An open-tube miniature X-ray tube with adjustable anode and its experimental evaluation platform

Abstract

This invention discloses an open-tube miniature X-ray tube with adjustable anode and its experimental evaluation platform, belonging to the field of miniature micro-focal spot X-ray tube technology. The system comprises an open-tube miniature X-ray tube system and an experimental platform. The open-tube miniature X-ray tube system includes a hot cathode filament, an electrostatic lens focusing system, and an anode target. The experimental evaluation system includes a vacuum chamber and interfaces for electrical input and vacuum input that cooperate with the vacuum chamber. The anode-cathode distance can be adjusted using the positioning holes on the electron optics system. The experimental evaluation system fixes the electron optics system and provides the necessary experimental conditions such as a high vacuum environment, accelerating voltage, and heating current. This invention enables open-tube experiments with adjustable anode for miniature X-ray tubes. Compared to closed-tube experiments, open-tube experiments facilitate adjustments to the miniature tube design and reduce experimental costs.

Description

Technical Field

[0001] This invention belongs to the field of cathode optical structures for miniature X-ray tubes, and specifically relates to an experimental method for optimizing the cathode structure of miniature X-ray tubes. Background Technology

[0002] Due to size constraints, conventional miniature X-ray tubes often employ a closed-tube structure that does not require an additional vacuum system. However, this closed-tube structure necessitates a pre-treatment sealing process, which is complex and time-consuming. Furthermore, once damaged, a closed-tube X-ray tube cannot be repaired, failing to meet the need for experimental convenience.

[0003] Electro-optical design often relies on electro-optical software simulations, but simulations often require approximations for ease of calculation, which often result in errors between the simulation results and the actual situation. Simulations often cannot determine the optimal electro-optical structure.

[0004] In order to experimentally determine a better structure for miniature X-ray tubes, an experimental method suitable for miniature X-ray tubes that is both time-saving and cost-effective is needed. Summary of the Invention

[0005] The technical problem solved by this invention is to propose an open-tube micro X-ray tube with adjustable anode and its experimental platform structure, which is more conducive to the experimental evaluation of the performance of micro X-ray tubes with different electron optical structures, saving experimental time and reducing experimental costs.

[0006] The objective of this invention can be achieved through the following technical solution: An open-tube miniature X-ray tube with adjustable anode: The open-tube miniature X-ray tube has a gate fixing ring at its end, which is fixed to the gate by threads. The filament is fixed to the gate by a set wire. The rear end of the gate fixing ring is a metal flange, which can be connected to an aviation connector to achieve vacuum sealing and simultaneously provide the actual voltage and filament heating current. An insulator is compactly placed at the front end of the gate fixing ring, and a positioning hole is provided at the front end of the insulator for fixing the anode position. An electron beam channel is provided at the center of the anode, and the anode outlet position is fixed to the X-ray anode target by welding. Several insulating gaskets can be added between the gate fixing ring and the insulator to adjust the distance between the anode and the cathode. The relative positions of the gate and the anode are fixed by positioning holes on the outer positioning ceramic body and positioning insulating pillars. The experimental platform for realizing the open-tube miniature X-ray tube is a metal cavity with flanges on all six sides. The open-tube miniature X-ray tube is fixedly connected by the rear flange, and a high X-ray transmittance sealed window is fixed to the front flange. X-rays pass through the sealed window and are received by the detector. The left and right flanges are used to connect the vacuum system and the vacuum measurement system. The upper flange connects to a vacuum high-voltage insulated electrode to provide the anode voltage, while the lower flange can be used with X-ray evaluation methods to mount an evaluation device.

[0007] The present invention has the following beneficial effects:

[0008] 1. This invention replaces the closed-tube structure with an open-tube micro X-ray tube structure, which avoids the sealing process required for the closed-tube structure. At the same time, the entire system, except for the anode target, is mechanically connected, avoiding the welding process, thereby saving experimental time and costs.

[0009] 2. This invention uses an adjustable anode mechanical connection, which allows the anode position to be adjusted by adding or reducing the number of insulating pads. This eliminates the need to reprocess parts, saves time and costs, and facilitates experimental evaluation of different structures. Attached Figure Description

[0010] Figure 1 This is a cross-sectional view of an open-tube micro X-ray tube with adjustable anode and its experimental platform proposed in this invention.

[0011] Figure 2 This is a cross-sectional view of an open-tube micro X-ray tube with adjustable anode proposed in this invention.

