X-ray tube anode target rod and X-ray tube
By introducing a liquid-absorbing core layer and working fluid into the anode target rod of the X-ray tube, the problem of focus shift caused by thermal expansion of the anode target rod was solved, thus improving image quality and spatial resolution.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- YIRUI ELECTRIC VACUUM TECH (NANJING) CO LTD
- Filing Date
- 2025-04-18
- Publication Date
- 2026-05-05
AI Technical Summary
The axial thermal expansion of the anode target rod in existing microfocus X-ray tubes causes a change in the focal position, resulting in a decrease in the quality and spatial resolution of the reconstructed image.
The design includes a target rod body, a liquid-absorbing core layer, and a working fluid. The flow of the working fluid in the liquid-absorbing core layer enables efficient heat removal, reduces the axial thermal expansion of the target rod, and minimizes focus drift.
It effectively reduces focus drift, improves the quality and spatial resolution of reconstructed images, and reduces the difficulty of the system algorithm in correcting focus shift.
Smart Images
Figure CN224204094U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of X-ray tube technology, and relates to an X-ray tube anode target rod and an X-ray tube. Background Technology
[0002] Micro-CT uses micron and submicron X-ray sources as the core components for achieving high-resolution imaging. Microfocus X-ray tubes have the characteristics of high spatial resolution and high-precision non-destructive testing, and have been widely used in micro-CT systems.
[0003] Typically, the anode target rod of a microfocus X-ray tube is a one-piece oxygen-free copper rod, and its structure is as follows: Figure 1 As shown, when the electron beam bombards the X-ray focal point of the target surface, localized high temperatures are generated. This heat is conducted into the anode target rod. Due to the increased temperature, and based on the thermal expansion properties of the material, the anode target rod will experience a certain axial displacement. Figure 2 As shown, the axial expansion of the anode target rod will change the position of the X-ray focus. Since the trajectory of the electron beam remains unchanged, the image point will shift, which in turn will lead to a decrease in the quality and spatial resolution of the reconstructed image.
[0004] Therefore, how to provide an X-ray tube anode target rod and X-ray tube to improve the quality of reconstructed images and spatial resolution has become a technical problem that urgently needs to be solved by those skilled in the art. Utility Model Content
[0005] In view of the shortcomings of the prior art described above, the purpose of this utility model is to provide an X-ray tube anode target rod and an X-ray tube to solve the problem of reduced image quality and spatial resolution caused by anode target rod focus shift in the prior art.
[0006] To achieve the above and other related objectives, this utility model provides an X-ray tube anode target rod, comprising:
[0007] The target rod body has a first end face and a second end face arranged opposite to each other. The second end face is provided with an anode target face. The target rod body has a sealed hollow part inside and a stepped support surface on its surface.
[0008] The liquid-absorbing core layer is located on the inner wall of the hollow region in the target rod body. The distance between the liquid-absorbing core layer and the first end face is less than the distance between the supporting surface and the first end face, and the distance between the liquid-absorbing core layer and the second end face is less than the distance between the supporting surface and the second end face.
[0009] The working fluid is located in the liquid-absorbing core layer, wherein the working fluid is capable of flowing in the liquid-absorbing core layer.
[0010] Optionally, the shortest distance between the liquid-absorbing core layer and the second end face is 1 to 15 mm.
[0011] Optionally, in the direction perpendicular to the first end face and pointing to the second end face, the size of the target rod body between the support surface and the first end face is larger than the size of the target rod body between the support surface and the second end face, and the size of the hollow portion between the support surface and the first end face is larger than the size of the hollow portion between the support surface and the second end face.
[0012] Optionally, in the direction perpendicular to the first end face and pointing to the second end face, the size of the target rod body between the support surface and the first end face is larger than the size of the target rod body between the support surface and the second end face, and the size of the hollow portion between the support surface and the first end face is equal to the size of the hollow portion between the support surface and the second end face.
