A method for producing a focus-controllable x-ray tube

Abstract

The application relates to a preparation method of a focus-controllable X-ray tube, and belongs to the technical field of X-rays, solving the problems of low CT imaging quality of X-rays generated by the existing X-ray tube and poor focus adjustment flexibility. The method comprises the following steps: preparing an electron beam generator, a focusing device, a lens assembly, a target material assembly and a tube body; the lens assembly comprises two electron optical lenses; the prepared electron beam generator, the focusing device, the lens assembly and the target material assembly are sequentially fixed in the tube body; when the lens assembly is fixed, the first electron optical lens is first fixed, then the second electron optical lens is arranged at a position with a preset distance from the first electron optical lens, and the second electron optical lens is rotated so that the pole plate with the opposite polarity to the pole plate of the first electron optical lens is aligned in the axial direction of the tube body. The micro-focus X-rays generated by the prepared X-ray tube have a more circular focus and higher adjustment flexibility.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of X-ray technology, in particular to a preparation method of an X-ray tube with controllable focal point. BACKGROUND

[0002] The X-ray tube based on the principle of X-ray radiation from the target bombarded by a fine focusing electron beam is a key core component of industrial micro-CT. The focal point size, shape and power density distribution of the X-ray generated by the X-ray tube will affect the CT image, for example, the smaller the focal point size, the higher the resolution of the CT image; the closer the focal point shape to a circle, the less the geometric shadow of the CT image, and the clearer the boundary; the more uniform the focal point power distribution, the smaller the aberration of the CT image, and the higher the definition. Due to the influence of the geometric structure, the focal point size of the reflected closed tube micro-focus X-ray device is large, the actual effective focal point is elliptical, and the power distribution is uneven, thereby reducing the imaging quality of the CT image. At the same time, the existing reflected closed tube micro-focus X-ray tube has poor flexibility in focal point adjustment, which cannot meet more imaging needs. SUMMARY

[0003] In view of the above analysis, the embodiments of the present application aim to provide a preparation method of an X-ray tube with controllable focal point, so as to solve the problems of large X-ray focal point size, elliptical shape or uneven power distribution of the existing X-ray tube, which leads to low CT imaging quality and poor focal point adjustment flexibility.

[0004] In one aspect, the embodiments of the present application provide a preparation method of a micro-focus X-ray tube with controllable focal point, which comprises:

[0005] Preparation of an electron beam generator, a focusing device, a lens assembly, a target material assembly and a tube body; the lens assembly comprises two electron optical lenses;

[0006] The prepared electron beam generator, focusing device, lens assembly and target material assembly are sequentially fixed in the tube body, so as to obtain the prepared X-ray tube;

[0007] Wherein, when the lens assembly is fixed, the first electron optical lens is fixed first, then the second electron optical lens is arranged at a position with a preset distance from the first electron optical lens, and the second electron optical lens is rotated so that the pole plate with opposite polarity to the pole plate of the first electron optical lens is aligned along the axial direction of the tube body.

[0008] Based on the further improvement of the above method, the preparation of the lens assembly comprises preparation of two identical electron optical lenses;

[0009] The preparation of the electron optical lens comprises the following steps:

[0010] The eight pole plates are made of stainless steel material;

[0011] The prepared pole plates are evenly arranged in the circumferential direction;

[0012] A ceramic strip is arranged between two adjacent pole plates;

[0013] A lens electrode is welded on the outer wall of each pole plate, so that an electron optical lens with controllable focal point size is obtained.

[0014] Based on the further improvement of the above method, the shape of the pole plate is a concave circle with an angle of curvature of 15° to 30°, a thickness of 0.1mm to 0.5mm, and a length of 1mm to 5mm.

[0015] Based on the further improvement of the above method, the preset distance is 10mm to 20mm.

