An acceleration structure, welding process and cooling system for a particle linear accelerator.

Abstract

This application discloses an acceleration structure, welding process, and cooling system for a particle linear accelerator, relating to the field of particle acceleration equipment technology. The acceleration structure includes a left-shaped component and a right-shaped component, whose joint surfaces are welded together using alloy gaskets. The corresponding first and second acceleration half-cavities inside are assembled to form a complete disk-loaded acceleration cavity. A buffer gap is reserved between the mating edges of the two half-cavities. A vacuum maintenance component is provided above to extract the internal vacuum, and an radio frequency energy feeding component is provided on the outside to feed in external microwave energy. The supporting welding process employs local deposition of a metal barrier layer and a wetting layer, combined with alloy gaskets for temperature-controlled brazing, avoiding softening of the oxygen-free copper substrate during annealing. Furthermore, a semiconductor-based cooling system is provided around the acceleration structure to control heat deformation. This invention effectively avoids extrusion deformation of critical internal structures after welding, reduces the risk of high-frequency arcing, and significantly improves the integration and structural stability of the entire device.

Description

Technical Field

[0001] This invention relates to the field of particle acceleration equipment technology, and more specifically, to an acceleration structure, welding process, and cooling system for a particle linear accelerator. Background Technology

[0002] In existing particle linear accelerators, in order to reduce the processing difficulty of the internal microwave cavity, a split processing scheme is usually adopted, that is, multiple parts are spliced ​​together into a complete acceleration structure through high-temperature brazing process.

[0003] As accelerator technology advances towards higher frequencies and more compact structures, existing split-type accelerator structures, when assembled and welded, typically have tightly fitted internal accelerating chamber surfaces lacking sufficient thermal expansion buffer space. The thermal stress generated by the high temperatures of welding easily leads to compression deformation of critical internal microwave structures and can easily trigger high-frequency arcing under high-power microwave input. Furthermore, existing accelerator structures usually require additional welding or installation of components such as microwave couplers and vacuum connectors at the beginning and end as separate parts, resulting in cumbersome assembly processes and increased risk of vacuum leakage. Simultaneously, traditional high-temperature integral brazing processes often subject oxygen-free copper to temperatures of around 700-800 degrees Celsius, causing the work-hardening copper to undergo complete annealing and softening, significantly reducing the mechanical strength and radio frequency breakdown resistance of the accelerator tube. During equipment operation, the large amount of heat generated by high-frequency electromagnetic losses, if not dissipated in time, can lead to thermal expansion deformation of the tube, causing resonant cavity frequency drift. Therefore, there is an urgent need to design an accelerator structure, welding process, and cooling system for a particle linear accelerator to address these issues. Summary of the Invention

[0004] The present invention aims to solve the problems of easy extrusion deformation of key internal features during welding, cumbersome assembly of external microwave and air extraction components, and low integration in the prior art of split acceleration structures.

[0005] To address the aforementioned problems, this invention provides an acceleration structure for a particle linear accelerator, comprising a left forming component and a right forming component arranged opposite to each other. The left forming component has multiple first acceleration semi-cavities on its mating surface, and the right forming component has a second acceleration semi-cavity corresponding to the first acceleration semi-cavities on its mating surface. The first and second acceleration semi-cavities are combined to form a disk-loaded acceleration cavity. The mating surface of the left forming component and the mating surface of the right forming component are welded together via alloy gaskets to form an acceleration tube body. A buffer gap is reserved between the mating edges of the first and second acceleration semi-cavities. The left and right forming components have beam input and beam output ports respectively at their ends, communicating with the disk-loaded acceleration cavity. The invention also includes: an integrated vacuum maintenance assembly disposed above the left and right forming components for evacuating the interior of the acceleration structure; and a radio frequency energy feeding assembly disposed outside the left and right forming components for feeding energy from an external microwave power source into the disk-loaded acceleration cavity.

