The present invention relates to an X-ray source for the generation of fluorescent X-rays. The X-ray source is realized by an electron source for the emission of electrons and a target which emits X-rays in response to the incidence of the electrons, the target comprising a ring-shaped primary target for the emission of primary X-rays in response to the incidence of the electrons and a secondary target for the emission of fluorescent X-rays in response to the incidence of the primary X-rays. To obtain an enhanced radiance, it is proposed that the primary target comprises a liquid metal channel arranged in a radial direction relative to a central axis, and that a liquid metal circulates in the liquid metal channel during operation of the X-ray source in the radial direction from an inner side to an outer side of the ring-shaped primary target.