[0013] Optionally, the wall thickness of the target rod body between the support surface and the first end face is 0.5 to 2 mm, and the wall thickness of the target rod body between the support surface and the second end face is 0.7 to 2.5 mm.
[0014] Optionally, the thickness of the liquid-absorbing core layer is 0.5 to 2.5 mm.
[0015] Optionally, the maximum distance between the liquid-absorbing core layer and the first end face is 4 to 10 mm.
[0016] Optionally, the liquid-absorbing core layer is made of a wire mesh layer, a porous silica layer, a porous alumina layer, a copper powder sintered layer, or a nickel powder sintered layer, and the working fluid is deionized water.
[0017] Optionally, the surface finish of the outer surface of the target rod body is not higher than 0.8 μm.
[0018] This utility model also provides an X-ray tube, which includes the X-ray tube anode target rod described in any of the above claims.
[0019] As described above, in the X-ray tube anode target rod and X-ray tube of this invention, the anode target rod includes a target rod body, a liquid-absorbing core layer and a working fluid, which can reduce the axial thermal expansion of the target rod, thereby reducing the focus drift phenomenon, reducing the difficulty of the system algorithm to correct the focus shift, and helping to improve the quality and spatial resolution of the reconstructed image. Attached Figure Description
[0020] Figure 1 The diagram shown is of an integrated anode target rod.
[0021] Figure 2This is a schematic diagram showing the focus shift after the thermal expansion of the anode target.
[0022] Figure 3 The diagram shown is a schematic diagram of the first type of X-ray tube anode target rod in Embodiment 1 of this utility model.
[0023] Figure 4 The diagram shown is a schematic diagram of the second type of X-ray tube anode target rod in Embodiment 1 of this utility model.
[0024] Figure 5 The diagram shown is a schematic diagram of the opening in the blank in Embodiment 2 of this utility model.
[0025] Figure 6 This is a schematic diagram showing the placement of the mold in Embodiment 2 of this utility model.
[0026] Figure 7 The diagram shown is a schematic diagram of the injection of oxygen-free copper powder in Embodiment 2 of this utility model.
[0027] Figure 8 This is a schematic diagram showing the process of machining a blank into a target rod shape in Embodiment 2 of this utility model.
[0028] Figure 9 This is a schematic diagram of the first end face cold sealing in Embodiment 2 of this utility model.
[0029] Component designation explanation
[0030] 1 Target body
[0031] 100 First end face
[0032] 101 Second end face
[0033] 102 Hollow Section
[0034] 103 Support Surface
[0035] 2. Liquid Absorption Core Layer
[0036] 3. Raw material
[0037] 4. Mold
[0038] 5. Oxygen-free copper powder layer Detailed Implementation
[0039] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model.
[0040] Please see Figures 3 to 9 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of this utility model. Therefore, the drawings only show the components related to this utility model and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.
[0041] Example 1
[0042] This embodiment provides an X-ray tube anode target rod. Please refer to [link / reference]. Figure 3 The X-ray tube anode target rod includes a target rod body 1, a liquid-absorbing core layer 2, and a working fluid. The target rod body 1 has a first end face 100 and a second end face 101 disposed opposite to each other. The second end face 101 is provided with an anode target surface. The target rod body 1 has a sealed hollow portion 102 inside, and a stepped support surface 103 is provided on the surface of the target rod body 1. The liquid-absorbing core layer 2 is located on the inner wall of the region of the hollow portion 102 in the target rod body 1. The distance between the liquid-absorbing core layer 2 and the first end face 100 is less than the distance between the support surface 103 and the first end face 100, and the distance between the liquid-absorbing core layer 2 and the second end face 101 is less than the distance between the support surface 103 and the second end face 101. The working fluid is located in the liquid-absorbing core layer 2, and the working fluid is capable of flowing in the liquid-absorbing core layer 2.
[0043] As an example, the target rod body 1 is made of oxygen-free copper.
