Device for detecting the flatness of the electric field in a radio frequency cavity in a low-temperature environment

Abstract

The present invention relates to the technical field of particle accelerators, and particularly to a device for detecting the electric field flatness of a radio frequency cavity in a low-temperature environment. The device includes: a housing structure, which is hermetically connected to the radio frequency cavity, and the cavity of the housing structure is communicated with the acceleration cavity of the radio frequency cavity; a rotating member, which is arranged in the cavity of the housing structure; a driving mechanism, which is installed in the cavity of the housing structure and connected to the rotating member for driving the rotating member to rotate; a vacuum feedthrough, which is installed at the flange of the housing structure for transmitting signals from the air to the driving mechanism in the low-temperature vacuum; the two housing structures are symmetrically arranged at both ends of the acceleration cavity, and a fishing line with both ends respectively wound around the rotating member penetrates through the acceleration cavity; a perturbing body that can move in the acceleration cavity along with the rotation of the rotating member is arranged on the fishing line, so as to reliably detect the acceleration cavity in a low-temperature environment.

Description

Technical Field

[0001] The present invention relates to the technical field of particle accelerators, and particularly to a device for detecting the electric field flatness of a radio frequency cavity in a low-temperature environment. Background Art

[0002] Currently, in the scientific research and application of radio frequency cavity accelerating cavities, two methods are often used to cool the accelerating cavity body at low temperature: liquid nitrogen immersion cooling and contact conduction cooling. The low-temperature copper cavity structure has high shunt impedance, low resistivity, and low radio frequency loss, and it is easier to achieve advantages such as small size, high gradient, low heat dissipation, and low spark rate, and is widely used in low-temperature environments below 77K (Kelvin).

[0003] In addition, the accelerating cavity is divided into two forms: standing wave cavity and traveling wave cavity. Generally, the electric field distribution of the standing wave cavity is the same at normal temperature and low temperature. The electric field flatness can be measured at normal temperature, tuned to a reasonable range, and then the accelerating cavity is placed in a complex liquid nitrogen cooling device or low-temperature cavity for verification. In a normal temperature environment, the electric field flatness of the accelerating cavity is usually detected by the bead method. The bead method is to use a fishing line with a perturbation body to pass through the internal beam pipe of the accelerating cavity, and make the perturbation body move uniformly in the beam pipe to form a perturbation test on the internal electric field of the accelerating cavity.

[0004] However, the electric field distribution of the traveling wave cavity is different at normal temperature and low temperature. The electric field flatness measured at normal temperature cannot be accurately directly applied to the low-temperature environment. Moreover, the bead method is also difficult to directly apply to the traveling wave cavity in a low-temperature environment. Because in a low-temperature environment, the accelerating cavity needs to be kept in a vacuum state to ensure that the inner wall does not freeze and does not interfere with the electric field distribution. Using the bead method to detect the electric field flatness of the traveling wave cavity in a low-temperature environment not only requires vacuum sealing of the accelerating cavity, but also requires setting up a mechanism that can drive the fishing line to move inside the accelerating cavity and ensure the vacuum sealing state. Therefore, there is an urgent need for a solution that can reliably detect the radio frequency cavity in a low-temperature environment. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the related art. For this purpose, the present invention provides a device for detecting the electric field flatness of a radio frequency cavity in a low-temperature environment, so as to achieve the purpose of reliably detecting the electric field flatness of the radio frequency cavity in a low-temperature environment.

[0006] The present invention provides a device for detecting the electric field flatness of a radio frequency cavity in a low-temperature environment. The detection device includes: a housing structure, which is hermetically connected to the radio frequency cavity, and the cavity of the housing structure is communicated with the accelerating cavity of the radio frequency cavity;

[0007] a rotating member, which is arranged in the cavity of the housing structure;

[0008] A driving mechanism, installed in the cavity of the housing structure and connected to the rotating member, for driving the rotating member to rotate;

[0009] Wherein, the two housing structures are symmetrically arranged at both ends of the acceleration cavity, a fishing line is threaded through the acceleration cavity, and both ends of the fishing line are respectively wound around the rotating member; the driving mechanism is communicated with the circuit outside the housing structure through a vacuum feedthrough arranged on the housing structure;

[0010] A perturbation body is arranged on the fishing line and can move in the acceleration cavity along with the rotation of the rotating member, for disturbing the internal electric field of the acceleration cavity.