[0016] Based on the further improvement of the above method, the preparation of the electron beam generator comprises the following steps:

[0017] One end of the single crystal cerium hexaboride rod is ground into a cone body using a high-precision grinding tool;

[0018] A tantalum cylinder is sleeved on the other end of the single crystal cerium hexaboride rod, and the tantalum cylinder is welded on the end of the single crystal cerium hexaboride rod by vacuum brazing;

[0019] Two Kovar alloy rods are welded on the outer walls of the tantalum cylinder as heating electrodes, so that a single crystal cerium hexaboride emitter is obtained.

[0020] A grid cover is made of non-magnetic stainless steel material, and a round hole is provided at one end of the grid cover as an extraction hole for extracting the electron beam;

[0021] The prepared grid cover is sleeved on the outer periphery of the single crystal cerium hexaboride emitter, the extraction hole is axially aligned with the conical end of the single crystal cerium hexaboride emitter, and the extraction hole is spaced apart from the conical end of the single crystal cerium hexaboride emitter by a preset distance;

[0022] A ceramic material is used to prepare a spacer ring, and the prepared spacer ring is arranged between the grid cover and the single crystal cerium hexaboride emitter;

[0023] Two Kovar alloy rods are welded on the outer walls of the grid cover as grid control electrodes, so that an electron beam generator with controllable beam current is obtained.

[0024] Based on the further improvement of the above method, the preparation of the focusing device comprises the following steps:

[0025] Two focusing cylinders are made of non-magnetic stainless steel, and mounting pads with the same diameter as the focusing cylinders are made of ceramic material;

[0026] A through hole is arranged in the center of each focusing cylinder and the center of the mounting pad along the axial direction;

[0027] Two focusing cylinders are fixed at the two ends of the mounting pad respectively;

[0028] A Kovar alloy rod is welded on the outer wall of each focusing cylinder as a focusing electrode, so as to obtain a focusing device with controllable focal point.

[0029] Based on the further improvement of the above method, the length of the focusing cylinder is 0.5mm to 5mm, and the diameter of the through hole in the center of the focusing cylinder is 0.5mm to 2mm.

[0030] Based on the further improvement of the above method, the method further comprises:

[0031] A base is made of ceramic material, and four mounting holes are arranged on the base respectively; the four mounting holes are used as first mounting holes of two grid control electrodes and second mounting holes of two focusing electrodes respectively,

[0032] The free ends of the two grid control electrodes of the electron beam generator are inserted into the two first mounting holes respectively and fixed by welding;

[0033] The free ends of the two focusing electrodes of the focusing device are inserted into the two second mounting holes respectively and fixed by welding, so as to integrate the electron beam generator and the focusing device on the base.

[0034] Based on the further improvement of the above method, the preparation of the target assembly comprises:

[0035] A heat dissipation base is made of single crystal diamond or polycrystalline diamond;

[0036] A target body is made of tungsten, molybdenum or copper material;

[0037] The target body is inlaid on the heat dissipation base, so as to obtain the target assembly.

[0038] Based on the further improvement of the above method, the preparation of the target assembly further comprises:

[0039] A cylindrical column with a preset size is made of diamond-copper composite material;

[0040] One end of the cylindrical column is processed into an inclined plane, so as to obtain the base of the target assembly;

[0041] The heat dissipation substrate of the target material assembly is embedded in the inclined plane of the base.

[0042] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0043] 1. In this invention, the prepared X-ray tube uses a lens assembly composed of two electron optical lenses for assisted focusing. When installing the lens assembly in the tube body, the first electron optical lens is fixed first, and then the second electron optical lens is set at a predetermined distance from the first electron optical lens. The second electron optical lens is rotated so that its electrode plate, which has the opposite polarity to that of the first electron optical lens, is aligned along the axial direction of the tube body. This allows the two electron optical lenses to focus the electron beam in a symmetrical direction, improving the quality of the electron beam, making the effective focal point of the generated micro-focus X-ray closer to a circle, and making the power distribution of the electron beam more uniform. This also corrects aberrations and improves the imaging quality of CT images.