[0006] The acceleration structure of a particle linear accelerator provided by this invention has, but is not limited to, the following beneficial effects compared to the prior art: To address the issues of easy extrusion deformation of key internal features during welding, cumbersome assembly of external microwave and exhaust components, and low integration in existing split-type acceleration structures, this structure mainly comprises a left and a right forming component arranged opposite each other. Both are integrally milled from oxygen-free copper material with excellent electrical and thermal conductivity. Multiple first acceleration semi-cavities are formed on the mating surface of the left forming component, while a second acceleration semi-cavity is formed on the corresponding mating surface of the right forming component. When the left and right forming components are spliced ​​together and welded using alloy gaskets on the mating surface, the first and second acceleration semi-cavities merge to form a complete disk-loaded acceleration cavity, allowing particles to travel and accelerate within it. During actual operation, the microwave power generated by the external microwave source is smoothly fed into the disk-loaded acceleration cavity formed by the left and right forming components under the action of the radio frequency energy feeding component. Simultaneously, the particle beam to be accelerated is injected into the acceleration cavity from the beam input port at the beginning of the acceleration structure. As the microwave electromagnetic field propagates forward continuously within the multiple first and second acceleration semi-cavities arranged sequentially along the microwave transmission direction... Under the continuous action of the electric field, particles continuously gain energy and are accelerated to the target energy level. Finally, the high-energy particle beam is extracted from the beam output hole at the end of the accelerating structure and bombards the target material or is directly used for downstream ray generation equipment. The remaining microwave energy that is not completely consumed is smoothly exported to the external microwave absorption load through the integrated output coupler and impedance transformer at the end, thus completing the efficient capture and stable acceleration process of the particle beam. In particular, a certain buffer gap is reserved between the docking edges of the first and second accelerating half-cavities. This buffer gap plays a role in absorbing the thermal expansion stress of the oxygen-free copper substrate during high-temperature brazing, effectively preventing the edges of the internal key microwave cavity from being squeezed and deformed. This greatly reduces the probability of high-frequency arcing when fed into a high-power radio frequency electric field, significantly reducing the risk of arcing and the difficulty of processing. Since the radio frequency current on the inner wall flows parallel to the buffer gap along the beam direction, the existence of the buffer gap will not damage the performance of the electromagnetic field. At the same time, the coordinated arrangement of the peripheral components also effectively improves the overall integration of the device, resulting in better performance.

[0007] Furthermore, the integrated vacuum maintaining assembly includes an exhaust section disposed on the top of the welding surfaces of the left and right molded parts, and an extraction channel formed by the buffer gap; when the left and right molded parts are fixed together, the two exhaust sections are joined to form a total extraction hole, and an extraction pipe is disposed in the total extraction hole; one end of the extraction channel communicates with the internal space of the buffer gap, and the other end extends toward the edge of the acceleration structure and merges with the total extraction hole, so that the gas inside the acceleration chamber is discharged through the buffer gap and the total extraction hole.

[0008] Furthermore, the radio frequency energy feeding component includes an input section and an output section integrated at the beginning and end of the acceleration structure, respectively; the input section includes an interconnected input coupling cavity and an input impedance transformer for feeding energy from an external microwave power source into the disk-loaded acceleration cavity; the output section includes an interconnected output coupling cavity and an output impedance transformer for guiding the remaining accelerated microwave energy to an external load; and both the input impedance transformer and the output impedance transformer are provided with flange interface surfaces for direct connection to an external standard waveguide.

[0009] Furthermore, the first and second acceleration half-cavities are arranged sequentially along the microwave transmission direction, and the axial cavity thickness of the first and second acceleration half-cavities gradually increases along the microwave transmission direction, so as to keep the microwave phase velocity in the acceleration cavity synchronized with the real-time flight velocity of the accelerated particles. Adjacent first acceleration half-cavities and adjacent second acceleration half-cavities are connected by through slots.

[0010] Furthermore, the axial cavity thickness of the first acceleration half-cavity and the second acceleration half-cavity is proportional to their cavity diameter, and the axial cavity thickness of the first acceleration half-cavity and the second acceleration half-cavity is inversely proportional to the aperture of the through groove.

[0011] Furthermore, it also includes an assembly alignment component, which is disposed on the welding surface of the left molded part and the right molded part, for constraining the relative degrees of freedom of the left molded part and the right molded part in the normal plane before welding, and making the central axes of the first acceleration half cavity and the second acceleration half cavity coincide.

[0012] Furthermore, the assembly alignment component includes a positioning hole disposed on the left molded part and a positioning pin disposed on the right molded part that is adapted to the positioning hole, and the positioning holes are distributed diagonally or symmetrically along the center.

[0013] The present invention also provides a welding process based on the above-mentioned accelerating structure, comprising the following steps: S1: Provide a left molded part and a right molded part, the left molded part and the right molded part are made of hard oxygen-free copper material that has not been annealed, and their mating surfaces are processed with symmetrical internal radio frequency cavity structures; S2: A localized brush plating process is adopted, in which a metal barrier layer and an anti-oxidation wetting layer are deposited sequentially on the welding surfaces of the left and right molded parts. The metal barrier layer is a locally brush-plated nickel layer, which is used to block the diffusion of tin elements into the copper substrate during welding. The anti-oxidation wetting layer is a locally brush-plated gold layer, which covers the nickel layer. S3: Gold-tin alloy spacers are pre-placed between the welding surfaces that have undergone partial brush plating pretreatment to form the assembly to be welded; S4: Apply a heat source to the assembly to be welded to melt the alloy gasket and seal the welding surface; during the welding process, control the heat input so that the temperature of the surface of the radio frequency cavity inside the accelerated structure is always kept below the annealing softening temperature of the oxygen-free copper material, thus achieving temperature-controlled welding operation.

