Curved-surface hot cathode structure

Abstract

The utility model provides a curved surface hot cathode structure, which comprises an insulating base, a metal sheet and a plurality of pins, the insulating base comprises a supporting part and end parts which are positioned at two ends of the supporting part and are connected with the supporting part, and the supporting part is of an arc-shaped structure of which the center protrudes out of the two ends; the metal sheet is of an arc-shaped structure with the center protruding out of the two ends, the curvature of the metal sheet is the same as that of the supporting part, the metal sheet is attached to the supporting part and welded to the supporting part, and a lamp filament pattern penetrating through the metal sheet is arranged at the preset position of the metal sheet; the plurality of pins are separately arranged at two ends of the metal sheet, a part of the pins are electrically connected with one end of the metal sheet, and a part of the pins are electrically connected with the other end of the metal sheet. According to the curved-surface thermionic cathode structure, the metal sheet is tightly attached to the insulating base, the anti-vibration capability is high, the curved-surface thermionic cathode structure is not prone to deformation after being heated, and the structural stability is good; the curved-surface filament is processed by laser, has smooth edge, uniform thickness control, uniform heating after voltage is applied, and long service life.

Description

Technical Field

[0001] The utility model belongs to the technical field of cathode electron sources and relates to a curved hot cathode structure. Background Art

[0002] A hot cathode generates electrons through thermionic emission from the cathode material. This emission mechanism occurs when, under high temperature conditions, the cathode material excites electrons through thermal energy, causing them to escape from the cathode surface and form an electron stream. Hot cathodes are widely used in vacuum electronic devices, such as cathode electronics, X-ray tubes, and microwave vacuum electronic devices.

[0003] Hot cathodes are usually made of high-melting-point, easily deformable materials (such as tungsten, tantalum, niobium, etc.) and are usually wound and processed, usually in a spiral structure. However, high-melting-point metals are difficult to process (for example, the melting point of tungsten is 3422°C). The extremely high melting point requires special high-temperature equipment and technology for the heating, forming, and winding processes. Tungsten is very brittle at room temperature. When wound into a thin filament, this brittleness can easily lead to material breakage, which is especially difficult when processing extremely thin filaments. Tungsten has good plasticity at high temperatures, but the physical properties of tungsten (such as the coefficient of expansion) will change during high-temperature operation, which needs to be taken into consideration during the design and processing process, especially when the filament is wound into a complex geometric shape.

[0004] Since spiral filaments are typically wound with metal wire, the large bend angle at the intersection of the spiral structure and the filament legs can easily lead to uneven thickness. Consequently, when powered on and heated, localized overheating can occur, increasing the probability of the filament fusing, reducing its lifespan and stability. Furthermore, the spirally wound filament is supported by two filament legs, which can cause the filament to deform and collapse during long-term heating. Furthermore, the raw material for wound filaments is round metal wire, and electrons overflow from the metal surface, resulting in isotropic electron emission. Winding filaments requires high pitch dimensional accuracy, and the shape of the filament is difficult to change at will. Therefore, the electron emission direction is highly random, increasing the size of the electron focal spot and the probability of secondary electron emission from stray electrons. This places higher demands on the focusing of the subsequent electron beam. Some long filaments are not suitable for applications that require high uniformity of the focal spot shape.

[0005] Therefore, how to provide a curved hot cathode structure, optimize the emission direction of electrons, and improve the stability and service life of the hot cathode has become a technical problem that needs to be urgently solved by those skilled in the art. Utility Model Content

[0006] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a curved hot cathode structure to solve the problems of poor stability and short service life of the hot cathode structure in the prior art.

[0007] To achieve the above-mentioned and other related purposes, the present invention provides a curved hot cathode structure, comprising:

[0008] An insulating base, the insulating base comprising a support portion and end portions located at both ends of the support portion and connected to the support portion, wherein the support portion is an arc-shaped structure with a center protruding from both ends;

[0009] a metal sheet having an arc-shaped structure with a center protruding from both ends, the curvature of the metal sheet being the same as that of the support portion, the metal sheet being attached to and welded to the support portion, wherein a filament pattern penetrating the metal sheet is provided at a predetermined position of the metal sheet in a direction from the metal sheet toward the support portion;

[0010] A plurality of pins are separately arranged at both ends of the metal sheet, wherein a portion of the pins are electrically connected to one end of the metal sheet, and a portion of the pins are electrically connected to the other end of the metal sheet.

