Abstract: | Parametric resonance phenomena are investigated in a plasma layer with thickness d and thin inhomogeneous boundary regions. The modulated UHF electric field is parallel to the plasma layer. We consider both strong and low modulation of the field amplitude and suppose, that the carrier frequency ω0 of the pump wave is much larger than the Langmuir frequency ωLe. We find the region for the modulation frequency ω, in which the parametric growing of the asymmetric and symmetric surface waves occurs. The maximum growth rates of these waves, the direction of their propagation and the threshold value of the modulation depth α of the UHF pump field are calculation. |