A forming and assembling method of an ultra-low frequency kicker model cavity

Abstract

The application provides a forming and assembling method of an ultralow-frequency kicker model cavity, and aims at solving the technical problems that a large-diameter copper pipe cannot be directly wound outside an insulating support body made of polytetrafluoroethylene material by a high-temperature heating method, and a large-diameter copper coil cannot be accurately inserted into a slot during forming and assembling of an existing ultralow-frequency kicker model cavity. The application first completes preparation of the large-diameter copper coil by means of a tool, and then sequentially inserts the insulating support body designed as a split structure into the large-diameter copper coil. Meanwhile, the large-diameter copper coil is fixed on the insulating support body by a clamp, the resilience of the large-diameter copper coil is effectively controlled, accurate nesting and fixing of the insulating support body and the large-diameter copper coil are realized, and the accuracy of the resonance frequency of the ultralow-frequency kicker model cavity is ensured. The forming and assembling method of the ultralow-frequency kicker model cavity is convenient, has high reliability, and can accurately realize the target frequency of the ultralow-frequency kicker model cavity.

Description

Technical Field

[0001] This invention relates to an ultra-low frequency beam kicker model cavity, and more particularly to a molding and assembly method for an ultra-low frequency beam kicker model cavity. Background Technology

[0002] A particle accelerator is a device that artificially generates beams of high-energy charged particles. It uses electromagnetic fields of a specific shape to accelerate charged particles such as electrons, protons, and light and heavy ions to speeds of thousands, tens of thousands, or even close to the speed of light per second. These high-energy particle beams are crucial tools for studying "elementary particles" and understanding the deep structure of matter. They also have wide applications in industrial and agricultural production, medical and health care, and scientific and technological fields.

[0003] Based on the type of charged particles being accelerated, particle accelerators can be classified into electron accelerators, proton accelerators, and heavy ion accelerators. Currently, the forefront of proton accelerator technology internationally is mainly developing in two directions: high energy and high current. With the development of disciplines and directions such as fast neutron physics, neutron (proton) radiography, and radiation hardening, high-current proton accelerators, as key devices capable of generating high-current neutrons through target firing, have gradually become a research hotspot in the field of particle accelerators. Currently, high-current proton accelerators at the 100-milliampere level represent the highest level achievable in the world. Multi-pulse compression technology based on path modulation, as one of the key technologies, can further improve the instantaneous current intensity, achieving longitudinal compression of multiple micropulses before target firing, ultimately forming a single short-pulse-width and small-diameter proton cluster, enabling simultaneous target firing. The ultra-low frequency kicking cavity, as a key component at the entrance of the multi-pulse compression system, primarily functions to laterally deflect the successively passing micropulse clusters at different angles. The deflected micropulses then pass through multiple subsequent magnet paths. Ultra-low frequency kicking cavities are essentially resonant cavities. Internationally, there is considerable research on resonant cavities for particle acceleration or deflection, but almost all of these are high-frequency cavities, mostly above 100MHz, with relatively simple internal structures. Examples include: 500MHz single-cell ellipsoidal superconducting resonant cavities, 1.3GHz 9-cell Tesla superconducting resonant cavities, 162.5MHz radio frequency quadrupole resonant cavities (RFQ), and 325MHz spoke cavities. These cavities do not contain discrete components, complex molding processes, or support structures, thus posing no significant technical challenges in mechanical molding and assembly. However, the ultra-low frequency kicking cavity of this invention is designed with a target resonant frequency of 13.5MHz. In the field of radio frequency cavities, this frequency is in the ultra-low range and cannot be achieved with typical cavity designs. Theoretically, increasing the cavity size could lower the cavity frequency, but particle accelerator devices often do not allocate significant space for the resonant cavity, making this method unsuitable for reducing the cavity frequency.

[0004] The application of ultra-low frequency kicking cavities in high-current proton accelerators requires achieving ultra-low frequency, high deflection electric field, low power consumption, and high-precision kicking, which presents significant technical challenges. It is necessary to first explore the forming process of ultra-low frequency kicking model cavities. Only after conducting cold testing experiments on the fabricated ultra-low frequency kicking model cavities to verify the feasibility of the structure can we further develop vacuum ultra-low frequency kicking cavities.

[0005] Based on existing international research progress, the FRANZ project group in Frankfurt, Germany, designed and fabricated a model cavity for an RF beam kicker in 2011. This model cavity adopts a discrete component structure, consisting of a pair of deflection plates, a metal coil, and metal rods. Since the resonant cavity can be equivalent to an RCL circuit, the introduction of the deflection plates increases the equivalent capacitance contribution, and the metal coil increases the equivalent inductance and capacitance contribution. The resonant cavity frequency is inversely proportional to the equivalent capacitance and inductance, resulting in a significant reduction in the resonant frequency. However, the aforementioned model cavity did not adequately consider and design the support for the discrete components. The design of the support structure for discrete components should follow the principle of structural simplification. However, the eight-turn coil involved is supported by three support rods, and the fixing of the deflection plates adds two more support rods. This support scheme lacks integrity, complicating the internal structure of the cavity. This will undoubtedly increase beam loss in the subsequent vacuum cavity and is detrimental to belt-driven operation. Furthermore, the aforementioned model cavity did not consider the applicability of the support scheme for the subsequent vacuum cavity operating with a belt. The support for the vacuum cavity cannot be made of polytetrafluoroethylene (PTFE) and must be made of ceramic materials suitable for vacuum. However, the support rod structure in the aforementioned model cavity is not suitable for ceramic materials and has poor mechanical stability. Therefore, the existing support and reinforcement scheme cannot be continued for subsequent vacuum cavities. Thus, the development of the model cavity cannot provide technical experience for subsequent vacuum cavities.

