Preparation method of focus-controllable X-ray tube

Abstract

The invention relates to a preparation method of a focus-controllable X-ray tube, belongs to the technical field of X-rays, and solves the problems that the CT imaging quality of X-rays generated by an existing X-ray tube is low and the focus adjustment flexibility is poor. 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; sequentially fixing the prepared electron beam generator, the focusing device, the lens assembly and the target material assembly in the tube body; when the lens assembly is fixed, the first electron optical lens is fixed firstly, then the second electron optical lens is arranged at the position which is spaced from the first electron optical lens by a preset distance, and the second electron optical lens is rotated to enable a polar plate of the second electron optical lens to be aligned with a polar plate, opposite to the first electron optical lens in polarity, of the first electron optical lens in the axial direction of the tube body. The focus of the micro-focus X-ray generated by the ray tube prepared by the invention is closer to a circle, and the adjustment flexibility is higher.

Description

Technical Field

[0001] The invention relates to the technical field of X-rays, and in particular to a method for preparing an X-ray tube with controllable focus. Background Art

[0002] X-ray tubes, which are based on the principle of radiating X-rays by bombarding a target with a finely focused electron beam, are the key core components of industrial micro-CT. The focal size, shape, and power density distribution of the X-rays generated by the X-ray tube will affect the CT image. For example, the smaller the focal size, the higher the resolution of the CT image; the closer the focal shape is to a circle, the fewer geometric shadows and the clearer the boundaries of the CT image; the more uniform the focal power distribution, the smaller the aberration of the CT image and the higher the clarity. Due to the influence of its geometric structure, the X-ray focal size of the reflective closed-tube micro-focus X-ray device is large, the actual effective focal point is elliptical, and the power distribution is uneven, which reduces the imaging quality of the CT image. At the same time, the focus adjustment flexibility of existing reflective closed-tube micro-focus X-ray tubes is poor and cannot meet more imaging needs. Summary of the invention

[0003] In view of the above analysis, an embodiment of the present invention aims to provide a method for preparing a focus-controllable X-ray tube, so as to solve the problem that the X-ray focus generated by the existing X-ray tube is large in size, elliptical in shape or has uneven power distribution, resulting in low CT imaging quality and poor focus adjustment flexibility.

[0004] On the one hand, an embodiment of the present invention provides a method for preparing a micro-focus X-ray tube with controllable focus, the method comprising:

[0005] Prepare an electron beam generator, a focusing device, a lens assembly, a target assembly and a tube body; the lens assembly includes two electron optical lenses;

[0006] The prepared electron beam generator, focusing device, lens assembly and target assembly are sequentially fixed in the tube body, thereby obtaining the prepared X-ray tube;

[0007] When fixing the lens assembly, the first electron optical lens is fixed first, and then the second electron optical lens is set at a position with a preset distance from the first electron optical lens, and the second electron optical lens is rotated so that its electrode plate is aligned with the electrode plate with opposite polarity of the first electron optical lens along the axial direction of the tube body.

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

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

[0010] Eight plates are made of stainless steel;

[0011] Arranging the prepared electrode plates evenly along the circumferential direction;

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

[0013] Lens electrodes are welded on the outer wall of each electrode plate respectively, so as to obtain an electron optical lens with controllable focal size.

[0014] Based on the further improvement of the above method, the shape of the electrode plate is concave circular, the arc angle is 15° to 30°, the thickness is 0.1mm to 0.5mm, and the length is 1mm to 5mm.

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

[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 a single crystal cerium hexaboride rod is ground into a cone using a high-precision grinding tool;

[0018] Sleeving a tantalum tube on the other end of the single crystal cerium hexaboride rod, and welding the tantalum tube to the end of the single crystal cerium hexaboride rod by vacuum brazing;

[0019] Welding two Kovar alloy rods on the outer walls of both sides of the tantalum cylinder as heating electrodes, thereby obtaining a single crystal cerium hexaboride emitter;

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

[0021] Sleeve the prepared gate cover on the outer periphery of the single crystal cerium hexaboride emitter, align the lead-out hole with the conical end of the single crystal cerium hexaboride emitter along the axial direction, and space the lead-out hole and the conical end of the single crystal cerium hexaboride emitter by a preset distance;

[0022] Using ceramic material to prepare an isolation ring, and arranging the prepared isolation ring between the gate cover and the single crystal cerium hexaboride emitter;

[0023] Two Kovar alloy rods are respectively welded on the outer walls of both sides of the grid cover to serve as grid-controlled electrodes, thereby obtaining an electron beam generator with controllable beam current.

