A source for generating ionizing radiation and in particular x-rays, to an assembly includes a plurality of sources and to a process for producing the source. The source for generating ionizing radiation comprises: a vacuum chamber; a cathode that is able to emit an electron beam into the vacuum chamber; an anode that receives the electron beam and that comprises a target that is able to generate ionizing radiation from the energy received from the electron beam; and an electrode that is placed in the vicinity of the cathode and forming a wehnelt. The electrode is formed from a conductive surface adhering to a concave face of a dielectric.