Dramatic improvement of surface wave plasma performance using a corrugated dielectric plate

Surface wave plasmas (SWPs) of large area and high density are conventionally produced under a flat dielectric window for microwave irradiation through slot antennas. However, the SWPs often show discontinuous jumps in plasma density, and they tend to localize near the slots in the case of electronegative gas discharge. In this letter we report that such problems can be avoided by using a corrugated dielectric window with a periodicity of ∼10 mm pitch and 5 mm depth. Compared with the conventional flat plate, the corrugated plate gives a widely spreading uniform plasma with higher power efficiency and no density jump. Three-dimensional numerical simulations of microwave excitation under the experimental conditions clearly show a dramatic change in the wave propagation along the corrugated surface, supporting the experimental observations.