[0012] In the diagram, 1. Hot cathode filament; 101. Pure metal hot cathode; 102. Filament terminal; 103. Ceramic body; 2. Grid; 3. Electron beam; 4. Anode; 5. Anode target; 501. Heavy metal target coating; 502. Anode substrate; 6. Insulator; 7. Positioning insulator; 8. Grid fixing ring; 9. Insulating gasket; 10. Insulating positioning post; 11. Vacuum cavity; 12. Vacuum high-voltage insulating electrode; 13. High X-ray transmittance sealing window; 14. High vacuum flange; 15. X-ray. Detailed Implementation

[0013] The present invention will now be explained in conjunction with the accompanying drawings of the embodiments thereof. The description in this section is merely illustrative and explanatory and should not be construed as limiting the scope of protection of the present invention.

[0014] Please refer to the following: Figure 1-Figure 2 In this invention, the anode-adjustable open-tube micro X-ray tube and its experimental platform include: a hot cathode filament 1, a pure metal hot cathode 101, a filament terminal block 102, a ceramic body 103, a grid 2, an anode 4, an anode target 5, a heavy metal target coating 501, an anode substrate 502, an insulator 6, a positioning insulator 7, a grid fixing ring 8, an insulating gasket 9, an insulating positioning post 10, a vacuum chamber 11, a vacuum high-voltage insulating electrode 12, a high X-ray transmittance sealing window 13, and a high vacuum flange 14; the grid fixing ring 8, the anode 4, and the insulator 6 are all fixed on the positioning insulator 7, the hot cathode filament 1 is fixed on the grid 2, and is fixed along with the grid 2 and the grid fixing ring 8, and the grid fixing ring 8, the vacuum high-voltage insulating electrode 12, the high X-ray transmittance sealing window 13, and the high vacuum flange 14 are all fixed on the vacuum chamber 11;

[0015] The pure metal thermionic cathode 101 is used to emit electrons. Commercially available thermionic cathodes such as tungsten filament or lanthanum hexaboride can be selected. The thermionic cathode can be fixed to the filament terminal 102 by pressure welding. The heating current is provided through the filament terminal to make the thermionic cathode reach the working temperature to realize electron emission. The advantage of tungsten filament and lanthanum hexaboride cathode is that the electron beam spot is smaller and the implementation is simple. The filament terminal 102 is fixed to the ceramic body 103 by brazing. The ceramic body 103 has a positioning groove and is fixedly assembled to the grid 2 by a set screw.

[0016] The gate 2 is pencil-shaped, consisting of a hollow cylinder and a hollow frustum. A small limiting hole is opened in the center to control the size of the emitted electron beam 3. Several slightly larger circular holes are opened around the limiting hole to adjust the electric field distribution on the cathode surface. The gate 2 is preferably made of high-temperature resistant and electron beam bombardment resistant materials such as molybdenum, rhenium, and tungsten. The outer side of the gate 2 is provided with threads, which are used to fix it to the gate fixing ring 8.

[0017] The insulator 6 is a hollow cylindrical structure used for electrical insulation between the gate and the anode. The front end of the insulator 6 has a positioning hole that matches the positioning hole on the anode 4 to fix the two together. The insulator 6 is preferably made of a material such as polytetrafluoroethylene, which has good insulation properties and is easy to process.

[0018] The anode 4 is an axisymmetric cylindrical structure with a restricted hole, loaded with a positive voltage of 10-50 kV. The anode substrate 502 is connected to the anode 4 by welding, and a heavy metal target coating 501 is deposited on the anode substrate 502 by a metal coating process. After being accelerated by the anode 4, the electron beam 3 bombards the heavy metal target coating 501 to generate X-rays. The anode 4 is preferably made of high-temperature resistant and electron beam-resistant materials such as molybdenum, rhenium, and tungsten, and the heavy metal target coating 501 is preferably made of high atomic number metals such as tungsten. The anode substrate 502 needs to be made of a low atomic number material with good electrical and thermal conductivity, such as diamond. The front and rear ends of the anode 4 are both provided with positioning holes. The front positioning hole mates with the insulator 6, and the rear positioning hole is fixedly engaged with the positioning insulator 7.

[0019] Positioning insulator 7 has positioning holes around its front and rear parts to achieve overall relative fixation of the miniature X-ray tube. The positioning holes at the front end are evenly distributed to achieve fixed connection with the gate fixing ring 8. The rear end has spiral rising positioning holes. After adding different numbers of insulating pads 9, the positioning holes on the anode 4 need to match the positioning holes on the positioning insulator 7 in different directions to achieve fixation. The positioning insulator 7 and the insulating pads 9 are preferably made of polytetrafluoroethylene.

