Surface waves in nonuniform plasmas and their absorption at the localization of surface plasmons

Plasma produced by traveling surface waves are connected with density nonuniformities both in radial direction and in axial direction. Radial density profiles may lead to plasmon excitation close to the discharge tube walls and thus increased energy transfer to the plasma. Here the effect of axial plasma inhomogeneity is considered. In the geometrical optics approach---usually employed for models of this type of plasmas---at the end of the discharge resonant behaviour is expected, though the validity of approximation fails. The resonance is investigated on the basis of a second-order and one-dimensional differential equation for the distribution of the electromagnetic surface wave field along a plane plasma-vacuum interface, assuming an axially linear density profile as often observed. Enhancement of electric field strength, storage of surface charge density, and strong absorption can be expected in the region of spatial localization of surface plasmons. The strength of the resonance is noticeably affected by collisions