A novel ceramic x-ray tube and method of making same

Abstract

This invention discloses a novel ceramic X-ray tube and its manufacturing method. The novel ceramic X-ray tube includes a beryllium window assembly and a cathode assembly. The beryllium window assembly includes a beryllium window support, within which a beryllium plate is sealed and fixedly connected. A target material is coated on the side of the beryllium plate closest to the cathode assembly. The cathode assembly includes a core assembly and a focusing sleeve. The core assembly includes a first electrode, a second electrode, and a ceramic inner tube. The focusing sleeve is fixedly mounted on the first electrode of the core assembly. Two Kovar wires are disposed within the focusing sleeve, respectively fixedly mounted on the first and second electrodes of the core assembly, and respectively fixedly connected to the two ends of a filament. A non-evaporable getter is fixedly mounted on the outside of the focusing sleeve. This invention has the advantages of reducing production steps, improving production efficiency, and facilitating mass production.

Description

Technical Field

[0001] This invention relates to the field of X-ray tube technology, and in particular to a novel ceramic X-ray tube and its manufacturing method. Background Technology

[0002] An X-ray tube is a vacuum diode in which electrons emitted from the cathode collide with the anode target under the action of an accelerating electric field. During the collision, the electrons suddenly decelerate, and some of their lost kinetic energy is released as photons, forming X-rays.

[0003] To achieve a stable working state for X-ray tubes, they are typically operated under ultra-high vacuum conditions. To achieve this ultra-high vacuum environment, traditional X-ray tubes, including cathode assemblies, beryllium window assemblies, tube shells, and exhaust pipes for venting, involve assembly and sealing, venting, and testing. However, the specialized equipment and time required for the venting process generally hinder mass production; furthermore, the welding of the exhaust pipes not only increases the manufacturing cost of the X-ray tube but also leads to a higher defect rate, resulting in certain defects. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a novel ceramic X-ray tube and its manufacturing method. This invention has the advantages of reducing production steps, improving production efficiency, and facilitating mass production.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a novel ceramic X-ray tube, comprising: a ceramic outer tube, a beryllium window assembly, and a cathode assembly. The beryllium window assembly is connected to one side of the ceramic outer tube via an anode Kovar, and the cathode assembly is disposed inside the other side of the ceramic outer tube. The beryllium window assembly includes a beryllium window support, a beryllium plate, and a target material. The beryllium plate is sealed and welded inside the beryllium window support, and the side of the beryllium plate closest to the cathode assembly is coated with the target material. The cathode assembly includes a focusing sleeve, a filament, a core assembly, a non-evaporable getter, and two Kovar wires. The core assembly includes a first electrode, a second electrode, and a ceramic inner tube, which are sealed and welded together. The two Kovar wires and the filament are both disposed inside the focusing sleeve. The two Kovar wires are respectively fixedly installed on the first electrode and the second electrode of the core assembly, and the two ends of the filament are respectively fixedly connected to the two Kovar wires. The non-evaporable getter is fixedly installed on the outside of the focusing sleeve. The focusing sleeve is fixedly installed on the second electrode of the core assembly.

[0006] Preferably, a beryllium window assembly is formed by depositing a target metal with a thickness of 50μm-2000μm on the beryllium sheet. The beryllium window assembly serves as both the window of the X-ray tube and the anode of the X-ray tube.

[0007] Preferably, the non-evaporable getter in the aforementioned novel ceramic X-ray tube is a non-evaporable getter that can be activated by heating.

[0008] The aforementioned method for manufacturing a novel ceramic X-ray tube includes the following steps:

[0009] Step 1: Assemble and weld the first electrode, the second electrode, and the ceramic inner tube to form the core assembly;

[0010] Step 2: Assemble and weld the core assembly, focusing sleeve, filament, two Kovar wires, and non-evaporable getter to form the cathode assembly;

[0011] Step 3: Using vacuum coating technology, the target material is deposited on the beryllium sheet by vapor deposition. The thickness of the target material is generally between 50μm and 2000μm.

[0012] Step 4: Vacuum weld the cathode assembly with the beryllium plate, ceramic outer tube, beryllium window support and Kovar anode to form the novel ceramic X-ray tube;

[0013] Step 5: Perform performance testing on the new ceramic X-ray tube.