[0014] The present invention also provides a cooling system for cooling the acceleration structure of the aforementioned particle linear accelerator, including a cooling component disposed outside the acceleration mechanism. The cooling component is in direct contact with the outer surface of the cavity wall of the acceleration structure to cool down by heat conduction. The cooling component includes a semiconductor cooler, and the cold end face of the semiconductor cooler is coated with thermally conductive adhesive to achieve a tight fit with the outer surface of the cavity wall of the acceleration structure.

[0015] Furthermore, a cooling fan is connected to the hot end face of the semiconductor cooler, and heat dissipation fins are provided between the hot end face of the semiconductor cooler and the cooling fan. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the left and right forming parts in the acceleration structure of a particle linear accelerator according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the right forming component in the acceleration structure of a particle linear accelerator according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the acceleration tube body in the acceleration structure of a particle linear accelerator according to an embodiment of the present invention; Figure 4 This is a cross-sectional view of the accelerating tube body in the accelerating structure of a particle linear accelerator according to an embodiment of the present invention. Figure 5 This is a cross-sectional schematic diagram of the left forming part in the acceleration structure of a particle linear accelerator according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the left forming part and alloy gasket in the acceleration structure of a particle linear accelerator according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the internal vacuum model of the acceleration structure of a particle linear accelerator according to an embodiment of the present invention; Figure 8 This is a schematic diagram of a cooling system according to an embodiment of the present invention; Figure 9 This is a schematic flowchart of a welding process for a particle linear accelerator according to an embodiment of the present invention.

[0017] Explanation of reference numerals in the attached figures: 1. Left molded part; 11. First acceleration half-cavity; 2. Right molded part; 21. Second acceleration half-cavity; 31. Disc-loaded acceleration cavity; 32. Buffer gap; 33. Beam input port; 34. Beam output port; 4. Alloy gasket; 5. Integrated vacuum maintenance assembly; 51. Exhaust section; 52. Evacuation channel; 53. Evacuation pipe; 6. RF energy delivery assembly; 61. Input section; 611. Input coupling cavity; 612. Input impedance converter; 62. Output section; 621. Output coupling cavity; 622. Output impedance converter; 7. Through slot; 8. Assembly alignment assembly; 81. Positioning hole; 82. Positioning pin; 9. Cooling assembly; 91. Semiconductor cooler; 92. Cooling fan; 93. Heat sink fins; 10. Acceleration tube body. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments of this application are described clearly and completely below with reference to the accompanying drawings. It should be understood that the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort will fall within the scope of protection of this application.

[0019] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing specific embodiments only and is not intended to limit this application; the terms "comprising," "including," "having," "containing," "comprise," etc., in the specification, claims, and accompanying drawings of this application are open-ended terms, indicating that a method comprises one or more steps, or an apparatus comprises one or more elements, but do not exclude the inclusion of other steps or elements. The terms "first," "second," etc., in the specification, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or primary / secondary relationship. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0020] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0021] Furthermore, in the attached diagram, the X-axis represents the horizontal direction, that is, the left and right position, and the positive direction of the X-axis (that is, the direction the arrow points to) represents the right, and the negative direction of the X-axis (that is, the direction opposite to the positive direction of the X-axis) represents the left; in the attached diagram, the Y-axis represents the vertical direction, that is, the front and back position, and the positive direction of the Y-axis (that is, the direction the arrow points to) represents the front, and the negative direction of the Y-axis (that is, the direction opposite to the positive direction of the Y-axis) represents the back; in the attached diagram, the Z-axis represents the vertical direction, that is, the up and down position, and the positive direction of the Z-axis (that is, the direction the arrow points to) represents the up, and the negative direction of the Z-axis (that is, the direction opposite to the positive direction of the Z-axis) represents the down.

[0022] It should also be noted that the aforementioned X-axis, Y-axis and Z-axis are only for the purpose of facilitating the description of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0023] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0024] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0025] See Figures 1-7An acceleration structure for a particle linear accelerator according to an embodiment of the present invention includes a left forming part 1 and a right forming part 2 arranged opposite to each other. The left forming part 1 has a plurality of first acceleration semi-cavities 11 formed on its mating surface. The right forming part 2 has a second acceleration semi-cavity 21 corresponding to the first acceleration semi-cavities 11 formed on its mating surface. The first acceleration semi-cavities 11 and the second acceleration semi-cavities 21 are assembled to form a disk-loaded acceleration cavity 31. The mating surface of the left forming part 1 and the mating surface of the right forming part 2 are welded together to form an acceleration tube body 10. The mating edge of the first acceleration semi-cavity 11 is connected to the second acceleration semi-cavity 21. A buffer gap 32 is reserved between the mating edges of the accelerating half-cavity 21. The left molding part 1 and the right molding part 2 are respectively provided with a beam input port 33 and a beam output port 34 that are connected to the disk-loaded accelerating cavity 31. It also includes: an integrated vacuum maintenance component 5, which is disposed above the left molding part 1 and the right molding part 2, and is used to evacuate the inside of the accelerating structure; and an radio frequency energy feeding component 6, which is disposed outside the left molding part 1 and the right molding part 2, and is used to feed the energy of an external microwave power source into the disk-loaded accelerating cavity 31.

