Graphene coated tungsten-based hot cathode and preparation method thereof

Abstract

The graphene coated tungsten-based hot cathode comprises a graphene layer and a tungsten-based cathode layer, the upper surface of the tungsten-based cathode layer is coated with the graphene layer, and a lamp filament is arranged below the tungsten-based cathode layer. The preparation method comprises the following steps: (1) preparing a tungsten substrate with a smooth surface; (2) coating the tungsten substrate with a graphene layer; and (3) assembling the cathode heater assembly. The invention provides a metal coated tungsten-based hot cathode which is simple in structure, easy to prepareand excellent in emission performance. Simulation shows that the surface work function of the metal coated tungsten-based hot cathode is 1.745 eV under the condition that the surface of the metal coated tungsten-based hot cathode is coated with single-layer graphene.

Description

Technical field

[0001] The invention relates to the technical field of microwave vacuum electronics, in particular to a graphene-coated tungsten-based hot cathode and a preparation method thereof.Background technique

[0002] Because of their high frequency and high output power, vacuum electronic devices have been widely used in various power microwave systems such as communications, displays, medical CT, non-destructive testing, particle accelerators, free electron lasers, electron microscopes, and precision testing equipment. Class equipment and systems. As the electron source of the vacuum microelectronic device, the cathode's emission ability directly affects the performance indicators of the device and the system. Hot cathode has significant advantages such as large emission current and long working life, and has been widely used. Further improving the emission capability of the cathode or extending the life of the cathode is the development direction of the cathode, and simplifying...

Examples

Embodiment 1

[0028]Such asfigure 1 As shown, a graphene-coated tungsten-based hot cathode includes a graphene layer 1 and a tungsten base layer 2. The upper surface of the tungsten base layer 2 is covered with a single-layer graphene layer 1. Such asfigure 2As shown in the top view of the structure, the graphene layer-tungsten cathode layer composite structure 3 is placed in the support tube 4 and fixed by the side wall of the support tube 4, and a filament 5 is arranged under the tungsten base layer 2 in the support tube 4 to form a hot cathode. The tungsten base layer 2 and the filament 5 can be directly connected, and a spacer layer 7 can also be added. The anode 6 is arranged relative to the hot cathode, above the hot cathode, and the positional relationship is asfigure 1 Shown. The hot cathode and the anode 6 can adopt a flat structure or a curved structure.

[0029]The preparation method of the above-mentioned graphene-coated tungsten-based hot cathode includes the following steps:

[0030]Step ...

Embodiment 2

[0037]The only difference from Embodiment 1 is that the graphene-coated tungsten-based hot cathode of this embodiment uses a tungsten-osmium alloy cathode layer, and a grid is added to the surface of the hot cathode to adjust the surface emission of the hot cathode. The grid uses a ring or Mesh structure, the grid is isolated from the graphene layer 1 by an insulating dielectric layer or vacuum. By adjusting the voltage of the grid, the emission capability of the cathode can be adjusted.

Embodiment 3

[0039]The only difference from Example 1 is that the graphene-coated tungsten-based hot cathode of this embodiment uses a carbon-doped tungsten cathode layer, and the graphene layer 1 is a double-layer graphene; during the preparation process, wet transfer is used. The method realizes the graphene layer on the tungsten substrate.

Technical field

[0001] The invention relates to the technical field of microwave vacuum electronics, in particular to a graphene-coated tungsten-based hot cathode and a preparation method thereof.Background technique

[0002] Because of their high frequency and high output power, vacuum electronic devices have been widely used in various power microwave systems such as communications, displays, medical CT, non-destructive testing, particle accelerators, free electron lasers, electron microscopes, and precision testing equipment. Class equipment and systems. As the electron source of the vacuum microelectronic device, the cathode's emission ability directly affects the performance indicators of the device and the system. Hot cathode has significant advantages such as large emission current and long working life, and has been widely used. Further improving the emission capability of the cathode or extending the life of the cathode is the development direction of the cathode, and simplifying...

Examples

Embodiment 1

[0028]Such asfigure 1 As shown, a graphene-coated tungsten-based hot cathode includes a graphene layer 1 and a tungsten base layer 2. The upper surface of the tungsten base layer 2 is covered with a single-layer graphene layer 1. Such asfigure 2As shown in the top view of the structure, the graphene layer-tungsten cathode layer composite structure 3 is placed in the support tube 4 and fixed by the side wall of the support tube 4, and a filament 5 is arranged under the tungsten base layer 2 in the support tube 4 to form a hot cathode. The tungsten base layer 2 and the filament 5 can be directly connected, and a spacer layer 7 can also be added. The anode 6 is arranged relative to the hot cathode, above the hot cathode, and the positional relationship is asfigure 1 Shown. The hot cathode and the anode 6 can adopt a flat structure or a curved structure.

[0029]The preparation method of the above-mentioned graphene-coated tungsten-based hot cathode includes the following steps:

[0030]Step ...

Embodiment 2

[0037]The only difference from Embodiment 1 is that the graphene-coated tungsten-based hot cathode of this embodiment uses a tungsten-osmium alloy cathode layer, and a grid is added to the surface of the hot cathode to adjust the surface emission of the hot cathode. The grid uses a ring or Mesh structure, the grid is isolated from the graphene layer 1 by an insulating dielectric layer or vacuum. By adjusting the voltage of the grid, the emission capability of the cathode can be adjusted.

Embodiment 3

[0039]The only difference from Example 1 is that the graphene-coated tungsten-based hot cathode of this embodiment uses a carbon-doped tungsten cathode layer, and the graphene layer 1 is a double-layer graphene; during the preparation process, wet transfer is used. The method realizes the graphene layer on the tungsten substrate.

Images