Cavity tuning assembly and use method thereof

Abstract

The invention relates to the technical field of microwaves, discloses a cavity tuning assembly and a use method thereof, and is particularly suitable for high-power coupler testing. Through the design of the tuning part, the fastening part, the bottom flange and the like, the problem of cavity resonant frequency deviation can be solved in a low-cost, risk-free and short-period manner; the assembly comprises a movable tuning part and a fixed tuning part, height fine tuning is realized through threaded connection, and the resonant frequency of a cavity is accurately changed; the device is installed at a vacuum mesh, vacuum sealing is not needed, the risk of vacuum leakage is avoided, and system safety is ensured. The method is not only suitable for coupler testing, but also can be widely applied to equipment such as resonant cavities, filters and accelerators, and has remarkable economical efficiency and high efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of microwave technology, and particularly relates to a cavity tuning assembly and a method thereof, which is especially suitable for high-power coupler testing process, and provides a low-cost, risk-free and short-period cavity tuning solution for the problem of cavity resonance frequency shift caused by the change of the insertion depth of the coupler conductor, and can be widely applied to resonant cavities, filters and accelerators and other devices. BACKGROUND

[0002] In the field of microwave technology, as a key device of the accelerator microwave system, the stability and reliability of the performance of the high-power coupler are crucial. Generally, before being assembled with the cavity, the function of the coupler needs to be verified by high-power testing to prevent the performance of the cavity from being degraded due to the problem of the coupler. For a coaxial coupler, in the frequency range of about 30MHz-500MHz, a 1 / 4 wavelength cavity (test bench) is usually used to connect two couplers for high-power testing to improve the testing efficiency. However, in order to reduce the cost and avoid the heating of the test bench itself, the design of the coupler test bench is often simple, and the peripheral sealed vacuum interface only includes two coupler mounting ports and one vacuum suction port.

[0003] The coupling mode between the coupler and the test bench is electrical coupling, and the insertion depth of the coupler conductor relative to the wall surface of the test bench has a significant impact on the system resonance frequency. In actual application, due to installation tolerance or high-frequency cavity design changes, the length of the coupler conductor may change greatly, resulting in the mismatch of the transmission of the entire system after the coupler is connected with the test bench. For example, when the CSNS-Ⅱ coupler prototype is manufactured, the superconducting high-frequency cavity index requires that the length of the inner conductor is L; but in actual batch production, the superconducting high-frequency cavity index is improved, and the length of the inner conductor is required to be reduced by about 6mm than L. This change results in that the transmission S21 of the entire system at the resonance frequency of 324MHz is only about 0.5 after the two couplers are connected with the test bench, which cannot meet the use requirements.

[0004] For the problem of system transmission mismatch, the traditional modification scheme has many limitations. If the insertion depth of the inner conductor of the coupler relative to the wall surface of the test table is too deep, the test table needs to be reworked or the gasket thickness needs to be changed, but reworking the test table is long in period and expensive (several hundred thousand yuan), and changing the gasket thickness is limited by the problem of vacuum sealing. If the insertion depth of the inner conductor of the coupler relative to the wall surface of the test table is too shallow, the test table needs to be reworked or a part of the coupler mounting port needs to be cut off and a new length of the mounting port needs to be re-welded. The scheme of re-welding the coupler mounting port not only has the risk of test table scrap, but also increases the difficulty of re-welding due to the water cooling channel and the copper-plated inner surface of the coupler mounting port, and has high cost and long period. Therefore, for the test table that has been processed, in the case that the insertion depth of the inner conductor of the coupler relative to the wall surface thereof is greatly changed, how to modify it at low cost, without risk and in short period becomes a problem to be solved. SUMMARY

[0005] In view of the above problems, the present application aims to provide a cavity tuning assembly and a method thereof, which can be widely used in resonant cavities, filters and accelerators and the like, and is used to solve the problem of system resonance frequency deviation caused by the change of the length of the inner conductor of the coupler or the processing and installation errors when the high-power coupler is assembled with the test table, so as to realize low-cost, risk-free and short-period cavity frequency tuning and ensure that the system works at the target frequency.