[0026] In this embodiment, addressing the problems of easy extrusion deformation of key internal features during welding, cumbersome assembly of external microwave and exhaust components, and low integration in existing split-type acceleration structures, this structure mainly includes a left forming part 1 and a right forming part 2 arranged opposite to each other. Both are integrally milled from oxygen-free copper material with excellent electrical and thermal conductivity. Multiple first acceleration semi-cavities 11 are formed on the mating surface of the left forming part 1, while a second acceleration semi-cavity 21 is formed on the corresponding mating surface of the right forming part 2. When the left forming part 1 and the right forming part 2 are spliced ​​together and the alloy gasket 4 is provided on the mating surface... During welding, the first accelerating half-cavity 11 and the second accelerating half-cavity 21 are assembled to form a complete disk-loaded accelerating cavity 31, which allows particles to travel and accelerate inside. In actual operation, the microwave power generated by the external microwave source is smoothly fed into the disk-loaded accelerating cavity 31, which is formed by the left forming part 1 and the right forming part 2, under the action of the radio frequency energy feeding component 6. At the same time, the particle beam to be accelerated is injected into the accelerating cavity from the beam input hole 33 at the head end of the accelerating structure. As the microwave electromagnetic field passes through the multiple first accelerating half-cavities 11 and second accelerating half-cavities arranged sequentially along the microwave transmission direction, the acceleration is accelerated. Within the second acceleration half-cavity 21, particles continuously propagate forward, gaining energy and accelerating to the target energy level under the sustained action of the electric field. The high-energy particle beam is then extracted from the beam output aperture 34 at the tail end of the accelerating structure and bombards the target material or is directly used in downstream ray generation equipment. The remaining microwave energy, not fully consumed, is smoothly exported to the external microwave absorption load via the integrated output coupler and impedance transformer at the tail end, thus completing the efficient capture and stable acceleration process of the particle beam. Specifically, a buffer is reserved between the docking edge of the first accelerating half-cavity 11 and the docking edge of the second accelerating half-cavity 21. Gap 32; This buffer gap 32 plays a role in absorbing the thermal expansion stress of the oxygen-free copper substrate during high-temperature brazing, effectively preventing the edge of the internal key microwave cavity from being squeezed and deformed, thereby greatly reducing the probability of high-frequency arcing when a high-power radio frequency electric field is fed in, significantly reducing the risk of arcing and the difficulty of processing. Moreover, since the radio frequency current on the inner wall flows parallel to the buffer gap 32 along the beam direction, the existence of the buffer gap 32 will not damage the performance of the electromagnetic field. At the same time, the coordinated setting of the peripheral components also effectively improves the overall integration of the device, resulting in better performance.

[0027] Optional, please refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 6The integrated vacuum maintaining assembly 5 includes an exhaust portion 51 disposed on the top of the welding surfaces of the left molded part 1 and the right molded part 2, and an exhaust channel 52 formed by the buffer gap 32. When the left molded part 1 and the right molded part 2 are fixedly connected, the two exhaust portions 51 are joined together to form an exhaust port, and an exhaust pipe 53 is disposed in the exhaust port. One end of the exhaust channel 52 communicates with the internal space of the buffer gap 32, and the other end extends to the edge of the acceleration structure and merges with the exhaust port, so that the gas inside the acceleration chamber is discharged through the buffer gap 32 and the exhaust port.

[0028] In this embodiment, the vacuum pump unit is connected to the top suction pipe 53 via a flange and starts working. The airflow inside the acceleration cavity enters the buffer gap 32 due to the pressure difference and extends to the edge along the suction channel 52 formed by the buffer gap 32, eventually converging at the main suction hole and being discharged to the outside. This design cleverly reuses the thermal stress buffer gap 32 as a vacuum suction channel 52, avoiding the damage to the microwave field distribution caused by directly opening holes on the key surface of the microwave cavity. While simplifying the mechanical structure and processing procedures, it greatly improves the efficiency and reliability of the whole machine's vacuuming.

[0029] Optional, please refer to Figure 2 , Figure 3 , Figure 4 , Figure 6 and Figure 7 The radio frequency energy feeding component 6 includes an input section 61 integrated at the beginning of the acceleration structure and an output section 62 integrated at the end. The input section 61 includes an input coupling cavity 611 and an input impedance transformer 612 connected to each other, used to feed energy from an external microwave power source into the disk-loaded acceleration cavity 31. The output section 62 includes an output coupling cavity 621 and an output impedance transformer 622 connected to each other, used to guide the remaining accelerated microwave energy to an external load. Both the input impedance transformer 612 and the output impedance transformer 622 are provided with flange interface surfaces for direct connection to external standard waveguides.

