In a radiation source for the generation of short-wavelength radiation, it is the object of the invention to effectively increase the protection of the collimator optics by a buffer gas without substantially reducing the radiation transmission. A vacuum chamber which encloses a radiation-emitting plasma and is outfitted with at least one feed line and one outlet line for a buffer gas in order to ensure protection against debris for at least one optical element which directs the radiation to a radiation outlet opening in the vacuum chamber has chamber areas with particle deceleration of varying magnitude by the buffer gas. The particle deceleration is greater at least in a first chamber area in which the optical element is arranged than in any other chamber area.