[0006] The technical scheme adopted by the present application to solve the technical problems is: a cavity tuning assembly, comprising: a tuning component, including a movable tuning component, a fixed tuning component and a mounting support rod (12); wherein the movable tuning component is a class I-shaped structure, hollow inside, the outer diameter of the bottom ring is slightly larger and the outside is pre-threaded, matched with the internal thread on the fixed tuning component; the fixed tuning component is a class convex structure, hollow inside and different diameters in the upper and lower parts, a groove is opened on the inside of the upper part, a fine tooth internal thread is arranged inside the groove for matching with the movable tuning component, and a certain length of thread is arranged on the inside of the lower part for matching with the mounting support rod; a fastening component, which is a class concave structure and is composed of a first half fastening flange and a second half fastening flange, used for fastening the installed tuning component; a bottom flange, which is a circular ring structure, six counterbores are opened in the circumferential direction for screwing and fixing the installed tuning component; The tuning assembly is installed in the test cavity through the vacuum grid reserved by the vacuum extraction section, used to change the cavity resonance frequency, so as to compensate for the frequency deviation caused by the change of the insertion depth of the device to be tested relative to the cavity.

[0007] The bottom of the movable tuning component is internally reserved with a hexagonal structure for connecting with the adjusting tool to rotate the movable tuning component, thereby finely adjusting the distance between the movable tuning component and the fixed tuning component.

[0008] The fixed tuning component is externally provided with a groove for cooperating with and mounting the fastening component, and the bottom surface is provided with six threaded holes for fastening the cooperating tuning component and the fastening component.

[0009] The mounting support rod is a rod-like structure, the top of which is slightly larger in diameter and is reserved with a thread for being screwed with the fixed tuning component to move as a whole.

[0010] The first half fastening flange and the second half fastening flange of the fastening component are each internally provided with two threaded blind holes for fastening the mounted tuning component.

[0011] The tuning assembly is mounted on the vacuum grid of the test cavity, is mounted through a vacuum suction port, and after being mounted, the tuning assembly is completely in a vacuum environment.

[0012] A use method of a cavity tuning assembly, comprising the following steps: S1, placing the first half fastening flange and the second half fastening flange on the grid from bottom to top through the central hole of the vacuum grid; S2, threading the movable tuning component into the fixed tuning component and adjusting to the target height through threaded connection; S3, connecting the mounting support rod with the fixed tuning component through threaded connection to form a complete tuning component assembly; S4, adjusting the position of the tuning component in the vertical direction by hand-holding the mounting support rod to pass the tuning component through the central hole of the vacuum grid from bottom to top; S5, pinching the first half fastening flange and the second half fastening flange to form the fastening component through the two holes at the side of the grid, so that the tuning component and the fastening component complete the concave-convex cooperation; S6, keeping the pinching state of the first half fastening flange and the second half fastening flange, rotating the tuning component until the hole positions on the tuning component, the fastening component and the bottom flange are aligned; S7, using an inner hexagonal bolt with appropriate length and shortness to complete fastening; S8, if fine adjustment is needed, an inner hexagonal support rod adapted to the bottom of the movable tuning component is used to complete adjustment.

[0013] After the tuning assembly is mounted, fine adjustment of the resonant frequency is realized by rotating the movable tuning component to compensate for errors occurring in the installation or processing process.

[0014] The tuning assembly is suitable for use in resonant cavities, filters and accelerator devices, for adjusting the resonant frequency of the cavity to ensure that the system works at the target frequency.

[0015] The vacuum grid can be replaced by any structure with holes for installing the tuning assembly; and the cooperation between the fastener and the tuning component can be replaced by other forms, such as threads or special-shaped clamping groove structures; and the cooperation between the movable tuning component and the fixed tuning component in the fine tuning structure can be changed to other ways, such as bellows connection or special-shaped clamping groove.

[0016] Compared with the prior art, the present application has the following beneficial effects: The cavity tuning assembly provided by the present application can accurately change the cavity resonant frequency by installing a tuner at the reserved vacuum grid of the cavity, effectively compensating for the system operating frequency deviation caused by the change of the insertion depth of the inner conductor of the to-be-tested device (such as a coupler) relative to the cavity wall. This feature enables the resonant frequency of the system to remain consistent with the operating frequency before the insertion depth of the inner conductor of the coupler is changed when the test bench is connected with two couplers with changed insertion depths of the inner conductor, thereby ensuring that the system operates at the target frequency, and improving the efficiency and reliability of the test.

