a critical discussion of the Bohm criterion. We find that, in the viscous limit, quasineutrality holds even at values of the Mach number above unity. A nonlinear boundary value problem is defined. Asymptotic matching techniques are used to resolve the structures of the boundary layers.
authors.affiliation: Istituto Nazionale di Fisica della Materia and Politecnico di Torino, 10129 Turin, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Baritello
authors.forename: F
authors.initials: F
authors.lastname: Porcelli
authors.forename: F
authors.initials: F
authors.lastname: Subba