Self-shielded x-ray tube and x-ray device having the same

Abstract

The utility model discloses a kind of self-shielding ray tube and the X-ray equipment with it, self-shielding ray tube includes: tube shell assembly;Cathode component, be located at one end of tube shell assembly, cathode component includes the cathode for emitting electron beam;Anode component, be located at the other end of tube shell assembly, anode component includes anode target and cover anode cover on anode target, anode cover is defined with opening towards one end of cathode component, the relative distance parameter of cathode, anode target and opening, and the size characteristic parameter of cathode and electron beam are respectively configured to make electron beam focus to open again to anode target after shooting, anode target is bombarded by electron beam and emits X-ray.According to the self-shielding ray tube of the utility model embodiment, by making the beam waist of electron beam be located in opening, the purpose of reducing the leakage dose of invalid X-ray and secondary electron from anode end is realized, the weight and volume of shielding structure in ray tube are reduced, and the manufacturing difficulty of ray tube is reduced.

Description

Technical Field

[0001] This utility model belongs to the field of X-ray equipment technology, specifically relating to a self-shielded X-ray tube and an X-ray device having the same. Background Technology

[0002] During operation, X-ray tubes generate a large number of scattered rays and secondary electrons, which will reduce the clarity of X-ray imaging and increase the workload of radiation shielding.

[0003] Existing X-ray tubes generally employ conventional focusing techniques, ensuring that the minimum focal point of the radiation falls on or behind the target surface. Therefore, the opening of the anode cover cannot be too small, otherwise it will obstruct the transmission of the electron beam. Due to the insufficient opening size, the shielding effect of the anode cover on secondary electrons and radiation is not ideal. Therefore, a larger cathode cover is needed for shielding, as well as a stronger lateral focusing electric field to suppress the escape of secondary electrons and unwanted radiation. This increases the overall weight of the radiation source, hindering the lightweight design of portable radiation sources such as material analyzers and backscatter imaging systems.

[0004] Existing technologies aim to reduce the escape of secondary electrons and ineffective X-rays by modifying the structure or material of the anode cover. For example, patent CN202310973711.6 discloses setting an electron dissipation layer inside the anode cover to reduce the generation of stray scattered rays. This structure, on the one hand, increases the manufacturing cost of the anode cover, and on the other hand, provides relatively limited shielding against stray scattered rays. Since there is no improvement at the opening of the anode cover, when the electron beam impacts the inner wall of the anode cover from different angles, a considerable portion of secondary electrons or ineffective X-rays will still escape from the larger opening of the anode cover. This approach cannot fundamentally reduce the dose of leaked ineffective X-rays or the number of secondary electrons, and it is also difficult to reduce the overall weight of portable X-ray sources such as material analysis equipment and backscatter imaging equipment. Summary of the Invention

[0005] The purpose of this utility model embodiment is to provide a self-shielded X-ray tube and an X-ray device having the same, so as to solve the problem that the existing X-ray tubes are difficult to miniaturize and reduce the leakage of invalid X-rays and secondary electrons.

[0006] The first aspect of this utility model provides a self-shielding X-ray tube, comprising:

[0007] Tube and shell assembly;

[0008] A cathode assembly is disposed at one end of the housing assembly, the cathode assembly including a cathode for emitting an electron beam;

[0009] An anode assembly is disposed at the other end of the housing assembly. The anode assembly includes an anode target and an anode cover covering the anode target. The anode cover has an opening at one end facing the cathode assembly. The relative distance parameters of the cathode, the anode target, and the opening, as well as the size characteristic parameters of the cathode and the electron beam, are respectively configured to focus the electron beam onto the opening before it is directed toward the anode target. The anode target emits X-rays after being bombarded by the electron beam.

[0010] Furthermore, the cathode is helical in shape, and the diameter D of the opening satisfies the following formula: Where, ha is the relative distance parameter from the opening to the anode target, hca is the relative distance parameter from the cathode to the opening, Lc is the length characteristic parameter of the cathode, La is the length characteristic parameter of the electron beam that can form a focal point on the anode target after being focused on the opening without the action of a focusing magnetic field, and dc is the diameter characteristic parameter of the cathode.

[0011] Furthermore, the cathode is disk-shaped, and the diameter D of the opening satisfies the following formula: Where, ha is the relative distance parameter from the opening to the anode target, hca is the relative distance parameter from the cathode to the opening, Dc is the diameter characteristic parameter of the cathode, and Da is the length characteristic parameter of the electron beam that can form a focal point on the anode target after being focused on the opening without the action of a focusing magnetic field.

