A vacuum electron tube comprises at least one electron-emitting cathode and at least one anode arranged in a vacuum chamber, the cathode having a planar structure comprising a substrate comprising a conductive material, a plurality of nanotube or nanowire elements electrically insulated from the substrate, the longitudinal axis of the nanotube or nanowire elements substantially parallel to the plane of the substrate, and at least one first connector electrically linked to at least one nanotube or nanowire element so as to be able to apply a first electrical potential to the nanowire or nanotube element.

A cathode assembly design is provided that includes two flat emitters, a longer emitter filament and a shorter emitter filament. In one implementation the focal spot sizes produced by the long and short emitters overlap over a range. Thus, one emitter filament may be suitable for generating small and concentrated focal spot sizes while the other emitter filament is suitable for generating small and large focal spots sizes.

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.

A filament assembly includes a core and a filament. At least a central portion of the filament is disposed on the core. At least the central portion may be straight or may have a high-resistance configuration such as one in which the filament follows a path that changes direction. A thermionically emissive layer may be disposed on the core so as to encapsulate at least the central portion. The filament assembly may be utilized in any application requiring the production of electrons.

The embodiments provide a thermionic emission device and a method for tuning a work function in a thermionic emission device is provided. The method includes illuminating an N type semiconductor material of a first member of a thermionic emission device, wherein a work function of the N type semiconductor material is lowered by the illuminating. The method includes collecting, on one of the first member or a second member of the thermionic emission device, electrons emitted from one of the first member or the second member.

The embodiments provide a thermionic emission device and a method for tuning a work function in a thermionic emission device is provided. The method includes illuminating an N type semiconductor material of a first member of a thermionic emission device, wherein a work function of the N type semiconductor material is lowered by the illuminating. The method includes collecting, on one of the first member or a second member of the thermionic emission device, electrons emitted from one of the first member or the second member.

Provided is a field emission apparatus including a pipe-shaped emitter holder comprising an electrically conductive material and a first internal space communicated in a first direction, and an emitter electrode having one or more yarns each having a structure extending in the first direction in which a plurality of CNTs that extend in the first direction are aggregated, and the emitter electrode is inserted in the first internal space while extending in the first direction.

Provided is a field emission apparatus including a pipe-shaped emitter holder comprising an electrically conductive material and a first internal space communicated in a first direction, and an emitter electrode having one or more yarns each having a structure extending in the first direction in which a plurality of CNTs that extend in the first direction are aggregated, and the emitter electrode is inserted in the first internal space while extending in the first direction.

An electron source has an insulating base, a pair of conductive terminals, an insulating support member, a drift isolation member, an emitter-cathode, and one or more heating elements. The conductive terminals are exposed from a first surface of the insulating base. The insulating support member extends from the first surface of the insulating base. The drift isolation member is disposed at an end of the insulating support member remote from the insulating base. The emitter-cathode is coupled to the drift isolation member. The one or more heating elements are coupled to the conductive terminals and the drift isolation member. The combination of the drift isolation member with the insulating support member can prevent stress-induced drift from impacting position of the emitter-cathode, thereby improving the mechanical stability of the electron source.

An electron source has an insulating base, a pair of conductive terminals, an insulating support member, a drift isolation member, an emitter-cathode, and one or more heating elements. The conductive terminals are exposed from a first surface of the insulating base. The insulating support member extends from the first surface of the insulating base. The drift isolation member is disposed at an end of the insulating support member remote from the insulating base. The emitter-cathode is coupled to the drift isolation member. The one or more heating elements are coupled to the conductive terminals and the drift isolation member. The combination of the drift isolation member with the insulating support member can prevent stress-induced drift from impacting position of the emitter-cathode, thereby improving the mechanical stability of the electron source.