[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 material, and mounting gaskets with the same diameter as the focusing cylinders are made of ceramic material;

[0026] A through hole penetrating in the axial direction is provided at the center of the two focusing cylinders and the center of the mounting gasket;

[0027] Fixing the two focusing tubes at two ends of the mounting gasket respectively;

[0028] A kovar alloy rod is welded to the outer wall of each of the two focusing tubes to serve as a focusing electrode, thereby obtaining a focusing device with controllable focus.

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

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

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

[0032] Inserting the free ends of the two grid-controlled electrodes of the electron beam generator into the two first mounting holes respectively and fixing them by welding;

[0033] 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, so that the electron beam generator and the focusing device are integrated on the base.

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

[0035] The heat dissipation substrate is prepared by using single crystal diamond or polycrystalline diamond;

[0036] The target is made of tungsten, molybdenum or copper materials;

[0037] The target body is embedded in the heat dissipation substrate to obtain the target material assembly.

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

[0039] A diamond copper composite material is used to prepare a cylinder of a preset size;

[0040] Processing one end of the cylinder into an inclined plane to obtain a base of the target assembly;

[0041] The heat dissipation substrate of the target assembly is embedded on 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 the present invention, the prepared X-ray tube adopts a lens assembly composed of two electron optical lenses to assist in focusing. When the lens assembly is installed in the tube body, the first electron optical lens is first fixed, and then the second electron optical lens is set at a position with a preset distance from the first electron optical lens. The second electron optical lens is rotated so that its electrode plate is aligned with the electrode plate with opposite polarity of the first electron optical lens along the axial direction of the tube body, so that the two electron optical lenses can focus the electron beam in a symmetrical direction, improve the quality of the electron beam, make the effective focus of the generated micro-focus X-ray closer to a circle, and make the power distribution of the electron beam more uniform, which plays a role in correcting the aberration, thereby improving the imaging quality of the CT image.

[0044] At the same time, the combination of two electron optical lenses can more accurately control the focusing degree of the electron beam, thereby providing higher adjustment flexibility, and the focus position and size can be adjusted according to different application requirements to adapt to different imaging tasks. And it can form a smaller focus on the target material, which is conducive to improving resolution and enhancing imaging quality.

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

[0046] 3. When preparing the electron beam generator in the present invention, the emitter is prepared by using high conductivity and single crystal cerium hexaboride materials. Single crystal cerium hexaboride has high conductivity, good thermal stability and chemical stability, so as to ensure the generation of a stable electron beam. At the same time, the single crystal cerium hexaboride rod is ground into a cone using a high-precision grinder to ensure the accuracy and consistency of the emitter, the stability and precise control of the electron beam, and the electron beam can be drawn out through the 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. The Kovar alloy rod is welded to the outer wall of the grid cover as a grid-controlled electrode, and the density of the electron beam can be precisely controlled. The electron beam generator prepared by the method of the present invention has high performance, high stability and long life, and is suitable for various high-precision and high-demand applications.

[0047] 4. When preparing the focusing device in the present invention, the focusing tube is made of non-magnetic stainless steel material, which can avoid magnetic field interference and help maintain the accuracy and stability of the focusing device. A through hole is set in the center of the focusing tube along the axial direction to allow the electron beam to pass through and achieve precise focusing. The installation gasket is made of ceramic material, which can simultaneously achieve the isolation and installation of the two focusing tubes. The Kovar alloy rod is welded on the outer wall of the focusing tube as a focusing electrode, so that the position and size of the focus can be accurately controlled by adjusting the voltage on the focusing electrode. The focusing device prepared by the method of the present invention has the advantages of high performance, high stability and long life, and is suitable for various applications requiring precise focusing.

[0048] 5. When preparing the target assembly in the present invention, tungsten, molybdenum or copper materials are used to prepare the target body. The target body of tungsten, molybdenum or copper materials has a high melting point and is suitable for high temperature environments. The heat dissipation matrix is ​​prepared by single crystal diamond or polycrystalline diamond, which can effectively conduct and dissipate heat and improve the heat dissipation efficiency and stability of the target assembly. At the same time, the combination of the diamond matrix and the tungsten, molybdenum or copper target body provides excellent structural stability. The high thermal conductivity and low thermal expansion coefficient of diamond help maintain the stability of the target assembly under temperature changes. The method of the present invention provides a high-performance and high-stability target assembly by combining the high thermal conductivity and high hardness characteristics of diamond with the high melting point and chemical stability of tungsten, molybdenum or copper.

