[en] Full-scale quasi-steady fusion reactors are likely to operate in an ion density regime where the plasma is ''impermeable'' to neutral particles. A neutral gas blanket then develops between the plasma and the chamber walls, and is separated from the fully ionized plasma body by a partially ionized, dense, cool boundary layer of finite size. The dynamics of the plasma in this layer is strongly affected by the collision processes between various kinds of charged and neutral particles. For wave and instability modes of moderately high frequencies there is a strong plasma-neutral gas coupling, which is represented by a kind of compound plasma-neutral gas viscosity. A simple localized analysis indicates that flute-type perturbations should become completely stabilized by a joint viscosity-resistivity-pressure effect. If this result also becomes applicable to full-scale fusion reactors, it may provide an alternative to minimum average-B stabilization in the boundary layer, i.e. when such a stabilization becomes inefficient on account of incomplete magnetic line-tying. (author)