A contamination prevention system constructed and arranged to prevent material emanating from a radiation source from propagating with radiation from the radiation source into or within a lithographic apparatus. The contamination prevention system includes a channel barrier constructed and arranged to traverse the radiation from the radiation source. The channel barrier includes a plurality of elongated channel members constructed and arranged to absorb or deflect the material. The channel members are rotatable around an axis of rotation by a drive connected to the channel barrier. The contamination prevention system also includes a cooling system provided on an outer surface of the channel barrier.