A precision three-coaxial ceramic-metal vacuum-tight electrode structure for a neutron tube

Abstract

The embodiment of the present invention provides a neutron tube precision three-coaxial ceramic metal vacuum tight-joint electrode structure, which belongs to the technical field of neutron tubes. The electrode structure includes: a connector, multiple groups of metal tubes, and a ceramic tube, wherein the connector is nested in the periphery of the neutron tube vacuum cavity; the number of the metal tubes in each group is at least two, which are nested in the periphery of the connector; the ceramic tube is nested between the connector and the metal tube, and the number of the ceramic tube is at least one, which is arranged between two adjacent metal tubes, and is used to connect the high-voltage power supply to the neutron tube. The problem of large size, poor insulation, and high cost of the precision three-coaxial ceramic metal vacuum tight-joint electrode structure of the neutron tube is solved.

Description

Technical Field

[0001] The invention relates to the technical field of neutron tubes, and in particular to a precise three-coaxial ceramic-metal vacuum-tightly-jointed electrode structure for a neutron tube. Background Art

[0002] With the development of neutron technology, neutrons have been widely used as a research tool in many fields such as chemical industry, exploration, coal quality analysis, industrial flaw detection, medical treatment, explosives and drug detection, and play an irreplaceable role. There are many types of neutron sources, such as reactors, particle accelerators, isotope neutron sources, and neutron tubes. Neutron tubes have the advantages of good energy monochromaticity, high yield, no gamma rays, and the ability to emit pulsed neutrons. They can provide neutrons for a variety of neutron analysis methods, and neutron tubes are small in size and do not produce neutrons when closed, so they are more convenient to transport, store, and use.

[0003] Usually, the neutron tubes produced in China use the Penning (PIG) ​​ion source to extract positive ions. A negative high voltage of 60KV to 120KV is added to the target end to accelerate the deuterium (D) ions and tritium (T) ions produced by the ion source, and a nuclear reaction occurs on the target to produce neutrons. As the performance requirements for neutron tubes in fields such as well logging become higher, the required neutron tube size needs to be controlled within 30mm, and the vacuum leakage rate of the neutron tube is not greater than 10-10. The internal structure size of the existing neutron tube is large. Once the volume is reduced, the accuracy of the existing ceramic and metal parts during the structural tooling is difficult to meet the requirements, and the coaxial position of all electrodes cannot be accurately controlled. In addition, the materials used are relatively complex and the cost is high. Summary of the invention

[0004] The purpose of the embodiment of the present invention is to provide a neutron tube precision three-coaxial ceramic metal vacuum tight electrode structure, which solves the problems of large size, poor insulation and high cost of the neutron tube precision three-coaxial ceramic metal vacuum tight electrode structure.

[0005] In order to achieve the above object, the present invention provides a neutron tube precision three-coaxial ceramic-metal vacuum close-jointed electrode structure, the electrode structure comprising:

[0006] A connecting piece, which is nested in the periphery of the neutron tube vacuum cavity;

[0007] A plurality of groups of metal tubes, each group of the metal tubes having at least two metal tubes, are nested on the periphery of the connector;

[0008] A ceramic tube is nested between the connector and the metal tube. The number of the ceramic tube is at least one and the ceramic tube is arranged between two adjacent metal tubes to connect a high voltage power supply to the neutron tube.

[0009] Optionally, the ceramic tube is a coaxial Z-shaped cross-sectional structure, and two ends of the Z-shaped cross-sectional structure are respectively connected to two adjacent metal tubes.

[0010] Optionally, a bifurcated cross-section structure is provided at the connection between the ceramic tube and the metal tube.

[0011] Optionally, the connecting piece is parallel to the ceramic tube.

[0012] Optionally, a vacuum insulation structure is provided between the connecting piece and the ceramic tube.

[0013] Optionally, the connector, the metal tube, and the ceramic tube are coaxial structures, and the coaxiality is less than or equal to 0.1 mm.

[0014] Optionally, the outer diameter of the electrode structure is less than or equal to 20 mm.

