Patent Number: 
Section: claims

1. A lithographic apparatus, comprising:a collector configured to collect radiation from a radiation source, said collector comprising a plurality of shells forming separate compartments; anda 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 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 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, anda control system configured to control the relative amount of each of said sub flows. 2. A lithographic apparatus according to claim 1, wherein said control system further comprises valves configured to control said sub flows. 3. A lithographic apparatus according to claim 1, wherein said control system further comprises a diaphragm, said diaphragm being configured to control one of said sub flows. 4. A lithographic apparatus according to claim 1, wherein said control system further comprises a ring configured to control at least part of one of said sub flows. 5. A lithographic apparatus according to claim 1, wherein said distribution system comprises tubes configured to direct said sub flows into the compartments. 6. A lithographic apparatus according to claim 1, wherein said gas comprises H radicals. 7. A lithographic apparatus according to claim 1, wherein said cleaning arrangement comprises a H radical source at an entrance of each compartment. 8. A lithographic apparatus according to claim 1, wherein said collector comprises a plurality of substantially tubular shells forming separate compartments, and said collector further comprises cross walls extending in a radial direction and subdividing said compartments. 9. A lithographic apparatus according to claim 1, wherein the distribution system is provided on one of an upstream side or a downstream side of the collector. 10. A lithographic apparatus according to claim 1, wherein the gas inlet and the gas outlet are provided on opposite ends of the collector. 11. A lithographic apparatus according to claim 1, wherein the gas flow is guided from said inlet through said compartments to said outlet so that the gas flows between opposite ends of the collector. 12. 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; anda 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, anda control system configured to control the relative amount of each of said sub flows. 13. A lithographic apparatus according to claim 12, further comprising an EUV radiation source. 14. A lithographic apparatus according to claim 13, wherein said EUV source is a Sn source. 15. A lithographic apparatus according to claim 12, wherein the distribution system is provided on one of an upstream side or a downstream side of the collector. 16. A lithographic apparatus according to claim 12, wherein the gas inlet and the gas outlet are provided on opposite ends of the collector. 17. A collector for a lithographic apparatus, said collector comprising a plurality of substantially tubular shells forming separate compartments each compartment being configured to guide a gas flow through said collector, wherein said collector further comprises cross walls extending fully between adjacent shells in a radial direction and subdividing said compartments, wherein at least one compartment extends substantially radially to a center of the collector. 18. A cleaning arrangement comprising a gas inlet and a gas outlet, said cleaning arrangement configured, during use, to be removably arranged at a position adjacent an entrance or an exit of a collector of a lithographic apparatus and being configured to clean surfaces of shells of the collector by guiding a gas flow from said inlet through compartments of said collector 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; anda control system configured to control the relative amount of each of said sub flows. 19. A cleaning arrangement according to claim 18, wherein the distribution system is provided on one of an upstream side or a downstream side of the collector. 20. 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; andcontrolling the relative amount of each of said sub flows. 21. A method of cleaning a collector according to claim 20, wherein said compartments are divided into sub compartments by cross walls extending in a radial direction and crossing said shells. 22. A method of cleaning a collector according to claim 20, wherein the cleaning arrangement comprises a gas inlet that is provided on one of the first end or second end of the collector. 23. A cleaning arrangement according to claim 19, wherein the gas inlet and the gas outlet are provided on opposite ends of the collector.