[0049] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

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

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

[0053] Figure 3 The figure is a schematic diagram of the distribution position of the pole plates of the electron optical lens according to an embodiment of the present invention.

[0054] Reference numerals:

[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-controlled electrode; 201 - focusing tube; 202 - focusing electrode; 203 - mounting gasket; 301 - electrode plate. DETAILED DESCRIPTION

[0058] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a 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 used to limit the scope of the present invention.

[0059] One embodiment of the present invention provides a method for preparing a micro-focus X-ray tube with controllable focus, such as Figure 1 The method comprises:

[0060] Prepare an electron beam generator, a focusing device, a lens assembly, a target assembly 40 and 10; 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 electron optical lens 30 is fixed first, and then the second electron optical lens 30 is set at a position with a preset distance from the first electron optical lens 30, and 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 with opposite polarity along the axial direction of 10.

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

[0064] It should be noted that, during implementation, half of the plates 301 of the electronic optical lens 30 are cathode plates, and the other half are anode plates, and the cathode plates and the anode plates are alternately distributed along the circumferential direction.

[0065] Compared with the prior art, in the present invention, the prepared X-ray tube adopts a lens assembly composed of two electron optical lenses 30 to assist in 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 position with a preset distance from the first electron optical lens 30, and the second electron optical lens 30 is rotated so that its pole plate 301 is aligned with the pole plate 301 of the first electron optical lens 30 with opposite polarity along the axial direction of 10, so that the two electron optical lenses 30 can focus the electron beam in a symmetrical direction, improve the quality of the electron beam, make the effective focus of the generated micro-focus X-ray closer to a circle, and make the power distribution of the electron beam more uniform, which plays a role in correcting the aberration, thereby improving the imaging quality of the CT image.

[0066] At the same time, the combination of two electron optical lenses 30 can more accurately control the focusing degree of the electron beam, thereby providing higher adjustment flexibility, and the focus position and size can be adjusted according to different application requirements to adapt to different imaging tasks. And a smaller focus can be formed on the target material, which is conducive to improving resolution and enhancing imaging quality.

[0067] In a specific embodiment, the preparation of the lens assembly includes preparing two identical electron optical lenses 30. The preparation of the electron optical lens 30 includes the following steps:

[0068] Eight plates 301 are made of stainless steel;

[0069] Arrange the prepared electrode plates 301 evenly along the circumferential direction;

[0070] A ceramic strip is arranged between two adjacent pole plates 301;

[0071] Lens electrodes are welded on the outer wall of each electrode plate 301 respectively, so as to obtain an electron optical lens 30 with controllable focal size.

[0072] During implementation, among the eight plates 301 of the electron optical lens 30, cathode voltage is applied to the lens electrodes of four plates 301 to serve as cathode plates, and anode voltage is applied to the lens electrodes of the other four plates 301 to serve as anode plates, and the cathode plates and anode plates are alternately distributed along the circumferential direction. By changing the voltage difference between the cathode plates and the anode plates, the focus of the electron beam can be precisely controlled.

[0073] In the present invention, an octupole structured electron optical lens 30 is prepared. The distribution of the electric field or magnetic field of the octupole structured electron optical lens 30 is more uniform and the focusing ability is stronger. The combined use of two octupole structured 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 in a concave circular shape with an arc angle of 15° to 30°, a thickness of 0.1 mm to 0.5 mm, and a length of 1 mm to 5 mm.

[0075] Among them, the shapes of the pole plate 301 of the electron optical lens 30 are different, the directions of the magnetic field are different, and the effects on the electron beam are different. The concave pole plate 301 can achieve a good focusing effect on the electron beam.

