Transmission type X-ray tube

Abstract

The invention discloses a transmission type X-ray tube which comprises a ceramic welding assembly, an electron gun assembly, a magnetic deflection assembly and a target assembly. The ceramic welding assembly comprises an anode base body, a cathode base body and a ceramic cavity, and the anode base body, the cathode base body and the ceramic cavity are welded into a whole in a brazing mode. A mode of combining a closed tube structure and a transmission target material is adopted, and the electron emission device has the advantages of being simple in manufacturing process, low in manufacturing cost, high in resolution ratio, long in service life and the like. According to the manufacturing process, ceramic is adopted as a main body and can bear pressure resistance higher than that of glass, so that better performance is obtained, and the brazing mode is more efficient and reliable than glass sealing; from the aspect of service life, the magnetic deflection assembly is introduced between the target material and the electron gun, and an electron beam can deflect in the X-Y axial direction by adjusting voltage and current on the coil, so that the focus position is changed, and breakdown of the target material caused by long-time work is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of electron emission, and in particular to a transmission type X-ray tube. Background Art

[0002] X-ray tubes can be divided into open tubes and closed tubes. Open tubes are open X-ray tubes, and closed tubes are closed X-ray tubes. Closed tubes use the refraction principle, and the window is still a certain distance from the focus. The actual focus size is the size of the ray irradiating the window; open tubes generally use magnetic focusing transmission, with a large window size and a small focus. According to the above principle, it is easier to obtain a smaller focus with an open tube than with a closed tube, so the magnification of the X-ray analysis system can be higher, and the geometric clarity will not have much impact on the actual image quality. In terms of equipment life, open tubes require frequent maintenance, and maintenance costs are expensive. Usually, maintenance is required after 300 to 500 hours of use. Some open tubes have a service life of 1000 to 1500 hours. If improperly maintained, it will affect the function of the equipment and even damage the equipment. Closed tubes usually do not require maintenance within 5000-8000 hours, so they are more convenient and trouble-free to use, but their life will end with the end of the filament life. Once the cathode filament in the closed tube is damaged, the entire X-ray tube must be replaced. The performance of open tube is better than that of closed tube in all aspects, so the price of open tube equipment is much more expensive than that of closed tube, but the filament of open tube is cheaper than that of closed tube. When the filament is damaged or expires, it can continue to work by simply replacing it with a new one, but the vacuum needs to be destroyed during replacement, and it takes a long time to regain the vacuum, which is not conducive to continuous detection operation scenarios.

[0003] The existing closed X-ray tube has a large focal spot, resulting in a low magnification of the X-ray analysis system. The geometric clarity will affect the actual image quality, and its life will end with the end of the filament life. Once the cathode filament in the closed tube is damaged, the entire X-ray tube must be replaced, which is inconvenient to use. Summary of the invention

[0004] The object of the present invention is to provide a transmission X-ray tube to solve the above technical problems.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A transmission type X-ray tube comprises a ceramic welding assembly, on which an electron gun assembly, a magnetic deflection assembly and a target assembly are respectively arranged;

[0007] The ceramic welding assembly comprises an anode substrate, a cathode substrate, and a ceramic cavity, and the anode substrate, the cathode substrate, and the ceramic cavity are welded into a whole by brazing;

[0008] An electron gun assembly, comprising a cathode emitter, a stem assembly and a cathode cap, wherein the cathode emitter is arranged on the cathode cap, the stem assembly and the cathode cap are fixedly connected by a conductive metal material, and the cathode emitter and the stem assembly are fixedly connected by a conductive metal material;

[0009] A magnetic deflection assembly, comprising a coil and a magnetic deflection outer ring, wherein the coil is fixedly connected to the inner side of the magnetic deflection outer ring;

[0010] The target assembly comprises a diamond window assembly, a target substrate and a magnetically permeable column, wherein the diamond window assembly and the magnetically permeable column are welded on the target substrate.

[0011] As a further solution of the present invention: the coils are provided in four groups, and the four groups of coils are distributed in a cross shape.

