X-ray tube capable of maintaining high vacuum degree

Abstract

This invention provides an X-ray tube capable of maintaining a high vacuum, comprising a cathode assembly and an anode assembly; a housing forming a vacuum cavity with the anode and cathode assemblies; a cathode exhaust pipe, with its first end connected to the cathode assembly and its second end sealed; and a cavity exhaust pipe, with its first end connected to the X-ray tube cavity via an exhaust port located on the housing and its second end sealed. Alternatively, the X-ray tube may further include a vacuum maintaining mechanism outside the housing, with the second end of the cavity exhaust pipe connected to the vacuum maintaining mechanism. This invention, by employing a vacuum maintaining mechanism such as a vacuum pump or ion pump, evacuates the X-ray tube during the aging process, maintaining an ultra-high vacuum level inside the tube, which can significantly improve the working stability of the X-ray tube and extend its lifespan.

Description

Technical Field

[0001] This invention relates to the field of X-ray tube technology. More specifically, it relates to an X-ray tube capable of maintaining a high vacuum. Background Technology

[0002] High-energy X-ray tubes (such as 450kV tubes) are key components in industrial non-destructive testing, medical CT, and scientific research. Their basic working principle involves generating X-rays by bombarding a metal target (usually a tungsten target) with a high-speed electron beam. To ensure that the electron beam's energy does not decay during acceleration from the cathode to the anode, and to prevent ionization from collisions with gas molecules that could lead to discharge breakdown, an ultra-high vacuum environment (typically requiring 10 kV) must be maintained inside the X-ray tube. ﹣7 (Pa level or higher). Therefore, the ability to maintain the vacuum level inside the tube directly determines the working stability, reliability, and service life of the high-energy X-ray tube.

[0003] Currently, achieving ultra-high vacuum mainly relies on high-vacuum exhaust system. During manufacturing, the assembled core is connected to the exhaust system, and a pumping system consisting of molecular pumps, sputtering ion pumps, etc., is used for prolonged baking and evacuation, achieving an ultimate vacuum of up to 10⁻⁶. ﹣8 The pressure is in the Pa range. After the required vacuum level is reached, the connecting pipe clamp is broken and pressed shut using cold welding clamps, making the housing an independent vacuum-sealed unit.

[0004] However, the aforementioned traditional process has an inherent and insurmountable flaw: the problem of maintaining the vacuum level of the vacuum sealing unit after sealing. During the aging and use of X-ray tubes, the cathode and anode assemblies undergo frequent electron bombardment and micro-discharge processes under a high-voltage electric field. This continuously causes the internal materials such as metal electrodes, ceramic insulators, and solder to release adsorbed or newly generated gases. This process is known as "gas release." These released gases can significantly degrade the vacuum level inside the tube core, causing instability in the operating current and fluctuations in the X-ray output dose rate, or even severe vacuum breakdown (arson), permanent damage to the electrodes, and even complete failure of the casing.

[0005] Existing technologies offer very limited and reactive solutions to this problem. One approach is to extend the baking and evacuation time of the exhaust station as much as possible, and to perform preliminary aging, aiming to remove any potentially released gases before sealing. However, this method is inefficient, significantly increasing manufacturing costs and time, and cannot eliminate the risk of material venting during subsequent use. Another approach relies on getters on the inner wall of the casing to adsorb some of the gas. However, the adsorption capacity and speed of these getters are limited; for the large amounts of gas generated during the aging process of the high-energy tube, the adsorption effect is often insufficient, making it impossible to dynamically maintain the vacuum level. Utility Model Content

[0006] The purpose of this invention is to provide an X-ray tube that can maintain a high vacuum level, so as to solve at least one of the above-mentioned technical problems.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention provides an X-ray tube capable of maintaining a high vacuum, comprising:

[0009] Cathode assembly and anode assembly;

[0010] The housing that forms a vacuum cavity with the anode and cathode assemblies;

[0011] The cathode exhaust pipe has a first end connected to the cathode assembly and a second end sealed.

[0012] The cavity exhaust pipe has its first end connected to the X-ray tube cavity via an exhaust port located in the housing, and its second end is sealed, or...

[0013] The X-ray tube further includes a vacuum maintaining mechanism outside the housing, and the second end of the cavity exhaust pipe is connected to the vacuum maintaining mechanism.

[0014] Preferably, the vacuum maintaining mechanism is a vacuum pump or an ion pump.

[0015] A preferred embodiment is that an inwardly recessed portion is formed on the circumferential sidewall of the housing, and the exhaust port of the cavity exhaust pipe is disposed in the recessed portion.

[0016] In a preferred embodiment, the exhaust port of the cavity exhaust pipe is located on the anode assembly side of the housing.

[0017] In a preferred embodiment, the X-ray tube further includes a focusing disk between the cathode assembly and the anode assembly.