[0006] Currently, a model cavity for an ultra-low frequency (UHF) beam kicker with a support structure has been proposed in China. This cavity includes a cylindrical outer shell, a pair of deflection plates, a large-diameter copper coil, an insulating support, and a metal rod. Polytetrafluoroethylene (PTFE) is chosen as the insulating support due to its low dielectric constant, low power dissipation factor, and good high-voltage resistance. After completing the electromagnetic field design of the UHF beam kicker model cavity with the support structure, the development of the UHF beam kicker model cavity is urgently needed. However, its internal structure is complex due to the multiple discrete components. Furthermore, according to the electromagnetic field design, the internal structural dimensions of the UHF beam kicker model cavity are a key factor affecting the resonant frequency. This places higher demands on mechanical forming and assembly. If the errors in mechanical forming and assembly are not controlled within acceptable limits, the target frequency of the cavity cannot be accurately achieved, directly affecting subsequent cold testing experiments of the UHF beam kicker model cavity and the development of the vacuum beam kicker cavity. However, there is no reference to the technical experience in the forming, fixing, and assembly processes of the discrete components, presenting the following technical challenges:

[0007] (I) Forming of Large-Diameter Copper Coils: Most copper coils in the current mechanical field have very small cross-sectional diameters and winding radii, approximately a few millimeters. Small-sized copper tubes are highly ductile, making them easy to bend and wind. Typically, the coil can be fabricated by directly winding the copper tube into a stainless steel or other metal groove. However, the copper coil inside the ultra-low frequency kicker mold cavity has a cross-sectional diameter of up to 24mm and a winding radius of up to 190mm. The large cross-sectional diameter and winding radius of the copper coil make it extremely difficult to bend and wind large-diameter copper tubes. While it is possible to soften the large-diameter copper tube through high-temperature treatment and simultaneously wind and embed it into the support groove, the problem is that the high-temperature treatment temperature for large-diameter copper tubes reaches as high as 800℃, while the insulating support is made of polytetrafluoroethylene (PTFE), which only withstands temperatures up to 260℃. Therefore, the above forming method is not feasible.

[0008] (II) Achieving the Target Resonant Frequency Through Precise Insertion of Large-Diameter Copper Coils into the Grooves: According to the electromagnetic field design, the resonant frequency of the kicker model cavity is highly sensitive to the distance between each coil turn and the coil winding radius. During the mechanical forming process, precise control of the distance between each coil turn and the coil winding radius is crucial to achieving the target resonant frequency. However, when large-diameter copper coils are wound and embedded into the grooves of the insulating support, a significant springback force exists between the large-diameter copper coil and the insulating support, preventing precise insertion of the large-diameter copper coil into the grooves. This results in deviations in the distance between each coil turn and the coil winding radius, thus affecting the resonant frequency of the kicker model cavity. Summary of the Invention

[0009] The purpose of this invention is to solve the technical problems faced by existing ultra-low frequency kicker model cavities during molding and assembly, such as the inability to directly wind large-diameter copper tubes onto the outside of polytetrafluoroethylene insulating supports using high-temperature heating methods, and the inability to accurately insert large-diameter copper coils into slots. The invention provides a molding and assembly method for ultra-low frequency kicker model cavities.

[0010] To achieve the above objectives, the technical solution of the present invention is as follows:

[0011] A method for molding and assembling a model cavity for an ultra-low frequency beam kicker, characterized by the following steps:

[0012] Step 1, Preparation of large-diameter copper coils;

[0013] Prepare a tooling with the same dimensions as the insulating support inside the cavity of the ultra-low frequency kicker model; use oxygen-free copper straight tube as the raw material for large-diameter copper coils; soften the oxygen-free copper straight tube by high-temperature heating treatment; and wind it on the outer wall of the tooling according to the preset number of turns and coil spacing to form a large-diameter copper coil.

[0014] Step 2, Preparation of the insulating support;

[0015] The insulating support made of polytetrafluoroethylene is designed as a split structure, including M insulating support blocks, an upper flange and a lower flange, where M≥4; the M insulating support blocks are circumferentially connected to form a hollow cylinder, and the upper flange and the lower flange are fixed to the upper and lower end faces of the hollow cylinder respectively to realize the assembly of the insulating support; an integral coil groove is prepared on the outer wall of the assembled insulating support.

[0016] Step 3: Assembly of the insulating support and the large-diameter copper coil;

[0017] After the coil groove is prepared, the insulating support is disassembled, and M-1 insulating support blocks are sequentially placed into the large-diameter copper coil prepared in step 1, so that the large-diameter copper coil is clamped in the corresponding part of the coil groove. In order to ensure that there is a suitable space inside the coil to place the Mth insulating support block, the large-diameter copper coil needs to be expanded outward by external force before the Mth insulating support block is placed in, so that the remaining part of the large-diameter copper coil is aligned with the coil groove of the Mth insulating support block. Then, upper flanges and lower flanges are installed at the upper and lower ends of the M insulating support blocks respectively. When the external force is released, it will be found that the rebound force is very large after the large-diameter copper coil is fully embedded in the coil groove of the insulating support. Therefore, this invention uses insulating clamps to fix the large-diameter copper coil as a whole in the coil groove on the outer side wall of the insulating support, thereby realizing the assembly of the insulating support and the large-diameter copper coil.

