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 BaOCaOAl.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 BaOCaOAl.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.

An electron gun includes: a cathode, which has a cathode holder and a cathode body; and a Wehnelt cylinder. The cathode holder receives the cathode body and the Wehnelt cylinder is suitable for bundling free electrons, which can escape from the cathode body toward the Wehnelt cylinder, to form an electron beam. The Wehnelt cylinder is interlockingly arranged, at least in some parts along a first inner surface facing the cathode holder, on an outer surface of the cathode holder and at least partly extends around the cathode holder.

A filament assembly can include: a button having a planar emitter region with one or more apertures extending from an emission surface of the planar emitter region to an internal surface opposite of the emission surface; an inlet electrical lead coupled to the button at a first side; an outlet electrical lead coupled to the button at a second side opposite of the first side; and a low work function object positioned adjacent to the internal surface of the planar emitter region and retained to the button. The planar emitter region can include a plurality of apertures. The low work function object can include a porous ceramic material having the barium, and may have a polished external surface. An electron gun can include the filament assembly. An additive manufacturing system can include the electron gun having the filament assembly.

The invention relates to the field of production of barium-scandate dispenser cathodes or other barium-scandate materials. A target (66) containing a mixture of BaO, CaO, Al.sub.2O.sub.3 and Sc.sub.2O.sub.3 tends to be more stable, the higher the scandia (scandium oxide) content is. However, an increased scandia content results in a reduced emission capability. A destabilizing effect of BaO and CaO reactions is counteracted by the more inert Sc.sub.2O.sub.3 and also Al.sub.2O.sub.3 components, as not only an increased scandia content stabilizes the material but also an increased alumina (aluminum oxide) content improves the stability.

The invention relates to the field of production of barium-scandate dispenser cathodes or other barium-scandate materials. A target (66) containing a mixture of BaO, CaO, Al.sub.2O.sub.3 and Sc.sub.2O.sub.3 tends to be more stable, the higher the scandia (scandium oxide) content is. However, an increased scandia content results in a reduced emission capability. A destabilizing effect of BaO and CaO reactions is counteracted by the more inert Sc.sub.2O.sub.3 and also Al.sub.2O.sub.3 components, as not only an increased scandia content stabilizes the material but also an increased alumina (aluminum oxide) content improves the stability.

A method of manufacturing carburized Lu.sub.2O.sub.3 doped Mo cathodes for thermionic emission for magnetrons is described. The Lu.sub.2O.sub.3 doped Mo powder is prepared by sol-gel method. The powder is reduced thoroughly in hydrogen atmosphere. Afterwards, the powder is die-pressed into pellets, followed by sintering in hydrogen and carburization in activated carbon powder to obtain the carburized Lu.sub.2O.sub.3 doped Mo cathode.

A method of manufacturing carburized Lu.sub.2O.sub.3 doped Mo cathodes for thermionic emission for magnetrons is described. The Lu.sub.2O.sub.3 doped Mo powder is prepared by sol-gel method. The powder is reduced thoroughly in hydrogen atmosphere. Afterwards, the powder is die-pressed into pellets, followed by sintering in hydrogen and carburization in activated carbon powder to obtain the carburized Lu.sub.2O.sub.3 doped Mo cathode.