A high-temperature component made of a refractory metal or a refractory metal alloy, includes a coating for increasing thermal emissivity. The coating is formed substantially of tungsten and rhenium, i.e. of at least 55 wt. % rhenium and at least 10 wt. % tungsten, and has a Re3W phase of at least 35 wt. %. A process for producing a high-temperature component having a coating for increasing thermal emissivity, is also provided.

An electron source according to the present disclosure includes a columnar portion made of a first material having an electron emission characteristic; and a tubular portion that is disposed to surround the columnar portion and made of a second material having a higher work function than the first material, wherein a hole that extends in a direction from one end face toward the other end face and has a substantially circular cross-sectional shape is formed in the tubular portion, and the columnar portion has a substantially triangular or substantially quadrangular cross-sectional shape and is fixed to the tubular portion in an abutting engagement with an inner surface of the hole.

An ion source is provided. The ion source may include an ion source chamber, and a cathode disposed in the ion source chamber and configured to emit electrons to generate a plasma within the ion source chamber, the cathode comprising a refractory metal, wherein the refractory metal comprises a macrocrystalline structure.

The cathode member for electron beam generation of the present disclosure includes: 95% by area or more of a single phase or two phases of a compound composed of iridium and cerium. A total content of one or more subcomponents of metallic iridium and an oxide of one or more elements of iridium and cerium is 5% by area or less of the cathode member.

Aspects include a method for treating a polycrystalline material, the method comprising: exposing a surface of the polycrystalline material to a plasma thereby changing the surface of the polycrystalline material from being characterized by a starting condition to being characterized by a treated condition; wherein: the surface comprises a plurality of crystallites each having the composition MB.sub.6, M being a metal element; the plasma comprises ions, the ions being characterized by an average ion flux selected from the range of 1.5 to 100 A/cm.sup.2 and an average ion energy that is less than a sputtering threshold energy; the starting condition of the surface is characterized by a first average work function and the treated condition of the surface is characterized by a second average work function; and the second average work function is less than the first average work function.

Electron emitters and methods of fabricating the electron emitters are disclosed. According to certain embodiments, an electron emitter includes a tip with a planar region having a diameter in a range of approximately (0.05-10) micrometers. The electron emitter tip is configured to release field emission electrons. The electron emitter further includes a work-function-lowering material coated on the tip.

A method to reduce the work function of a carbon-coated lanthanum hexaboride (LaB6) cathode wherein the exposed tip of the cathode is exposed to moisture between two heat treatments is provided. The work function may be reduced by 0.01 eV or more.

An electron gun device that emits an electron beam by heating to a high temperature in a vacuum. The surface of a material, which emits an electron beam, is a hydrogenated metal that is melted and in a liquid state during a high-temperature operation. The liquid hydrogenated metal is contained in a hollow cover tube container, which is in a solid state during the high-temperature operation, in the form of a hydrogenated liquid metal or in the form of a liquid metal before hydrogenation, and heated together with the cover tube container to a high temperature. The hydrogenated liquid metal is exposed from the cover tube container and forms a liquid surface where gravity, the electric field and the surface tension of the liquid surface are balanced; and an electron beam is emitted from the exposed surface of the hydrogenated liquid metal.

A cathode head can include: a first electron emitter filament having a first size; a first grid pair defining walls of a first filament slot having the first filament therein, each grid member of the first grid pair being electronically coupled to different voltage sources; a second electron emitter filament; and a second grid pair defining walls of a second filament slot having the first electron emitter therein, each grid member of the second grid pair being electronically coupled to different voltage sources. The first grid pair can have a first and second grid members; and the second grid pair can have the second grid member and a third grid member. The first grid member and third grid member are electronically coupled to the same voltage source and the second grid member being electronically coupled to a different voltage source.

An array of carbon nanotube micro-tip structure includes an insulating substrate and a plurality of patterned carbon nanotube film structures. The insulating substrate includes a surface. The surface includes an edge. A plurality of patterned carbon nanotube film structures spaced from each other. Each of the plurality of patterned carbon nanotube film structures is partially arranged on the surface of the insulating substrate. Each of the plurality of patterned carbon nanotube film structures comprises two strip-shaped arms joined together forming a tip portion protruding and suspending from the edge of the surface of the insulating substrate. Each of the two strip-shaped arms comprises a plurality of carbon nanotubes parallel to the surface of the insulating substrate.