[0018] In a preferred embodiment, the exhaust port of the cavity exhaust pipe is located on the anode assembly side of the clustering disk.

[0019] A preferred embodiment is that the X-ray tube includes a cathode insulating ceramic ring and an anode insulating ceramic ring, and each insulating ceramic ring has a coating on its surface inside the cavity that reduces the secondary electron emission coefficient.

[0020] In a preferred embodiment, the cathode assembly is connected to the top wall of the housing by brazing and extends into the interior of the housing; the cathode assembly includes a cathode support and a filament structure located in a vacuum cavity and fixed to the lower end of the cathode support; the filament structure includes a filament cover fixed to the cathode support and a filament holder and a filament fixed inside the filament cover; the outer surface of the filament cover is mirrored, and a rectangular hole for initial focusing of the electron beam is provided on the lower end face of the filament cover.

[0021] In a preferred embodiment, the anode assembly is connected to the bottom wall of the housing by brazing and extends into the interior of the housing; the anode assembly includes an anode rod, a tungsten target brazed to the inclined surface at the top of the anode rod, a shield brazed to the anode rod, and an anode cap fixed to the shield; the tungsten target, the shield, and the anode cap are all located inside the vacuum chamber.

[0022] In a preferred embodiment, the X-ray tube further includes a beryllium window disposed on the side wall of the housing.

[0023] The beneficial effects of this utility model are as follows:

[0024] This invention provides an X-ray tube capable of maintaining a high vacuum, comprising a cathode assembly and an anode assembly; a housing forming a vacuum cavity with the anode and cathode assemblies; a cathode exhaust pipe, with its first end connected to the cathode assembly and its second end sealed; and a cavity exhaust pipe, with its first end connected to the X-ray tube cavity via an exhaust port located on the housing and its second end sealed. Alternatively, the X-ray tube may further include a vacuum maintaining mechanism outside the housing, with the second end of the cavity exhaust pipe connected to the vacuum maintaining mechanism. By providing a cavity exhaust pipe connected to the X-ray tube cavity, a vacuum pump can be used to extract the gas released from the housing during the aging and operation of the X-ray tube, thereby maintaining the vacuum level within the housing and achieving dynamic maintenance of the vacuum level inside the tube. This effectively solves the problem of vacuum deterioration caused by material outgassing during aging and operation, thus improving the tube's operational stability and service life. Furthermore, this invention provides a vacuum maintaining mechanism outside the X-ray tube that is connected to the second end of the cavity exhaust pipe. This vacuum maintaining mechanism can not only maintain the high vacuum of the cavity during the aging process, but also maintain the high vacuum of the cavity when the X-ray is in use. This reduces the amount of gas released by the material inside the X-ray tube during the process of applying high pressure to the anode, which adheres to the X-ray tube wall as particles. This avoids high-pressure arcing caused by the gas released and the adhered particles during operation, and significantly extends the life of the X-ray tube.

[0025] The X-ray tube provided by this invention has its cathode and anode located at the upper and lower ends of the housing, respectively, requiring connection to extremely high negative and positive voltages. By mounting the vacuum maintaining mechanism, such as that of a vacuum pump or ion pump, on the outside of the housing sidewall, the area of ​​the high-voltage electrical interfaces at both ends is perfectly avoided. This fundamentally eliminates the risk of creepage, discharge, or short circuit between the high-voltage leads and the pump body, greatly improving the electrical safety and reliability of the equipment.

[0026] The connection between the cavity exhaust pipe and the shell sidewall provides optimal operating space and perspective for the cold welding sealing process of the exhaust pipe after aging. Operators can perform the sealing operation horizontally, which is easier to apply force and control compared to the compact top or bottom, ensuring a smooth, even, and reliable seal. During aging, the electrodes and ceramic components release gas due to electron bombardment. Placing the exhaust port on the shell sidewall, closer to the main gas release sources (such as the focusing disk and anode assembly), allows for more efficient and rapid extraction or ionization of the released gas, preventing localized gas accumulation within the shell and thus more effectively maintaining a high vacuum throughout the entire pipe. Attached Figure Description

[0027] The specific embodiments of this utility model will be further described in detail below with reference to the accompanying drawings.

[0028] Figure 1 This is a schematic diagram of the overall structure of the X-ray tube in the first embodiment of this utility model.

[0029] Figure 2 This is a schematic diagram of the X-ray tube after the aging process is completed and the cavity exhaust pipe is cold-welded and sealed in the second embodiment of this utility model. Detailed Implementation

[0030] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present invention.

