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.

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.

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.

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 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 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.