A charged particle beam emitting device includes at least two charged particle beam guns, each of the at least two charged particle beam guns having a separate charged particle emitter with an emitting surface for emitting a respective charged particle beam. The charged particle beam emitting device further includes an aperture element comprising at least one aperture opening and a deflector unit. The deflector unit is adapted for alternatively directing the charged particle beams of the at least two charged particle beam guns on the at least one aperture opening so that, at the same time, one of the at least two charged particle beams is directed on the aperture opening while the respective other charged particle beam of the at least two charged particle beams is deflected from the aperture opening by the deflector unit. At the same time, only one of the two charged particle beam guns is used so that the temporarily unused charged particle beam gun can be subjected to a cleaning procedure. This ensures that the emitting surfaces of both charged particle beam guns can be alternatively and frequently cleaned with minimum interruption of the operation of the charged particle beam device.