[0012] Furthermore, the diameter of the opening is 0.2 mm to 5 mm.

[0013] Furthermore, the anode target is a reflective target, which reflects the X-rays after being bombarded by the electron beam, and the sidewall of the anode cover is defined with an anode window for the X-rays to pass through.

[0014] Furthermore, the anode target is a transmission target, which transmits the X-rays after being bombarded by the electron beam, and the self-shielding X-ray tube further includes:

[0015] A focusing magnetic ring is formed as a ring so that the electron beam can pass through it. The focusing magnetic ring is embedded in the inner wall of the anode cover at the end facing the anode target. The focusing magnetic ring is used to generate a magnetic field in the same direction as the electron beam to focus the electron beam onto the anode target.

[0016] Furthermore, the self-shielding ray tube also includes:

[0017] A compensating magnetic ring, formed as an annular element, allows the electron beam to pass through it. The compensating magnetic ring is embedded in the inner wall surface of the anode cover located between the opening and the anode target. The compensating magnetic ring is used to generate a magnetic field opposite to the direction of electron beam movement to defocus the electron beam passing through the opening.

[0018] Furthermore, the self-shielding ray tube also includes:

[0019] A first magnetic shielding element is covered on the outer surface of the focusing magnetic ring for magnetic shielding;

[0020] The second magnetic shielding element covers the outer surface of the compensating magnetic ring for magnetic shielding.

[0021] Furthermore, the focusing magnetic ring is an electromagnetic element or a permanent magnet element; the compensation magnetic ring is an electromagnetic element or a permanent magnet element.

[0022] A second aspect of this utility model provides an X-ray device having the aforementioned self-shielding X-ray tube.

[0023] According to the embodiments of the present invention, the self-shielded X-ray tube achieves the purpose of reducing the dose of ineffective X-rays and secondary electron leakage from the anode by placing the beam waist of the electron beam inside the opening and minimizing the radial dimension of the opening as much as possible. This further reduces the weight and volume of the shielding structure in the X-ray tube, as well as the manufacturing difficulty of the X-ray tube. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a self-shielding X-ray tube with a reflective target according to an embodiment of the present invention;

[0025] Figure 2 This is another structural schematic diagram of a self-shielding ray tube with a reflective target according to an embodiment of the present invention;

[0026] Figure 3 This is a structural schematic diagram of a self-shielded X-ray tube with a transmission target according to an embodiment of the present invention;

[0027] Figure 4 This is another structural schematic diagram of a self-shielded X-ray tube with a transmission target according to an embodiment of the present invention.

[0028] Attached Figure

[0029] 100 self-shielded X-ray tube;

[0030] Shell assembly 10;

[0031] Cathode assembly 20; Cathode 21; Cathode cover 22;

[0032] Anode assembly 30; Anode target 31; Reflective target 311; Transmitting target 312; Anode cover 32; Opening 321; Heat sink 33;

[0033] Focusing magnetic ring 40; electromagnetic element 41; permanent magnet element 42; electromagnet power supply 43; compensating magnetic ring 50; first magnetic shield 60; second magnetic shield 70; electron beam 80; X-ray 90. Detailed Implementation

[0034] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present utility model.

[0035] The terms "first," "second," etc., used in the specification and claims of this utility model are used to distinguish similar objects and are not used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of this utility model can be implemented in orders other than those illustrated or described herein. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0036] The following is combined Figures 1 to 4 The self-shielding X-ray tube 100 provided in this utility model embodiment will be described in detail through specific embodiments and application scenarios.

[0037] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0038] According to an embodiment of the present invention, the self-shielded X-ray tube 100 includes a tube shell assembly 10, a cathode assembly 20, and an anode assembly 30.

[0039] Specifically, the cathode assembly 20 is located at one end of the housing assembly 10, and the cathode assembly 20 includes a cathode 21 for emitting an electron beam 80; the anode assembly 30 is located at the other end of the housing assembly 10, and the anode assembly 30 includes an anode target 31 and an anode cover 32 covering the anode target 31. The end of the anode cover 32 facing the cathode assembly 20 defines an opening 321. The relative distance parameters of the cathode 21, the anode target 31 and the opening 321, as well as the size characteristic parameters of the cathode 21 and the opening 321, are respectively configured to focus the electron beam 80 onto the opening 321 and then onto the anode target 31. After being bombarded by the electron beam 80, the anode target 31 emits X-rays 90.