[0030] In this embodiment, microwaves generated by an external microwave power source enter the input impedance converter 612 through the flange interface to complete waveguide mode conversion. Subsequently, they are fed into the disk-load acceleration cavity 31 through the input coupling cavity 611 to provide an accelerating electric field for the particles. The remaining microwave energy that is not consumed reaches the tail end and is led out to the external load through the output coupling cavity 621 and the output impedance converter 622 to be safely absorbed. The integrated microwave coupler and impedance converter design facilitates direct and rapid docking with external standard waveguides, eliminating the risk of air leakage and microwave reflection caused by the additional welding of traditional split couplers, and improving the assembly efficiency and spatial layout flexibility of the whole machine.

[0031] Optional, please refer to Figure 1 , Figure 4 , Figure 6 and Figure 7 The first acceleration half-cavity 11 and the second acceleration half-cavity 21 are arranged sequentially along the microwave transmission direction, and the axial cavity thickness of the first acceleration half-cavity 11 and the second acceleration half-cavity 21 gradually increases along the microwave transmission direction, so as to keep the microwave phase velocity in the acceleration cavity synchronized with the real-time flight velocity of the accelerated particles. Adjacent first acceleration half-cavities 11 and adjacent second acceleration half-cavities 21 are connected by through slots 7.

[0032] In this embodiment, to achieve synchronization between the microwave field and the dynamics of charged particles, the geometric arrangement of the internal core accelerating cavity is defined. Specifically, the multiple first accelerating half-cavities 11 and second accelerating half-cavities 21 on the left molding part 1 and the right molding part 2 are not uniformly arranged, but sequentially arranged along the physical transmission direction of microwaves and particles. Furthermore, in terms of dimensional parameters, the axial cavity thickness of each first accelerating half-cavity 11 and its corresponding second accelerating half-cavity 21 exhibits a regular, gradually increasing state along the microwave transmission direction. The fundamental purpose of this gradually thickening cavity design is... This is used to force a corresponding change in the phase velocity of the microwaves propagating inside the accelerating cavity, thereby enabling them to maintain a strict relative synchronization with the accelerated particles whose real-time flight speed continuously increases due to the continuous acquisition of acceleration energy during this process. Furthermore, to ensure smooth propagation and interconnection of microwave energy between the isolated resonant chambers, adjacent first accelerating half-cavities 11 and adjacent second accelerating half-cavities 21 are interconnected through a circular through-slot 7 located at the center of the disk. When a beam of electrons or charged particles with a low initial velocity enters the accelerating tube from the beginning, it is subjected to longitudinal microwave current within the first accelerating half-cavity. The accelerating thrust of the field causes a significant increase in velocity upon exiting the cavity compared to its entry. When it enters the next accelerating half-cavity, to ensure it still aligns with the peak of the accelerating phase of the microwave electric field rather than the decelerating phase, the microwave's transit time within this cavity must match the particle's flight time. Since the particle's velocity increases, the axial cavity thickness of the next accelerating half-cavity is increased accordingly. This ensures that the time required for the particle to traverse the cavity distance still matches the periodic variation of the microwave field. This mechanism of adjusting the local microwave phase velocity through incremental geometric thickness ensures that the microwave peak always moves in a forward-leaning manner. Like waves, the particles are propelled forward, while the through slot 7 in the center of the disk serves as a necessary medium for the coupling and exchange of electromagnetic field energy between adjacent chambers. This gradually varying thickness arrangement effectively overcomes the severe phase slip and detachment phenomenon that often occurs in the later stages of acceleration in traditional equal-impedance accelerator tubes. This allows the active microwave power to be converted into the kinetic energy of the particles to the maximum extent, significantly improving the initial beam capture efficiency and overall acceleration gradient of the entire accelerator system. This plays a crucial role in obtaining a high-quality, stable output beam with minimal energy divergence and high beam intensity at the exit end, resulting in better performance.

[0033] Optional, please refer to Figure 1 , Figure 4 , Figure 6 and Figure 7 The axial cavity thickness of the first acceleration half-cavity 11 and the second acceleration half-cavity 21 is proportional to their cavity diameter, and the axial cavity thickness of the first acceleration half-cavity 11 and the second acceleration half-cavity 21 is inversely proportional to the aperture of the through groove 7.