[0031] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0032] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0033] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0034] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0035] X-ray tube aging is a process that uses electrical discharge to eliminate microscopic protrusions, impurities, and defects on the electrode surface. During aging, a small current is discharged to melt and evaporate the microscopic protrusions on the surface, making the electrode surface smooth and flat, reducing the enhancement effect of the local electric field, and increasing the breakdown voltage. Current 450kV high-voltage X-ray tubes face a problem: the ultimate vacuum level achievable by the exhaust station before sealing is significantly different from the actual vacuum level maintained inside the tube after sealing, especially after aging and long-term use. This challenge in maintaining vacuum has become a technical bottleneck restricting further improvements in the performance, reliability, and lifespan of high-energy X-ray tubes.

[0036] This invention provides an X-ray tube capable of maintaining an ultra-high vacuum level within a cavity.

[0037] Figure 1This invention illustrates an X-ray tube capable of maintaining a high vacuum, according to a first embodiment of the present invention. The X-ray tube includes: a cathode assembly 1 and an anode assembly 2; a housing 6 forming a vacuum cavity with the anode assembly 2 and the cathode assembly 1; a cathode exhaust pipe 16, with its first end connected to the cathode assembly 1 and its second end sealed; and a cavity exhaust pipe 61, with its first end connected to the X-ray tube cavity via an exhaust port located on the housing 6 and its second end sealed. The X-ray tube further includes a vacuum maintaining mechanism 4 outside the housing 6, and the second end of the cavity exhaust pipe 61 is connected to the vacuum maintaining mechanism 4. The vacuum maintaining mechanism 4 can specifically be a vacuum pump or an ion pump. The cathode and anode of the X-ray tube of this invention are located at the upper and lower ends of the housing, respectively, requiring connection to extremely high negative and positive voltages. By installing the vacuum maintaining mechanism 4, such as a vacuum pump or ion pump, outside the side wall of the housing 6, the area of ​​the high-voltage electrical interfaces at both ends is perfectly avoided, fundamentally eliminating the risk of creepage, discharge, or short circuit between the high-voltage leads and the pump body, greatly improving the electrical safety and reliability of the equipment. More specifically, the aforementioned X-ray tube includes a cylindrical housing 6 made of metal; and a cathode assembly 1 and an anode assembly 2 fixed to both ends of the housing 6 along its axial direction (i.e., vertical direction). A vacuum cavity is formed between the housing 6, the cathode assembly 1, and the anode assembly 2, providing an unobstructed acceleration path for the electron beam from the cathode assembly 1 to the anode assembly 2. The X-ray tube also includes a vacuum maintaining mechanism 4 connected to the peripheral sidewall of the housing 6. The vacuum maintaining mechanism 4 communicates with the vacuum cavity and is used to extract or ionize and adsorb the gas released inside the housing 6 during the aging and operation of the X-ray tube, thereby maintaining the vacuum level inside the housing 6, i.e., maintaining the vacuum level of the vacuum cavity. Throughout the aging and operation process, a vacuum pump or ion pump continuously extracts the gas inside the housing 6 to maintain an ultra-high vacuum level inside the tube. The housing 6 is coaxially arranged with the cathode assembly 1 and the anode assembly 2. Furthermore, the upper end of the housing 6 is sealed with the cathode assembly 1 by brazing and argon arc welding, and the lower end is connected to the anode assembly 2 in the same manner. The three together form a sealed cavity, which becomes a vacuum cavity after evacuation. The initial evacuation of the housing 6 requires evacuation through an exhaust platform. The exhaust platform is connected to the cathode exhaust pipe 16 connected to the top of the cathode assembly 1. After reaching the predetermined vacuum level in the cavity, a vacuum cavity is formed, and the cathode exhaust pipe 16 at the top of the cathode assembly 1 is sealed off, allowing the X-ray tube to detach from the exhaust platform. Using an exhaust platform for initial evacuation is more efficient, and since the gas inside the X-ray tube is mostly concentrated at the top of the cavity, i.e., where the cathode assembly 1 is located, the evacuation effect is better when the exhaust platform evacuates from the top of the cathode assembly 1 outwards.Because the X-ray tube needs to be sealed in a cooling oil tank and high voltage needs to be applied to the cathode during aging, it is impossible for a fragile exhaust pipe, which requires maintaining an ultra-high vacuum, to pass through the sealed oil tank and connect to the exhaust platform. A metal pipe connecting the X-ray tube and the grounded exhaust platform would become a direct path between high voltage and ground, which would cause severe high-voltage breakdown and discharge, instantly destroying the equipment. Therefore, the existing exhaust platform cannot be connected to the X-ray tube during aging and operation. After the X-ray tube is evacuated using the exhaust platform, the vacuum maintaining mechanism 4 is activated while the X-ray tube is aging and evacuated during operation. The ultra-high vacuum is dynamically maintained inside the housing by a vacuum pump or ion pump.