[0017] The tuning assembly of the present application is provided with a fine tuning structure, and the height adjustment is specifically achieved through the threaded connection between the movable tuning component and the fixed tuning component. After installation, the fine tuning structure can be used to make small adjustments to the resonant frequency to compensate for errors that may occur during installation or processing.

[0018] The cavity tuning assembly and its installation scheme of the present application are simple and easy to implement, and the machining and installation period is short. Compared with the traditional modification scheme, the present scheme does not need to redo the test bench or perform complex welding operations, greatly reducing the modification cost (about several thousand yuan), and has significant economic efficiency. At the same time, due to the simplicity of processing and installation, the modification period is shortened, and the work efficiency is improved.

[0019] The tuning assembly of the present application is completely in a vacuum environment and is installed through a vacuum port, without the need to consider the vacuum sealing problem. This feature avoids the risk of vacuum leakage that may be caused by welding and other operations in the traditional modification scheme, ensuring the stability and reliability of the vacuum environment of the test cavity, and thereby ensuring the safety of the system after modification.

[0020] The cavity tuning assembly of the present application is not only suitable for the testing scene of high-power couplers, but also can be widely applied to devices such as resonant cavities, filters and accelerators, for adjusting the cavity resonant frequency and ensuring that the system operates at the target frequency. In addition, the grid in the present application can be replaced by any structure with holes, and the cooperation between the fastener and the tuning component and the cooperation between the movable tuning component and the fixed tuning component in the fine tuning structure can be replaced by other forms, such as threads, special-shaped clamping groove structures or bellows connection, etc., further improving the flexibility and applicability of the tuning assembly. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 This is a schematic diagram of the cross-sectional structure of the cavity tuning assembly and its mounting rod of the present invention; Figure 2 This is a schematic diagram of the cavity tuning assembly and its mounting rod after assembly according to the present invention; Figure 3 This is an exploded structural diagram of the present invention; Figure 4 This is a view of the tuner and cavity assembled in this invention, where the length L is the insertion depth of the inner conductor relative to the test stage wall. Figure 5 After reducing the insertion depth of the inner conductor of the coupler by 6 mm, the S11 parameter of the cavity tuning component in this invention is not used. Figure 6 After reducing the coupler insertion depth by 6 mm, the S11 parameter of the cavity tuning component in this invention is used. Figure 7 This is the heat distribution of the cavity and tuner when the forward average power is 20 kW, at a room temperature of 25°C.

[0022] Figure labeling: 1-Tuning component, 10-Modible tuning component, 11-Fixed tuning component, 12-Mounting support rod, 2-Fastening component, 20-First semi-fastening flange, 21-Second semi-fastening flange, 3-Vacuum grid, 4-Bottom flange, 5-Coupler inner conductor one, 6-Coupler inner conductor two, 7-Coupler mounting port one, 8-Coupler mounting port two, 9-Vacuum extraction port. Detailed Implementation

[0023] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings: like Figures 1-7 As shown, a cavity tuning assembly includes: Tuning component 1 includes a movable tuning component 10, a fixed tuning component 11, and a mounting support rod 12. The movable tuning component 10 has an I-shaped structure with a hollow interior. The outer diameter of the bottom ring is slightly larger and has an external thread that mates with the internal thread on the fixed tuning component 11. The fixed tuning component 11 has a convex structure with a hollow interior and different diameters in the upper and lower parts. The upper part of the interior has a groove with a fine internal thread for mates with the movable tuning component 10, and the lower part of the interior has a thread of a certain length for mates with the mounting support rod 12. Fastening component 2 has a concave structure and consists of a first semi-fastening flange 20 and a second semi-fastening flange 21. It is used to fasten the tuning component after installation. The bottom flange 4 is a circular structure with six countersunk holes in its circumference for threading screws and fixing the tuner assembly after installation. The tuning assembly is installed in the test cavity through the vacuum grid 3 reserved by the vacuum extraction section, used to change the cavity resonance frequency, to offset the frequency shift caused by the change of the insertion depth of the device to be tested relative to the cavity.

