Surface-wave propagation along a corrugated plasma–dielectric interface

Recently it has been found that the performance of surface-wave (SW) sustained microwave discharges can be enhanced by corrugating the dielectric–plasma interface guiding the SW. The present contribution explains this behavior in terms of the SW dispersion as modified by the presence of corrugations. The latter are treated as an anisotropic dielectric medium with effective permittivity tensor governed by the corrugation depth, pitch and dielectric loading ratio 0 < γ < 1. Closed form SW dispersion equations are introduced. We demonstrate that the corrugations significantly lower the threshold electron density above which SW propagation is possible. Moreover they can reduce the SW group velocity and thus improve the wave–plasma interaction. Additional advantage is that one can custom-tune the SW dispersion and the wave–plasma interaction by controlling the dielectric loading ratio γ.