The present disclosure provides an electron beam device (500) for inspecting a sample (10) with an electron beam, comprising an electron beam source comprising a cold field emitter (100) for emitting an electron beam, electron beam optics for directing and focusing the electron beam onto the sample (10), and a detector device (540) for detecting secondary charged particles generated by impingement of the electron beam on the sample (10). The cold field emitter (100) includes an emitter tip (110), a base arrangement (120) configured for supporting the emitter tip (110) and comprising a first base element (122) and a second base element (124), and a filament (130) having at least a first filament portion (132) and a second filament portion (134) attaching the emitter tip (110) to the base arrangement (120), wherein the first filament portion (132) extends between the emitter tip (110) and the first base element (122) and the second filament portion (134) extends between the emitter tip (110) and the second base element (124), wherein a length (L) of each of the first filament portion (132) and the second filament portion (134) is 4 mm or less, and wherein a diameter of a cross-section of each of the first filament portion (132) and the second filament portion (134) is 0.13 mm or less.

An electron microscope (100) is described. The electron microscope comprises an electron source (110) for generating an electron beam, a condenser lens (130) for collimating the electron beam downstream of the electron source, and an objective lens (140) for focusing the electron beam onto a specimen (16). The electron source comprises a cold field emitter with an emission tip (112), an extractor electrode (114) for extracting the electron beam (105) from the cold field emitter for propagation along an optical axis (A), the extractor electrode having a first opening (115) configured as a first beam limiting aperture, a first cleaning arrangement (121) for cleaning the emission tip (112) by heating the emission tip, and a second cleaning arrangement (122) for cleaning the extractor electrode (114) by heating the extractor electrode. Further described is a method of operating such an electron microscope.

An electron gun and an apparatus incorporating the electron gun. The electron gun includes an electron emission element, an electrode, a control element, and a control circuit. The electron emission element is arranged to be activated to emit electron beam. The electrode is arranged to be electrically connected with a power supply to accelerate the emitted electron beam. The control element may be arranged between the electron emission element and the electrode. The control element is arranged to be electrically connected with the power supply to provide an electric field to control emission of electron beams from the electron emission element. The control circuit is electrically connected with the control element for changing the electric field provided by the control element.