Aspects of the present disclosure relate generally to isolator devices, components thereof, and methods associated therewith for substrate processing chambers. In one implementation, a substrate processing chamber includes an isolator ring disposed between a pedestal and a pumping liner. The isolator ring includes a first surface that faces the pedestal, the first surface being disposed at a gap from an outer circumferential surface of the pedestal. The isolator ring also includes a second surface that faces the pumping liner and a protrusion that protrudes from the first surface of the isolator ring and towards the outer circumferential surface of the pedestal. The protrusion defines a necked portion of the gap between the pedestal and the isolator ring.