[0044] Furthermore, the combined use of two electro-optical lenses allows for more precise control over the focusing of the electron beam, providing greater adjustment flexibility. The focal point position and size can be adjusted according to different application requirements to adapt to various imaging tasks. It also enables the formation of a smaller focal point on the target, which helps improve resolution and enhance image quality.

[0045] 2. In this invention, an octet structure electron optical lens is prepared. The electric field or magnetic field distribution of the octet structure electron optical lens is more uniform, and the focusing ability is stronger. The combined use of two octet structure electron optical lenses can focus the electron beam uniformly in more symmetrical directions, further improving the quality of the electron beam.

[0046] 3. In the electron beam generator fabrication of this invention, a high-conductivity, single-crystal cerium hexaboride material is used to prepare the emitter. Single-crystal cerium hexaboride possesses high conductivity, good thermal stability, and chemical stability, thereby ensuring the generation of a stable electron beam. Simultaneously, using a high-precision grinding tool to grind the single-crystal cerium hexaboride rod into a cone shape ensures the accuracy and consistency of the emitter, guaranteeing the stability and precise control of the electron beam. Furthermore, the electron beam can be extracted through a circular hole on the grid cover. By changing the size and shape of the circular hole on the grid cover, the size and shape of the electron beam can be adjusted. A Kovar alloy rod is welded as a gate control electrode to the outer wall of the grid cover, allowing for precise control of the electron beam density. The electron beam generator fabricated by the method of this invention exhibits high performance, high stability, and long lifespan, making it suitable for various high-precision and high-requirement applications.

[0047] 4. In the preparation of the focusing device in this invention, a non-magnetic stainless steel material is used to make the focusing cylinder, which avoids magnetic field interference and helps maintain the accuracy and stability of the focusing device. An axially penetrating through-hole is set in the center of the focusing cylinder to allow the electron beam to pass through, achieving precise focusing. A ceramic material is used to prepare the mounting gasket, which can simultaneously isolate and install the two focusing cylinders. A Kovar alloy rod is welded to the outer wall of the focusing cylinder as a focusing electrode, thereby allowing precise control of the position and size of the focal point by adjusting the voltage on the focusing electrode. The focusing device prepared by the method of this invention has the advantages of high performance, high stability, and long lifespan, and is suitable for various applications requiring precise focusing.

[0048] 5. In the preparation of the target assembly in this invention, tungsten, molybdenum, or copper materials are used to prepare the target body. Tungsten, molybdenum, or copper targets have high melting points, making them suitable for environments requiring high temperatures. Single-crystal or polycrystalline diamond is used to prepare the heat dissipation substrate, which can effectively conduct and dissipate heat, improving the heat dissipation efficiency and stability of the target assembly. Simultaneously, the combination of the diamond substrate and the tungsten, molybdenum, or copper target provides excellent structural stability. The high thermal conductivity and low coefficient of thermal expansion of diamond help maintain the stability of the target assembly under temperature changes. The method of this invention, by combining the high thermal conductivity and high hardness of diamond with the high melting point and chemical stability of tungsten, molybdenum, or copper, provides a high-performance, high-stability target assembly.

[0049] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0050] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0051] Figure 1 A flowchart illustrating a method for fabricating a focus-controllable X-ray tube according to an embodiment of the present invention;

[0052] Figure 2 This is a schematic diagram of the structure of an X-ray tube prepared according to an embodiment of the present invention;

[0053] Figure 3 This is a schematic diagram showing the electrode distribution of an electron optical lens according to an embodiment of the present invention.

[0054] Figure label:

[0055] 10-Tube body; 20-Base; 30-Electron optical lens; 40-Target assembly; 50-Base;

[0056] 101 - Single crystal cerium hexaboride; 102 - Tantalum cylinder; 103 - Heating electrode; 104 - Grid cover;

[0057] 105 - Grid control electrode; 201 - Focusing cylinder; 202 - Focusing electrode; 203 - Mounting gasket; 301 - Electrode plate. Detailed Implementation

[0058] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0059] One embodiment of the present invention provides a method for fabricating a focus-controllable microfocus X-ray tube, such as... Figure 1 As shown in the figure. The method includes:

[0060] An electron beam generator, a focusing device, a lens assembly, and a target assembly 40 and 10 are fabricated; the lens assembly includes two electron optical lenses 30.