[0011] According to a device for detecting the electric field flatness of a radio frequency cavity in a low-temperature environment provided by the present invention, the housing structure is provided with a first connecting portion, and the first connecting portion extends upward in the vertical direction and protrudes from the top of the housing structure;

[0012] The vacuum feedthrough is arranged at the upper end of the first connecting portion.

[0013] According to a device for detecting the electric field flatness of a radio frequency cavity in a low-temperature environment provided by the present invention, the housing structure is provided with a second connecting portion, and the second connecting portion extends horizontally and protrudes from the side wall of the housing structure;

[0014] A positioning disk is arranged at the overhanging end of the second connecting portion, for ensuring that the fishing line moves along the central axis of the acceleration cavity.

[0015] According to a device for detecting the electric field flatness of a radio frequency cavity in a low-temperature environment provided by the present invention, the first connecting portion is provided with a knife-edge flange, and is connected to the vacuum feedthrough through the knife-edge flange;

[0016] The second connecting portion is provided with a knife-edge flange, and is connected to the acceleration cavity through the knife-edge flange;

[0017] The positioning disk is arranged on the side where the knife-edge flange contacts the acceleration cavity.

[0018] According to a device for detecting the electric field flatness of a radio frequency cavity in a low-temperature environment provided by the present invention, the housing structure is provided with a first fixing seat for fixing the driving mechanism, and a slot is opened on the first fixing seat, for adjusting the position of the driving mechanism in the cavity of the housing structure.

[0019] According to a device for detecting the electric field flatness of a radio frequency cavity in a low-temperature environment provided by the present invention, the first fixing seat is further provided with a motor adapter, for adjusting the position of the rotating member in the cavity of the housing structure.

[0020] A device for detecting the electric field flatness of a radio frequency cavity in a low-temperature environment according to the present invention further includes a liquid nitrogen cooling component for providing a low-temperature environment. The liquid nitrogen cooling component includes a liquid nitrogen tank and a liquid nitrogen reservoir, and the liquid nitrogen tank and the liquid nitrogen reservoir are connected through a pipeline;

[0021] The accelerating cavity and the housing structure are placed in the liquid nitrogen tank, and the liquid level of the liquid nitrogen is higher than the top of the accelerating cavity.

[0022] A device for detecting the electric field flatness of a radio frequency cavity in a low-temperature environment according to the present invention, the accelerating cavity is provided with a ceramic waveguide window for ensuring vacuum sealing and signal transmission, and the ceramic waveguide window is installed at the coupler outlet of the accelerating cavity.

[0023] A device for detecting the electric field flatness of a radio frequency cavity in a low-temperature environment according to the present invention further includes a network analyzer for acquiring frequency signals. The accelerating cavity is provided with a waveguide-to-coaxial structure for electrically connecting with the network analyzer;

[0024] The waveguide-to-coaxial structure is connected to the ceramic waveguide window.

[0025] A device for detecting the electric field flatness of a radio frequency cavity in a low-temperature environment according to the present invention, the radio frequency cavity is set as a traveling wave cavity, and the manufacturing material of the accelerating cavity is made of oxygen-free copper.

[0026] One or more of the above technical solutions in the present invention have at least one of the following technical effects:

[0027] Sealingly connecting the housing structure with the accelerating cavity to be measured to form an integral structure, and installing a mechanism for driving the fishing line to move along the accelerating cavity in the cavity of the housing structure can ensure the reliable operation of the detection device in a low-temperature vacuum environment, reduce the difficulty of sealing during the detection process, avoid the risk of dynamic sealing in a low-temperature environment, simplify the structure of the detection device, reduce the setting cost, and broaden the applicability of the detection device.