[0034] In this embodiment, in order to maintain the consistency of the high-frequency resonance characteristics of the entire tube under the premise that the axial thickness of the aforementioned acceleration half-cavity changes continuously, geometric constraints are imposed on the proportions of other coupling dimensions of the cavity. At the underlying logic of the structural design, the increase in the axial cavity thickness of each first acceleration half-cavity 11 and second acceleration half-cavity 21 must maintain a direct proportional function relationship with the increase in the cavity diameter of its cylindrical large cavity. Furthermore, the change in the axial cavity thickness of the first acceleration half-cavity 11 and second acceleration half-cavity 21 also needs to maintain an inverse proportional scaling relationship with the aperture size of the central through-slot 7 connecting adjacent cavities. That is, when a certain... When the axial thickness of the chamber in the later stage of acceleration is increased to match the high-speed particles, the diameter of its outer chamber must be proportionally enlarged to compensate for the changes in local capacitance and inductance parameters caused by the increased thickness. Simultaneously, the diameter of the through-hole of its central slot 7 must be proportionally reduced. For example, in a Ku-band electron accelerator, the axial cavity thickness of the first accelerating half-cavity 11 and the second accelerating half-cavity 21 can be set between 4mm and 7mm. When the axial cavity thickness changes, the size of the through-hole 7 and the cavity diameter also need to be slightly altered; that is, the larger the axial cavity thickness, the larger the cavity diameter, and the smaller the through-hole 7 diameter. This arrangement facilitates the matching of microwave phase velocity and particle velocity, improves beam trapping efficiency and acceleration gradient, and reduces phase slip, resulting in better performance.

[0035] Optional, please refer to Figure 1 and Figure 2 It also includes an assembly alignment component 8, which is disposed on the welding surface of the left molded part 1 and the right molded part 2, and is used to constrain the relative degrees of freedom of the left molded part 1 and the right molded part 2 in the normal plane before welding, and to make the central axis of the first acceleration half cavity 11 and the second acceleration half cavity 21 coincide.

[0036] In this embodiment, at the instant the left molded part 1 and the right molded part 2 are assembled, the assembly alignment component 8 locks the relative position of the two through mechanical interference, eliminating their sliding allowance in the lateral and longitudinal directions, so that the corresponding first acceleration half cavity 11 and second acceleration half cavity 21 are perfectly aligned; this component can effectively prevent the component misalignment caused by uneven heating of materials during the subsequent high-temperature brazing process, ensuring that the inner wall of the acceleration cavity after assembly fits perfectly, and ensuring the symmetry and uniformity of the internal radio frequency electromagnetic field distribution.

[0037] Optional, please refer to Figure 1 and Figure 2The assembly alignment component 8 includes a positioning hole 81 disposed on the left molded part 1 and a positioning pin 82 disposed on the right molded part 2 that is adapted to the positioning hole 81, and the positioning holes 81 are distributed diagonally or symmetrically along the center.

[0038] In this embodiment, during assembly, the positioning pin 82 on the right forming part 2 is directly inserted into the positioning hole 81 on the left forming part 1 to form an interference fit or a tight clearance fit. The diagonal or centrally symmetrical distribution utilizes the torque balance principle to completely eliminate the rotational degrees of freedom between the parts. This pin-hole fit mechanical centering structure design is not only easy to process and low in cost, but also intuitive and reliable to operate. It greatly reduces the dependence on complex external assembly tooling and improves the batch assembly efficiency and structural positioning accuracy of the accelerator tube.

[0039] This invention also provides a welding process based on the above-described accelerating structure, see below. Figure 9 Specifically, it includes the following steps: In step S1, a left molded part 1 and a right molded part 2 are first provided, which are made of hard oxygen-free copper material with high strength cold work hardening characteristics and without any destructive high temperature annealing treatment, and it is confirmed that various symmetrical internal radio frequency cavity structures have been precisely machined on their mating surfaces. In step S2, a precise local electrochemical brush plating process is adopted. Using special tools, a metal barrier layer and an anti-oxidation wetting layer are deposited locally and densely on the flat welding surfaces of the left molded part 1 and the right molded part 2 that are in contact. The metal barrier layer is a locally brush-plated nickel layer of uniform thickness. Its main purpose is to prevent the liquid tin element from diffusing into the deep lattice of the oxygen-free copper substrate during subsequent high-temperature welding. The anti-oxidation wetting layer is a pure gold layer locally brush-plated on the surface of the rough nickel layer. Its function is to cover the nickel layer to prevent nickel oxidation and provide an excellent capillary wetting interface. In step S3, between the two metal welding surfaces that have undergone the above-mentioned complex local brush plating pretreatment, an alloy gasket 4 made of gold-tin material with a low melting point formula is precisely pre-placed using a tooling, and the final assembly to be welded is formed after the mold is closed. In step S4, the assembly to be welded is pushed into a vacuum heating furnace and a heat source is applied for slow heating and welding. The alloy gasket 4 sandwiched in the middle gradually melts and completely seals the complex welding surface by capillary action. Throughout the heating and heat preservation welding process, the heat input and peak temperature of the heat source are strictly controlled by the silicon controlled rectifier closed-loop system. This ensures that the actual physical temperature of the RF cavity surface, which is surrounded by a thick copper block inside the acceleration structure, is always maintained and never exceeds the annealing softening critical temperature for grain growth of oxygen-free copper material throughout the entire cycle, thereby achieving precise temperature-controlled welding operation.