[0061] The prepared electron beam generator, focusing device, lens assembly and target assembly 40 are sequentially fixed in 10 to obtain the prepared X-ray tube;

[0062] When fixing the lens assembly, the first electro-optical lens 30 is first fixed, and then the second electro-optical lens 30 is set at a position with a preset distance from the first electro-optical lens 30. The second electro-optical lens 30 is rotated so that its electrode plate 301 is aligned with the electrode plate 301 of the first electro-optical lens 30 along the axis of the 10.

[0063] Specifically, the preset distance is 10mm to 20mm.

[0064] It should be noted that, in practice, half of the electrode plates 301 of the electron optical lens 30 are cathode plates and the other half are anode plates, with the cathode plates and anode plates being distributed alternately along the circumferential direction.

[0065] Compared with the prior art, in this invention, the X-ray tube is equipped with a lens assembly consisting of two electron optical lenses 30 for auxiliary focusing. When the lens assembly is installed in 10, the first electron optical lens 30 is first fixed, and then the second electron optical lens 30 is set at a predetermined distance from the first electron optical lens 30. The second electron optical lens 30 is rotated so that its electrode plate 301 is aligned with the electrode plate 301 of the first electron optical lens 30 along the axis of 10, so that the two electron optical lenses 30 can focus the electron beam in a symmetrical direction, which improves the quality of the electron beam, makes the effective focal point of the generated micro-focus X-ray closer to a circle, and makes the power distribution of the electron beam more uniform, which corrects aberrations and improves the imaging quality of CT images.

[0066] Meanwhile, the combined use of two electron optical lenses 30 allows for more precise control of the electron beam's focusing, providing greater adjustment flexibility. The focus position and size can be adjusted according to different application requirements to adapt to various imaging tasks. Furthermore, it enables the formation of a smaller focus on the target material, which is beneficial for improving resolution and enhancing image quality.

[0067] In one specific embodiment, fabricating the lens assembly includes fabricating two identical electro-optical lenses 30. Fabricating the electro-optical lenses 30 includes the following steps:

[0068] Eight electrode plates 301 were fabricated using stainless steel.

[0069] The prepared electrode plates 301 are arranged uniformly along the circumferential direction;

[0070] A ceramic strip is disposed between two adjacent electrode plates 301;

[0071] Lens electrodes are welded to the outer wall of each electrode plate 301 to obtain an electro-optical lens 30 with controllable focal size.

[0072] In practice, of the eight electrodes 301 of the electron optical lens 30, four electrodes 301 are subjected to cathode voltages to serve as cathode electrodes, and the other four electrodes 301 are subjected to anode voltages to serve as anode electrodes. The cathode and anode electrodes are alternately distributed along the circumferential direction. By changing the voltage difference between the cathode and anode electrodes, the focusing of the electron beam can be precisely controlled.

[0073] In this invention, an octet structure electron optical lens 30 is prepared. The electric field or magnetic field distribution of the octet structure electron optical lens 30 is more uniform, and the focusing ability is stronger. The combined use of two octet structure electron optical lenses 30 can focus the electron beam uniformly in more symmetrical directions, further improving the quality of the electron beam.

[0074] Specifically, the electrode plate 301 is concave circular in shape, with an arc angle of 15° to 30°, a thickness of 0.1mm to 0.5mm, and a length of 1mm to 5mm.

[0075] Among them, the shape of the electrode plate 301 of the electron optical lens 30 is different, the direction of the magnetic field is different, and the effect on the electron beam is different. The concave circular electrode plate 301 can play a good focusing effect on the electron beam.

