A lithographic projection apparatus is disclosed. The apparatus includes a radiation system to transmit a beam of radiation emitted from a radiation source, and a support structure constructed to hold a patterning structure to be irradiated by the beam. A substrate holder is constructed to hold a substrate, and a projection system is constructed and arranged to project an irradiated portion of the patterning structure onto a target portion of the substrate. A first screen is positioned in a path of the beam between the radiation system and an optical element and a positive voltage is applied to the first screen to repel positively charged particles away from the optical element. A second screen is positioned in the path of the beam on at least one side of the first screen, and a negative voltage is applied to the second screen to repel negative particles away from the first screen.