[0024] Embodiment 1 The embodiment provides a cavity tuning assembly and a method thereof, aiming to solve the problem of system resonance frequency shift caused by the change of the insertion depth of the inner conductor of the coupler after the high-power coupler is connected to the test table. The following will be described in combination with the drawings in the description Figures 1-7 The specific implementation of the embodiment is described in detail.

[0025] P1, cavity tuning assembly structure The cavity tuning assembly in the embodiment mainly includes three parts of a tuning part 1, a fastening part 2 and a bottom flange 4, and the specific structure and connection relationship of each part are as follows: Tuning part 1 Movable tuning part 10: a structure similar to an I-shaped structure (as shown in 10 of Figure 1 and Figure 2 ), made of metal with good conductivity. Hollow inside, providing a channel for vacuum extraction, the top is rounded to avoid high-frequency sparking, the bottom ring has an outer diameter slightly larger and an external thread reserved, matched with the internal thread on the fixed tuning part 11. The bottom ring has a hexagonal structure reserved inside, used to connect with the adjusting tool to rotate the movable tuning part 10, thereby fine-tuning the distance between the movable tuning part 10 and the fixed tuning part 11.

[0026] Fixed tuning part 11: a structure similar to a convex shape (as shown in 11 of Figure 1 and Figure 2 ), also made of metal with good conductivity. Hollow inside and with different diameters in the upper and lower parts, a groove is opened on the inside, with a fine-threaded internal screw thread inside, used to cooperate with the movable tuning part 10. Two half-rings can be used on the top of the groove, and after the movable tuning part 10 is inserted, they are rotated from the top of the fixed tuning part 11 to the inside, used for limiting; a screw thread of a certain length is provided on the lower part of the groove, used to cooperate with the installation support rod 12 to install the movable tuning part 10 and the fixed tuning part 11. The external groove of the fixed tuning part 11 is used for cooperation and installation with the fastening part 2, and the bottom surface is provided with six threaded holes for the fastened and cooperated tuning part 1 and the fastening part 2.

[0027] Installation support rod 12: a structure similar to a rod (as shown in 12 of Figure 1 and Figure 2 ), with a slightly larger diameter at the top and a thread, used to move as a whole after being screwed with the fixed tuning part 11. Made of material with good support, without conductivity requirement.

[0028] Fastening component 2: The fastening component 2 is a concave structure (as shown in Figure 1 and Figure 2 2), which is machined from a circular ring and cut into two equal parts: the first half fastening flange 20 and the second half fastening flange 21. The material is a metal with good electrical conductivity. The first half fastening flange 20 and the second half fastening flange 21 each have two threaded blind holes inside for fastening the tuned component after installation.

[0029] Bottom flange 4: The bottom flange 4 is a circular ring structure (as shown in Figure 1 and Figure 2 4), which has six counterbores in the circumferential direction for screwing and fixing the tuned assembly after installation.

[0030] P2, installation conditions and principles Installation condition restriction: Due to the closed nature of the test bench, the tuned assembly cannot be installed directly from the inside of the test bench or the upper part of the vacuum grid, but can only be installed into the test bench from the periphery of the test bench.

[0031] Principle: By installing a Tuner (i.e. the tuned assembly of the present application) through the reserved vacuum grid port of the test bench, the change in the coupling insert depth is supplemented, and finally the resonant frequency of the system after connecting the test bench with two coupling inserts with changed inner conductor insertion depths is consistent with the operating frequency before the change in the coupling insert inner conductor insertion depth. In addition, a threaded connection structure is added at the Tuner, which can achieve fine tuning after installation of the Tuner, and is used to compensate for the frequency deviation caused by the machining or installation error of the coupling insert inner conductor.

[0032] P3, specific implementation steps Size preparation: In this embodiment, the maximum outer diameter of the assembly 1 is slightly smaller than the diameter d of the central hole on the vacuum grid 3, ensuring that the assembly 1 can pass through the central hole on the vacuum grid 3 below.