[0076] In one specific embodiment, the fabrication of the electron beam generator includes the following steps:

[0077] One end of a single-crystal cerium hexaboride rod is ground into a cone shape using a high-precision grinding tool;

[0078] The tantalum cylinder 102 is fitted onto the other end of the single crystal cerium hexaboride rod, and the tantalum cylinder 102 is welded to that end of the single crystal cerium hexaboride rod by vacuum brazing.

[0079] Two Kovar alloy rods are welded to the outer walls on both sides of the tantalum cylinder 102 to serve as heating electrodes 103, thereby obtaining a single-crystal cerium hexaboride 101 emitter;

[0080] The gate cover 104 is made of non-magnetic stainless steel, and a circular hole is provided at one end of the gate cover 104 as an extraction hole for extracting the electron beam.

[0081] The prepared gate cover 104 is fitted onto the outer periphery of the single crystal cerium hexaboride 101 emitter, so that the lead-out hole is aligned with the conical end of the single crystal cerium hexaboride 101 emitter along the axial direction, and a preset distance is spaced between the lead-out hole and the conical end of the single crystal cerium hexaboride 101 emitter.

[0082] An isolation ring is prepared using ceramic material and placed between the gate cover 104 and the single crystal cerium hexaboride 101 emitter.

[0083] Two Kovar alloy rods are welded to the outer walls on both sides of the gate cover 104 to serve as gate control electrodes 105, thereby obtaining an electron beam generator with controllable beam current.

[0084] In this embodiment of the invention, the electron beam generator is fabricated using a high-conductivity, single-crystal cerium hexaboride material. Single-crystal cerium hexaboride 101 possesses high conductivity, good thermal stability, and chemical stability, ensuring the generation of a stable electron beam. Simultaneously, the single-crystal cerium hexaboride rod is ground into a cone shape using a high-precision grinding tool, ensuring the accuracy and consistency of the emitter and guaranteeing the stability and precise control of the electron beam. The electron beam is extracted through a circular hole on the gate cover 104. By changing the size and shape of the circular hole on the gate cover 104, the size and shape of the electron beam can be adjusted. A Kovar alloy rod is welded to the outer wall of the gate cover 104 as a gate control electrode 105. By adjusting the voltage on the gate control electrode 105, the electron beam density can be precisely controlled. The electron beam generator fabricated by the method of this embodiment of the invention exhibits high performance, high stability, and long lifespan, making it suitable for various high-precision and high-requirement applications.

[0085] In one specific embodiment, the preparation of the focusing device includes the following steps:

[0086] Two focusing cylinders 201 are made of non-magnetic stainless steel, and mounting gaskets 203 with the same diameter as the focusing cylinders 201 are made of ceramic material.

[0087] Through holes extending axially are provided at the center of the two focusing cylinders 201 and at the center of the mounting gasket, respectively;

[0088] The two focusing cylinders 201 are respectively fixed at both ends of the mounting pad 203;

[0089] A Kovar alloy rod is welded to the outer wall of each of the two focusing cylinders 201 to serve as a focusing electrode 202, thereby obtaining a focusing device with controllable focus.

[0090] In this embodiment of the invention, the focusing device is fabricated using non-magnetic stainless steel to avoid magnetic field interference, which helps maintain the accuracy and stability of the focusing device. An axially penetrating through-hole is provided at the center of the focusing cylinder 201 to allow the electron beam to pass through, achieving precise focusing. A ceramic mounting pad 203 is fabricated to simultaneously isolate and mount the two focusing cylinders 201. A Kovar alloy rod is welded to the outer wall of the focusing cylinder 201 as a focusing electrode 202. By adjusting the voltage on the focusing electrode 202, the position and size of the focal point can be precisely controlled. The focusing device prepared by the method of this invention has the advantages of high performance, high stability, and long lifespan, and is suitable for various applications requiring precise focusing.

[0091] Specifically, the length of the focusing cylinder 201 is 0.5mm to 5mm, and the diameter of the through hole at the center of the focusing cylinder 201 is 0.5mm to 2mm.