[0015] Through the above technical solution, the connectors, multiple groups of metal tubes and ceramic tube high-temperature tooling are installed around the vacuum cavity of the neutron tube to form an electric vacuum device with compact structure, safety, reliability, convenience and low cost. The connectors and metal tubes are connected to form the overall frame of the entire motor structure. The metal tubes and ceramic tubes are alternately assembled in this overall frame to form the high-voltage power supply part at the front end of the neutron tube. The ceramic tube increases the contact area between the overall frames and improves the stability of the vacuum-tight electrode structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0017] Figure 1 It is a cross-sectional view of a neutron tube precision three-coaxial ceramic-metal vacuum close-jointed electrode structure according to one embodiment of the present invention;

[0018] Figure 2 It is a schematic diagram of a bifurcated cross-sectional structure in a neutron tube precision three-coaxial ceramic-metal vacuum close-jointed electrode structure according to one embodiment of the present invention;

[0019] Figure 3 It is a schematic diagram of a Z-shaped cross-section structure in a neutron tube precision three-coaxial ceramic-metal vacuum close-contact electrode structure according to one embodiment of the present invention;

[0020] Figure 4 It is a schematic diagram of a vacuum insulation structure in a neutron tube precision three-coaxial ceramic-metal vacuum close-contact electrode structure according to one embodiment of the present invention;

[0021] Figure 5It is a schematic diagram of a square cavity in a precision three-coaxial ceramic-metal vacuum-tight electrode structure of a neutron tube according to an embodiment of the present invention.

[0022] Description of Reference Numerals

[0023] 1. Connectors 2. Metal pipes

[0024] 3. Ceramic tube 21, first metal tube

[0025] 22. Second metal tube 23. Third metal tube

[0026] 31. First ceramic tube 32. Second ceramic tube DETAILED DESCRIPTION

[0027] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0028] In the embodiments of the present application, unless otherwise specified, directional words such as "up, down, top, bottom" are usually used with reference to the directions shown in the drawings or are used to describe the relative positional relationships of components in the vertical, perpendicular or gravity direction.

[0029] In addition, if there are descriptions involving "first", "second", etc. in the implementation methods of this application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various implementation methods can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0030] like Figure 1 As shown, Figure 1 is a schematic diagram of a neutron tube precision three-coaxial ceramic-metal vacuum close-jointed electrode structure according to an embodiment of the present invention, in which Figure 1In the embodiment, the electrode structure includes: a connector 1, multiple groups of metal tubes 2, and a ceramic tube 3, wherein the connector 1 is nested in the periphery of the neutron tube vacuum cavity; each group of metal tubes is at least two, and is nested in the periphery of the connector 1; the ceramic tube 3 is nested between the connector 1 and the metal tube 2, and the number of the ceramic tube 3 is at least one, and is arranged between two adjacent metal tubes 2, for connecting the neutron tube to a high-voltage power supply. The connector 1, multiple groups of metal tubes 2, and ceramic tube 3 are high-temperature tooled around the neutron tube vacuum cavity to form an electric vacuum device with a compact structure, safety and reliability, easy use, and low cost. The connector 1 and the metal tube 2 are connected to form the overall frame of the entire motor structure, and the metal tube 2 and the ceramic tube 3 are alternately assembled in this overall frame to form the high-voltage power supply part at the front end of the neutron tube. The ceramic tube 3 increases the contact area between the overall frames and improves the stability of the vacuum-tight electrode structure.

[0031] In this embodiment, the number of metal tubes 2 can be a plurality known to those skilled in the art. In one embodiment of the present invention, the number of metal tubes 2 is three, namely, a first metal tube 21, a second metal tube 22, and a third metal tube 23, wherein the first metal tube 21 is disposed above the periphery of the connector 1, the second metal tube 22 is disposed below the periphery of the connector 1, and the third metal tube is disposed below the vacuum chamber of the neutron tube. A high voltage potential difference of 5 kV is formed between the first metal tube 21 and the second metal tube 22, and a high voltage potential difference of 15 kV is formed between the second metal tube 22 and the third metal tube 23.

[0032] In this embodiment, the number of ceramic tubes 3 can be various known to those skilled in the art. In one embodiment of the present invention, the number of ceramic tubes 3 is two, namely, a first ceramic tube 31 and a second ceramic tube 32, wherein the first ceramic tube 31 is disposed between the first metal tube 21 and the second metal tube 22, and the second ceramic tube 32 is disposed between the second metal tube 22 and the third metal tube 23. The first ceramic tube 31 is used as a first insulator to insulate the 5kv high-voltage power supply that is powered in the neutron tube, and the second ceramic tube 32 is used as a second insulator to insulate the 15kv high-voltage power supply that is powered in the neutron tube.