[0012] As a further solution of the present invention: the magnetic deflection outer ring and the anode substrate are connected by argon arc welding.

[0013] As a further solution of the present invention: the core column assembly includes ceramic, a core column and an outer ring, the interior of the outer ring is provided with ceramic, and a plurality of core columns are welded to the ceramic.

[0014] As a further solution of the present invention: the cathode emitter is a tungsten filament, an oxide cathode, a barium tungsten cathode, lanthanum hexaboride and a carbon nanotube cathode material.

[0015] As a further solution of the present invention: the transmission X-ray tube is provided with a magnetic deflection assembly between the target assembly and the electron gun assembly, and the magnetic field is obtained by means of an electromagnetic coil or a permanent magnet;

[0016] The electromagnetic coil adjusts the voltage and current on the coil to make the electron beam deflect in the XY axis, thereby changing the focus position of the electron beam; the permanent magnet changes the center position of the magnetic field by adjusting the relative position of the relative magnet and the center, thereby changing the focus position of the electron beam; avoiding the breakdown of the target material during long-term operation, so that the performance of the transmission X-ray tube is more stable and the service life is longer.

[0017] As a further solution of the present invention: the magnetically permeable column cooperates with the magnetic deflection assembly to adjust the voltage and current on the coil, or adjust the relative position of the permanent magnet, so that the electron beam is deflected in the XY axis, thereby changing the focal position.

[0018] Beneficial effects of the present invention:

[0019] The present application adopts a closed tube structure combined with a transmission target material, which has the advantages of simple manufacturing process, low cost, high resolution and long life. From the manufacturing process point of view, ceramics are used as the main body to withstand higher pressure than glass, so as to obtain better performance. The brazing method is also more efficient and reliable than glass sealing. From the service life point of view, a magnetic deflection assembly is introduced between the target material and the electron gun. The electron beam can be deflected in the XY axis by adjusting the voltage and current on the coil, or adjusting the relative position of the permanent magnet, thereby changing the focal position and avoiding the breakdown of the target material during long-term operation.

[0020] This application uses a transmission target material, and the radiation angle on the plane is almost 180 degrees. When the radiation angle is large, the stage can be tilted and moved, and at the same time, a resolution of 2 microns can be achieved to obtain better imaging effects.

[0021] The present application adopts a magnetic deflection structure. The magnetically permeable column cooperates with the magnetic deflection assembly to adjust the voltage and current on the coil, or adjust the relative position of the permanent magnet, so that the electron beam undergoes XY axial deflection, thereby changing the focal position. Compared with the fixed focus of a closed tube, the focus of the X-ray tube in the present application is not fixed, the use area of ​​the diamond window and the target material is greatly increased, and the service life is also greatly improved.

[0022] The present application uses ceramic as the main body which can withstand higher pressure than glass to obtain better performance, and the brazing method is also more efficient and reliable than glass sealing.

[0023] The present application integrates the focusing function into one body by adopting the cathode cap in the electron gun and has the pressure resistance capability, thereby reducing the number of parts, making the structure more stable and reliable, and reducing the number of process steps.

[0024] The present application adopts a diamond window target material designed on the target assembly, and the diamond window target material adopts a diamond tungsten plating process, which greatly improves the heat dissipation performance.

[0025] This application adopts a transmission structure. Compared with the traditional closed ray tube, the distance between the target and the object to be measured is closer. There is no distance between the target and the window, so the transmission X-ray tube is closer to the object to be measured, with a larger beam angle, and a higher imaging magnification ratio. The electrostatic focusing electric lens structure is adopted, which can converge the electron beam to the micron level and obtain a high-resolution imaging effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below in conjunction with the accompanying drawings.

[0027] Figure 1 It is a schematic diagram of the present invention;

[0028] Figure 2 An exploded view of the present invention;

[0029] Figure 3 is a schematic diagram of an electron gun assembly of the present invention;

[0030] Figure 4 is a schematic diagram of a ceramic welding assembly of the present invention;

[0031] Figure 5 is a schematic diagram of a magnetic deflection assembly of the present invention;

[0032] Figure 6 Schematic diagram of the target assembly of the present invention.