[0092] In a preferred embodiment, the method further includes:

[0093] A base 20 is made of ceramic material, and four mounting holes are respectively provided on the base 20; the four mounting holes serve as the first mounting holes for the two gate control electrodes 105 and the second mounting holes for the two focusing electrodes 202.

[0094] The free ends of the two gated electrodes 105 of the electron beam generator are respectively inserted into the two first mounting holes and fixed by welding;

[0095] The free ends of the two focusing electrodes 202 of the focusing device are respectively inserted into the two second mounting holes and fixed by welding, thereby integrating the electron beam generator and the focusing device on the base 20.

[0096] In this embodiment, the electrodes of the electron beam generator and the focusing device are mounted on the base 20, thereby integrating the electron beam generator and the focusing device together to form a fine focusing electron gun. The electrodes of the electron beam generator and the focusing device are both integrated on the base 20, which facilitates the application of voltage to control the generated electron beam current.

[0097] In one specific embodiment, the preparation of the target assembly 40 includes the following steps:

[0098] The heat dissipation substrate is prepared using single-crystal diamond or polycrystalline diamond;

[0099] The target is prepared using tungsten, molybdenum, or copper materials;

[0100] The target is embedded in the heat dissipation substrate to obtain the target material assembly 40.

[0101] Compared with existing technologies, in the embodiments of the present invention, the target assembly 40 is prepared using tungsten, molybdenum, or copper materials. Tungsten, molybdenum, or copper targets have high melting points, making them suitable for environments requiring high temperatures. Single-crystal or polycrystalline diamond is used to prepare the heat dissipation substrate, which effectively conducts and dissipates heat, improving the heat dissipation efficiency and stability of the target assembly 40. Simultaneously, the combination of the diamond substrate and the tungsten, molybdenum, or copper target provides excellent structural stability. The high thermal conductivity and low coefficient of thermal expansion of diamond help maintain the stability of the target assembly 40 under temperature changes. The method of the embodiments of the present invention, by combining the high thermal conductivity and high hardness of diamond with the high melting point and chemical stability of tungsten, molybdenum, or copper, provides a high-performance, high-stability target assembly 40.

[0102] More specifically, the preparation of the target assembly 40 further includes the following steps:

[0103] A cylinder of a predetermined size is prepared using a diamond-copper composite material;

[0104] One end of the cylinder is machined into an inclined plane to obtain the base 50 of the target assembly 40;

[0105] The heat dissipation substrate of the target assembly 40 is embedded in the inclined plane of the base 50.

[0106] In this embodiment, a base 50 made of a diamond-copper composite material with high thermal conductivity is used to support the target assembly 40. The diamond-copper composite material combines the ultra-high thermal conductivity of diamond with the low cost, ease of processing, and high thermal conductivity of copper matrix. At the same time, the base 50 is provided with an inclined plane to facilitate the reflection of X-rays after the electron beam bombards the target, and the inclined plane also facilitates heat dissipation of the target assembly 40.

