The invention relates the field of electron emitter of an X-ray tube. More
specifically the invention relates to flat thermionic emitters to be used
in X-ray systems with variable focus spot size and shape. The emitter
provides two main terminals (3, 5) which form current conductors and
which support at least two emitting portions (7, 9). The emitting
portions are structured in a way so that they are electron optical
identical or nearly identical increasing the emergency operating options
in case of emitter damage.