[0018] Step 4: Two pairs of embedded steps adapted to the deflection plates are symmetrically set on the top of the upper flange of the insulating support. The two deflection plates are initially fixed to the upper end of the insulating support through the corresponding two pairs of embedded steps.

[0019] Step 5: Based on the electromagnetic field simulation results, prepare a metal outer cavity cylinder. The metal outer cavity cylinder includes a top flange and a bottom flange at both ends of the cylinder. Machin a first positioning groove adapted to the first metal rod on the top flange, and a second positioning groove adapted to the third metal rod on the bottom flange. Weld one end of the first metal rod to one of the deflection plates, and fix the other end in the first positioning groove. Weld both ends of the second metal rod to the other deflection plate and the upper end of the large-diameter copper coil, respectively. Weld one end of the third metal rod to the lower end of the large-diameter copper coil, and fix the other end in the second positioning groove, thus completing the forming and assembly of the ultra-low frequency beam kicker model cavity.

[0020] Furthermore, in step 3, the insulating clamp is made of polytetrafluoroethylene and includes a retaining ring that is clamped onto a large-diameter copper coil and a fixing plate connected to both ends of the retaining ring.

[0021] Four second through holes are respectively provided on the two fixed plates, and a second threaded hole is provided on the outer wall of the insulating support body at the position corresponding to the second through holes;

[0022] Eight polytetrafluoroethylene screws pass through the corresponding second through holes and are fixed to the corresponding threaded holes, thus fixing the large-diameter copper coil onto the insulating support.

[0023] Furthermore, in step 3, the number of insulating clamps is three: one insulating clamp fixes the upper end of the large-diameter copper coil to the outer wall of the insulating support, and the other two insulating clamps fix the lower end of the large-diameter copper coil to the outer wall of the insulating support.

[0024] Further, in step 2, M = 4, and the M insulating support blocks are circumferentially connected to form a hollow cylinder. The upper flange and lower flange are fixed to the upper and lower end faces of the hollow cylinder, respectively, to achieve the assembly of the insulating support body.

[0025] The four insulating support blocks are circumferentially connected to form a hollow cylinder. Multiple first through holes are provided circumferentially on the upper and lower flanges respectively. First threaded holes are opened on the upper and lower end faces of the hollow cylinder corresponding to the positions of the first through holes. Multiple polytetrafluoroethylene screws are used to pass through the first through holes of the upper and lower flanges and connect to the corresponding first threaded holes on the hollow cylinder to realize the assembly of the insulating support body.

[0026] Furthermore, in step 4, the depth of the embedded step in the vertical direction is 5mm.

[0027] Furthermore, in step 5, the depth of both the first positioning groove and the second positioning groove in the vertical direction is 2mm.

[0028] Furthermore, in step 1, the oxygen-free copper straight tube is a hollow structure, and the oxygen-free copper straight tube is wound on the outer wall of the tooling using a segmented method of simultaneous high-temperature heating and winding.

[0029] Furthermore, in step 1, before the oxygen-free copper straight tube is wound on the outer wall of the fixture, the spacing between adjacent coils is accurately marked on the outer wall of the fixture.

[0030] Furthermore, in step 4, fixing the two deflection plates to the upper end of the insulating support body through the corresponding embedded steps specifically involves: placing the two deflection plates on the corresponding embedded steps to achieve initial fixation, and then fixing the two deflection plates to the corresponding embedded steps with bolts.

[0031] Furthermore, in step 1, when using oxygen-free copper straight tubes as coil raw materials, the tubes are first polished to reduce the roughness R of the inner and outer surfaces. a The thickness is ≤0.5μm. After ultrasonic cleaning to remove oil and oxide layers from the inner and outer surfaces of the oxygen-free copper straight tube, it is then subjected to high-temperature treatment and winding.

[0032] After the large-diameter copper coil is formed, it is immersed in chromic acid solution for 2-4 hours, then rinsed with deionized water. The large-diameter copper coil is then baked in an oven at 60-80℃ for 12 hours, then removed, sealed with nitrogen, and stored to complete the preparation of the large-diameter copper coil.

[0033] The advantages of this invention compared to the prior art are as follows:

[0034] 1. This invention provides a method for molding and assembling an ultra-low frequency beam kicker model cavity. First, a large-diameter copper coil is prepared using a high-temperature heating method with tooling. Then, an insulating support body, designed as a split structure, is sequentially installed into the large-diameter copper coil, achieving assembly of the large-diameter copper coil and the polytetrafluoroethylene (PTFE) insulating support body. Simultaneously, addressing the problem of inaccurate slot insertion due to the large rebound force of the large-diameter copper coil, this invention uses clamps to fix the large-diameter copper coil to the insulating support body, effectively controlling the rebound force of the large-diameter copper coil and achieving precise nesting and fixation of the insulating support body and the large-diameter copper coil, ensuring the accuracy of the resonant frequency of the ultra-low frequency beam kicker model cavity. This method for molding and assembling the ultra-low frequency beam kicker model cavity is convenient to assemble, highly reliable, and can accurately achieve the target frequency of the ultra-low frequency beam kicker model cavity. It provides important research experience and guidance for subsequent cold testing experiments of the model cavity and mechanical molding of vacuum beam kicking cavities with bundled operation.