[0038] More specifically, during the exhaust process of the X-ray tube in this invention, the vacuum maintaining mechanism 4 is initially deactivated. Voltage is applied to the cathode, but not to the anode. The cathode exhaust pipe 16, in conjunction with the exhaust pipe of the exhaust platform, connects the exhaust platform to the second end (upper end) of the cathode exhaust pipe 16 to evacuate the X-ray tube. Simultaneously, exhaust is applied to the cathode in its working state. After the required vacuum level is achieved within the tube, the second end of the cathode exhaust pipe 16 is sealed. Specifically, cold welding clamps can be used to cold-press and seal the cathode exhaust pipe 16, separating it from the exhaust platform. Then, the exhausted X-ray tube undergoes aging. Voltage is applied to the anode, exhaust is applied to the anode in its working state, and the vacuum maintaining mechanism 4 is used to evacuate the X-ray tube, maintaining the vacuum level of the cavity during aging. After aging is complete, the vacuum maintaining mechanism 4 is closed, resulting in an X-ray tube with the cavity exhaust pipe connected to the vacuum maintaining mechanism. This X-ray tube maintains a high vacuum level by drawing a vacuum during the aging process, while simultaneously expelling the gas emitted from the anode into the cavity. This prevents impurities from adhering to the cavity wall and condensing into metal particles, reducing the possibility of arcing during high-voltage operation of the X-ray tube. Overall, this improves the working stability, service life, and safety of the 450KV X-ray tube.

[0039] During the operation of the X-ray tube, voltage is applied to both the cathode and anode, and the vacuum maintenance mechanism 4 is activated simultaneously. This mechanism, in conjunction with the cavity exhaust pipe 61, evacuates the X-ray tube, maintaining its vacuum level during operation. In this first embodiment, a vacuum maintenance mechanism 4 connected to the second end of the cavity exhaust pipe 61 is provided outside the X-ray tube. This mechanism not only maintains a high vacuum level in the cavity during aging but also during X-ray tube use. This reduces the amount of gas released from the material inside the X-ray tube during the anode high-pressure process, which adheres to the tube wall as particles. This prevents high-pressure arcing caused by released gas and adhered particles during operation, significantly extending the lifespan of the X-ray tube.

[0040] In one specific embodiment, a cavity exhaust pipe 61, communicating with the vacuum chamber, is fixedly mounted on the circumferential side wall of the housing 6. The cavity exhaust pipe 61 is horizontally positioned with its inner exhaust port facing the anode assembly 2. The vacuum maintaining mechanism 4 communicates with the vacuum chamber through the cavity exhaust pipe 61. The exhaust port of the cavity exhaust pipe 61 is located on the anode assembly 2 side of the housing 6. The fundamental purpose of horizontally positioning the cavity exhaust pipe 61 with its inner exhaust port facing the anode assembly 2 is to construct the shortest and most direct high-speed gas extraction channel from the anode to the vacuum maintaining mechanism 4. This invention, by employing a vacuum maintaining mechanism such as a vacuum pump or ion pump, continuously extracts or ionizes the rarefied gas inside the high-pressure X-ray tube, maintaining an ultra-high vacuum level inside the tube. This reduces process requirements while improving the vacuum level of the high-pressure tube and extending its lifespan. Furthermore, by connecting the vacuum pump or ion pump to the side wall of the X-ray tube's metal housing, the problems of difficult pump installation, inconvenient operation, and low gas extraction efficiency are effectively solved. This layout optimizes the housing space structure, avoids interference with high-voltage lines, and significantly improves electrical safety and assembly process reliability. At the same time, the exhaust port of the exhaust pipe is closer to the gas release source, which can maintain the ultra-high vacuum inside the tube more efficiently, thereby improving the overall working stability, service life and safety of the 450KV X-ray tube.

[0041] In one specific embodiment, an inwardly recessed portion is formed on the peripheral sidewall of the housing 6, and the exhaust port of the cavity exhaust pipe 61 is disposed in the recessed portion. A partially planar sidewall is formed on the peripheral sidewall of the housing 6, thus forming the recessed portion, and the cavity exhaust pipe 61 penetrates this partially planar sidewall and is fixed to the housing 6. The exhaust port of the vacuum maintaining mechanism 4, used for extracting or ionizing the gas released from the housing, is connected to the cavity exhaust pipe 61. The cavity exhaust pipe 61 can achieve a perfect circumferential connection with the plane, forming a uniform, regular, and high-quality annular weld, making welding simpler and more convenient. The flat contact surface ensures uniform heat distribution during welding, allowing the solder to fully fill, resulting in high weld strength and reliable airtightness, which is the foundation for ensuring an ultra-high vacuum environment.

