RADIATION CONDUIT

A radiation source (SO) for an EUV lithography apparatus is disclosed. The radiation source comprises a chamber (9) comprising a plasma formation region (4), a radiation collector (5) arranged in the chamber and configured to collect radiation emitted at the plasma formation region and to direct the collected radiation towards an intermediate focus region (6), and a radiation conduit (300) disposed between the radiation collector and the intermediate focus region. The radiation conduit comprises at least one outlet (320, 325) on an inner surface of a wall of the radiation conduit for directing a protective gas flow, and at least one guide portion (335, 345) extending from the inner surface of the wall of the radiation conduit and configured to redirect the protective gas flow. Also disclosed is a method of reducing debris and/or vapor deposition in the radiation conduit by providing a protective gas flow to the at least one outlet of the radiation conduit, such that the protective gas flow is redirected by the at least one guide portion.