Electron beam emitter with slotted gun

An electron beam emitter includes an electron generator for generating electrons. The electron generator can have a housing containing at least one electron source for generating the electrons. The at least one electron source has a width. The electron generator housing can have an electron permeable region spaced from the at least one electron source for allowing extraction of the electrons from the electron generator housing. The electron permeable region can include a series of narrow elongate slots and ribs formed in the electron generator housing and extending laterally beyond the width of the at least one electron source. The electron permeable region can be configured and positioned relative to the at least one electron source for laterally spreading the electrons that are generated by the at least one electron source.