[0040] This innovative multi-layer brush plating combined with a temperature-controlled welding process using a specific low-melting-point alloy completely bypasses and avoids the technical defect of traditional high-temperature integral silver-copper brazing, which inevitably leads to the softening of oxygen-free copper through heating and annealing. Because the melting point of the gold-tin alloy gasket 4 is 280℃, which is far lower than the annealing temperature of copper (700-800℃), the accelerator tube body 10 after exiting the furnace successfully retains the high-strength cold-worked mechanical state of copper. This not only prevents macroscopic collapse and deformation of the tube body during subsequent processing or vacuuming, but also greatly suppresses the field emission effect at the tip of the tube. This significantly improves the accelerator structure's resistance to high-frequency electrical breakdown during continuous operation under extreme high microwave electric field power, resulting in better performance.

[0041] The present invention also provides a cooling system, see reference. Figure 8 The acceleration structure for cooling the aforementioned particle linear accelerator includes a cooling component 9 disposed outside the acceleration mechanism. The cooling component 9 is in direct contact with the outer surface of the cavity wall of the acceleration structure to cool down by heat conduction. The cooling component 9 includes a semiconductor cooler 91. The cold end face of the semiconductor cooler 91 is coated with thermally conductive adhesive to achieve a tight fit with the outer surface of the cavity wall of the acceleration structure.

[0042] In this embodiment, after the DC power is turned on, the semiconductor cooler 91 generates a continuous heat absorption effect on its cold end face according to the Peltier effect. Since the thermally conductive adhesive eliminates the microscopic air gap thermal resistance, the cold end face quickly absorbs and transfers the heat accumulated on the surface of the accelerator tube body 10 due to microwave ohmic loss to its own system through the metal interface heat conduction. The active solid-state direct cooling using the semiconductor cooler 91 has the advantages of small size, light weight and no mechanical vibration compared with the traditional water cooling system. It can accurately and quickly control the cavity wall temperature of a specific area of ​​the accelerator tube and effectively reduce the frequency drift phenomenon caused by material heating and deformation.

[0043] Optional, please refer to Figure 8 The hot end face of the semiconductor cooler 91 is connected to a cooling fan 92, and a heat dissipation fin 93 is also provided between the hot end face of the semiconductor cooler 91 and the cooling fan 92.

[0044] In this embodiment, the electromagnetic waste heat absorbed by the cold end of the semiconductor cooler 91 and transferred to the hot end is first conducted to the metal heat sink fins 93 with a large surface area for large-area temperature diffusion. Subsequently, multiple cooling fans 92 are activated and generate forced air convection to quickly strip the heat attached to the fin surface and discharge it into the surrounding air. This hot-end exhaust architecture forms a complete closed-loop heat dissipation circuit, preventing the accumulation of heat at the hot end of the cooler from causing a decrease in cooling efficiency or device burnout. This fully ensures the long service life and system stability of the linear accelerator under high-load conditions of continuous beam output, resulting in better performance.

[0045] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. An accelerating structure of a particle linear accelerator, characterized by, The system includes a left forming part (1) and a right forming part (2) arranged opposite to each other. The left forming part (1) has multiple first acceleration semi-cavities (11) on its mating surface. The right forming part (2) has a second acceleration semi-cavity (21) corresponding to the first acceleration semi-cavities (11) on its mating surface. The first acceleration semi-cavities (11) and the second acceleration semi-cavities (21) are combined to form a disk-loaded acceleration cavity (31). The mating surface of the left forming part (1) is welded to the mating surface of the right forming part (2) via an alloy gasket (4) to form an acceleration tube body (10). A buffer gap (32) is reserved between the mating edge of the first acceleration semi-cavities (11) and the mating edge of the second acceleration semi-cavities (21). The left forming part (1) and the right forming part (2) have beam input holes (33) and beam output holes (34) respectively connected to the disk-loaded acceleration cavity (31). The system also includes: An integrated vacuum maintenance assembly (5) is disposed above the left molding part (1) and the right molding part (2) for evacuating the internal structure of the acceleration structure. Radio frequency energy feeding component (6) is disposed on the outside of the left molded part (1) and the right molded part (2) for feeding the energy of the external microwave power source into the disk-loaded acceleration cavity (31).