[0040] In other words, the cathode assembly 20 and the anode assembly 30 are respectively located at both ends of the tube shell assembly 10 and are coaxially arranged with the tube shell assembly 10. The cathode assembly 20 includes a cathode cover 22 and a cathode 21, and the anode assembly 30 includes an anode target 31 and an anode cover 32. Existing X-ray tubes all use conventional focusing technology, so that the minimum focal point of the X-ray tube is on or behind the target surface. Therefore, the opening on the anode cover cannot be too small, otherwise it will block the transmission of the electron beam. However, a large opening also results in the anode cover having an unsatisfactory shielding effect against secondary electrons and X-rays. This embodiment employs the concept of overfocusing. By adjusting the distance relationship between the cathode 21, the anode cover 32, and the opening 321, as well as the characteristic dimensions of the electron beam 80 and the cathode 21, the electron beam 80 is first focused within the opening 321. In other words, the waist of the electron beam (the axial position where the electron beam cross-section is smallest) is located within the opening 321. As a result, the size of the opening 321 on the anode cover 32 can be set to be smaller. According to the principle of equal area, since the size of the opening 321 is smaller, the dose of secondary electrons and scattered rays overflowing from the opening 321 is also smaller.

[0041] Therefore, the self-shielded X-ray tube 100 according to the present invention achieves the purpose of reducing the leakage dose of invalid X-rays and secondary electrons from the anode by placing the electron beam waist inside the opening 321 and minimizing the radial dimension of the opening 321 as much as possible, thereby further reducing the weight and volume of the shielding structure in the X-ray tube and the manufacturing difficulty of the X-ray tube.

[0042] In existing technologies, the opening diameter of the anode cover is at least greater than This resulted in a significant leakage of secondary electrons and X-rays.

[0043] Unlike existing technologies, according to one embodiment of this utility model, such as Figure 1 As shown, for the spiral-shaped cathode 21, that is, the cathode 21 is a long strip made of tungsten wire, the diameter D of the opening 321 should satisfy the following formula: ,

[0044] Where, ha is the relative distance parameter from the opening 321 to the target surface of the anode target 31, hca is the relative distance parameter from the cathode 21 to the opening 321, Lc is the length characteristic parameter of the cathode 21, La is the length characteristic parameter of the electron beam 80 emitted by the cathode 21 on the target surface, La is the length characteristic parameter of the electron beam 80 that can form a focal point on the anode target 31 after being focused on the opening 321 without the action of a focusing magnetic field, and dc is the diameter characteristic parameter of the cathode 21. When the size parameters and positional relationship of the structure corresponding to the self-shielded X-ray tube 100 satisfy the above formula, the opening 321 can not only be made very small, but also does not affect the passage of the electron beam 80, and the shielding effect is good.

[0045] It should be noted that if the anode target 31 is a reflective target 311, then... Figure 1 As shown, La is the length characteristic parameter of the actual focal point formed by the electron beam 80 emitted by the cathode 21 on the target surface of the anode target 31. If the anode target 31 is a transmission target 312, as shown... Figure 3 As shown, La is the envelope of the electron beam 80 emitted from cathode 21 after over-focusing under no focusing magnetic field. Figure 3 The dotted dashed lines in the diagram correspond to the length characteristic parameters at the target surface position.

[0046] Furthermore, such as Figure 2 As shown, for the disc-shaped cathode 21, that is, the shape of the cathode is similar to that of a coiled incense stick, the diameter D of the opening 321 satisfies the following formula: ,

[0047] Where, ha is the relative distance parameter from the opening 321 to the target surface of the anode target 31, hca is the relative distance parameter from the cathode 21 to the opening 321, Dc is the diameter characteristic parameter of the disc-shaped cathode 21, and Da is the length characteristic parameter of the electron beam 80 that can form a focal point on the anode target 31 after being focused onto the opening without the action of a focusing magnetic field.

[0048] Preferably, the diameter of the opening 321 is 0.2 mm to 5 mm.

[0049] In one embodiment of this utility model, such as Figure 1 and Figure 2 As shown, the anode target 31 is a reflective target 311. After being bombarded by the electron beam 80, the reflective target 311 reflects X-rays 90. The side wall of the anode cover 32 is defined with an anode window (not shown) for the X-rays 90 to pass through.