[0033] In the figure: 1. electron gun assembly; 101. cathode emitter; 102. core column assembly; 1021. ceramic; 1022. core column; 1023. outer ring; 103. cathode cap; 2. ceramic welding assembly; 201. anode substrate; 202. ceramic cavity; 203. cathode substrate; 3. magnetic deflection assembly; 301. coil; 302. magnetic deflection outer ring; 4. target assembly; 401. diamond window assembly; 4011. diamond window target; 402. target substrate; 403. magnetically permeable column. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] See also Figure 1-6 As shown, the present invention is a transmission type X-ray tube, comprising a ceramic welding assembly 2, wherein the ceramic welding assembly 2 comprises an anode substrate 201, a ceramic cavity 202 and a cathode substrate 203, wherein the anode substrate 201 ensures the sealing inside the tube and is connected to the target assembly 4, the cathode substrate 203 ensures the sealing inside the tube and is connected to the electron gun assembly 1, the ceramic cavity 202 plays a role of high voltage insulation, the upper and lower surfaces of the ceramic need to be metallized and brazed with a Kovar ring, and the anode substrate 201, the ceramic cavity 202 and the cathode substrate 203 are brazed into a whole;

[0036] The ceramic welding assembly 2 is respectively provided with an electron gun assembly 1, a magnetic deflection assembly 3 and a target assembly 4;

[0037] The electron gun assembly 1 provides electron emission, and the ceramic cavity 202 plays a role of high-voltage insulation. The electron beam reaches the magnetic deflection position, and the position of the electron beam is adjusted by adjusting the current on the coil 301. The focus finally falls on the diamond window target 4011 for transmission, and the X-ray is emitted from the position of the diamond window target 4011;

[0038] The electron gun assembly 1 includes a cathode emitter 101, a stem assembly 102 and a cathode cap 103. The cathode emitter 101 is an electrode used to generate electron emission in a vacuum electronic device. The stem assembly 102 is used for high voltage feedthrough inside and outside the tube to apply negative high voltage to the emitter 101. The number of stems 1022 can be set in different quantities according to needs. The cathode cap 103 focuses the electron beam and is applied with a voltage more negative than that of the cathode emitter 101. The magnitude of this voltage can be adjusted to achieve good focusing. The cathode emitter 101 is set on the cathode cap 103. The stem assembly 102 and the cathode cap 103 are fixedly connected by a conductive metal material. The cathode emitter 101 and the stem assembly 102 are fixedly connected by a conductive metal material.

[0039] The stem assembly 102 includes a ceramic 1021 , a stem 1022 and an outer ring 1023 . The ceramic 1021 is disposed inside the outer ring 1023 , and a plurality of stems 1022 are welded to the ceramic 1021 .

[0040] The cathode emitter of the electron gun can be made of cathode materials such as tungsten filament, oxide cathode, barium tungsten cathode, lanthanum hexaboride and carbon nanotube, all of which have the same function. Figure 3 The example of using barium tungsten cathode is given, and the schematic diagram of the heating element is shown. Multiple core columns are welded on a ceramic substrate, which can provide power supply requirements for multiple components in the electron gun while ensuring good centering performance, which helps to provide good coaxiality for electron optics.

[0041] The magnetic deflection assembly 3 can be a permanent magnet structure or an electromagnetic coil structure. Figure 5 The electromagnetic coil structure is listed, wherein the magnetic deflection assembly 3 includes a coil 301 and a magnetic deflection outer ring 302. The coil 301 is usually rectangular and replaceable. The number of coils 301 is generally an even number, and the structure of the corresponding magnetic deflection outer ring 302 also needs to be adjusted. In order to ensure the uniformity and symmetry of the magnetic field and facilitate the operation of magnetic deflection, before installing the coil 301, the magnetic deflection outer ring 302 is connected to the anode substrate 201 by argon arc welding to ensure the sealing inside the tube. The coil 301 is provided with four groups, and the four groups of coils 301 are distributed in a cross shape. The coil 301 is fixedly connected to the magnetic deflection outer ring 302.