[0035] 2. The present invention provides a molding and assembly method for an ultra-low frequency beam kicker model cavity. Two embedded steps are symmetrically arranged on the top of the flange of the insulating support body. The two deflection plates and the large-diameter copper coil can be fixed simultaneously through the insulating support body, reducing the introduction of other support structures, avoiding the complexity of the internal structure of the cavity, and thus reducing the beam loss during the subsequent operation of the vacuum beam kicker cavity.

[0036] 3. The present invention provides a molding and assembly method for an ultra-low frequency beam kicker model cavity. A first positioning groove adapted to a first metal rod is machined on the top flange, and a second positioning groove adapted to a third metal rod is machined on the bottom flange. The other end of the first metal rod is fixed in the first positioning groove, and the other end of the third metal rod is fixed in the second positioning groove. This connection method not only achieves a detachable connection, which facilitates subsequent cold testing of the ultra-low frequency beam kicker model cavity, but also ensures a stable connection, effectively reduces contact resistance, and avoids the influence on the cavity resonant frequency.

[0037] 4. When the oxygen-free copper straight tube of the present invention is wound on the outer wall of the tooling, a segmented method of simultaneous high-temperature heating and winding is adopted, which is convenient to operate, highly feasible, and facilitates the forming of oxygen-free copper straight tube. Attached Figure Description

[0038] Figure 1This is a schematic diagram of the structure of the ultra-low frequency beam kicker model cavity formed and assembled according to an embodiment of the present invention;

[0039] Figure 2 This is a schematic flowchart illustrating an embodiment of the molding and assembly method for an ultra-low frequency beam kicker model cavity according to the present invention.

[0040] Figure 3 This is a schematic diagram of the structure of the large-diameter copper coil formed in step 1 of the present invention;

[0041] Figure 4 This is a schematic diagram of the split-type insulating support structure in step 2 of an embodiment of the present invention;

[0042] Figure 5 This is a schematic diagram of the insulating clamp structure in step 3 of an embodiment of the present invention;

[0043] Figure 6 This is a schematic diagram of the structure in step 4 of the present invention, in which two embedded steps are symmetrically arranged on the top of the upper flange of the insulating support;

[0044] Figure 7 This is a schematic diagram of the structure in step 4 of the present invention, in which two third through holes are respectively machined at the upper ends of the two deflection plates;

[0045] Figure 8 This is a schematic diagram of the structure in step 5 of the present invention, in which a positioning groove adapted to the first metal rod 4 is machined on the top flange.

[0046] The specific labeling in the attached diagram is as follows:

[0047] 1-Deflection plate; 2-Large diameter copper coil; 3-Insulating support body; 31-Insulating support block; 32-Upper flange; 33-Lower flange; 34-First through hole; 4-First metal rod; 5-Third metal rod; 6-Metal outer cavity cylinder; 7-Top flange; 8-Bottom flange; 9-Second metal rod; 10-Insulating clamp; 101-Clamping ring; 102-Fixing plate; 1021-Second through hole; 11-Embedded step; 12-Third through hole; 13-First positioning groove. Detailed Implementation

[0048] To make the advantages and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] This invention aims to explore a method for the mechanical forming, support, and assembly of an ultra-low frequency beam kicker model cavity, so as to realize the mechanical forming and assembly of discrete component cavity structures in the ultra-low frequency band, provide important technical experience for the development of subsequent vacuum beam kicker cavity devices, and lay a technical foundation for realizing high-current proton multi-pulse compression.

[0050] The resonant frequency of the ultra-low frequency beam kicker model cavity in this embodiment is 13.5MHz, which is in an extremely low frequency range. Based on the electromagnetic field design of the model cavity, a discrete component structure is required to achieve the ultra-low frequency. For example... Figure 1 As shown, the discrete components of the ultra-low frequency beam kicker model cavity include a metal outer cavity cylinder 6, a large-diameter copper coil 2, a pair of deflection plates 1, an insulating support 3, a first metal rod 4, a second metal rod 9, and a third metal rod 5. The insulating support 3 is made of polytetrafluoroethylene (PTFE). The metal outer cavity cylinder 6 has a top flange 7 and a bottom flange 8 at its two ends. One deflection plate 1 is connected to the top flange of the metal outer cavity cylinder 6 via the first metal rod 4, and the other deflection plate is connected to the upper end of the large-diameter copper coil via the second metal rod 9. The lower end of the large-diameter copper coil is connected to the bottom flange 8 of the metal outer cavity cylinder 6 via the third metal rod 5. The deflection plates 1 provide a transverse deflection electric field for the beam, which passes through the gap between the plates along the length of the plates. The large-diameter copper coil 2 provides a magnetic field, and its introduction increases the equivalent capacitance and inductance contributions. It can be seen that the deflection plates 1 and the large-diameter copper coil 2 are the core structures of the ultra-low frequency beam kicker model cavity. The insulating support 3 supports the large-diameter copper coil 2 and the deflection plate 1, ensuring the mechanical stability of the device. The metal outer cavity 6 forms a closed space, increasing the conductor surface area through which current flows, thereby reducing conductor loss and avoiding radiation loss. The first metal rod 4, the second metal rod 9, and the third metal rod 5 connect the discrete components such as the deflection plate 1, the large-diameter copper coil 2, and the metal outer cavity 6, ultimately forming an equivalent RCL circuit. Compared to conventional cavities, the internal structure of the ultra-low frequency beam kicker model cavity is complex, especially the molding and fixing of the large-diameter copper coil 2, which presents significant technical challenges.

