Abstract: A chuck body mounts a substrate within a vacuum chamber. Contiguous portions of the substrate and the chuck body form a heat-transfer interface. An intermediate sealing structure seals the chuck body to the substrate independently of any contact between the chuck body and the substrate and forms a separately pressurizable region within the vacuum chamber. A control system promotes flows of fluid through a periphery of the heat-transfer interface within the separately pressurizable region for controlling fluid pressures and related transfers of heat at the heat-transfer interface according to an overall aim of regulating the substrate temperature.