[0028] In addition to the technical problems solved by the present invention, the technical features of the technical solutions constituted, and the advantages brought by these technical features of the technical solutions described above, the other technical features of the present invention and the advantages brought by these technical features will be further described in conjunction with the drawings or understood through the practice of the present invention. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 An overall schematic diagram of a device for detecting the electric field flatness of a radio frequency cavity in a low temperature environment provided by an embodiment of the present invention.

[0031] Figure 2 A schematic top view of a shell structure and an accelerating cavity of a radio frequency cavity provided in an embodiment of the present invention being arranged in a liquid nitrogen tank.

[0032] Figure 3 for Figure 2 Schematic diagram of the cross section of section AA.

[0033] Figure 4 A schematic diagram of a housing structure provided by an embodiment of the present invention when viewed from the bottom upward.

[0034] Figure 5 for Figure 4 Schematic cross-sectional view of the BB section.

[0035] Figure 6 for Figure 5 Schematic diagram looking up from the CC section.

[0036] Figure 7 A schematic structural diagram of a vacuum feedthrough provided in an embodiment of the present invention.

[0037] Reference numerals:

[0038] 1. Acceleration chamber; 2. Fishing line; 3. Rotating member; 4. Driving mechanism; 5. Network analyzer; 6. Signal transmission line; 7. Motor controller; 8. Computer; 9. Shell structure; 9a. First connecting part; 9b. Second connecting part; 10. Liquid nitrogen tank; 11. On-off valve; 12. Liquid nitrogen tank; 13. Liquid nitrogen pipeline; 14. Vacuum feedthrough; 15. Transfer waveguide; 16. Ceramic waveguide window; 17. Waveguide to coaxial structure; 18. Test bracket; 19. Bottom support of acceleration chamber; 20. Motor adapter; 21. Positioning disk; 22. First fixing seat; 23. Second fixing seat; 24. Feedthrough body; 25. Insulator; 26. Connector. DETAILED DESCRIPTION

[0039] To make the objectives, technical solutions and advantages of the present invention clearer, the following will clearly describe the technical solutions in the present invention in conjunction with the accompanying drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0040] In the description of the embodiments of the present invention, it should be noted that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the embodiments of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0041] In the description of the embodiments of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "connected" and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0042] In the embodiments of the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature can be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature can be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0043] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0044] In the present invention, a radio frequency cavity (RF Cavity) refers to a device used to accelerate charged particles or change their phase. The radio frequency cavity is applied to devices such as particle accelerators, free electron lasers, and cyclotrons. It realizes the energy transfer or manipulation of the particle beam by generating an oscillating electromagnetic field inside the cavity.

[0045] Vacuum feedthroughs refer to a device used to transfer electrical signals, gases, or liquids in a vacuum system. The main function of the vacuum feedthrough is to connect cables, pipelines, or other devices located inside and outside the vacuum chamber, so as to achieve data or energy transmission in a vacuum environment. The vacuum feedthrough can maintain the seal between two different environments.

[0046] A transition waveguide refers to a component used to convert electromagnetic waves from one type of waveguide structure to another type of waveguide structure. The transition waveguide can minimize signal loss and ensure efficient energy transfer.

[0047] A knife-edge flange is a connecting piece specially used for a vacuum system. Its edge is processed into a very sharp "knife edge" shape to ensure extremely tight contact when the two flange surfaces are fitted together, thereby achieving almost perfect sealing. The knife-edge flange also gets its name from its unique edge design.

[0048] Currently, in the scientific research and application of radio frequency cavity accelerating cavities, two methods are often used for cryogenic cooling of the accelerating cavity: liquid nitrogen immersion cooling and contact conduction cooling. The cryogenic copper cavity structure has high shunt impedance, low resistivity, low radio frequency loss, and is relatively easy to achieve advantages such as small size, high gradient, low heat dissipation, and low sparking rate, and is widely used in cryogenic environments below 77K (Kelvin).