[0051] Taking the aforementioned ultra-low frequency beam kicker model cavity as an example, the present invention provides a molding and assembly method for an ultra-low frequency beam kicker model cavity, such as... Figure 2 As shown, the specific steps include:

[0052] Step 1, Preparation of large-diameter copper coil 2.

[0053] The large-diameter copper coil 2 uses oxygen-free copper straight tubes as the raw material. The oxygen-free copper straight tubes are softened through high-temperature heating and then wound to obtain the large-diameter copper coil. Preferably, the oxygen-free copper straight tube is a hollow straight tube. In this embodiment, the outer diameter of the oxygen-free copper straight tube is 24mm and the inner diameter is 20mm. The forming process of the large-diameter copper coil is as follows:

[0054] (1) Tooling Forming: Since the insulating support 3 is made of polytetrafluoroethylene (PTFE), it cannot withstand high temperatures. However, the winding of the oxygen-free copper straight tube needs to be completed under high-temperature conditions. Therefore, it is necessary to first prepare a tooling with the same dimensions as the insulating support 3 inside the ultra-low frequency kicker model cavity. Therefore, the tooling is made of stainless steel and machined on a lathe. To ensure the spacing between adjacent coils, the spacing between adjacent coils can be marked on the outer wall of the tooling before the oxygen-free copper straight tube is wound on the outer wall of the tooling. This spacing is the size of the ultra-low frequency kicker model cavity after electromagnetic field simulation optimization, which is 20mm in this embodiment.

[0055] (2) Raw material inspection: Inspect the inner and outer surfaces of the oxygen-free copper straight tubes. Use coarse sandpaper to remove large defects, and then use fine sandpaper to polish the inner and outer surfaces to ensure the surface roughness R. a ≤0.5μm.

[0056] (3) Ultrasonic Cleaning: Sanding the oxygen-free copper straight tube introduces a lot of contaminants, including grease introduced by mechanical sanding, skin oil brought in by hand contact with the cavity, and dust adhering to the environment. An ultrasonic cleaner with a frequency of 40kHz is selected, and the ultrasonic temperature is controlled between 40 and 60℃. This temperature range maximizes cavitation intensity and provides the best cleaning effect. For the selection of ultrasonic cleaning agents, Liquinox alkaline cleaning agent is first used to ultrasonically remove oil stains from the surface of the oxygen-free copper straight tube, and then Citranox acidic cleaning agent is used to ultrasonically remove the oxide layer from the surface of the oxygen-free copper straight tube. This can ensure the cleanliness of the oxygen-free copper straight tube surface to a certain extent.

[0057] (4) High-temperature treatment and winding of oxygen-free copper straight tube: To facilitate the winding of oxygen-free copper straight tube, a segmented heating and winding method can be adopted. Specifically, a handheld flame gun is used to heat a local area of ​​the oxygen-free copper straight tube back and forth. The flame temperature can reach up to 800℃. Through high-temperature treatment, the hardness of the oxygen-free copper straight tube is reduced and softened. The softened oxygen-free copper straight tube is wound along a stainless steel tooling to form a large-diameter copper coil 2. Figure 3 As shown, the large-diameter copper coil 2 formed in this embodiment has a radius of 190mm, 3 turns, and a spacing of 20mm between adjacent coils.

[0058] (5) Secondary cleaning: After the large-diameter copper coil 2 is wound and shaped, the surface is oxidized. The shaped large-diameter copper coil 2 is immersed in chromic acid solution for 2-4 hours, then taken out and rinsed with deionized water. Then it is placed in an oven at 60-80℃ and baked for 12 hours. The next day, it is taken out, filled with nitrogen and sealed for storage.

[0059] Step 2, Preparation of insulating support 3.

[0060] In order not to affect the electromagnetic field distribution, the insulating support 3 must be made of insulating material. The specific process flow is as follows:

[0061] (1) Raw material selection: The insulating support material used for the resonant cavity is generally polytetrafluoroethylene (PTFE) or ceramic. PTFE is mainly used in non-vacuum model cavities, while ceramic is mainly used in actual vacuum cavities. Considering that this invention relates to a model cavity, PTFE is sufficient. According to the electromagnetic field design of the ultra-low frequency beam kicker model cavity, the optimal effect is achieved when the large-diameter copper coil 2 and the deflection plate 1 share a single insulating support 3. Figure 4 As shown, in this embodiment, the polytetrafluoroethylene blank is rough-machined into a hollow cylinder with an outer diameter of 380 mm and an inner diameter of 240 mm.