[0076] In a specific embodiment, the preparation of the electron beam generator comprises the following steps:

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

[0078] Putting the tantalum tube 102 on the other end of the single crystal cerium hexaboride rod, and welding the tantalum tube 102 to the end of the single crystal cerium hexaboride rod by vacuum brazing;

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

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

[0081] The prepared gate cover 104 is sleeved on 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 by using a ceramic material, and the prepared isolation ring is arranged between the gate cover 104 and the single crystal cerium hexaboride 101 emitter;

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

[0084] When preparing the electron beam generator in the embodiment of the present invention, the emitter is prepared by using high conductivity and single crystal cerium hexaboride materials. The single crystal cerium hexaboride 101 has high conductivity, good thermal stability and chemical stability, so as to ensure the generation of a stable electron beam. At the same time, the single crystal cerium hexaboride rod is ground into a cone using a high-precision grinder to ensure the accuracy and consistency of the emitter, the stability and precise control of the electron beam, and the electron beam can be drawn out through the circular hole on the grid cover 104. By changing the size and shape of the circular hole on the grid cover 104, the size and shape of the electron beam can be adjusted. The Kovar alloy rod is welded to the outer wall of the grid cover 104 as the grid control electrode 105. By adjusting the voltage on the grid control electrode 105, the density of the electron beam can be accurately controlled. The electron beam generator prepared by the method of the embodiment of the present invention has high performance, high stability and long life, and is suitable for various high-precision and high-demand applications.

[0085] In a specific embodiment, the preparation of the focusing device comprises the following steps:

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

[0087] A through hole penetrating in the axial direction is respectively provided at the center of the two focusing tubes 201 and the center of the mounting gasket;

[0088] Fix the two focusing tubes 201 at two ends of the mounting pad 203 respectively;

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

[0090] When preparing the focusing device in the embodiment of the present invention, the focusing tube 201 is made of non-magnetic stainless steel material, which can avoid magnetic field interference and help maintain the accuracy and stability of the focusing device. A through hole is set in the center of the focusing tube 201 along the axial direction to allow the electron beam to pass through and achieve precise focusing. The mounting gasket 203 is made of ceramic material, which can simultaneously achieve the isolation and installation of the two focusing tubes 201. A Kovar alloy rod is welded on the outer wall of the focusing tube 201 as a focusing electrode 202, so that the position and size of the focus can be accurately controlled by adjusting the voltage on the focusing electrode 202. The focusing device prepared by the method of the present invention has the advantages of high performance, high stability and long life, and is suitable for various applications requiring precise focusing.

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

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

[0093] The base 20 is made of ceramic material, and four mounting holes are respectively set on the base 20; the four mounting holes are respectively used as the first mounting holes of the two gate control electrodes 105 and the second mounting holes of the two focusing electrodes 202;

[0094] Inserting the free ends of the two grid-controlled electrodes 105 of the electron beam generator into the two first mounting holes respectively and fixing them 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, so that the electron beam generator and the focusing device are integrated 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 to form a fine focusing electron gun, and the electrodes of the electron beam generator and the focusing device are integrated on the base 20, so as to facilitate the application of voltage to control the generated electron beam current.

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

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

[0099] The target is made of tungsten, molybdenum or copper materials;

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

[0101] Compared with the prior art, when preparing the target assembly 40 in the embodiment of the present invention, tungsten, molybdenum or copper materials are used to prepare the target body. The target body of tungsten, molybdenum or copper materials has a high melting point and is suitable for high temperature environments. The heat dissipation substrate is prepared by using single crystal diamond or polycrystalline diamond, which can effectively conduct and dissipate heat, improve the heat dissipation efficiency and stability of the target assembly 40. At the same time, the combination of the diamond substrate and the tungsten, molybdenum or copper target body provides excellent structural stability. The high thermal conductivity and low thermal expansion coefficient of diamond help maintain the stability of the target assembly 40 under temperature changes. The method of the embodiment of the present invention provides a high-performance and high-stability target assembly 40 by combining the high thermal conductivity and high hardness characteristics of diamond with the high melting point and chemical stability of tungsten, molybdenum or copper.

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

[0103] A diamond copper composite material is used to prepare a cylinder of a preset size;

[0104] Processing one end of the cylinder into an inclined plane to obtain a base 50 of the target assembly 40;

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

[0106] In this embodiment, a diamond copper composite material with high thermal conductivity is used to make the base 50 for carrying the target assembly 40, wherein the diamond copper composite material combines the ultra-high thermal conductivity of diamond and the low cost, easy processing and high thermal conductivity of the copper matrix. At the same time, an inclined plane is provided on the base 50 to facilitate the reflection of the electron beam after bombarding the target body to generate X-rays, and the inclined plane also facilitates the heat dissipation of the target assembly 40.