[0107] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for fabricating a focus-controllable X-ray tube, characterized in that, The method includes: An electron beam generator, a focusing device, a lens assembly, a target assembly, and a tube are fabricated; the lens assembly includes two electron optical lenses; The prepared electron beam generator, focusing device, lens assembly and target assembly are sequentially fixed into the tube body to obtain the prepared X-ray tube; When fixing the lens assembly, the first electro-optical lens is first fixed, and then the second electro-optical lens is set at a position with a preset distance from the first electro-optical lens. The second electro-optical lens is rotated so that its electrode plate, which has the opposite polarity to that of the first electro-optical lens, is aligned along the axial direction of the tube. The fabrication of the lens assembly includes fabricating two identical electro-optical lenses; The fabrication of an electron optical lens includes the following steps: Eight electrode plates are fabricated using stainless steel. A cathode voltage is applied to the lens electrodes of four of the eight electrode plates to serve as cathode electrode plates, and an anode voltage is applied to the lens electrodes of the other four electrode plates to serve as anode electrode plates. The prepared electrode plates are arranged uniformly along the circumference, with the cathode electrode plate and anode electrode plate alternately distributed along the circumference. A ceramic strip is placed between two adjacent electrode plates; Lens electrodes are welded to the outer wall of each electrode plate to obtain an electro-optical lens with controllable focal size; The preparation of the electron beam generator includes the following steps: One end of a single-crystal cerium hexaboride rod is ground into a cone shape using a high-precision grinding tool; A tantalum sleeve is fitted over the other end of the single-crystal cerium hexaboride rod, and the tantalum sleeve is welded to the end of the single-crystal cerium hexaboride rod by vacuum brazing. Two Kovar alloy rods are welded to the outer walls on both sides of the tantalum cylinder to serve as heating electrodes, thereby obtaining a single-crystal cerium hexaboride emitter; A gate cover is made of non-magnetic stainless steel, and a circular hole is provided at one end of the gate cover as an extraction hole for extracting the electron beam. The prepared gate cover is fitted onto the outer periphery of the single-crystal cerium hexaboride emitter, so that the lead-out hole is aligned axially with the conical end of the single-crystal cerium hexaboride emitter, and a preset distance is placed between the lead-out hole and the conical end of the single-crystal cerium hexaboride emitter. An isolation ring is prepared using ceramic material and placed between the gate cover and the single-crystal cerium hexaboride emitter. Two Kovar alloy rods are welded to the outer walls on both sides of the gate cover to serve as gate control electrodes, thereby obtaining an electron beam generator with controllable beam current.

2. The method for preparing an X-ray tube according to claim 1, characterized in that, The electrode plate is concave circular in shape, with an arc angle of 15° to 30°, a thickness of 0.1mm to 0.5mm, and a length of 1mm to 5mm.

3. The method for preparing an X-ray tube according to any one of claims 1-2, characterized in that, The preset distance is 10mm to 20mm.

4. The method for preparing an X-ray tube according to claim 3, characterized in that, The preparation of the focusing device includes the following steps: Two focusing cylinders are made of non-magnetic stainless steel, and mounting gaskets with the same diameter as the focusing cylinders are made of ceramic material. Through holes extending axially are respectively provided at the center of the two focusing cylinders and at the center of the mounting pad; The two focusing cylinders are respectively fixed at both ends of the mounting pad; A Kovar alloy rod is welded to the outer wall of each of the two focusing cylinders to serve as a focusing electrode, thereby obtaining a focusing device with controllable focus.

5. The method for preparing an X-ray tube according to claim 4, characterized in that, The length of the focusing tube is 0.5mm to 5mm, and the diameter of the through hole at the center of the focusing tube is 0.5mm to 2mm.

6. The method for preparing an X-ray tube according to claim 5, characterized in that, The method further includes: A base is made of ceramic material, and four mounting holes are respectively provided on the base; the four mounting holes serve as the first mounting holes for the two gate control electrodes and the second mounting holes for the two focusing electrodes. The free ends of the two gated electrodes of the electron beam generator are respectively inserted into the two first mounting holes and fixed by welding; The free ends of the two focusing electrodes of the focusing device are respectively inserted into the two second mounting holes and fixed by welding, thereby integrating the electron beam generator and the focusing device on the base.

7. The method for preparing an X-ray tube according to any one of claims 1-2, characterized in that, The preparation of the target assembly includes the following steps: The heat dissipation substrate is prepared using single-crystal diamond or polycrystalline diamond; The target is prepared using tungsten, molybdenum, or copper materials; The target is embedded in the heat dissipation substrate to obtain the target material assembly.

8. The method for preparing an X-ray tube according to any one of claims 1-2, characterized in that, The preparation of the target assembly also includes the following steps: A cylinder of a predetermined size is prepared using a diamond-copper composite material; One end of the cylinder is machined into an inclined plane to obtain the base of the target assembly; The heat dissipation substrate of the target material assembly is embedded in the inclined plane of the base.

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