[0042] Regarding the structure of the cathode assembly 1, the cathode assembly 1 is connected to the top wall of the housing 6 by brazing and extends through the top wall into the interior of the housing 6; the cathode assembly 1 includes a cathode insulating ceramic ring 14 connected to the inner side of the top wall of the housing 6, a cathode support 15 connected to the inner edge of the cathode insulating ceramic ring 14, and a filament structure located in the vacuum cavity and fixed to the lower end of the cathode support 15; the filament structure includes a filament cover 12 fixed to the cathode support 15 and a filament holder 13 and a filament 11 fixed inside the filament cover 12; the outer surface of the filament cover 12 is mirrored, and a rectangular hole 121 for initial focusing of the electron beam is opened on the lower end face of the filament cover 12.

[0043] More specifically, the aforementioned cathode assembly 1 is used to generate and initially form a controllable electron beam directed towards the anode. An external filament power supply applies a relatively low voltage AC or DC current to the filament 11. Current flows through the tungsten filament, causing it to heat up rapidly due to resistance. At high temperatures, the thermal motion of free electrons within the filament increases dramatically. When the kinetic energy of the electrons is sufficient to overcome the work function of the metal surface, they evaporate from the filament surface and enter the surrounding vacuum space. The thermionic electrons emitted from the filament and diffused around it possess extremely high acceleration under the influence of a large electric field, causing them to move rapidly towards the anode. The filament cover 12 is a metal shield, typically at the same potential as the cathode (i.e., also under high negative voltage). It surrounds the filament, physically blocking electrons emitted from the sides and back of the filament 11, forcing electrons to exit only through the rectangular hole 121 at the lower end of the filament cover 12. The edges of the rectangular aperture 121 of the filament cover 12, the filament itself, and the high voltage of the anode work together to form an electrostatic lens system at the rectangular aperture 121 of the filament cover 12. This electrostatic lens exerts a force on the passing electrons, converging them towards the central axis, causing the originally divergent electrons to begin to converge towards the center, forming a pre-focused electron beam. The design of the rectangular aperture 121 allows the electron beam to be shaped into a flat rectangular beam as it passes through, which better meets the requirements for subsequent bombardment of the inclined tungsten target. The mirror finish on the outer surface of the filament cover 12 is crucial. The extremely high smoothness eliminates microscopic sharp points and burrs, greatly smoothing the electric field distribution on its surface, avoiding sharp discharge or vacuum breakdown caused by local electric field concentration under extremely high negative potentials, and ensuring operational stability. After the initial shaping and focusing of the filament cover 12, an electron beam with a certain shape (rectangular cross-section) and a certain convergence angle is emitted from the cathode assembly 1 and enters the main acceleration region dominated by the high voltage electric field between the cathode and anode. During this stage, electrons are continuously and powerfully accelerated by a 450kV electric field and fly towards the anode assembly. Subsequently, the electron beam passes through the focusing aperture 51 at the center of the focusing disk 5, is refocused, and further concentrated before finally bombarding the tungsten target 21 with extremely high energy and a very small spot size.

[0044] Regarding the structure of the anode assembly 2, the anode assembly 2 is connected to the bottom wall of the housing 6 by brazing and extends through the bottom wall into the interior of the housing 6. The anode assembly 2 includes an anode insulating ceramic ring 24 connected to the inner surface of the bottom wall of the metal housing, an anode rod 23 connected to the inner edge of the anode insulating ceramic ring 24 and extending into the vacuum cavity, a tungsten target 21 brazed to the inclined surface at the top of the anode rod 23, a shield 25 brazed to the anode rod 23, and an anode cap 22 fixed to the shield 25. The tungsten target 21, the shield 25, and the anode cap 22 are all located within the vacuum cavity. Further, the tungsten target 21 and the shield 25 are respectively formed with a first central through hole 221 and a second central through hole 252 for the electron beam to pass through, and both central through holes are corresponding to the rectangular hole 121. The transition edges and corners of the shield 25 are rounded. More specifically, the anode assembly 2 is used to receive the electron beam and generate X-rays. An electron beam emitted from cathode assembly 1 and accelerated by high voltage bombards the working inclined surface of tungsten target 21 at extremely high speed. The interaction between electrons and tungsten atoms generates X-rays, which are emitted from the inclined surface of the tungsten target at a specific angle, pass through beryllium window 3, and are then output for use.

[0045] The immense heat generated at the impact point first diffuses to the tungsten target 21 body through thermal conduction. It is then conducted to the anode rod 23. The anode rod 23 continuously conducts heat to its end outside the vacuum chamber. Externally, the anode rod 23 can dissipate heat into the surrounding environment by immersing itself in cooling oil. For more efficient heat dissipation, heat dissipation holes are evenly distributed inside the tungsten target 21, and heat dissipation channels are also designed inside the shield 25, which greatly enhances heat dissipation efficiency and prevents heat accumulation.