[0050] Specifically, the reflector target 311 is connected to the heat sink 33. After being bombarded by the electron beam 80, the reflector target 311 reflects X-rays 90. Due to the emission angle projection effect of the reflector target 311, when the waist of the electron beam is located at the opening 321, the emitted beam after the electron beam 80 is over-focused just meets the usage requirements.

[0051] In another embodiment of this utility model, such as Figure 3 and Figure 4 As shown, the anode target 31 is a transmission target 312. After being bombarded by the electron beam 80, the transmission target 312 transmits X-rays 90. The transmission-type self-shielded X-ray tube 100 also includes a focusing magnetic ring 40. The focusing magnetic ring 40 is formed as a ring so that the electron beam 80 can pass through it. The focusing magnetic ring 40 is embedded in the inner wall of the anode cover 32 facing the anode target 31. The focusing magnetic ring 40 is used to generate a magnetic field in the same direction as the movement direction of the electron beam 80 to focus the electron beam 80 to the anode target 31.

[0052] Specifically, such as Figure 3 and Figure 4 As shown, the transmission target 312 is fixed by a bracket. After the electron beam 80 bombards the transmission target 312, the X-ray 90 is emitted directly from the transmission target 312. Since the conventional focal spot is generally only about 1 mm, and there is no reflection angle projection effect of the reflection target 311, even with over-focusing design to place the focal point of the electron beam 80 within the opening 321, the optimization effect of the opening 321 is still not significant unless the opening of the anode cover 32 is tightly attached to the target surface of the transmission target 312. In order to further optimize the self-shielded X-ray tube 100 with the transmission target 312, one embodiment of this utility model adopts the "electrostatic over-focusing-magnetic secondary focusing" scheme, specifically, as follows... Figure 3 and Figure 4 As shown, the electron beam 80 diverges after passing through the opening 321, and an axial magnetic field is generated by the focusing magnetic ring 40. The direction of the magnetic field is parallel to the axial direction of the electron beam 80's propagation direction. Figure 3 and Figure 4 The direction of the downward-pointing solid arrow is the direction of the magnetic field. Thus, under the action of the Lorentz force, the electron beam 80 is refocused onto the target surface with a very small beam spot.

[0053] Furthermore, the self-shielded X-ray tube 100 also includes a compensating magnetic ring 50, which is formed as an annular element so that the electron beam 80 can pass through it. The compensating magnetic ring 50 is embedded in the inner wall surface of the anode cover 32 located between the opening 321 and the anode target 31. The compensating magnetic ring 50 is used to generate a magnetic field opposite to the direction of movement of the electron beam 80 to defocus the electron beam 80 passing through the opening 321.

[0054] In other words, although the size of the opening 321 is designed to be small, the central magnetic field can still leak into the upstream region of the electron beam 80, affecting the initial emission of the electron beam 80. Therefore, as... Figure 3 and Figure 4 As shown, a compensation magnetic ring 50 is installed on the upstream side of the focusing magnetic ring 40. The compensation magnetic ring 50 generates a compensation magnetic field with the opposite direction to the magnetic field generated by the focusing magnetic ring 40. The strength of the compensation magnetic field is basically the same as the edge field strength of the focusing magnetic field. The influence of the focusing magnetic field on the emission of the upstream electron beam 80 can be basically eliminated by the compensation magnetic ring 50.

[0055] According to another embodiment of the present invention, the self-shielding X-ray tube 100 further includes a first magnetic shielding member 60, which covers the outer surface of the focusing magnetic ring 40 for magnetic shielding.

[0056] Preferably, the self-shielded X-ray tube 100 further includes two magnetic shielding elements 70, which cover the outer surface of the compensating magnetic ring 50 for magnetic shielding.

[0057] The first magnetic shield 60 and the second magnetic shield 70 can minimize the leakage of the magnetic field generated by the focusing magnetic ring 40 to places outside the focusing area, so as to avoid affecting the emission of the electron beam 80. The first magnetic shield 60 and the second magnetic shield 70 can be made of high magnetic permeability materials.

