Symmetric vhf source for a plasma reactor

A plasma reactor comprising:

• a vacuum chamber enclosure with a center electrode and a dielectric ring surrounding the center electrode;
• a coaxial resonator comprising
• a conductively connected assembly that includes
• (a) a hollow inner conductive cylinder having a bottom edge contacting said center electrode,
• (b) a hollow outer conductive cylinder surrounding said inner conductive cylinder and having a bottom edge contacting said dielectric ring, and
• (c) an annular conductor extending between and electrically contacting said inner and outer conductive cylinders, and
• a hollow center conductive cylinder located between said inner and outer conductive cylinders, and having a bottom edge contacting said center electrode, said center conductive cylinder having a top edge facing an spaced from said annular conductor by an axial gap length;
• a power coupler including a first axial conductor electrically coupled to the hollow center conductive cylinder and an a cylindrical second axial conductor surrounding the first axial conductor and electrically coupled to the hollow inner conductive cylinder;
• and
• a VHF power generator to supply power to the coaxial resonator.