[0014] Preferably, the vacuum welding is vacuum brazing;

[0015] Preferably, the activation temperature of the non-evaporable getter in the aforementioned novel ceramic X-ray tube is 300-950 degrees Celsius;

[0016] Preferably, the vacuum brazing temperature is close to the activation temperature of the non-evaporable getter. The vacuum brazing temperature reaches the activation temperature of the non-evaporable getter, thereby activating the non-evaporable getter. After activation, the non-evaporable getter continuously removes residual gas inside the X-ray tube through the synergistic effect of surface adsorption and internal diffusion, maintaining an ultra-high vacuum environment inside the tube and ensuring stable operation of the X-ray tube.

[0017] Compared with existing technologies, this invention only includes a cathode assembly, a beryllium window assembly, and a ceramic outer tube, but does not include an exhaust pipe for venting. Instead, it uses a non-evaporable getter, which is activated during the welding and assembly of the X-ray tube. This allows the getter to continuously remove residual gas inside the X-ray tube, maintaining an ultra-high vacuum environment. The manufacturing method only involves assembly, sealing, and testing, without a dedicated venting process. Therefore, it is convenient for mass production, thereby reducing the number of production steps and improving production efficiency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the internal structure of the present invention from the front.

[0019] Figure 2 This is a top-view internal structure diagram of the present invention;

[0020] Figure 3 This is a schematic diagram of the internal structure of the cathode assembly of the present invention;

[0021] Figure 4 This is a graph showing the relationship between activation temperature and activation time for the non-evaporable getter 26 in Example 1.

[0022] Figure 5 This is a graph showing the relationship between activation temperature and activation time for the non-evaporative getter 26 in Example 2.

[0023] In the attached diagram: 1. Ceramic outer tube; 2. Cathode assembly; 21. Core column assembly; 211. First electrode; 212. Second electrode; 213. Ceramic inner tube; 22. Focusing sleeve; 23. Filament; 24. Kovar wire; 26. Non-evaporative getter; 3. Beryllium window assembly; 31. Beryllium window support; 32. Beryllium plate; 4. Anode Kovar. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1.

[0026] A new type of ceramic X-ray tube, such as Figure 1-3 As shown, it includes a ceramic outer tube 1, a beryllium window assembly 3, and a cathode assembly 2.

[0027] The cathode assembly 2 includes a core assembly 21, which includes a ceramic inner tube 213, a first electrode 211, and a second electrode 212. The ceramic inner tube 213 is disposed within the cavity of the first electrode 211, and the second electrode 212 is disposed within the cavity of the ceramic inner tube 213. The first electrode 211, the ceramic inner tube 213, and the second electrode 212 are sealed and welded together. The first electrode 211 is welded and fixed to one Kovar wire 24, and the second electrode 212 is welded and fixed to another Kovar wire 24. The first electrode 211 is fixedly connected to the focusing sleeve 22. The filament 23 and the two Kovar wires 24 are installed inside the focusing sleeve 22, and the non-evaporable getter 26 is installed outside the focusing sleeve 22.

[0028] The cathode assembly 2 is located at one end of the ceramic outer tube 1 and is sealed by welding. The ceramic outer tube 1 has strong corrosion resistance and is very stable under long-term exposure to moisture and chemically reactive substances. In terms of electrical insulation performance, it is much superior to other vacuum materials. It has high resistivity, which is very stable over a wide temperature range, and its dielectric loss is very low. It can withstand severe thermal shock, can operate normally at 800°C without damage, and maintains its strength even after prolonged operation at high temperatures. It can withstand strong vibrations and impacts, and exhibits no residual deformation under prolonged mechanical loads. Therefore, the ceramic outer tube 1, as the tube shell, can improve the service life of the X-ray tube.

[0029] The beryllium window assembly 3 includes a beryllium window bracket 31 and a beryllium plate 32. The beryllium window bracket 31 is fixedly connected to the other end of the ceramic outer tube 1 via an anode Kovar 4. The anode Kovar 4 is a Kovar material 4J33, which has a similar coefficient of thermal expansion to ceramics and serves as a transition material for welding the beryllium window bracket 31 and the ceramic outer tube 1. The beryllium plate 32 is fixedly installed on the beryllium window bracket 31. The beryllium plate 32 is coated using vacuum coating technology, that is, a target material is deposited on the beryllium plate 32. The target material thickness is generally between 50μm and 2000μm. The beryllium window bracket 31 is connected to a high voltage, generally greater than 5 kV. When the ceramic X-ray tube is working, the high voltage is applied first, and then the filament 23 is heated to about 2000 degrees. The electron cloud is attracted to the beryllium plate 32 by the electric field and the focusing sleeve 22.