[0033] In this embodiment, the outer diameter of the assembly 2 is greater than d to achieve the fastening effect after installation.

[0034] In this embodiment, the concave-convex fit of the assemblies 1 and 2 has a gap of <1mm in the vertical direction, facilitating installation while ensuring close contact of the high-frequency part.

[0035] After installation, part of the assembly 11 sinks into the central hole of the assembly 3, limiting the shaking of the assembly 1 in the circumferential direction and serving as a positioning function.

[0036] Installation process: Place the first half fastening flange 20 and the second half fastening flange 21 through the central hole of the vacuum grid 3 from below to above on the grid.

[0037] The movable tuning component 10 is inserted into the fixed tuning component 11 and adjusted to the target height via a threaded connection.

[0038] The mounting support rod 12 is connected to the fixed tuning component 11 by threads to form a complete tuning component 1 assembly.

[0039] Hold the mounting support rod 12 and push the tuning component 1 through the center hole of the vacuum grid 3 from bottom to top, adjusting the position of the tuning component 1 in the vertical direction.

[0040] The first semi-fastening flange 20 and the second semi-fastening flange 21 are joined together through two holes on the side of the mesh to form the fastening component 2, so that the tuning component 1 and the fastening component 2 complete the concave-convex fit.

[0041] While keeping the first semi-fastening flange 20 and the second semi-fastening flange 21 in a pinched state, rotate the tuning component 1 until the holes on the tuning component 1, the fastening component 2 and the bottom flange 4 are aligned.

[0042] Use an appropriate length of internal hex bolts to tighten the bolts.

[0043] Fine-tuning process: If fine-tuning is required, the adjustment is completed using the hexagonal support rod that is adapted to the bottom of the movable tuning component 10. The resonant frequency is fine-tuned by rotating the movable tuning component 10 to compensate for errors that occur during installation or processing.

[0044] P4. Implementation Results Frequency modulation effect: such as Figure 5 and Figure 6 As shown, without the addition of the tuning component, the S11 parameter of the system does not meet the usage requirements; after adding the tuning component, the resonant frequency of the system is pulled back to the operating frequency of 324MHz, achieving a good tuning effect.

[0045] Heat generation assessment: A simplified mechanical model was established in CST, and the system's heat generation was assessed when a forward continuous wave of 20kW power passed through. Since the tuning component is located in a low electromagnetic field, its maximum temperature rise is approximately 11.2℃ (ambient temperature 25℃), which is about half the maximum temperature rise of 24.1℃ in the test chamber, meeting practical application requirements (e.g., ...). Figure 7 (As shown).

[0046] Example 2: The structure and principle in the embodiment are the same as those in Embodiment 1, except that the vacuum grid 3 in the embodiment can be replaced by any structure with holes. The cooperation between the fastener 2 and the tuning component 1 can be replaced by other forms, such as a threaded or a special-shaped slot structure. The cooperation between the movable tuning component 10 and the fixed tuning component 11 in the fine tuning structure can be changed to other ways, such as a bellows connection way or a special-shaped slot way.

[0047] The fine tuning structure can be omitted in the embodiment, and the purpose of the application can still be achieved after the omission, but the fine tuning function is lost.

[0048] In summary, the cavity tuning assembly of the application achieves the change of the resonant frequency of the test cavity by installing the tuner at the vacuum grid, and compensates for the frequency deviation caused by the change of the insertion depth of the device to be tested relative to the cavity. At the same time, the tuning assembly has a fine tuning function after installation, which can compensate for the frequency deviation caused by the machining or installation error of the conductor in the coupler, and ensure that the system works at the target frequency. The tuning assembly and the installation scheme thereof have wide applicability and can be widely applied to devices such as resonant cavities, filters and accelerators.

