A thermionic dispenser cathode having a refractory metal matrix with scandium and barium compounds in contact with the metal matrix and methods for forming the same. The invention utilizes atomic layer deposition (ALD) to form a nanoscale, uniform, conformal distribution of a scandium compound on tungsten surfaces and further utilizes in situ high pressure consolidation/impregnation to enhance impregnation of a BaO—CaO—Al.sub.2O.sub.3 based emissive mixture into the scandate-coated tungsten matrix or to sinter a tungsten/scandate/barium composite structure. The result is a tungsten-scandate thermionic cathode having improved emission.

A thermionic dispenser cathode having a refractory metal matrix with scandium and barium compounds in contact with the metal matrix and methods for forming the same. The invention utilizes atomic layer deposition (ALD) to form a nanoscale, uniform, conformal distribution of a scandium compound on tungsten surfaces and further utilizes in situ high pressure consolidation/impregnation to enhance impregnation of a BaO—CaO—Al.sub.2O.sub.3 based emissive mixture into the scandate-coated tungsten matrix or to sinter a tungsten/scandate/barium composite structure. The result is a tungsten-scandate thermionic cathode having improved emission.

A thermionic emission device comprises a first electrode, a second electrode, a single carbon nanotube, an insulating layer and a gate electrode. The gate electrode is located on a first surface of the insulating layer. The first electrode and the second electrode are located on a second surface of the insulating layer and spaced apart from each other. The carbon nanotube comprises a first end, a second end opposite to the first end, and a middle portion located between the first end and the second end. The first end of the carbon nanotube is electrically connected to the first electrode, and the second end of the carbon nanotube is electrically connected to the second electrode.

A thermionic emission device comprises a first electrode, a second electrode, a single carbon nanotube, an insulating layer and a gate electrode. The gate electrode is located on a first surface of the insulating layer. The first electrode and the second electrode are located on a second surface of the insulating layer and spaced apart from each other. The carbon nanotube comprises a first end, a second end opposite to the first end, and a middle portion located between the first end and the second end. The first end of the carbon nanotube is electrically connected to the first electrode, and the second end of the carbon nanotube is electrically connected to the second electrode.

An electron emission element (20) includes a first electrode (30a) and a second electrode (40) which are arranged facing each other, an intermediate layer (50) that is provided between the first electrode (30a) and the second electrode (40), and an insulating layer (60) that is formed with a thickness d1 on a substrate (30). A level difference between the insulating layer (60) and the first electrode (30a) is smaller than the thickness d1 of the insulating layer (60).

An electron emission element (20) includes a first electrode (30a) and a second electrode (40) which are arranged facing each other, an intermediate layer (50) that is provided between the first electrode (30a) and the second electrode (40), and an insulating layer (60) that is formed with a thickness d1 on a substrate (30). A level difference between the insulating layer (60) and the first electrode (30a) is smaller than the thickness d1 of the insulating layer (60).

Methods for fabricating refractory metal scandate nanocomposite powders with homogeneous microstructured refractory metal grains and a uniform nanosized dispersion of scandia are provided. The powders prepared by the sol-gel methods have a spherical morphology, a narrow distribution of particle sizes and a very uniform dispersion of nanosized scandia particles joined to the tungsten grains. The powder particle sizes can range from nanometers to micrometers. The powders can be pressed into porous cathode structures that can be impregnated with emissive materials to produce high current density and long life cathodes for high-power terahertz vacuum electron devices. The sol-gel fabrication methods allow control over the materials, particle size, particle composition and pore size and distribution of the cathode structure by manipulation of the process parameters.

Methods for fabricating refractory metal scandate nanocomposite powders with homogeneous microstructured refractory metal grains and a uniform nanosized dispersion of scandia are provided. The powders prepared by the sol-gel methods have a spherical morphology, a narrow distribution of particle sizes and a very uniform dispersion of nanosized scandia particles joined to the tungsten grains. The powder particle sizes can range from nanometers to micrometers. The powders can be pressed into porous cathode structures that can be impregnated with emissive materials to produce high current density and long life cathodes for high-power terahertz vacuum electron devices. The sol-gel fabrication methods allow control over the materials, particle size, particle composition and pore size and distribution of the cathode structure by manipulation of the process parameters.

A method for manufacturing an electron source includes steps of sandwiching a welding object in which a tip of an electron emission material and a tungsten filament overlap in direct contact between a pair of welding electrodes, and welding the tip and the tungsten filament by causing a current to flow while pressing forces are applied to the welding object by the pair of welding electrodes. A thickness of the welding object is within a range of 50 to 500 m.

A method for manufacturing an electron source includes steps of sandwiching a welding object in which a tip of an electron emission material and a tungsten filament overlap in direct contact between a pair of welding electrodes, and welding the tip and the tungsten filament by causing a current to flow while pressing forces are applied to the welding object by the pair of welding electrodes. A thickness of the welding object is within a range of 50 to 500 m.