Field effect electron emitter with grouped part emission surfaces

A field effect electron emitter, comprising:

• a segmented emission surface, wherein the segmented emission surface has a plurality of field effect emitter needles and a number of segments, each segment having an activatable part emission surface, wherein the plurality of field effect emitter needles are distributed on the activatable part emission surfaces;
• and
• a control unit configured to activate various groups with at least one of the number of segments for a simultaneous electron emission from respective activatable part emission surfaces such that coherent and grouped part emission surfaces able to be activated in succession overlap in pairs by at least 25%,
• wherein the control unit is configured to vary an emitted flow of electrons per segment for each grouped part emission surface for a simultaneous asymmetrical electron emission such that all field effect emitter needles of a first segment generate a higher flow of electrons than all field effect emitter needles of a second segment.