[0049] In addition, the accelerating cavities are divided into two forms: standing-wave cavities and traveling-wave cavities. Generally, the electric field distributions of standing-wave cavities are the same at normal temperature and low temperature. The flatness of the electric field can be measured at normal temperature, tuned to a reasonable range, and then the accelerating cavity can be placed in a complex liquid nitrogen cooling device or cryogenic cavity for verification. In a normal temperature environment, the flatness of the electric field of the accelerating cavity is usually detected by the bead method. The bead method uses a fishing line with a perturbation body to pass through the internal beam pipe of the accelerating cavity, and the perturbation body moves uniformly in the beam pipe to form a perturbation test of the internal electric field of the accelerating cavity by the small ball.

[0050] However, the electric field distributions of traveling-wave cavities are different at normal temperature and low temperature. The flatness of the electric field measured at normal temperature cannot be directly and accurately applied to the low temperature environment. Moreover, it is difficult to directly apply the bead method to the traveling-wave cavity in a low temperature environment. Because in a low temperature environment, the accelerating cavity needs to be kept in a vacuum state to ensure that the inner wall does not freeze and does not interfere with the electric field distribution. Using the bead method to detect the flatness of the electric field of the traveling-wave cavity in a low temperature environment not only requires vacuum sealing of the accelerating cavity, but also requires setting up a mechanism that can drive the fishing line to move inside the accelerating cavity and ensuring the vacuum sealing state.

[0051] In order to reliably detect the radio frequency cavity in a low temperature environment, in the embodiments of the present invention, a device for detecting the flatness of the electric field of the radio frequency cavity in a low temperature environment is introduced.

[0052] As Figure 1 shown, the detection device mainly includes a housing structure 9, a rotating member 3, a driving mechanism 4, and a fishing line 2 passing through the accelerating cavity 1 and connected to the rotating member 3.

[0053] Specifically, the housing structure 9 is hermetically connected to the radio frequency cavity. The cavity of the housing structure 9 is communicated with the accelerating cavity 1 of the radio frequency cavity. The rotating member 3 is arranged in the cavity of the housing structure 9. The driving mechanism 4 is installed in the cavity of the housing structure 9 and connected to the rotating member 3 for driving the rotating member 3 to rotate.

[0054] At the same time, the driving mechanism 4 is communicated with the circuit outside the housing structure 9 through a vacuum feedthrough 14 provided on the housing structure 9, so that both the vacuum environment of the accelerating cavity 1 of the radio frequency cavity can be kept sealed and electric energy, electrical signals, etc. can be transmitted from outside the housing structure to the driving mechanism 4 located inside the housing structure.

[0055] As Figure 2 and Figure 3 shown, two housing structures 9 are symmetrically arranged at both ends of the accelerating cavity 1. A fishing line 2 is passed through the accelerating cavity 1, and both ends of the fishing line 2 are respectively wound around the rotating member 3. In particular, a perturbation body that can move in the accelerating cavity 1 as the rotating member 3 rotates is provided on the fishing line 2 for interfering with the internal electric field of the accelerating cavity 1.

[0056] Thus, by sealing and connecting the acceleration cavity 1 and the housing structure 9, an integral vacuum chamber can be formed, and components such as the rotating member 3, the driving mechanism 4, and the fishing line 2 operate within this vacuum chamber. Preferably, the rotating member 3 can be set as a pulley; the driving mechanism 4 can be set as a cryogenic-resistant motor.

[0057] Preferably, as Figure 7 shown, in this application, a vacuum feedthrough of model CF35H manufactured by Hangyu Jiutian is used. This vacuum feedthrough has the advantages of cryogenic resistance, low magnetic conductivity, and good sealing performance, which can ensure normal operation under low-temperature conditions and does not significantly affect the transmitted signal or energy.

[0058] Specifically, the structure of the vacuum feedthrough generally consists of three parts: the feedthrough body, the insulator, and the connector.

[0059] The feedthrough body is generally made of materials such as stainless steel, titanium alloy, or ceramic. Its main function is to lead the conductor or pipeline in the connector out of the vacuum chamber. The insulator is used to isolate electromagnetic interference and gas leakage between the feedthrough body and the conductor or pipeline, and is usually made of materials such as quartz, ceramic, or plastic.