[0030] The method for manufacturing a novel ceramic X-ray tube includes the following steps:

[0031] Step 1: Assemble and weld the first electrode 211, the second electrode 212, and the ceramic inner tube 213 to form the core assembly 21;

[0032] Step 2: Assemble and weld the core assembly 21, focusing sleeve 22, filament 23, two Kovar wires 24, and non-evaporable getter 26 to form the cathode assembly 2;

[0033] Step 3: Using vacuum coating technology, a target material is deposited on the beryllium sheet 32, with a target material thickness of 50μm-2000μm;

[0034] Step 4: Vacuum brazing is performed on the cathode assembly 2, beryllium plate 32, ceramic outer tube 1, beryllium window bracket 31, and anode Kovar 4 to form the novel ceramic X-ray tube described above;

[0035] Step 5: Perform performance testing on the novel ceramic X-ray tube.

[0036] The non-evaporable getter 26 is generally ring-shaped. It uses Group IVB metals and their alloys as core materials, with zirconium-aluminum alloy being the most widely used. This alloy contains various active intermetallic compound phases such as Zr5Al3 and Zr3Al2, exhibiting high getter rate and capacity. During manufacturing and storage, a passivation film forms on the surface of the non-evaporable getter 26, requiring heating to restore its getter activity. In the novel ceramic X-ray tube, step four utilizes the high temperature generated by the vacuum brazing process to simultaneously complete the activation, with the activation temperature between 750-900°C. At 50℃, the surface passivation film decomposes, exposing a fresh, active metal surface. During long-term storage and operation of the X-ray tube, H2, CO, N2, water vapor, and other gases generated inside the tube come into contact with the active surface of the getter and adhere to the surface through physical or chemical adsorption. Driven by the concentration gradient, the adsorbed gas molecules diffuse into the interior of the getter material, forming intermetallic compounds or solid solutions with the metal, thus achieving long-term gas storage. Through the synergistic effect of surface adsorption and internal diffusion, residual gases inside the X-ray tube are continuously removed, maintaining an ultra-high vacuum environment inside the tube and ensuring stable operation of the X-ray tube.

[0037] The activation conditions for the non-evaporable getter 26 are as follows: at the maximum initial pressure of 1 Pa, the activation temperature and activation time are as follows: Figure 4 As shown, different types of non-evaporable getters 26 require different brazing solders.

[0038] Preferred Option 1: The brazing solder is Ag72Cu28, with a melting point of 779℃ and a welding temperature of 790-820℃; the non-evaporative getter 26 is heated to the corresponding temperature of 790-820℃ and reaches... Figure 4 After the corresponding activation time is reached, activation will be completed.

[0039] Preferred Option 2: The brazing solder is Ag63Cu27In10, with a melting point of 685℃ and a welding temperature of 750-785℃; the non-evaporable getter 26 is heated to the corresponding temperature of 750℃-785℃ and reaches... Figure 4 After the corresponding activation time is reached, activation will be completed.

[0040] Preferred Option 3: The brazing solder is Ag58Cu32Pd10, with a melting point of 827℃ and a welding temperature of 850-900℃; the non-evaporable getter 26 is heated to the corresponding temperature of 850℃-900℃ and reaches... Figure 4 After the corresponding activation time is reached, activation will be completed.

[0041] Preferred Option 4: The brazing solder is Ag58Cu28Pd14, with a melting point of 880℃ and a welding temperature of 900-930℃; the non-evaporative getter 26 is heated to the corresponding temperature of 900℃-930℃ and reaches... Figure 4 After the corresponding activation time is reached, activation will be completed.

[0042] Example 2.

[0043] A novel ceramic X-ray tube, differing from Example 1, uses a non-evaporable getter 26 made of zirconium vanadium iron, with an activation temperature of 300-500℃. The activation conditions for the non-evaporable getter 26 are as follows: at a maximum initial pressure of 1 Pa, the activation temperature and activation time are as follows... Figure 5 As shown.