[0044] As an example, the first end face 100 is a sealing surface used to enclose the hollow portion 102 into a sealed area.
[0045] As an example, a high-melting-point tungsten layer is welded to the second end face 101 to form the anode target surface, i.e., electron beam bombardment of tungsten generates X-rays.
[0046] As an example, the target rod body 1 is cylindrical, and the stepped support surface 103 is distributed on the periphery of the target rod seat 1. The stepped support surface 103 is used to weld and fix the anode target rod and the anode mounting seat of the X-ray tube, and improves the structural stability of the anode target rod.
[0047] As an example, after the target rod body 1 is assembled into the anode mounting base of the X-ray tube, the area between the support surface 103 and the first end face 100 (including the first end face 100) is located outside the tube shell of the X-ray tube, that is, the area between the support surface 103 and the first end face 100 is in a non-vacuum environment; the area between the support surface 103 and the second end face 101 (including the second end face 101) is located inside the tube shell of the X-ray tube, that is, the area between the support surface 103 and the second end face 101 is in a vacuum environment.
[0048] As an example, in the direction perpendicular to the first end face 100 and pointing to the second end face 101, the size of the target rod body 1 between the support surface 103 and the first end face 100 is larger than the size of the target rod body 1 between the support surface 103 and the second end face 101. That is, in order to meet the assembly and use requirements of the anode target rod, the outer diameter of the target rod body 1 between the support surface 103 and the first end face 100 is larger than the outer diameter of the target rod body 1 between the support surface 103 and the second end face 101.
[0049] As an example, the hollow portion 102 is cylindrical. In the direction perpendicular to the first end face 100 and pointing to the second end face 101, the size (diameter) of the hollow portion 102 between the support surface 103 and the first end face 101 is larger than the size (diameter) of the hollow portion 102 between the support surface 103 and the second end face 101. That is, the liquid-absorbing core layer 2 is provided with a step, which reduces the sealing difficulty of the first end face 100 while ensuring the structural strength of the target rod body 1. In this embodiment, the distance L0 between the step of the liquid-absorbing core layer 2 and the end of the support surface 103 near the second end face 101 is 3 to 10 mm, the thickness of the liquid-absorbing core layer 2 is 0.5 to 2.5 mm, the wall thickness of the target rod body 1 between the support surface 103 and the first end face 100 is 0.5 to 2 mm, and the wall thickness of the target rod body 1 between the support surface 103 and the second end face 101 is 0.7 to 2.5 mm.
[0050] As an example, the maximum distance L1 between the absorbent core layer 2 and the first end face 100 is 4 to 10 mm. During the sealing process of the first end face 100, the sealing area will deform. By setting a distance between the absorbent core layer 2 and the first end face 100, the deformation of the sealing area can be avoided from damaging the absorbent core layer 2.
[0051] For example, please refer to Figure 4In another example, the size of the hollow portion 102 between the support surface 103 and the first end face 100 is equal to the size of the hollow portion 102 between the support surface 103 and the second end face 100. That is, the liquid-absorbing core layer 2 is not provided with a step, and the wall thickness of the target rod body 1 between the support surface 103 and the first end face 100 will increase. In order to reduce the sealing difficulty of the first end face 100, the wall thickness of the sealing area needs to be appropriately reduced.
[0052] As an example, the liquid-absorbing core layer 2 may be a wire mesh layer, a porous silica layer, a porous alumina layer, a copper powder sintered layer, or a nickel powder sintered layer. In this embodiment, the liquid-absorbing core layer 2 is a copper powder sintered layer 2, and the particle size of the copper powder is 10–100 μm. The working fluid is deionized water, which is injected into the liquid-absorbing core layer 2 through capillary action.
