Transmission Line RF Applicator for Plasma Chamber

A transmission line RF applicator apparatus and method for coupling RF power to a plasma in a plasma chamber. The apparatus comprises two conductors, one of which has a plurality of apertures. In one aspect, apertures in different portions of the conductor have different sizes, spacing or orientations. In another aspect, adjacent apertures at successive longitudinal positions are offset along the transverse dimension. In another aspect, the apparatus comprises an inner conductor and one or two outer conductors. The main portion of each of the one or two outer conductors includes a plurality of apertures that extend between an inner surface and an outer surface of the outer conductor.