Patent Number: 
Section: claims

1. A debris mitigation system for trapping contaminant material coming from a debris-generating EUV radiation source comprising:a contamination barrier constructed and arranged to rotate about an axis; anda magnet structure constructed and arranged to provide a magnetic field for deflecting charged debris from the radiation source, said magnet structure being constructed and arranged to provide a magnetic field through said contamination barrier, said magnetic field, when passing through the contamination barrier, being oriented along planes generally coinciding with the axis of rotation of the contamination barrier, the magnetic structure comprising a static ring provided around the contamination barrier. 2. A debris mitigation system according to claim 1, wherein said magnetic field is provided generally invariant for a predetermined rotation of the rotating contamination barrier. 3. A debris mitigation system according to claim 1, wherein said magnetic field is provided generally invariant for any rotation of the rotating contamination barrier. 4. A debris mitigation system according to claim 1, wherein said magnet structure further comprises a plurality of outer magnets arranged to have a magnetic axis arranged perpendicular to the rotation axis of the contamination barrier. 5. A debris mitigation system according to claim 1, wherein said outer magnet structure is rotatable with said contamination barrier. 6. A debris mitigation system according to claim 1, wherein a central magnet structure is provided centrally relative to the axis of rotation, said central magnet structure having magnetic poles opposite to the magnetic poles of the magnet structure. 7. A debris mitigation system according to claim 6, wherein said central magnet structure is provided static relative the contamination barrier. 8. A debris mitigation system according to claim 6, wherein said central magnet structure is rotatable with said the contamination barrier. 9. A debris mitigation system according to claim 6, wherein said central magnet structure comprises a magnet having a magnetic axis oriented concentrically with the axis of rotation of the rotating contamination barrier. 10. A debris mitigation system according to claim 1, wherein said contamination barrier comprises a plurality of foil plates positioned in respective planes which are parallel to a propagation direction of radiation. 11. A debris mitigation system according to claim 1, wherein the plates are oriented parallel to said magnetic field. 12. A debris mitigation system according to claim 11, wherein the magnetic field is provided to have magnetic field lines traversing the plates in axial direction, relative to the axis of rotation. 13. A debris mitigation system according to claim 11, wherein the magnetic field is provided to have magnetic field lines traversing the plates in radial direction, relative to the axis of rotation. 14. A debris mitigation system according to claim 1, further comprising a discharge produced or a laser induced plasma source. 15. A debris mitigation system according to claim 14, wherein said plasma source comprises tin, lithium, or xenon. 16. A debris mitigation system according to claim 1, further comprising a collector element. 17. A debris mitigation system according to claim 16, wherein said collector element is cylinder symmetric to the axis of rotation of the contamination barrier and comprises concentrically curved reflective surfaces. 18. A debris mitigation system according to claim 17, wherein said reflective surfaces are stacked at a distance ranging between about 2 and 7 cm. 19. A lithographic apparatus comprising:a patterning device constructed and arranged to pattern a beam of radiation;a projection system constructed and arranged to project the patterned beam of radiation onto a substrate; anda debris mitigation system constructed and arranged to trap contaminant material generated by a debris-generating EUV radiation source, the debris mitigation system comprisinga contamination barrier constructed and arranged to rotate about an axis; anda magnet structure constructed and arranged to provide a magnetic field for deflecting charged debris from the radiation source, said magnet structure being constructed and arranged to provide a magnetic field through said contamination barrier, said magnetic field, when passing through the contamination barrier, being oriented along planes generally coinciding with the axis of rotation of the contamination barrier, the magnetic structure comprising a static ring provided around the contamination barrier.