[0053] As an example, the shortest distance L2 between the liquid-absorbing core layer 2 and the second end face 101 is 1-15 mm. When the electron beam bombards the anode target surface, the generated heat is transferred to the interior of the target rod, causing the water in the liquid-absorbing core layer 2 to absorb heat and evaporate. The water vapor moves in the hollow part 102 towards the first end face 100. The non-vacuum area of the anode target rod is immersed in insulating oil, and the water vapor condenses into liquid and is then drawn into the liquid-absorbing core layer 2 through capillary siphon effect. That is, the working fluid in the liquid-absorbing core layer 2 absorbs heat and evaporates into water vapor in the area near the second end face 101, and the water vapor condenses into liquid in the area near the first end face 100 and returns to the liquid-absorbing core layer 2, forming a heat pipe with good thermal conductivity, which quickly and efficiently removes the heat generated by the electron beam bombarding the anode target surface, thereby reducing the thermal expansion of the anode target rod.
[0054] As an example, the surface finish Ra of the target rod body 1 is no higher than 0.8 μm. On the one hand, this reduces the adsorption of gas molecules, thereby maintaining the vacuum level inside the X-ray tube. On the other hand, it avoids stress concentration caused by surface defects, thereby improving mechanical strength and service life. Furthermore, the smooth target rod surface can reduce the generation of secondary electrons and scattered X-rays.
[0055] As an example, with Figure 1 The integrated oxygen-free copper anode target shown is a comparative example. Its highest temperature under stable conditions is 286°C, and the axial expansion length at the focal point is 217.3 μm. In this embodiment, the anode target includes a target body, a liquid-absorbing core layer, and a working fluid. Its highest temperature under stable conditions is 155°C, and the axial expansion length at the focal point is 19.4 μm, with the axial thermal expansion reduced by 91.1%.
[0056] As an example, during imaging, by marking the focus and eliminating the focus drift caused by thermal deformation of the X-ray source or micro-CT system in the imaging algorithm, the micro-focus X-ray tube anode target rod of this invention can reduce the axial thermal expansion of the target rod, thereby reducing the focus drift phenomenon, reducing the difficulty of the system algorithm to correct the focus offset, and helping to improve the quality and spatial resolution of the reconstructed image.
[0057] This embodiment also provides an X-ray tube, which includes the above-described X-ray tube anode target rod.
[0058] As described above, in this embodiment, the anode target rod of the X-ray tube includes a target rod body, a liquid-absorbing core layer, and a working fluid. This can reduce the axial thermal expansion of the target rod, thereby reducing the focus drift phenomenon, reducing the difficulty of the system algorithm to correct the focus shift, and helping to improve the quality and spatial resolution of the reconstructed image.
[0059] Example 2
[0060] This embodiment provides a method for manufacturing an anode target rod, used to manufacture the X-ray tube anode target rod described in Embodiment 1, including the following steps:
[0061] (a) such as Figure 5 As shown, an oxygen-free copper rod blank 3 with a diameter larger than the maximum diameter of the anode target rod is provided, and holes are made in the blank 3 according to the size of the hollow part in the target rod body;
[0062] (ii) Figure 6 As shown, a mold 4 is provided, and the mold 4 is placed inside the blank 3 after the hole is opened. The space between the mold 4 and the blank 3 is a region where a liquid-absorbing core layer is pre-formed.
[0063] (III) Figure 7 As shown, oxygen-free copper powder is injected into the area where the liquid-absorbing core layer is pre-formed to form an oxygen-free copper powder layer 5. The particle size of the oxygen-free copper powder 5 is 10-100μm. After the oxygen-free copper powder layer 5 is shaped, the mold 3 is taken out, and the blank 3 with the oxygen-free copper powder layer 5 is placed in a vacuum furnace or hydrogen furnace for sintering to form a liquid-absorbing core layer. The sintering temperature is 830±70℃.
[0064] (iv) such as Figure 8 As shown, the blank 3 is processed in a second process to shape the blank 3 into the shape of the target rod body. At this time, the first end face of the target rod body has not yet been sealed.
