Controlling the flow through the collector during cleaning

A lithographic apparatus, comprising:

• a collector configured to collect radiation from a radiation source, said collector comprising a plurality of shells forming separate compartments;
• an illumination system configured to condition a radiation beam;
• a support configured to support a patterning device, the patterning device being configured to impart the radiation beam with a pattern in its cross-section to form a patterned radiation beam;
• a substrate table configured to hold a substrate;
• a projection system configured to project the patterned radiation beam onto a target portion of the substrate;
• and
• a cleaning arrangement configured, during use, to be removably arranged at a position adjacent to an entrance or an exit of the collector and comprising a gas inlet and a gas outlet, said cleaning arrangement being configured to clean surfaces of said plurality of shells by guiding a gas flow from said inlet through said compartments to said outlet, wherein said cleaning arrangement further comprises:
• a distribution system configured to divide said gas flow into several sub flows, each of said sub flows corresponding to one or more of said compartments, and
• a control system configured to control the relative amount of each of said sub flows.

A method of cleaning a collector of a lithographic apparatus, said collector comprising a plurality of collector shells forming separate compartments configured to receive radiation at a first open end of said collector and to deliver radiation at a second open end of said collector, said method comprising:

• removably arranging a cleaning arrangement at a position adjacent an entrance or an exit of the collector, the cleaning arrangement configured to provide a gas flow;
• guiding the gas flow through said compartments in order to clean surfaces of said plurality of shells;
• dividing said gas flow into several sub flows, each of said sub flows corresponding to one of said compartments;
• and
• controlling the relative amount of each of said sub flows.