[0062] (2) Disassembly of the insulating support 3: Since the large-diameter copper coil 2 has already been wound and formed, the formed metal coil cannot be directly embedded into the coil groove on the outer wall of the insulating support 3. Therefore, this invention adopts a technical solution of disassembling the insulating support 3 into multiple parts without changing the external dimensions of the insulating support 3, that is, designing the insulating support 3 as a split structure. For example Figure 4 As shown, the split insulating support 3 includes four insulating support blocks 31, an upper flange 32, and a lower flange 33. The four insulating support blocks 31 are circumferentially connected to form a hollow cylinder. Sixteen first through holes 34 are respectively opened on the upper flange 32 and the lower flange 33. First threaded holes are opened on the upper and lower end faces of the hollow cylinder corresponding to the positions of each through hole. Thirty-two polytetrafluoroethylene (PTFE) screws are used to pass through the first through holes 34 of the upper and lower flanges and connect to the corresponding first threaded holes on the hollow cylinder, thereby fixing the upper flange 32 and the lower flange 33 to the upper and lower end faces of the hollow cylinder, respectively, thus achieving the assembly of the split insulating support 3.

[0063] (3) Milling coil grooves on insulating support 3: The coil grooves on the outer wall of the insulating support 3, which has been fixed as a whole, are milled using CNC. The coil grooves are semi-circular arcs with the same outer radius as the large-diameter copper coil 2. At this time, the preparation of insulating support 3 is completed.

[0064] Step 3: Assembly of the insulating support 3 and the large-diameter copper coil 2.

[0065] To assemble the insulating support 3 with the large-diameter copper coil 2, the insulating support 3 needs to be disassembled first. After disassembly, the first insulating support block 31 is placed inside the large-diameter copper coil 2 prepared in step 1, and a portion of the large-diameter copper coil 2 is embedded in the coil groove of the first insulating support block 31. Then, the second insulating support block 31 is placed, and a portion of the large-diameter copper coil 2 is embedded in the coil groove of the second insulating support block 31. Next, the third insulating support block 31 is placed, and a portion of the large-diameter copper coil 2 is embedded in the coil groove of the third insulating support block 31. Finally, by applying force with a jack, the large-diameter copper coil 2 is expanded outwards, leaving appropriate space to place the fourth insulating support block 31, and the remaining portion of the large-diameter copper coil 2 is embedded in the coil groove of the fourth insulating support block 31. After adjustment, the position of each turn of the large-diameter copper coil 2 is perfectly matched with the position of the coil groove on the outer wall of the insulating support 3. Then, the upper flange 32 and the lower flange 33 are installed, achieving the initial assembly of the insulating support 3 and the large-diameter copper coil 2.

[0066] After initial assembly and removal of external force, it is found that the large-diameter copper coil 2 exhibits significant rebound force, making precise placement of the large-diameter copper coil 2 into the slot impossible. Therefore, this invention incorporates an insulating clamp 10 to control the rebound force of the large-diameter copper coil 2. The insulating clamp 10 is made of polytetrafluoroethylene (PTFE) to ensure minimal interference with the field distribution. Figure 1 and Figure 5 As shown, the insulating clamp 10 includes a retaining ring 101 clamped onto the wall of the large-diameter copper coil 2 and a fixing plate 102 connected to both ends of the retaining ring. The fixing plate 102 has four second through holes 1021, and the outer wall of the insulating support 3 has second threaded holes corresponding to the second through holes 1021. Eight polytetrafluoroethylene screws pass through the corresponding second through holes 1021 and are fixed to the corresponding threaded holes, thus fixing the large-diameter copper coil 2 onto the insulating support 3 to control the rebound force of the large-diameter copper coil 2. Since the rebound force of the large-diameter copper coil 2 is mainly concentrated at its upper and lower ends connected to the metal rod, and considering the available space, this embodiment sets one insulating clamp 10 at the upper end and two insulating clamps 10 at the lower end of the large-diameter copper coil 2. By adding three insulating clamps 10, precise insertion of the large-diameter copper coil 2 into the slot is achieved, and the insulating support 3 and the large-diameter copper coil 2 achieve precise nesting and fixation.

[0067] Step 4: Forming and fixing the deflection plate 1.

[0068] (1) Raw material selection: The deflection plate 1 is made of oxygen-free copper. In this embodiment, a solid oxygen-free copper rod is selected as the raw material with a diameter of Φ = 230 mm and a height of 300 mm. The solid deflection plate 1 with a length of 300 m is machined by CNC.

[0069] (2) Fixing of deflection plate 1: such as Figure 6 As shown, two pairs of embedded steps 11, adapted to the deflection plates 1, are symmetrically arranged on the top of the upper flange of the insulating support 3. In this embodiment, the embedding depth of the embedded steps 11 in the vertical direction is 5mm. The two deflection plates 1 are initially fixed to the upper end of the insulating support by the corresponding two pairs of embedded steps 11, thus achieving basic fixation of the two deflection plates 1. Figure 7 As shown, a third through hole 12 with a diameter of 12mm is machined at each end of the two deflection plates 1. Finally, four bolts are threaded through the corresponding third through holes 12 and connected to the insulating support 3 to reinforce the two deflection plates 1. Preferably, the four third through holes 12 on the two deflection plates 1 are symmetrically distributed in pairs. Through electromagnetic field simulation calculations, the four bolt fixation has almost no impact on the electromagnetic field distribution, and therefore will not affect the resonant frequency of the ultra-low frequency beam kicker model cavity. In this way, the present invention simultaneously achieves the fixation of the two deflection plates 1 and the large-diameter copper coil 2 through the insulating support 3.