Claims

1. A cavity tuning assembly, characterized in that, include: The tuning component (1) includes a movable tuning component (10), a fixed tuning component (11), and a mounting support rod (12); wherein, the movable tuning component (10) is an I-shaped structure with a hollow interior, a slightly larger outer diameter of the bottom ring and an external thread reserved on the outside, which mates with the internal thread on the fixed tuning component (11); the fixed tuning component (11) is a convex structure with a hollow interior and different diameters in the upper and lower parts, a groove is opened on the upper part of the interior, and a fine internal thread is provided in the groove for mates with the movable tuning component (10), and a certain length of thread is provided on the lower part of the interior for mates with the mounting support rod (12); The fastening component (2) has a concave structure and consists of a first semi-fastening flange (20) and a second semi-fastening flange (21), and is used to fasten the tuning component after installation; The bottom flange (4) is a circular structure with six countersunk holes in its circumference for threading screws and fixing the tuner assembly after installation. The tuning component is installed in the test chamber through the vacuum grid (3) reserved in the vacuum extraction section. It is used to change the resonant frequency of the chamber to compensate for the frequency shift caused by the change in the insertion depth of the device under test relative to the chamber.

2. The cavity tuning assembly according to claim 1, characterized in that, The movable tuning component (10) has a hexagonal structure reserved inside the bottom ring, which is used to rotate the movable tuning component (10) after being connected to the adjustment tool, thereby finely adjusting the distance between the movable tuning component (10) and the fixed tuning component (11).

3. The cavity tuning assembly according to claim 1, characterized in that, The fixed tuning component (11) has a groove on its outside for fitting and installing with the fastening component (2); and its bottom surface has six threaded holes for fastening the tuning component (1) and the fastening component (2) after fitting.

4. The cavity tuning assembly according to claim 1, characterized in that, The mounting support rod (12) is a rod-like structure with a slightly larger top diameter and threads, used to move as a whole after being tightened with the fixed tuning component (11).

5. The cavity tuning assembly according to claim 1, characterized in that, The fastening component (2) has two threaded blind holes inside the first half-fastening flange (20) and the second half-fastening flange (21) for fastening the tuning component after installation.

6. The cavity tuning assembly according to claim 1, characterized in that, The tuning component is installed on the vacuum grid (3) of the test chamber through a vacuum extraction port, and after installation, the tuning component is completely in a vacuum environment.

7. A method of using the cavity tuning assembly as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1 places the first semi-fastening flange (20) and the second semi-fastening flange (21) on the grid from bottom to top through the center hole of the vacuum grid (3); S2 inserts the movable tuning component (10) into the fixed tuning component (11) and adjusts it to the target height via a threaded connection; S3 connects the mounting support rod (12) and the fixed tuning component (11) by thread to form a complete tuning component (1) assembly; S4 Handheld mounting support rod (12) from bottom to top to pass the tuning component (1) through the center hole of the vacuum grid (3) and adjust the position of the tuning component (1) in the vertical direction; The two holes on the side of the S5 mesh connect the first half-fastening flange (20) and the second half-fastening flange (21) to form a fastening component (2), so that the tuning component (1) and the fastening component (2) complete the concave-convex fit; S6 keeps the first half-fastening flange (20) and the second half-fastening flange (21) in a pinched state, and rotates the tuning component (1) until the holes on the tuning component (1), the fastening component (2) and the bottom flange (4) are aligned; S7 uses an appropriately sized hex bolt to complete the tightening; If S8 requires fine-tuning, the adjustment is accomplished using the internal hexagonal support rod that is adapted to the bottom of the movable tuning component (10).

8. The method of using the cavity tuning assembly according to claim 7, characterized in that, After the tuning component is installed, the resonant frequency can be finely adjusted by rotating the movable tuning component (10) to compensate for errors that occur during installation or processing.

9. The cavity tuning assembly according to any one of claims 1 to 6, characterized in that, The tuning component is suitable for use in resonant cavities, filters, and accelerator devices to adjust the cavity resonant frequency and ensure that the system operates at the target frequency.

10. The cavity tuning assembly according to any one of claims 1 to 6, characterized in that, The vacuum grid (3) can be replaced by any perforated structure for mounting the tuning component; and the fit between the fastener (2) and the tuning component (1) can be replaced by other forms, such as threaded or irregular slot structures; the fit between the movable tuning component (10) and the fixed tuning component (11) in the fine-tuning structure can be changed to other methods, such as bellows connection or irregular slot.

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