[0011] Optionally, the pin passes through the end portion, a voltage-conducting rod is provided between the pin and the metal sheet, one side of the voltage-conducting rod is welded to the metal sheet, and the other side of the voltage-conducting rod is welded to the pin.

[0012] Optionally, the pins include two first pins and two second pins, and the first pins and the second pins are separately arranged at both ends of the metal sheet, wherein the two first pins are welded to the same conductive voltage rod, and the two second pins are welded to the same conductive voltage rod.

[0013] Optionally, the filament pattern includes a first spiral groove and a second spiral groove, and the first spiral groove and the second spiral groove are intertwined to form a double helical structure.

[0014] Optionally, a width of the metal sheet between the first spiral groove and the second spiral groove ranges from 0.01 to 2 mm.

[0015] Optionally, the supporting portion includes a first side surface and a second side surface that are oppositely arranged, and the metal sheet is attached to the first side surface, or the metal sheet is attached to the second side surface.

[0016] Optionally, a through hole is provided at a preset position of the support portion, and in a direction from the support portion toward the metal sheet, the through hole covers the filament pattern.

[0017] Optionally, the filament pattern is located in a central area of the metal sheet, and the through hole is located in a central area of the support portion.

[0018] As described above, the curved cathode structure of the present invention has the following beneficial effects:

[0019] (1) The cathode surface area is larger than the cross-sectional area, and the emission area facing the anode is larger;

[0020] (2) The electron overflow surface all faces the anode, and the direction of electron movement can be optimized by controlling the curvature of the surface;

[0021] (3) The metal sheet fits tightly to the insulating base, is vibration-resistant, is not easily deformed after being heated, and has good structural stability;

[0022] (4) The curved filament is processed by laser, with smooth edges and uniform thickness control. It is heated evenly after voltage is applied and has a long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Shown is a three-dimensional schematic diagram of a first curved hot cathode structure in an embodiment of the present invention.

[0024] Figure 2 Shown is a three-dimensional schematic diagram of an insulating base in an embodiment of the present utility model.

[0025] Figure 3 Shown is a three-dimensional schematic diagram of a metal sheet in an embodiment of the present invention.

[0026] Figure 4 Shown is a three-dimensional schematic diagram of a second curved hot cathode structure in an embodiment of the present invention.

[0027] Component number description

[0028] 1 Insulation base

[0029] 100 Support

[0030] 101 end

[0031] 102 through holes

[0032] 103 Insertion hole

[0033] 2 metal sheets

[0034] 200 First spiral groove

[0035] 201 Second spiral groove

[0036] 3 pins

[0037] 4 Conductive rods DETAILED DESCRIPTION

[0038] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different perspectives and applications without departing from the spirit of the present invention.

[0039] See also Figures 1 to 4 It should be noted that the illustrations provided in this embodiment are merely schematic illustrations of the basic concept of the present invention. Therefore, the illustrations only show components relevant to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be arbitrarily changed, and the component layout may also be more complex.

[0040] This embodiment provides a curved hot cathode structure. Figures 1 to 3 The curved hot cathode structure includes an insulating base 1, a metal sheet 2 and a plurality of pins 3, wherein the insulating base 1 includes a support portion 100 and end portions 101 located at both ends of the support portion 100 and connected to the support portion 100, wherein the support portion 100 is an arc-shaped structure with a center protruding from both ends; the metal sheet 2 is an arc-shaped structure with a center protruding from both ends, and the curvature of the metal sheet 2 is the same as that of the support portion 100. The metal sheet 2 is attached to the support portion 100 and welded to the support portion 100, wherein in the direction along the metal sheet 2 pointing to the support portion 100, a filament pattern passing through the metal sheet 2 is provided at a preset position of the metal sheet 2; a plurality of the pins 3 are separately arranged at both ends of the metal sheet 2, wherein a part of the pins 3 are electrically connected to one end of the metal sheet 2, and a part of the pins 3 are electrically connected to the other end of the metal sheet 3.