[0033] In this embodiment, the material of the ceramic tube 3 can be a variety of materials known to those skilled in the art. In one embodiment of the present invention, the ceramic tube 3 is made of high-quality 95# ceramic powder sintered into vacuum ceramics, which is precisely ground to achieve a high dimensional accuracy. After screen printing and high-temperature sintering processes, the sealing surface between the ceramic and the metal is metallized to ensure the smoothness of the sealing surface and the sealing performance of the sealing interface.

[0034] In this embodiment, the structure of the ceramic tube 3 can be a variety of structures known to those skilled in the art. In one embodiment of the present invention, Figure 3 As shown, the ceramic tube 3 is a coaxial Z-shaped cross-sectional structure, and the two ends of the Z-shaped cross-sectional structure are respectively connected to the two adjacent metal tubes 2, that is, one end of the Z-shaped cross-sectional structure of the first ceramic tube 31 is connected to one end of the first metal tube 21, the other end of the Z-shaped cross-sectional structure of the first ceramic tube 31 is connected to one end of the second metal tube 22, one end of the Z-shaped cross-sectional structure of the second ceramic tube 32 is connected to the other end of the second metal tube 22, and the other end of the Z-shaped cross-sectional structure of the second ceramic tube 32 is connected to one end of the third metal tube 23. The ceramic tube 3 is a coaxial Z-shaped cross-sectional structure, which plays a role in ensuring precision through coaxial self-assembly, and can improve the creepage distance and increase the withstand voltage strength under the condition of a small volume of the internal structure of the neutron tube.

[0035] In this embodiment, the material of the connector 1 and the metal tube 2 can be a variety of materials known to those skilled in the art. In one embodiment of the present invention, a ceramic sealing Kovar alloy of grades such as 4J33 is used to process the metal tube 2 and the connector 1. This alloy material has a thermal expansion coefficient similar to that of ceramic materials and has good vacuum brazing properties. It is an important sealing structural material in the electric vacuum industry.

[0036] In this embodiment, if Figure 2 As shown, the connection between the ceramic tube 3 and the metal tube 2 is provided with a bifurcated cross-section structure, which can reduce the contact area between the metal and the ceramic, adopt a contact thickness of 0.6-0.8mm, reduce the possibility of bubbles generated during the sealing process of the contact surface, and improve the reliability of ceramic sealing. The connection between the ceramic tube 3 and the metal tube 2 is provided with a bifurcated structure, which can not only play the role of self-alignment of the ceramic tube 3 and the metal tube 2, but also can generate a square-section cavity near the contact surface of the ceramic tube 3 and the metal tube 2, such as Figure 5 As shown, this space can be used to fill solder. During the vacuum brazing process, the solder is adsorbed into the designed square cavity through capillary action, which increases the firmness and reliability of the welding. Finally, after testing, the vacuum leakage rate of the overall structure is below 10-11.

[0037] In this embodiment, the positional relationship between the connector 1 and the ceramic tube 3 can be various known to those skilled in the art. In one embodiment of the present invention, the connector 1 is parallel to the ceramic tube 3. In order to ensure the high voltage insulation strength inside the neutron tube, as Figure 4 As shown, a vacuum insulation structure is provided between the connecting piece 1 and the ceramic tube 3 .

[0038] In this embodiment, the connector 1, the metal tube 2, and the ceramic tube 3 are coaxial structures. After leaving the factory, the metal tube 2 is polished twice and the dimensional error is controlled within 0.01 mm. While the metal tube 2 is assembled to ensure coaxiality, the inner and outer convex structures in the designed bifurcated cross-section structure are self-calibrated and assembled with the precision-ground ceramic tube 3. No external tooling is required during welding, and the coaxiality can reach within 0.1 mm.

[0039] In this embodiment, considering the strict requirements on the size of the neutron tube, the radius of the electrode structure becomes smaller from top to bottom, and the maximum outer diameter of the electrode structure is 20 mm, thereby reducing the manufacturing cost.