[0046] When high-speed electrons bombard a tungsten target, some electrons are scattered back at lower energy. The shield 25 surrounding the tungsten target captures these scattered electrons and guides them to the ground wire, protecting the casing. This prevents scattered electrons from bombarding the casing or other components, which could lead to localized overheating, the generation of additional gas, or even breakdown. X-rays radiate in all directions; the shield 25 blocks X-rays radiating in unintended directions, attenuating them, improving the directionality and safety of the radiation output, and reducing radiation leakage. Under a high voltage of 450kV, any sharp edges and corners will cause extreme electric field concentration, easily triggering vacuum breakdown. Processing the transition edges and corners of the shield 25 into smooth arcs significantly smooths the electric field distribution, controlling the electric field strength within a safe range and preventing high-voltage discharge.

[0047] The X-ray tube includes a cathode insulating ceramic ring 14 and an anode insulating ceramic ring 24. Each insulating ceramic ring has a coating on its surface within the cavity that reduces the secondary electron emission coefficient. To effectively suppress surface flashover, the vacuum-facing surfaces of both the cathode insulating ceramic ring 14 and the anode insulating ceramic ring 24 are coated with a composite coating to suppress secondary electrons and accelerate surface charge dissipation. This effectively reduces the generation of secondary electrons and achieves rapid surface charge dissipation. Specifically, a ceramic coating is prepared by combining chromium oxide (with a low secondary electron emission coefficient) with manganese oxide or zinc oxide (with low surface resistivity). This coating is then sprayed onto the surface of alumina ceramics, which helps overcome the disadvantages of alumina ceramics, such as high secondary electron emission coefficient and low vacuum surface flashover voltage.

[0048] In one specific embodiment, the X-ray tube further includes a focusing disk 5 disposed within the housing 6 between the cathode assembly 1 and the anode assembly 2. A focusing aperture 51 is formed at the center of the focusing disk 5 for secondary focusing of the electron beam emitted from the cathode assembly 1. The focusing disk 5 is coaxial with and fixedly disposed within the housing 6. The exhaust port of the cavity exhaust pipe 61 is located on the anode assembly 2 side of the focusing disk 5. That is, along the direction of electron beam movement, the cavity exhaust pipe 61 is located below the focusing disk 5. During the aging process, the electrodes and ceramic components release gas when bombarded by electrons. By placing the exhaust port of the cavity exhaust pipe 61 on the side wall of the housing, and closer to the main gas release source (such as the focusing disk and the anode assembly), the released gas can be extracted or ionized and adsorbed more efficiently and quickly, avoiding local accumulation of gas within the housing, thereby more effectively maintaining a high vacuum throughout the entire tube.

[0049] In one specific embodiment, the X-ray tube further includes a beryllium window 3 disposed on the peripheral sidewall of the housing 6; the beryllium window 3 is welded to the housing 6, and is made of beryllium metal sheet and metal sealing ring by brazing, and connected to the peripheral sidewall of the housing 6 by high-temperature fusion welding methods such as argon arc welding and laser welding. A window 251 corresponding to the position of the beryllium window 3 is formed on the shield 25; the beryllium window 3 has a vertical flat plate structure. The electron beam emitted by the filament 11 of the cathode assembly 1 is initially focused by the filament cover 12 and then secondarily focused by the focusing disk 5. After being converged and accelerated, it bombards the tungsten target 21 of the anode assembly 2, thereby generating X-rays that exit from the beryllium window 3. The window 251 on the shield 25 is strictly aligned with the beryllium window 3, together forming an unobstructed ray channel from the tungsten target to the outside of the tube. The wall of the shield 25 blocks X-rays and scattered electrons radiating in other directions. This window 251 ensures that only the useful main beam pointing towards the beryllium window can pass through and exit smoothly, minimizing the obstruction and absorption of rays by the internal structure, thus guaranteeing output dose and efficiency. A vertical, flat beryllium window 3 matches this window 251. Both beryllium window 3 and window 251 use flat windows. Compared to curved windows, flat windows are simpler, more reliable, and less costly to manufacture (brazing the beryllium sheet to the metal sealing ring), weld to the housing (argon arc welding), and in optical design (ray transmission path calculation).

[0050] Figure 2 This invention illustrates a second embodiment of an X-ray tube capable of maintaining a high vacuum. The X-ray tube includes: a cathode assembly 1 and an anode assembly 2; a housing 6 forming a vacuum cavity with the anode assembly 2 and the cathode assembly 1; a cathode exhaust pipe 16, with its first end connected to the cathode assembly 1 and its second end sealed; and a cavity exhaust pipe 61, with its first end connected to the X-ray tube cavity through an exhaust port located in the housing 6 and its second end sealed.