[0041] As an example, the insulating base 1 has an "arch bridge" structure. The insulating base 1 is made of high-temperature resistant insulating material, preferably ceramic. In this embodiment, the insulating base 1 is made of A95 ceramic.

[0042] As an example, the metal sheet 2 is made of a material with strong electron emission capability, for example, it can be tungsten, tantalum or niobium, among which tantalum metal has good ductility and toughness, and can be cold-processed and hot-processed, and can be processed by forging, drawing and rolling at low temperature; tungsten metal is very hard and brittle, and is difficult to machine at low temperature, and usually needs to be processed at high temperature; niobium metal has good ductility and toughness, but has high hardness and strength, which makes it relatively difficult in certain processing operations; in this embodiment, the metal sheet 2 preferably uses tantalum metal sheet, which is easy to make curved surfaces of different shapes, and the metal sheet 2 is brazed to the support part 100 of the insulating base 1 using active AgCuTi solder.

[0043] As an example, the filament pattern is set in the central area of the metal sheet 2, and the filament pattern includes a first spiral groove 200 and a second spiral groove 201. The first spiral groove 200 and the second spiral groove 201 are intertwined and do not contact each other to form a double helix structure, wherein the width of the metal sheet 2 between the first spiral groove 200 and the second spiral groove 201 ranges from 0.01 to 2 mm, that is, the metal sheet 2 between the first spiral groove 200 and the second spiral groove 201 constitutes a narrow sheet structure. When a voltage is applied to both ends of the metal sheet 2, the narrow sheet structure is heated and electrons overflow.

[0044] As an example, a first extension groove is provided at the outer end of the first spiral groove 200, and a second extension groove is provided at the outer end of the second spiral groove 201. The extension directions of the first extension groove and the second extension groove are opposite, so as to divide the metal sheet 2 into two relative parts. The two relative parts of the metal sheet 2 are connected and conducted only through the narrow sheet structure between the first spiral groove 200 and the second spiral groove 201.

[0045] As an example, a femtosecond laser is used to cut the metal sheet 2 to form the filament pattern to process a narrow sheet structure. The laser energy is relatively high, and it is easy to process refractory metal sheets with high processing accuracy. The minimum groove width can be 0.01 mm. The ratio between the width of the narrow sheet structure and the groove width of the laser cutting can be between 1:9 and 9:1, and the specific size is determined by the size of the filament. In this embodiment, the width of the first spiral groove 200 and the second spiral groove 201 are both 0.03 mm, and the width of the metal sheet between the first spiral groove 200 and the second spiral groove 201 is 0.08 mm.

[0046] It should be noted that, in this embodiment, the filament pattern adopts a double helix structure. In other examples, by adjusting the laser beam width and the travel path, a fine filament structure of any shape and width can be processed to meet different application requirements.

[0047] As an example, a through hole 102 is provided in the central area of the support portion 100. In the direction along the support portion 100 pointing to the metal sheet 2, the through hole 102 covers the filament pattern, that is, the size of the through hole 102 is slightly larger than the heat emitting part, which is beneficial to the heat dissipation of the filament.

[0048] As an example, an insertion hole 103 is provided in the end 101 of the insulating base 1, and the pin 3 passes through the insertion hole 103. A conductive voltage rod 4 is provided between the pin 3 and the metal sheet 2. One side of the conductive voltage rod 4 is welded to the metal sheet 2 by laser welding, and the other side of the conductive voltage rod 4 is welded to the pin 3 by laser welding. The conductive voltage rod 4 plays a fixing and conductive role, and the pin 3 applies external pressure to the metal sheet 2 through the conductive voltage rod 4.

[0049] As an example, the voltage-conducting rod 4 is made of a Kovar metal rod or a nickel metal rod, and the pin 3 is fixed to the voltage-conducting rod 4 by welding. The pin 3 does not need to be welded to the insulating base 1 .

[0050] Specifically, the number of the pins 3 is four, including two first pins and two second pins, and the two first pins and the two second pins are separately arranged at the two ends of the metal sheet 2, wherein the two first pins are welded to the same conductive voltage rod 4, and the two second pins are welded to the same conductive voltage rod 4, that is, the number of the conductive voltage rods 4 is two.

