A plasma reactor for processing a workpiece includes a reactor chamber and a workpiece support within the chamber, the chamber having a ceiling facing the workpiece support, a toroidal plasma source comprising a hollow reentrant conduit external of the chamber and having a pair of ends connected to the interior of the chamber and forming a closed toroidal path extending through the conduit and across the diameter of the workpiece support, and an RF power applicator adjacent a portion of the reentrant external conduit, and an RF source power generator coupled to the RF power applicator of the toroidal plasma source. The reactor further includes a capacitively coupled plasma source power applicator comprising a source power electrode at one of: (a) the ceiling (b) the workpiece support, and plural VHF power generators of different fixed frequencies coupled to the capacitively coupled source power applicator, and a controller for independently controlling the power output levels of the plural VHF generators so as to control an effective VHF frequency applied to the source power electrode.