[0020] The miniature X-ray tube is fixedly connected to the vacuum chamber 11 via a metal flange on the gate fixing ring 8, and can be connected to an aviation plug via the metal flange to achieve sealing of the miniature X-ray tube and provide heating current to the hot cathode;

[0021] The vacuum chamber 11 has flange interfaces on six sides, which are respectively connected to the miniature X-ray tube, the vacuum system, the vacuum insulating electrode 12, and the high X-ray transmittance sealing window 13;

[0022] The high-voltage vacuum insulating electrode 12 is connected to the vacuum chamber 11 via a flange to provide an accelerating voltage of 0-50 kV to the anode;

[0023] The high X-ray transmittance sealing window 13 is fixedly connected to the vacuum chamber 11 via a high vacuum flange 14; the high X-ray transmittance sealing window 13 is preferably made of a material with high X-ray transmittance and good sealing performance, such as polypropylene;

[0024] The specific embodiments described in this invention are merely illustrative of the spirit of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. An open-tube miniature X-ray tube with adjustable anode, characterized in that, The open-tube miniature X-ray tube has a grid fixing ring at its end. The grid fixing ring (8) is fixed to the grid (2) by threads. The hot cathode filament (1) is fixed to the grid (2) by a set screw. The rear end of the grid fixing ring (8) is a metal flange, which can be connected to an aviation plug to achieve vacuum sealing and provide actual voltage and filament heating current. An insulator (6) is compactly placed at the front end of the grid fixing ring (8). The front end of the insulator (6) is provided with a positioning hole for fixing the position of the anode (4). An electron beam channel is provided in the center of the anode (4). The X-ray anode is fixed at the outlet position of the anode (4) by welding. Several insulating pads (9) can be added between the target (5), the gate fixing ring (8) and the insulator (6) to adjust the distance between the anode (4) and the cathode; the gate fixing ring (8), the anode (4) and the insulator (6) are all fixed on the positioning insulator (7); the front end and the rear end of the anode (4) are all surrounded by positioning holes; the front positioning hole cooperates with the insulator (6) and the rear positioning hole is fixedly cooperated with the positioning insulator (7); the relative positions of the gate (2) and the anode (4) are fixed by the positioning hole on the outer positioning insulator (7) and the positioning insulating post (10).

2. An experimental evaluation platform for implementing the open-tube miniature X-ray tube as described in claim 1, characterized in that, An open-tube miniature X-ray tube system is installed on an experimental evaluation platform. The platform provides the high vacuum environment, accelerating voltage, grid voltage, and filament heating current required for the miniature X-ray tube. X-ray signals are received and evaluated through an X-ray detector. The experimental platform is a vacuum chamber (11) with flanges on all six sides. The open-tube miniature X-ray tube is fixedly connected through the rear flange, and a high X-ray transmittance sealed window is fixed on the front flange. X-rays pass through the sealed window and are received by the detector. The left and right flanges are used to connect the vacuum system and the vacuum measurement system. The upper flange is connected to a vacuum high-voltage insulated electrode to provide the anode voltage, and the lower flange is equipped with an evaluation device in conjunction with the X-ray evaluation method.

3. The experimental evaluation platform according to claim 2, characterized in that, The gate (2) is a pencil-shaped structure composed of a hollow frustum and a cylinder; a small hole is opened in the center of the front end, and multiple circular holes are around the small hole to adjust the electric field distribution near the cathode.

4. The experimental evaluation platform according to claim 2, characterized in that, The anode target (5) is a conductive substrate coated with heavy metal target material.

5. The experimental evaluation platform according to claim 2, characterized in that, The insulator (6) and the positioning insulator (7) are made of polytetrafluoroethylene.

6. The experimental evaluation platform according to claim 2, characterized in that, The anode (4), insulator (6), and positioning insulator (7) have positioning holes, which, together with the insulating pad (9) and positioning insulating post (10), enable the assembly of the miniature X-ray tube and the adjustment of the anode height.

7. The experimental evaluation platform according to claim 2, characterized in that, The vacuum chamber (11) is cylindrical and has flanges on the top, bottom and sides for connecting to a vacuum pump, high-voltage electrode and micro X-ray tube system. The vacuum chamber (11) is made of 304 stainless steel.

8. The experimental evaluation platform according to claim 2, characterized in that, The vacuum high-voltage insulating electrode (12) is a three-layer structure with axisymmetric design. The center is a conductive metal electrode, the outer side of the electrode is a layer of insulating ceramic, and the outermost side is a metal flange.

9. The experimental evaluation platform according to claim 2, characterized in that, The high X-ray transmittance sealing window (13) is a thin circular sheet with low outgassing rate, made of polypropylene or polytetrafluoroethylene; the high X-ray transmittance sealing window (13) is fixed to the vacuum chamber (11) by a high vacuum flange (14).

10. The experimental evaluation platform according to claim 2, characterized in that, The hot cathode filament (1) is a direct-heated pure metal cathode.

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