[0044] Preferred Option 1: The brazing solder is Au80Sn20, with a melting point of 280℃ and a welding temperature of 300-350℃; the non-evaporating getter 26 is heated to the corresponding temperature of 300℃-350℃ and reaches... Figure 5 After the corresponding activation time is reached, activation will be completed.

[0045] Preferred Option 2: The brazing solder is Au80In20, with a melting point of 473℃ and a welding temperature of 500-550℃; the non-evaporating getter 26 is heated to the corresponding temperature of 500℃-550℃ and reaches... Figure 5 After the corresponding activation time is reached, activation will be completed.

[0046] Preferred Option 3: The brazing solder is Au75In25, with a melting point of 425℃ and a welding temperature of 450-500℃; the non-evaporative getter 26 is heated to the corresponding temperature of 450℃-500℃ and reaches... Figure 5 After the corresponding activation time is reached, activation will be completed.

[0047] To test the beneficial effects of the manufacturing method provided by this invention, the production efficiency and yield rate of conventional ceramic X-ray tubes (with exhaust pipes) and the novel ceramic X-ray tubes manufactured in Example 1 were statistically analyzed. The statistical results are shown in the table below:

[0048] Category Production quantity per person per day per device pass rate Conventional ceramic X-ray tube 10-12 80% Novel Ceramic X-ray Tube Prepared in Example 1 120-150 96%

[0049] It is evident that the novel ceramic X-ray tube manufactured using the method of this invention has significantly improved efficiency, with a yield rate of up to 96%, making it suitable for mass production and generating substantial economic benefits.

Claims

1. A novel ceramic X-ray tube, characterized in that: The device includes a beryllium window assembly (3) and a cathode assembly (2). The beryllium window assembly (3) is connected to one side of the ceramic outer tube (1) via an anode Kovar (4), and the cathode assembly (2) is disposed inside the other side of the ceramic outer tube (1). The beryllium window assembly (3) includes a beryllium window bracket (31), and a beryllium plate (32) is sealed and fixedly connected inside the beryllium window bracket (31). The beryllium plate (32) is plated with a target material on the side near the cathode assembly (2). The cathode assembly (2) includes a core assembly (21) and a focusing sleeve (22). The core assembly (21) contains a first electrode. The assembly includes an electrode (211), a second electrode (212), and a ceramic inner tube (213). The focusing sleeve (22) is fixedly installed on the first electrode (211) of the core column assembly (21). Two Kovar wires (24) are provided inside the focusing sleeve (22). The two Kovar wires (24) are fixedly installed on the first electrode (211) and the second electrode (212) of the core column assembly (21), respectively. The two Kovar wires (24) are fixedly connected to the two ends of the filament (23), respectively. A non-evaporable getter (26) is fixedly installed on the outside of the focusing sleeve (22).

2. The novel ceramic X-ray tube according to claim 1, characterized in that: The activation temperature of the non-evaporable getter (26) is 300-950 degrees.

3. The novel ceramic X-ray tube according to claim 1, characterized in that: The thickness of the target metal is 50μm-2000μm.

4. A method for manufacturing a novel ceramic X-ray tube according to any one of claims 1-3, characterized in that: Includes the following steps: Step 1: Assemble and weld the first electrode (211), the second electrode (212), and the ceramic inner tube (213) to form the core assembly (21). Step 2: Assemble and weld the core assembly (21), focusing sleeve (22), filament (23), two Kovar wires (24), and non-evaporable getter (26) to form the cathode assembly (2). Step 3: Vacuum deposition technology is used to deposit the target material on the beryllium sheet (32); Step 4: The cathode assembly (2), beryllium plate (32), ceramic outer tube (1), beryllium window bracket (31) and anode Kovar (4) are vacuum welded to form the novel ceramic X-ray tube described above; Step 5: Perform performance testing on the novel ceramic X-ray tube.

5. The method for manufacturing a novel ceramic X-ray tube according to claim 4, characterized in that: The vacuum welding is vacuum brazing.

6. The method for manufacturing a novel ceramic X-ray tube according to claim 5, characterized in that: The temperature of the vacuum brazing reaches the activation temperature of the non-evaporable getter (26), and the non-evaporable getter (26) is activated simultaneously.

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