Patent ID: 8885142

Claim:
A lithographic projection apparatus, comprising: a substrate table constructed to hold a substrate; a projection system configured to project a patterned radiation beam onto a target portion of the substrate; a liquid supply system configured to at least partly fill a space between the projection system and the substrate table with a liquid; an outlet configured to remove a mixture of liquid and gas; and an evacuation system configured to draw the mixture of liquid and gas through the outlet, the evacuation system comprising: a pump arranged to apply suction to draw the mixture of liquid and gas through the outlet, a manifold configured to receive the mixture of liquid and gas from the outlet and to provide the mixture toward the pump without substantial removal of liquid from the mixture at the manifold, a gas inlet configured to supply the manifold with a flow of gas, and a control system configured to measure a pressure in the manifold and to control the pressure in the manifold by controlling the flow of gas into the manifold from, the gas inlet in response to the measured pressure.