2. The accelerating structure of a particle linear accelerator according to claim 1, wherein The integrated vacuum maintenance assembly (5) includes an exhaust section (51) disposed on the top of the welding surfaces of the left molded part (1) and the right molded part (2), and an exhaust channel (52) formed by the buffer gap (32); when the left molded part (1) and the right molded part (2) are fixed together, the two exhaust sections (51) are joined together to form an exhaust port, and an exhaust pipe (53) is disposed in the exhaust port; one end of the exhaust channel (52) communicates with the internal space of the buffer gap (32), and the other end extends to the edge of the acceleration structure and merges with the exhaust port, so that the gas inside the acceleration chamber is discharged through the buffer gap (32) and the exhaust port.

3. The accelerating structure of a particle linear accelerator according to claim 2, wherein The radio frequency energy feeding component (6) includes an input section (61) integrated at the beginning of the acceleration structure and an output section (62) integrated at the end. The input section (61) includes an input coupling cavity (611) and an input impedance transformer (612) connected to each other, which are used to feed the energy of an external microwave power source into the disk-loaded acceleration cavity (31). The output section (62) includes an output coupling cavity (621) and an output impedance transformer (622) connected to each other, which are used to guide the remaining microwave energy after acceleration to an external load. Both the input impedance transformer (612) and the output impedance transformer (622) are provided with flange interface surfaces for direct connection to external standard waveguides.

4. The accelerating structure of a particle linear accelerator according to claim 3, wherein The first acceleration half-cavity (11) and the second acceleration half-cavity (21) are arranged sequentially along the microwave transmission direction, and the axial cavity thickness of the first acceleration half-cavity (11) and the second acceleration half-cavity (21) gradually increases along the microwave transmission direction, so as to keep the microwave phase velocity in the acceleration cavity synchronized with the real-time flight velocity of the accelerated particle. Adjacent first acceleration half-cavities (11) and adjacent second acceleration half-cavities (21) are connected by through slots (7).

5. The accelerating structure of a particle linear accelerator according to claim 4, wherein The axial cavity thickness of the first acceleration half-cavity (11) and the second acceleration half-cavity (21) is proportional to their cavity diameter, and the axial cavity thickness of the first acceleration half-cavity (11) and the second acceleration half-cavity (21) is inversely proportional to the aperture of the through groove (7).

6. The accelerating structure of a particle linear accelerator according to claim 1, wherein It also includes an assembly alignment component (8), which is disposed on the welding surface of the left molded part (1) and the right molded part (2) to constrain the relative degrees of freedom of the left molded part (1) and the right molded part (2) in the normal plane before welding, and to make the central axis of the first acceleration half cavity (11) and the second acceleration half cavity (21) coincide.

7. The accelerating structure of a particle linear accelerator according to claim 6, wherein The assembly alignment component (8) includes a positioning hole (81) provided on the left molded part (1) and a positioning pin (82) provided on the right molded part (2) that is adapted to the positioning hole (81), and the positioning holes (81) are distributed diagonally or symmetrically along the center.

8. A welding process based on the acceleration structure of any of claims 1-7, characterized in that, Includes the following steps: S1: Provide a left molding part (1) and a right molding part (2), the left molding part (1) and the right molding part (2) are made of hard oxygen-free copper material that has not been annealed, and their mating surfaces are processed with symmetrical internal radio frequency cavity structures; S2: Using a local brush plating process, a metal barrier layer and an anti-oxidation wetting layer are deposited sequentially on the welding surfaces of the left molded part (1) and the right molded part (2). The metal barrier layer is a locally brush-plated nickel layer used to block the diffusion of tin elements into the copper substrate during welding. The anti-oxidation wetting layer is a locally brush-plated gold layer covering the nickel layer. S3: A gold-tin alloy gasket (4) is pre-placed between the welding surfaces that have undergone localized brush plating pretreatment to form an assembly to be welded; S4: Apply a heat source to the assembly to be welded to melt the alloy gasket (4) and seal the welding surface; during the welding process, control the amount of heat input so that the temperature of the surface of the radio frequency cavity inside the accelerated structure is always kept below the annealing softening temperature of the oxygen-free copper material, thereby achieving temperature-controlled welding operation.

9. A cooling system for cooling the accelerating structure of the particle linac of any one of claims 1-7, characterized in that, The device includes a cooling assembly (9) disposed outside the acceleration mechanism. The cooling assembly (9) is in direct contact with the outer surface of the cavity wall of the acceleration structure to cool down by heat conduction. The cooling assembly (9) includes a semiconductor cooler (91). The cold end face of the semiconductor cooler (91) is coated with thermally conductive adhesive to achieve a tight fit with the outer surface of the cavity wall of the acceleration structure.

10. A cooling system according to claim 9, wherein, The hot end face of the semiconductor cooler is connected to a cooling fan (92), and a heat dissipation fin (93) is also provided between the hot end face of the semiconductor cooler (91) and the cooling fan (92).

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