Parametric excitation of surface waves in a strongly inhomogeneous plasma

The parametric excitation of surface waves in a warm inhomogeneous plasma is investigated. It is demonstrated that the coupling between the surface wave and plasmons that can be excited in the transition layer must be taken into account. The growth rate and the threshold value for the instability process are calculated. It is also shown that thermal effects are of importance even for very low temperatures, since the plasmons can now propagate out of the resonance region.