A method for removing contaminant particles, such as atoms, molecules, clusters, ions, and the like, produced by a radiation source during generation of short-wave radiation having a wavelength of up to approximately 20 nm, includes guiding a first gas between the radiation source and a particle trap arranged in a wall of a chamber. In order to protect an optical device and/or articles to be irradiated against contamination, the method introducing a second gas into the chamber and its pressure is adjusted such that it is at least as high as the pressure of the first gas.