[0051] As an example, the support portion 100 includes a first side surface and a second side surface that are oppositely disposed. Figure 1 and Figure 4 The metal sheet 2 can be attached to the first side of the support part 100, or the metal sheet 2 can be attached to the second side of the support part 100 to form a radial electron beam or a focused electron beam, depending on the specific application.

[0052] As an example, the curvature of the support portion 100 and the metal sheet 2 can also be optimized and adjusted according to product requirements, focal spot size, and other requirements, making them suitable for both large-focus and micro-focus applications. A large focal spot can withstand a larger beam current, which in turn can produce X-rays of sufficient brightness to meet long-term, high-brightness applications. Furthermore, the X-rays produced by a large focal spot cover a larger area, making them suitable for large-area imaging. Furthermore, a large focal spot can also be used in processes such as high-frequency degassing of vacuum tubes. The use of a large-focus curved hot cathode structure can achieve sufficient anode power with a lower power density to bombard superficial gases in the anode metal. A micro-focus can be used in high-resolution imaging situations, such as the detection of fine structures, breast X-ray examinations, and the observation of tiny lesions.

[0053] In summary, the curved hot cathode structure of the present invention has the following beneficial effects: (1) The cathode surface area is larger than the cross-sectional area, and the emission area facing the anode is larger; (2) The electron overflow curved surface all faces the anode, and the direction of electron movement can be optimized by controlling the curvature of the curved surface; (3) The metal sheet fits tightly to the insulating base, is vibration-resistant, and is not easily deformed after heating, with good structural stability; (4) The curved filament is laser-processed, with smooth edges and uniform thickness control. It is evenly heated after voltage is applied, and has a long service life. Therefore, the present invention effectively overcomes the various shortcomings of the existing technology and has high industrial utilization value.

[0054] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed in the present invention are intended to be covered by the claims of the present invention.

Claims

1. A curved hot cathode structure, characterized in that: include: An insulating base, the insulating base comprising a support portion and end portions located at both ends of the support portion and connected to the support portion, wherein the support portion is an arc-shaped structure with a center protruding from both ends; a metal sheet having an arc-shaped structure with a center protruding from both ends, the curvature of the metal sheet being the same as that of the support portion, the metal sheet being attached to and welded to the support portion, wherein a filament pattern penetrating the metal sheet is provided at a predetermined position of the metal sheet in a direction from the metal sheet toward the support portion; A plurality of pins are separately arranged at both ends of the metal sheet, wherein a portion of the pins are electrically connected to one end of the metal sheet, and a portion of the pins are electrically connected to the other end of the metal sheet.

2. The curved hot cathode structure according to claim 1, wherein: The pin passes through the end portion, a conductive voltage rod is provided between the pin and the metal sheet, one side of the conductive voltage rod is welded to the metal sheet, and the other side of the conductive voltage rod is welded to the pin.

3. The curved hot cathode structure according to claim 2, wherein: The pins include two first pins and two second pins, and the first pins and the second pins are separately arranged at both ends of the metal sheet, wherein the two first pins are welded to the same conductive voltage rod, and the two second pins are welded to the same conductive voltage rod.

4. The curved hot cathode structure according to claim 1, wherein: The filament pattern includes a first spiral groove and a second spiral groove, and the first spiral groove and the second spiral groove are wound around each other to form a double helical structure.

5. The curved hot cathode structure according to claim 4, characterized in that: The width of the metal sheet between the first spiral groove and the second spiral groove is in the range of 0.01 to 2 mm.

6. The curved hot cathode structure according to claim 1, wherein: The supporting portion includes a first side surface and a second side surface that are opposite to each other, and the metal sheet is attached to the first side surface, or the metal sheet is attached to the second side surface.

7. The curved hot cathode structure according to claim 1, wherein: A through hole is provided at a preset position of the support portion, and in a direction along the support portion pointing toward the metal sheet, the through hole covers the filament pattern.

8. The curved hot cathode structure according to claim 7, characterized in that: The filament pattern is located in a central area of the metal sheet, and the through hole is located in a central area of the support portion.

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