[0070] Step 5: Connect and fix the discrete components to the metal outer cavity 6.

[0071] (1) Forming of the outer metal cylinder 6: According to the electromagnetic field simulation results, the outer metal cylinder 6 of the ultra-low frequency beam kicker model cavity is a cylinder with a diameter of 600 mm and a height of 673 mm. Since the ultra-low frequency beam kicker model cavity does not involve a vacuum seal, aluminum 6061 is selected as the raw material for machining, and its wall thickness is 5 mm to ensure the mechanical stability of the ultra-low frequency beam kicker model cavity.

[0072] (2) Connection of discrete components: One end of the first metal rod 4 is connected and fixed to one of the deflection plates 1 by welding, and the other end is used to connect to the top flange 7; the two ends of the second metal rod 9 are welded to the other deflection plate 1 and the upper end of the large-diameter copper coil 2 respectively; one end of the third metal rod 5 is welded to the lower end of the large-diameter copper coil 2, and the other end is used to connect to the bottom flange 8. Specifically, each discrete component is soldered using tin soldering. According to electromagnetic field simulation calculations, the introduction of solder at the soldering point has almost no effect on the quality factor and frequency of the ultra-low frequency kicker model cavity.

[0073] (3) Fixing of discrete components to the metal outer cavity 6: This invention uses a first metal rod 4 and a third metal rod 5 to fix the discrete components to the metal outer cavity 6. Specifically, the other end of the first metal rod 4 is connected to the top flange 7 of the metal outer cavity 6, and the other end of the third metal rod 5 is connected to the bottom flange 8 of the metal outer cavity 6. This is a crucial step in ensuring the formation of an equivalent RCL circuit in the ultra-low frequency beam kicker model cavity. Poor contact here will significantly affect the resonant frequency of the ultra-low frequency beam kicker model cavity. If welding is used for fixing, the top flange 7 and bottom flange 8 cannot be opened during subsequent cold testing of the ultra-low frequency beam kicker model cavity. Therefore, this invention processes a first positioning groove 13 on the top flange 7 that matches the first metal rod 4, such as... Figure 8 As shown, the first positioning groove 13 has a diameter of 26mm and a vertical depth of 2mm. This design serves two purposes: firstly, it positions the first metal rod 4; secondly, it allows the first metal rod 4 to be embedded into the top flange 7 and then fixed with screws. This ensures sufficient contact between the first metal rod 4 and the outer metal cavity 6, avoiding contact resistance and facilitating the accurate achievement of the target frequency of the ultra-low frequency beam kicker model cavity. Similarly, the third metal rod 5 is fixed in the same way as the first metal rod 4. A second positioning groove with a diameter of 26mm and a vertical depth of 2mm is machined on the bottom flange 8. The third metal rod 5 is then embedded into the bottom flange 8, and screws are used to ensure sufficient contact between the third metal rod 5 and the outer metal cavity 6.

[0074] It is worth noting that although this embodiment explores the mechanical forming and assembly method for a 13.5MHz ultra-low frequency beam kicker model cavity, the mechanical forming, support, and assembly of other low-frequency discrete component structure cavities and vacuum cavities operating with a beam can also be performed according to the method disclosed in this invention. The above description is only used to illustrate the technical solutions of this invention and is not intended to limit it. For those skilled in the art, modifications can be made to the specific technical solutions described in the above embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions protected by this invention.

Claims

1. A method for molding and assembling a model cavity for an ultra-low frequency kicker, characterized in that, Includes the following steps: Step 1, Preparation of large-diameter copper coil (2); Prepare a tooling with the same dimensions as the insulating support (3) inside the cavity of the ultra-low frequency kicker model; use oxygen-free copper straight tube as the raw material for the large-diameter copper coil (2), soften the oxygen-free copper straight tube by high-temperature heating treatment, and wind it on the outer wall of the tooling according to the preset number of turns and coil spacing to form the large-diameter copper coil (2). Step 2, Preparation of the insulating support (3); The polytetrafluoroethylene insulating support (3) is designed as a split structure, including M insulating support blocks (31), an upper flange (32) and a lower flange (33), where M ≥ 4; the M insulating support blocks (31) are circumferentially connected to form a hollow cylinder, and the upper flange (32) and the lower flange (33) are fixed to the upper and lower end faces of the hollow cylinder respectively to realize the assembly of the insulating support (3); an integral coil groove is prepared on the outer wall of the assembled insulating support (3); Step 3, Assembly of the insulating support (3) and the large-diameter copper coil (2); After the coil groove is prepared, the insulating support (3) is disassembled, and M-1 insulating support blocks (31) are placed into the large-diameter copper coil (2) prepared in step 1 in sequence, so that the large-diameter copper coil (2) is clamped in the coil groove of the corresponding part; after the large-diameter copper coil (2) is expanded outward by external force, the Mth insulating support block (31) is placed in, so that the remaining part of the large-diameter copper coil (2) is aligned with the coil groove of the Mth insulating support block (31); then the upper flange (32) and lower flange (33) are installed on the upper and lower ends of the Mth insulating support blocks (31) respectively; the external force is released, and the large-diameter copper coil (2) is fixed in the coil groove of the outer wall of the insulating support (3) by the insulating clamp (10), so as to realize the assembly of the insulating support (3) and the large-diameter copper coil (2); Step 4: Two pairs of embedded steps (11) adapted to the deflection plates (1) are symmetrically arranged on the top of the upper flange (32) of the insulating support (3) to initially fix the two deflection plates (1) to the upper end of the insulating support (3) through the corresponding two pairs of embedded steps (11). Step 5: Prepare a metal outer cavity cylinder (6) based on the electromagnetic field simulation results. The metal outer cavity cylinder (6) includes a top flange (7) and a bottom flange (8) set at both ends of the cylinder. A first positioning groove (13) adapted to the first metal rod (4) is machined on the top flange (7), and a second positioning groove adapted to the third metal rod (5) is machined on the bottom flange (8). One end of the first metal rod (4) is welded to one of the deflection plates (1), and the other end is fixed in the first positioning groove (13). The two ends of the second metal rod (9) are welded to the other deflection plate (1) and the upper end of the large-diameter copper coil (2) respectively. One end of the third metal rod (5) is welded to the lower end of the large-diameter copper coil (2), and the other end is fixed in the second positioning groove, thus completing the forming and assembly of the ultra-low frequency kicker model cavity.

