Abstract: A vacuum plasma processor includes a chamber having a grounded wall and an outlet port. Plasma is excited at a first RF frequency in a chamber region spaced from the wall and outlet port. A structure confines the plasma to the region while enabling gas to flow from the region to the outlet port. RF electric power at a second frequency connected to the confining structure causes the confining structure to be at a potential different from ground to increase the size of a sheath between the plasma and confining structure and increase the confining structure effectiveness. The region includes an electrode connected to ground by a circuit that is series resonant to the first frequency and includes capacitance of the sheath.

Abstract: A vacuum plasma processor includes a chamber having a grounded wall and an outlet port. Plasma is excited at a first RF frequency in a chamber region spaced from the wall and outlet port. A. structure confines the plasma to the region while enabling gas to flow from the region to the outlet port. RF electric power at a second frequency connected to the confining structure causes the confining structure to be at a potential different from ground to increase the size of a sheath between the plasma and confining structure and increase the confining structure effectiveness. The region includes an electrode connected to ground by a circuit that is series resonant to the first frequency and includes capacitance of the sheath.