[0040] Through the above technical scheme, the connector 1, multiple groups of metal tubes 2 and ceramic tubes 3 are installed at high temperature around the vacuum cavity of the neutron tube to form an electric vacuum device with compact structure, safety and reliability, easy use and low cost. The connector 1 and the metal tube 2 are connected to form the connector 1 as the overall frame of the entire motor structure. The metal tube 2 and the ceramic tube 3 are alternately assembled in this overall frame to form the high-voltage power supply part at the front end of the neutron tube. The ceramic tube 3 increases the contact area between the overall frames and improves the stability of the vacuum-tight electrode structure. Specifically, firstly, the high-quality 95# ceramic powder is selected to sinter the designed ceramic tube 3, the 5kv negative high-voltage electrode and the first ceramic tube 31 and the 15kv negative high-voltage electrode and the second ceramic tube 32 are sealed together, and then the obtained ceramic tube 3 is finely ground so that the maximum error value of the size of the ceramic tube 3 is less than or equal to 0.01mm, and then the sealing surface of the ceramic tube 3 and the metal tube 2 is metallized. Pretreatment. The metal components are made of 4J33 Kovar alloy, and the metal tube 2 is polished to make the maximum size error of a single metal tube 2 less than or equal to 0.01 mm. Since the overall size is too small, it is difficult to achieve the precision requirements by welding with external tooling. Therefore, the overall structure can be self-aligned through the designed convex and concave structures. Before welding, the first metal tube 21 is placed on the outside of the connector 1, and the first ceramic tube 31 and the first metal tube 21 and the second metal tube 22 are arranged as follows: Figure 1 As shown, the first ceramic tube 31 is nested on both sides, the second ceramic tube 32 is nested inside the second metal tube 22, and the third metal tube 23 is nested inside the second ceramic tube 32. After all the parts are assembled, the solder is placed in the gap between the parts. During high-temperature welding, the solder melts, and under the influence of capillary action, the solder infiltrates into the designed annular space. The vacuum leakage rate of the final welded overall component is below the order of 10-11. The designed overall structure must remain concentric, and the concentricity error of the final overall component is less than or equal to 0.02mm.

[0041] The optional implementation modes of the examples of the present invention are described in detail above in conjunction with the accompanying drawings; however, the implementation modes of the present invention are not limited to the specific details in the above implementation modes; within the technical concept of the implementation modes of the present invention, a variety of simple modifications can be made to the technical solutions of the implementation modes of the present invention, and these simple modifications all belong to the protection scope of the implementation modes of the present invention.

[0042] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0043] In addition, various different embodiments of the embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed in the embodiments of the present invention.

Claims

1. A neutron tube precision three-coaxial ceramic-metal vacuum close-jointed electrode structure, characterized in that: The electrode structure comprises: A connecting piece, which is nested in the periphery of the neutron tube vacuum cavity; A metal tube is nested in the periphery of the connector; the metal tube comprises: The first metal tube is disposed above the periphery of the connecting piece; a second metal tube, disposed below the periphery of the connecting member; A third metal tube is disposed below the vacuum cavity of the neutron tube; A ceramic tube, nested between the connector and the metal tube, is used to connect the neutron tube to a high voltage power supply, and the ceramic tube includes: A first ceramic tube, disposed between the first metal tube and the second metal tube; The second ceramic tube is arranged between the second metal tube and the third metal tube.

2. The electrode structure according to claim 1, characterized in that: The ceramic tube is a coaxial Z-shaped cross-section structure, and two ends of the Z-shaped cross-section structure are respectively connected to two adjacent metal tubes.

3. The electrode structure according to claim 1, characterized in that: A bifurcated cross-section structure is provided at the connection between the ceramic tube and the metal tube.

4. The electrode structure according to claim 1, characterized in that: The connecting piece is parallel to the ceramic tube.

5. The electrode structure according to claim 4, characterized in that: A vacuum insulation structure is arranged between the connecting piece and the ceramic tube.

6. The electrode structure according to claim 1, characterized in that: The connector, metal tube and ceramic tube are coaxial structures, and the coaxiality is less than or equal to 0.1 mm.

7. The electrode structure according to claim 1, characterized in that: The outer diameter of the electrode structure is less than or equal to 20 mm.

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