A planar plasma waveguide with a single inteface between an isotropic
homogeneous plasma, considered as a nonlinear medium and a linear diel
ectric (vacuum), is studied theoretically with respect to the nonlinea
r effects of self-action of surface waves. Striction and ionization no
nlinearities within a weakly nonlinear limit are the mechanisms provid
ing a plasma inhomogeneity. The nonlinear wavenumber shift and the mod
ifications of the wave field distribution and power flow are the resul
ts obtained for the nonlinear wave behaviour. The analytical and numer
ical analysis covers the whole, electromagnetic, range of the surface
waves.