A radiation source is provided for generating short-wavelength radiation from plasma in which a molten liquid metal is used as a source material. In the radiation source having a revolving element for providing the source material, unused source material exiting from the plasma zone has to be reliably collected to prevent impairments of the radiation source through unused source material. This aim is met in that a receptacle for the unused source material is constructed as a catch trough having a trough opening below the plasma zone and the molten bath in direction of gravity force as well as an inclined side wall to catch the source material and concentrate it in a deepest catch trough area. A heating element and at least one temperature sensor are fastened to the catch trough for heating the source material and controlling its temperature above its melting temperature.