[0107] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a focus-controllable X-ray tube, characterized in that: The method comprises: Prepare an electron beam generator, a focusing device, a lens assembly, a target assembly and a tube body; the lens assembly includes two electron optical lenses; The prepared electron beam generator, focusing device, lens assembly and target assembly are sequentially fixed in the tube body, thereby obtaining the prepared X-ray tube; When fixing the lens assembly, the first electron optical lens is fixed first, and then the second electron optical lens is set at a position with a preset distance from the first electron optical lens, and the second electron optical lens is rotated so that its electrode plate is aligned with the electrode plate with opposite polarity of the first electron optical lens along the axial direction of the tube body.

2. The method for preparing an X-ray tube according to claim 1, characterized in that: The preparing the lens assembly comprises preparing two identical electron optical lenses; The preparation of an electron optical lens comprises the following steps: Eight plates are made of stainless steel; Arranging the prepared electrode plates evenly along the circumferential direction; A ceramic strip is arranged between two adjacent plates; Lens electrodes are welded on the outer wall of each electrode plate respectively, so as to obtain an electron optical lens with controllable focal size.

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

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

5. The method for preparing an X-ray tube according to any one of claims 1 to 3, characterized in that: The preparation of the electron beam generator comprises the following steps: One end of a single crystal cerium hexaboride rod is ground into a cone using a high-precision grinding tool; Sleeving a tantalum tube on the other end of the single crystal cerium hexaboride rod, and welding the tantalum tube to the end of the single crystal cerium hexaboride rod by vacuum brazing; Welding two Kovar alloy rods on the outer walls of both sides of the tantalum cylinder as heating electrodes, thereby obtaining a single crystal cerium hexaboride emitter; The grid cover is made of non-magnetic stainless steel material, and a circular hole is provided at one end of the grid cover to serve as an extraction hole for extracting the electron beam; Sleeve the prepared gate cover on the outer periphery of the single crystal cerium hexaboride emitter, align the lead-out hole with the conical end of the single crystal cerium hexaboride emitter along the axial direction, and space the lead-out hole and the conical end of the single crystal cerium hexaboride emitter by a preset distance; Using ceramic material to prepare an isolation ring, and arranging the prepared isolation ring between the gate cover and the single crystal cerium hexaboride emitter; Two Kovar alloy rods are respectively welded on the outer walls of both sides of the grid cover to serve as grid-controlled electrodes, thereby obtaining an electron beam generator with controllable beam current.

6. The method for preparing an X-ray tube according to claim 5, characterized in that: The preparation of the focusing device comprises the following steps: Two focusing cylinders are made of non-magnetic stainless steel material, and mounting gaskets with the same diameter as the focusing cylinders are made of ceramic material; A through hole penetrating in the axial direction is respectively provided at the center of the two focusing cylinders and the center of the mounting gasket; Fixing the two focusing tubes at two ends of the mounting gasket respectively; A kovar alloy rod is welded to the outer wall of each of the two focusing tubes to serve as a focusing electrode, thereby obtaining a focusing device with controllable focus.

7. The method for preparing an X-ray tube according to claim 6, characterized in that: The length of the focusing tube is 0.5 mm to 5 mm, and the diameter of the through hole in the center of the focusing tube is 0.5 mm to 2 mm.

8. The method for preparing an X-ray tube according to claim 6, characterized in that: The method further comprises: The base is made of ceramic material, and four mounting holes are respectively arranged on the base; the four mounting holes are respectively used as first mounting holes of the two gate control electrodes and second mounting holes of the two focusing electrodes; Inserting the free ends of the two grid-controlled electrodes of the electron beam generator into the two first mounting holes respectively and fixing them 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, so that the electron beam generator and the focusing device are integrated on the base.

9. The method for preparing an X-ray tube according to any one of claims 1 to 3, characterized in that: The preparation of the target assembly comprises the following steps: The heat dissipation substrate is prepared by using single crystal diamond or polycrystalline diamond; The target is made of tungsten, molybdenum or copper materials; The target body is embedded in the heat dissipation substrate to obtain the target material assembly.

10. The method for preparing an X-ray tube according to any one of claims 1 to 3, characterized in that: The preparation of the target assembly also includes the following steps: A diamond copper composite material is used to prepare a cylinder of a preset size; Processing one end of the cylinder into an inclined plane to obtain a base of the target assembly; The heat dissipation substrate of the target assembly is embedded on the inclined plane of the base.

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