[0065] (v) Polish the outer surface of the target rod body, with a surface finish Ra not exceeding 0.8μm;
[0066] (vi) Assemble the cathode assembly, tube shell and anode assembly of the X-ray tube, and keep the assembled structure at 450°C for 24 hours to exhaust the vacuum tube.
[0067] (vii) The working fluid (water) is injected into the absorbent core layer through the capillary effect;
[0068] (viii) such as Figure 9 As shown, cold sealing clamps are used to cold seal the first end face of the target rod body. In another example, electron beam welding can also be used to seal the first end face.
[0069] As an example, when the vacuum tube is venting at high temperature, the liquid-absorbing core layer is not injected with working fluid and the first end face is not sealed, which can protect the anode target rod. If the liquid-absorbing core layer is injected with working fluid and the first end face is sealed when the vacuum tube is venting at high temperature, the high temperature will cause the air pressure in the hollow part of the target rod body to be too high and damage the anode target rod.
[0070] In summary, the X-ray tube anode target rod of this invention, comprising a target rod body, a liquid-absorbing core layer, and a working fluid, reduces the axial thermal expansion of the target rod, thereby reducing focus drift and simplifying the difficulty of correcting focus shift in the system algorithm. This contributes to improving the quality and spatial resolution of the reconstructed image. Therefore, this invention effectively overcomes the various shortcomings of the prior art and possesses high industrial application value.
[0071] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.
Claims
1. An X-ray tube anode target rod, characterized in that, include: The target rod body has a first end face and a second end face arranged opposite to each other. The second end face is provided with an anode target face. The target rod body has a sealed hollow part inside and a stepped support surface on its surface. The liquid-absorbing core layer is located on the inner wall of the hollow region in the target rod body. The distance between the liquid-absorbing core layer and the first end face is less than the distance between the supporting surface and the first end face, and the distance between the liquid-absorbing core layer and the second end face is less than the distance between the supporting surface and the second end face. The working fluid is located in the liquid-absorbing core layer, wherein the working fluid is capable of flowing in the liquid-absorbing core layer.
2. The X-ray tube anode target rod according to claim 1, characterized in that: The shortest distance between the liquid-absorbing core layer and the second end face is 1 to 15 mm.
3. The X-ray tube anode target rod according to claim 1, characterized in that: In the direction perpendicular to the first end face and pointing to the second end face, the size of the target rod body between the support surface and the first end face is larger than the size of the target rod body between the support surface and the second end face, and the size of the hollow portion between the support surface and the first end face is larger than the size of the hollow portion between the support surface and the second end face.
4. The X-ray tube anode target rod according to claim 1, characterized in that: In the direction perpendicular to the first end face and pointing to the second end face, the size of the target rod body between the support surface and the first end face is larger than the size of the target rod body between the support surface and the second end face, and the size of the hollow portion between the support surface and the first end face is equal to the size of the hollow portion between the support surface and the second end face.
5. The X-ray tube anode target rod according to claim 1, characterized in that: The wall thickness of the target rod body between the support surface and the first end face is 0.5-2 mm, and the wall thickness of the target rod body between the support surface and the second end face is 0.7-2.5 mm.
6. The X-ray tube anode target rod according to claim 1, characterized in that: The thickness of the liquid-absorbing core layer is 0.5–2.5 mm.
7. The X-ray tube anode target rod according to claim 1, characterized in that: The maximum distance between the liquid-absorbing core layer and the first end face is 4 to 10 mm.
8. The X-ray tube anode target rod according to claim 1, characterized in that: The liquid-absorbing core layer is made of a wire mesh layer, a porous silica layer, a porous alumina layer, a copper powder sintered layer, or a nickel powder sintered layer, and the working fluid is deionized water.
9. The X-ray tube anode target rod according to claim 1, characterized in that: The surface finish of the outer surface of the target rod body is no higher than 0.8 μm.
10. An X-ray tube, characterized in that: The X-ray tube includes the X-ray tube anode target rod according to any one of claims 1-9.