[0058] Optionally, the focusing magnetic ring 40 can be an electromagnetic element 41 or a permanent magnet element 42. Figure 3 The focusing magnetic ring 40 is an electromagnetic element 41, which is electrically connected to the electromagnet power supply 43. This type of self-shielded X-ray tube 100 is only suitable for situations where the cathode is at a single-end high voltage and the anode is at ground potential. Figure 4 The focusing magnetic ring 40 is a permanent magnet element 42, and the anode of this self-shielded X-ray tube 100 can operate under high voltage.

[0059] The X-ray device according to the second aspect of the present invention includes the self-shielded X-ray tube 100 of the above embodiment. Since the self-shielded X-ray tube 100 according to the present invention has the advantages of reducing the leakage dose of invalid X-rays and secondary electrons, as well as miniaturization and ease of processing, the X-ray device according to the present invention also has the advantages of reducing the leakage dose of invalid X-rays and secondary electrons, as well as miniaturization and ease of processing and manufacturing.

[0060] The X-ray device according to the embodiments of this utility model can be a handheld backscatter imaging device for material analysis or detection, etc. Other structures and technologies of the X-ray device are existing technologies and will not be described in detail here.

[0061] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. A self-shielding X-ray tube, characterized in that, include: Tube and shell assembly; A cathode assembly is disposed at one end of the housing assembly, the cathode assembly including a cathode for emitting an electron beam; An anode assembly is disposed at the other end of the housing assembly. The anode assembly includes an anode target and an anode cover covering the anode target. The anode cover has an opening at one end facing the cathode assembly. The relative distance parameters of the cathode, the anode target, and the opening, as well as the size characteristic parameters of the cathode and the electron beam, are respectively configured to focus the electron beam onto the opening before it is directed toward the anode target. The anode target emits X-rays after being bombarded by the electron beam.

2. The self-shielding X-ray tube according to claim 1, characterized in that, The cathode is helical in shape, and the diameter D of the opening satisfies the following formula: Where, ha is the relative distance parameter from the opening to the anode target, hca is the relative distance parameter from the cathode to the opening, Lc is the length characteristic parameter of the cathode, La is the length characteristic parameter of the electron beam that can form a focal point on the anode target after being focused on the opening without the action of a focusing magnetic field, and dc is the diameter characteristic parameter of the cathode.

3. The self-shielding X-ray tube according to claim 1, characterized in that, The cathode is disk-shaped, and the diameter D of the opening satisfies the following formula: Where, ha is the relative distance parameter from the opening to the anode target, hca is the relative distance parameter from the cathode to the opening, Dc is the diameter characteristic parameter of the cathode, and Da is the length characteristic parameter of the electron beam that can form a focal point on the anode target after being focused on the opening without the action of a focusing magnetic field.

4. The self-shielding X-ray tube according to claim 1, characterized in that, The diameter of the opening is 0.2 mm to 5 mm.

5. The self-shielding X-ray tube according to claim 1, characterized in that, The anode target is a reflective target, which reflects the X-rays after being bombarded by the electron beam, and the sidewall of the anode cover is defined with an anode window for the X-rays to pass through.

6. The self-shielding X-ray tube according to claim 1, characterized in that, The anode target is a transmission target, which transmits X-rays after being bombarded by the electron beam. The self-shielding X-ray tube further includes: A focusing magnetic ring is formed as a ring so that the electron beam can pass through it. The focusing magnetic ring is embedded in the inner wall of the anode cover at the end facing the anode target. The focusing magnetic ring is used to generate a magnetic field in the same direction as the electron beam to focus the electron beam onto the anode target.

7. The self-shielding X-ray tube according to claim 6, characterized in that, Also includes: A compensating magnetic ring, formed as an annular element, allows the electron beam to pass through it. The compensating magnetic ring is embedded in the inner wall surface of the anode cover located between the opening and the anode target. The compensating magnetic ring is used to generate a magnetic field opposite to the direction of electron beam movement to defocus the electron beam passing through the opening.

8. The self-shielding X-ray tube according to claim 7, characterized in that, Also includes: A first magnetic shielding element is covered on the outer surface of the focusing magnetic ring for magnetic shielding; The second magnetic shielding element covers the outer surface of the compensating magnetic ring for magnetic shielding.

9. The self-shielding X-ray tube according to claim 7, characterized in that, The focusing magnetic ring is an electromagnetic element or a permanent magnet element; the compensating magnetic ring is an electromagnetic element or a permanent magnet element.

10. An X-ray device, characterized in that, Includes the self-shielded X-ray tube according to any one of claims 1-9.

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