[0051] This second embodiment only discusses the differences from the first embodiment; the similarities are not discussed further. When venting the X-ray tube of this invention, the second end of the cavity vent pipe 61 is first connected to a vacuum pump, which can be a vacuum pump. The vacuum pump is initially not operational. Voltage is applied to the cathode, but not to the anode. The cathode vent pipe 16, in conjunction with the venting platform, is connected to the second end (upper end) of the cathode vent pipe 16 to evacuate the X-ray tube, while simultaneously venting the cathode in its working state. After reaching the designed vacuum level, the second end of the cathode vent pipe 16 is sealed. Specifically, cold welding clamps can be used to cold-press and seal the cathode vent pipe 16, separating it from the venting platform. After venting the X-ray tube, it undergoes aging. Voltage is applied to the anode, and the working anode is vented. Simultaneously, the vacuum pump is used to evacuate the X-ray tube, thus maintaining the vacuum level of the cavity during aging. The vacuum pump is then turned off after aging is complete. During the operation of the X-ray tube, voltage is applied to both the cathode and anode, and the vacuum pump is simultaneously activated to maintain the vacuum level of the X-ray tube during operation. By providing a cavity exhaust pipe 61 connected to the X-ray tube cavity, the vacuum pump removes the gas released from the shell during the aging and operation of the X-ray tube, thus maintaining the vacuum level within the shell and achieving dynamic maintenance of the tube's vacuum level. This effectively solves the problem of vacuum deterioration caused by material release during aging and operation, thereby improving the tube's operational stability and service life. If the vacuum pump is no longer needed after aging, the second end of the cavity exhaust pipe 61 can be sealed by cold pressing, separating the vacuum pump from the cavity exhaust pipe 61. Furthermore, after the aging process is completed, cold welding clamps can be used to perform cold pressing at the pre-machined sealing edge on the cavity exhaust pipe 61, and the vacuum pump can be removed. After aging, the cavity exhaust pipe 61 can be sealed using a cold welding process. The highest point of the sealing blade, after being flattened, is lower than the outer peripheral sidewall of the housing 6 to avoid interference with external equipment. The connection between the cavity exhaust pipe 61 and the sidewall of the housing 6 provides optimal operating space and viewing angle for the cold welding sealing process after aging. Operators can perform the sealing operation horizontally, which is easier to apply force and control compared to the compact top or bottom, ensuring a flat, smooth, and reliable seal.

[0052] In summary, this utility model provides an X-ray tube capable of maintaining a high vacuum, comprising a cathode assembly and an anode assembly; a housing forming a vacuum cavity with the anode and cathode assemblies; a cathode exhaust pipe, with its first end connected to the cathode assembly and its second end sealed; and a cavity exhaust pipe, with its first end connected to the X-ray tube cavity via an exhaust port located in the housing and its second end sealed. Alternatively, the X-ray tube may further include a vacuum maintaining mechanism outside the housing, with the second end of the cavity exhaust pipe connected to the vacuum maintaining mechanism. By providing a cavity exhaust pipe connected to the X-ray tube cavity, a vacuum pump can be used to extract the gas released from the housing during the aging and operation of the X-ray tube to maintain the vacuum level within the housing, achieving dynamic maintenance of the vacuum level inside the tube. This effectively solves the problem of vacuum deterioration caused by material outgassing during aging and operation, thereby improving the tube's operational stability and service life. Furthermore, this invention provides a vacuum maintaining mechanism outside the X-ray tube that is connected to the second end of the cavity exhaust pipe. This vacuum maintaining mechanism can not only maintain the high vacuum of the cavity during the aging process, but also maintain the high vacuum of the cavity when the X-ray is in use. This reduces the amount of gas released by the material inside the X-ray tube during the process of applying high pressure to the anode, which adheres to the X-ray tube wall as particles. This avoids high-pressure arcing caused by the gas released and the adhered particles during operation, and significantly extends the life of the X-ray tube.

[0053] The X-ray tube provided by this invention has its cathode and anode located at the upper and lower ends of the housing, respectively, requiring connection to extremely high negative and positive voltages. By mounting the vacuum maintaining mechanism, such as that of a vacuum pump or ion pump, on the outside of the housing sidewall, the area of ​​the high-voltage electrical interfaces at both ends is perfectly avoided. This fundamentally eliminates the risk of creepage, discharge, or short circuit between the high-voltage leads and the pump body, greatly improving the electrical safety and reliability of the equipment.

[0054] The connection between the cavity exhaust pipe and the shell sidewall provides optimal operating space and perspective for the cold welding sealing process of the exhaust pipe after aging. Operators can perform the sealing operation horizontally, which is easier to apply force and control compared to the compact top or bottom, ensuring a smooth, even, and reliable seal. During aging, the electrodes and ceramic components release gas due to electron bombardment. Placing the exhaust port on the shell sidewall, closer to the main gas release sources (such as the focusing disk and anode assembly), allows for more efficient and rapid extraction or ionization adsorption of the released gas, preventing localized gas accumulation within the shell and thus more effectively maintaining a high vacuum throughout the entire pipe.

