CN-224232636-U - Grid electrode for vacuum electronic device, electron gun and X-ray tube

CN224232636UCN 224232636 UCN224232636 UCN 224232636UCN-224232636-U

Abstract

The utility model provides a grid electrode, an electron gun and an X-ray tube for a vacuum electronic device, wherein the grid electrode comprises a grid electrode substrate, the grid electrode substrate is a flat sheet, the thickness of the grid electrode substrate is 0.1 mm-3 mm, the thermal conductivity of the material of the grid electrode substrate is greater than 200W/(m.K), electron beam through holes are formed in the grid electrode substrate, the axial direction of the electron beam through holes is perpendicular to two surfaces of the thickness direction of the grid electrode substrate, the electron beam through holes enable the grid electrode substrate to be provided with through hole parts and solid parts except the through hole parts, after the electron beam through holes are formed in the grid electrode substrate, an outer wrapping layer is fixedly arranged on the surface of the solid parts, and the outer wrapping layer is made of metal material and has the thickness of 10nm-50 mu m. The grid electrode provided by the utility model can conduct away a large amount of heat generated when an electron beam bombards the grid electrode, has higher electron passing rate at a low kV of less than 5kV, and is well suitable for various cathode emission materials such as field emission, thermal field emission and the like.

Inventors

YANG ENHUI
LIANG YU
CAO CHANGWEI
Guo Zongyan
YIN YIYUAN
TANG ZHIHONG

Assignees

上海超群检测科技股份有限公司

Dates

Publication Date: 20260512
Application Date: 20250530

Claims (11)

1. A grid for a vacuum electronic device is characterized by comprising a grid substrate, wherein the grid substrate is a flat sheet and has a thickness of 0.1-3 mm, and the thermal conductivity of the material of the grid substrate is more than 200W/(m.K); The grid substrate is provided with at least one electron beam through hole penetrating along the thickness direction of the grid substrate, the axial direction of the electron beam through hole is perpendicular to two surfaces of the grid substrate in the thickness direction, and the electron beam through hole enables the grid substrate to be provided with a through hole part and a solid part except the through hole part; And an outer wrapping layer is fixedly arranged on the surface of the solid part of the grid substrate, and the outer wrapping layer is made of a metal material and has a thickness of 10nm-50 mu m.
2. A gate electrode for a vacuum electronic device as set forth in claim 1 wherein said gate electrode substrate is made of any one of diamond, cubic boron nitride, single crystal SiC, beryllium oxide, and graphene.
3. The grid electrode for vacuum electronic device according to claim 1, wherein the diameter of the electron beam via hole is 0.1mm to 1mm, and when there are a plurality of electron beam via holes, the duty ratio between the via hole portion and the solid portion on the grid electrode substrate is 2.
4. A gate electrode for a vacuum electronic device as claimed in claim 1, wherein the material of the outer cladding layer is any one of gold, copper, chromium, nickel, molybdenum and tungsten.
5. The grid electrode for a vacuum electronic device according to claim 1, wherein the outer wrapping layer is fixedly attached to the surface of the solid portion by means of magnetron sputtering, chemical vapor deposition, or vapor deposition.
6. A gate electrode for a vacuum electronic device according to claim 1, wherein the surface roughness of both surfaces in the thickness direction of the gate electrode substrate does not exceed Ra0.8.
7. A gate electrode for a vacuum electronic device as claimed in claim 1, wherein the gate electrode substrate is provided with a transition layer between the solid portion and the outer envelope layer, the transition layer having a thickness of not more than 150nm.
8. A gate electrode for a vacuum electronic device as claimed in claim 7, wherein the material of the transition layer is titanium, chromium, or nickel.
9. The grid electrode for vacuum electronic device according to claim 7, wherein the transition layer is fixedly attached to the surface of the solid portion by means of magnetron sputtering, chemical vapor deposition, or vapor deposition, and the outer wrapping layer is fixedly attached to the surface of the transition layer by means of magnetron sputtering, chemical vapor deposition, or vapor deposition.
10. An electron gun comprising a cathode having an electron emitter, and further comprising a grid electrode according to any one of claims 1 to 9, the grid electrode being fixed to one side of the cathode in an electron beam emission direction.
11. The X-ray tube comprises a tube shell with a vacuum tube cavity inside, and an anode hermetically connected to one end of the tube shell, wherein the anode is provided with an anode target, and the X-ray tube is characterized by further comprising the electron gun as claimed in claim 10, wherein the electron gun is hermetically connected to the other end of the tube shell, and the cathode, the grid electrode and the anode target are sequentially arranged along the emission direction of electron beams.