2. The molding and assembly method for an ultra-low frequency beam kicker model cavity according to claim 1, characterized in that: In step 3, the insulating clamp (10) is made of polytetrafluoroethylene and includes a retaining ring (101) clamped on the large-diameter copper coil (2) and a fixing plate (102) connected to both ends of the retaining ring (101); Four second through holes (1021) are respectively opened on the two fixing plates (102), and a second threaded hole is opened on the outer wall of the insulating support (3) at the position corresponding to the second through holes (1021); Eight polytetrafluoroethylene screws pass through the corresponding second through hole (1021) and are fixed to the corresponding threaded hole to fix the large-diameter copper coil (2) on the insulating support (3).

3. The molding and assembly method for an ultra-low frequency beam kicker model cavity according to claim 2, characterized in that: In step 3, there are three insulating clamps (10). One insulating clamp (10) fixes the upper end of the large-diameter copper coil (2) to the outer wall of the insulating support (3), and the other two insulating clamps (10) fix the lower end of the large-diameter copper coil (2) to the outer wall of the insulating support (3).

4. The molding and assembly method for an ultra-low frequency beam kicker model cavity according to any one of claims 1-3, characterized in that: In step 2, M = 4, and M insulating support blocks (31) are circumferentially connected to form a hollow cylinder. The upper flange (32) and lower flange (33) are fixed to the upper and lower end faces of the hollow cylinder, respectively, to realize the assembly of the insulating support (3). The four insulating support blocks (31) are circumferentially connected to form a hollow cylinder. Multiple first through holes (34) are provided circumferentially on the upper flange (32) and the lower flange (33). First threaded holes are opened on the upper and lower end faces of the hollow cylinder corresponding to the positions of the first through holes. Multiple polytetrafluoroethylene screws are used to pass through the first through holes (34) of the upper flange (32) and the lower flange (33) and connect to the corresponding first threaded holes on the hollow cylinder to realize the assembly of the insulating support (3).

5. The molding and assembly method for an ultra-low frequency beam kicker model cavity according to claim 4, characterized in that: In step 4, the depth of the embedded step (11) in the vertical direction is 5mm.

6. The molding and assembly method for an ultra-low frequency beam kicker model cavity according to claim 5, characterized in that: In step 5, the depth of the first positioning groove (13) and the second positioning groove in the vertical direction is 2mm.

7. The molding and assembly method for an ultra-low frequency beam kicker model cavity according to claim 1, characterized in that: In step 1, the oxygen-free copper straight tube is a hollow structure. When the oxygen-free copper straight tube is wound on the outer wall of the tooling, a segmented method of simultaneous high-temperature heating and winding is adopted.

8. The molding and assembly method for an ultra-low frequency beam kicker model cavity according to claim 7, characterized in that: In step 1, before winding the oxygen-free copper straight tube on the outer wall of the fixture, the spacing between adjacent coils is accurately marked on the outer wall of the fixture.

9. The molding and assembly method for an ultra-low frequency beam kicker model cavity according to claim 1, characterized in that: In step 4, fixing the two deflection plates (1) to the upper end of the insulating support (3) through the corresponding embedded steps (11) is specifically as follows: the two deflection plates (1) are placed on the corresponding embedded steps (11) respectively to achieve initial fixation, and then the two deflection plates (1) are fixed on the corresponding embedded steps (11) respectively by bolts.

10. The molding and assembly method for an ultra-low frequency beam kicker model cavity according to claim 9, characterized in that: In step 1, when using oxygen-free copper straight tubes as coil raw materials, the tubes are first polished to reduce the roughness R of the inner and outer surfaces. a The thickness is ≤0.5μm. After ultrasonic cleaning to remove oil and oxide layers from the inner and outer surfaces of the oxygen-free copper straight tube, it is then subjected to high-temperature treatment and winding. After the large-diameter copper coil (2) is formed, it is immersed in chromic acid solution for 2-4 hours and then rinsed with deionized water. The large-diameter copper coil (2) is then placed in an oven at 60-80℃ and baked for 12 hours. After baking, it is then removed, filled with nitrogen, sealed and stored to complete the preparation of the large-diameter copper coil (2).

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