[0055] This invention also provides a method for manufacturing an X-ray tube capable of maintaining a high vacuum. The X-ray tube includes a cathode assembly and an anode assembly; a housing forming a vacuum cavity with the anode and cathode assemblies; a cathode exhaust pipe, the first end of which is connected to the cathode assembly; and a cavity exhaust pipe, the first end of which is connected to the X-ray tube cavity through an exhaust port disposed in the housing, and the second end of which is connected to a vacuum maintaining mechanism. The manufacturing method includes disabling the vacuum maintaining mechanism, applying voltage to the cathode and disabling voltage to the anode, evacuating the X-ray tube using the cathode exhaust pipe, and sealing the second end of the cathode exhaust pipe.

[0056] Furthermore, after sealing the second end of the cathode exhaust pipe, the preparation method further includes applying voltage to the anode, simultaneously using the vacuum maintaining mechanism to evacuate the X-ray tube to maintain the vacuum level of the cavity; and closing the vacuum maintaining mechanism or sealing the second end of the cavity exhaust pipe.

[0057] This invention also provides a method for operating an X-ray tube capable of maintaining a high vacuum. The X-ray tube includes a cathode assembly and an anode assembly; a housing forming a vacuum cavity with the anode and cathode assemblies; a vacuum maintaining mechanism located outside the X-ray tube housing; a cathode exhaust pipe, with its first end connected to the cathode assembly and its second end sealed; and a cavity exhaust pipe, with its first end connected to the X-ray tube cavity through an exhaust port located in the housing and its second end connected to the vacuum maintaining mechanism. The operating method includes applying voltage to the X-ray tube cathode and anode, while simultaneously using the vacuum maintaining mechanism to evacuate the X-ray tube and maintain its vacuum level.

[0058] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating this utility model, and are not intended to limit the implementation of this utility model. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of this utility model are still within the protection scope of this utility model.

Claims

1. An X-ray tube capable of maintaining a high vacuum degree, characterized by comprising: include: Cathode assembly and anode assembly; The housing that forms a vacuum cavity with the anode and cathode assemblies; The cathode exhaust pipe has a first end connected to the cathode assembly and a second end sealed. The cavity exhaust pipe has its first end connected to the X-ray tube cavity via an exhaust port located in the housing, and its second end is sealed, or... The X-ray tube further includes a vacuum maintaining mechanism outside the housing, and the second end of the cavity exhaust pipe is connected to the vacuum maintaining mechanism.

2. The X-ray tube of claim 1, wherein The vacuum maintaining mechanism is a vacuum pump or an ion pump.

3. The X-ray tube of claim 1, wherein An inwardly recessed portion is formed on the circumferential sidewall of the housing, and the exhaust port of the cavity exhaust pipe is located in the recessed portion.

4. The X-ray tube of claim 1, wherein The exhaust port of the cavity exhaust pipe is located on the anode assembly side of the housing.

5. The X-ray tube of claim 1, wherein The X-ray tube further includes a focusing disk between the cathode assembly and the anode assembly.

6. The X-ray tube of claim 1, wherein The exhaust port of the cavity exhaust pipe is located on the anode assembly side of the clustering disk.

7. The X-ray tube capable of maintaining a high vacuum according to claim 1, characterized in that, The X-ray tube includes a cathode insulating ceramic ring and an anode insulating ceramic ring, and each insulating ceramic ring has a coating on its surface inside the cavity to reduce the secondary electron emission coefficient.

8. The X-ray tube capable of maintaining a high vacuum according to claim 1, characterized in that, The cathode assembly is connected to the top wall of the housing by brazing and extends into the housing; the cathode assembly includes a cathode support and a filament structure located in the vacuum cavity and fixed to the lower end of the cathode support; the filament structure includes a filament cover fixed to the cathode support and a filament holder and filament fixed inside the filament cover; the outer surface of the filament cover is mirrored, and a rectangular hole for initial focusing of the electron beam is provided on the lower end face of the filament cover.

9. The X-ray tube capable of maintaining a high vacuum according to claim 1, characterized in that, The anode assembly is connected to the bottom wall of the housing by brazing and extends into the interior of the housing; the anode assembly includes an anode rod, a tungsten target brazed to the inclined surface at the top of the anode rod, a shield brazed to the anode rod, and an anode cap fixed to the shield; the tungsten target, the shield, and the anode cap are all located inside the vacuum chamber.

10. The X-ray tube capable of maintaining a high vacuum according to claim 1, characterized in that, The X-ray tube also includes a beryllium window disposed on the side wall of the housing.

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