Description

Grid electrode for vacuum electronic device, electron gun and X-ray tube Technical Field The present utility model relates to the field of vacuum electronic devices, and more particularly to a grid for a vacuum electronic device, an electron gun equipped with the grid, and an X-ray tube equipped with the electron gun. Background The grid electrode is an electrode for various vacuum electronic devices such as an X-ray tube, a magnetron, a traveling wave tube, an electron microscope and the like, and is widely applied to the fields of industry, medical treatment, scientific instruments and the like. In general, a grid electrode is disposed between an emitter electrode (i.e., a cathode) and an anode of a vacuum electronic device, and is used for regulating and controlling electron beam current from the cathode to the anode after passing through the grid electrode by giving a potential relative to the cathode, so as to play a role in regulating electron beam current intensity, electron beam spot size, electron beam spot direction, even turning on/off electron beam current, and the like. Depending on the electron emission mechanism of the cathode material (such as field emission, thermal emission and thermal field emission), the gate potential of thermal emission and thermal field emission is typically less than several hundred volts, while the gate potential of field emission is typically less than several thousand volts. Because the grid is subjected to bombardment of electron beam for a long time, the grid material needs to have the requirements of high pressure resistance, high temperature resistance, electron bombardment resistance, excellent mechanical stability, deformation resistance, low thermal expansion coefficient, low saturated vapor pressure and the like. Currently, the most common grids are molybdenum, tungsten and nickel grids or meshes of single or porous structure. The grid is arranged right above the cathode electron emission material and parallel to the plane of the cathode electron emission material, and meanwhile, the distance between the grid and the cathode is very small, usually less than 1mm, most of which is less than 0.5mm, even 0.1 or 0.2mm. In order to have a high electron pass rate, the thickness of the gate electrode is usually thin, 0.05-0.3mm. In the using process of the grid sheet or the metal thin grid of the grid mesh structure, the metal thin grid is bombarded by electron beam current for a long time, and almost all electron kinetic energy is converted into heat energy except that less than 1% of electron energy generates X-rays on the grid. Therefore, the bombardment force of the long-term electron beam and a large amount of heat which is accumulated on the grid and cannot be conducted away in time and is generated by the electron beam bombardment cause the deformation of the grid sheet or the metal thin grid of the grid mesh structure, so that the electric field between the grid and the cathode and the position of the mesh on the grid relative to the cathode are influenced, the electron beam regulation effect is disabled, and even the short circuit between the grid and the cathode is caused due to the small interval between the grid and the cathode and the deformation of the grid. In addition, when the electron beam impinges on the grid, X-rays are generated on the grid, the yield of the X-rays is related to the thickness and atomic number of the grid material, the larger the atomic number of the grid material is, the larger the yield of the X-rays is, when the thickness of the grid material is not more than the free path of electrons in the material, the thicker the grid material is, the larger the yield of the X-rays is, the grid sheets or grids made of molybdenum, tungsten and nickel are provided with larger atomic numbers, the higher the yield of the X-rays is, and the X-rays generated by the non-anode target are not desirable, so that additional shielding measures are needed to shield the X-rays generated on the grid. In the prior art, the Chinese patent application with the application number of 20201302224. X discloses a graphene sponge grid structure with high electron transmittance, which utilizes the graphene sponge grid structure to replace the existing metal micro grid, improves the electron passing rate of the grid and the collimation of electron movement, still maintains conductivity and certain mechanical strength, and enhances the bombardment resistance of the grid. However, due to the problem of the manufacturing process, the direction of the electron beam through hole on the graphene sponge grid is difficult to control to be consistent with the emission direction of the electron beam, and the metal film layer on the surface of the sponge graphene has no mesh, so that electrons can be blocked from passing, and the electron passing rate is very low under the grid voltage of less than 5kV, so that the graphene sponge grid is only suitable for occasions with