[0042] The target assembly 4 includes a diamond window assembly 401, a diamond window target material 4011, a target substrate 402, and a magnetically permeable column 403. Finally, X-rays are emitted from the diamond window target material 4011. The diamond window target material 4011 is mounted on the top of the target substrate 402. The target substrate 402 is provided with a groove for mounting the diamond window assembly 401. The diamond window target material 4011 adopts a diamond tungsten plating process, which greatly improves the heat dissipation performance.

[0043] The present invention adopts a closed tube structure combined with a transmission target material, and has the advantages of simple manufacturing process, low cost, high resolution and long service life. From the perspective of manufacturing process, ceramics are used as the main body to withstand a higher pressure than glass, so as to obtain better performance. The brazing method is also more efficient and reliable than glass sealing. From the perspective of service life, a magnetic deflection component is introduced between the target material and the electron gun. The electron beam can be deflected in the XY axis by adjusting the voltage and current on the coil or the relative position of the permanent magnet, thereby changing the focal position and avoiding breakdown of the target material during long-term operation. By adopting a transmission target material, the radiation angle is almost 180 degrees on the plane. When the radiation angle is large, the stage can be tilted and moved, and a resolution of 2 microns can be achieved to obtain a better imaging effect.

[0044] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A transmission X-ray tube, characterized in that: It comprises a ceramic welding assembly, on which an electron gun assembly, a magnetic deflection assembly and a target assembly are respectively arranged, and is characterized in that: The ceramic welding assembly comprises an anode substrate, a cathode substrate, and a ceramic cavity, and the anode substrate, the cathode substrate, and the ceramic cavity are welded into a whole by brazing; An electron gun assembly, comprising a cathode emitter, a stem assembly and a cathode cap, wherein the cathode emitter is arranged on the cathode cap, the stem assembly and the cathode cap are fixedly connected by a conductive metal material, and the cathode emitter and the stem assembly are fixedly connected by a conductive metal material; A magnetic deflection assembly, comprising a coil and a magnetic deflection outer ring, wherein the coil is fixedly connected to the inner side of the magnetic deflection outer ring; The target assembly comprises a diamond window assembly, a target substrate and a magnetically permeable column, wherein the diamond window assembly and the magnetically permeable column are welded on the target substrate.

2. A transmission X-ray tube according to claim 1, characterized in that: The coils are arranged in four groups, and the four groups of coils are distributed in a cross shape.

3. A transmission X-ray tube according to claim 1, characterized in that: The magnetic deflection outer ring and the anode substrate are connected by argon arc welding.

4. A transmission X-ray tube according to claim 1, characterized in that: The core column assembly comprises ceramic, a core column and an outer ring. The ceramic is arranged inside the outer ring, and a plurality of core columns are welded on the ceramic.

5. A transmission X-ray tube according to claim 1, characterized in that: The cathode emitter is a tungsten filament, an oxide cathode, a barium tungsten cathode, lanthanum hexaboride and a carbon nanotube cathode material.

6. A transmission X-ray tube according to claim 1, characterized in that: The transmission X-ray tube is provided with a magnetic deflection assembly between the target assembly and the electron gun assembly, and the magnetic field is obtained by means of an electromagnetic coil or a permanent magnet; The electromagnetic coil deflects the electron beam in the XY direction by adjusting the voltage and current on the coil, thereby changing the focal position of the electron beam. The permanent magnet changes the focal position of the electron beam by adjusting the relative position of the relative magnet and the center to change the center position of the magnetic field.

7. A transmission X-ray tube according to claim 6, characterized in that: The magnetically permeable column cooperates with the magnetic deflection assembly to adjust the voltage and current on the coil, or adjust the relative position of the permanent magnet, so that the electron beam is deflected in the XY axis, thereby changing the focus position.

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