[0060] The connector is used to connect the feedthrough body and the conductor or pipeline and ensure the sealing performance.

[0061] In addition, components such as the rotating member 3, the driving mechanism 4, and the fishing line 2 can be directly installed on the acceleration cavity 1, and then a cover is provided to cover their outer periphery. And, an air extraction port is provided on the cover, and the gas in the cover is pumped away through the air extraction port to form a vacuum chamber.

[0062] In this application, the first form of vacuum chamber is adopted. Because the acceleration cavity 1 and the housing structure 9 are sealed and connected to form an integral vacuum chamber, the structure is simpler and more compact, which is convenient for post-test tuning.

[0063] Furthermore, the acceleration cavity 1 and the housing structure 9 are placed together in the liquid nitrogen tank 10. The liquid level of the liquid nitrogen covers the top of the acceleration cavity 1, which is convenient for uniform heat conduction.

[0064] As Figure 1 shown, the detection device is also provided with a network analyzer 5 connected to the acceleration cavity 1 for acquiring frequency signals. The detection device is also provided with a motor controller 7 and a computer 8 connected to the driving mechanism 4 for controlling the fishing line 2 to drive the perturbator to pass through the acceleration cavity 1 to be detected slowly and evenly.

[0065] Furthermore, the liquid nitrogen tank 10 and the liquid nitrogen tank 12 are connected through a liquid nitrogen pipeline 13. A cut-off valve 11 is provided at the bottom of the liquid nitrogen tank 10. After the detection is completed, the liquid nitrogen is recovered to the liquid nitrogen tank 12 by controlling the cut-off valve 11.

[0066] Preferably, two rotating members 3 can be respectively arranged at both ends of the acceleration cavity 1. Moreover, the four rotating members 3 are distributed in a "square" shape, and the fishing line 2 is wound around the four rotating members 3. At the same time, the driving mechanism 4 is connected to any one of the rotating members 3 for controlling the rotating member 3 to drive the fishing line 2 to move at a uniform speed. In particular, one side of the "square" formed by the fishing line 2 is inserted into the beam pipe of the acceleration cavity 1.

[0067] Furthermore, the RF cavity is set as a traveling wave cavity. The manufacturing material of the acceleration cavity 1 is made of oxygen-free copper.

[0068] In this embodiment, the housing structure 9 is hermetically connected to the acceleration cavity 1 to be measured to form an integral structure, and a mechanism for driving the fishing line 2 to move along the acceleration cavity 1 is installed in the cavity of the housing structure 9, which can ensure the reliable operation of the detection device in a low-temperature vacuum environment, reduce the difficulty of sealing during the detection process, avoid the risk of dynamic sealing in a low-temperature environment, simplify the structure of the detection device, reduce the setting cost, and broaden the applicability of the detection device.

[0069] Based on the above embodiments, in another embodiment of the present invention, a device for detecting the electric field flatness of an RF cavity in a low-temperature environment is introduced.

[0070] As Figure 4 and Figure 5 shown, the housing structure 9 is provided with a first connecting portion 9a. The first connecting portion 9a extends vertically upward and protrudes from the top of the housing structure 9.

[0071] A vacuum feedthrough 14 is arranged at the upper end of the first connecting portion 9a for the line transmission of the driving mechanism 4.

[0072] Based on the above embodiments, in another embodiment of the present invention, a device for detecting the electric field flatness of an RF cavity in a low-temperature environment is introduced.

[0073] As Figure 5 shown, the housing structure 9 is provided with a second connecting portion 9b. The second connecting portion 9b extends horizontally and protrudes from the side wall of the housing structure 9.

[0074] A positioning disc 21 is arranged at the overhanging end of the second connecting portion 9b for ensuring that the fishing line 2 moves along the central axis of the acceleration cavity 1.

[0075] Based on the above embodiments, in another embodiment of the present invention, a device for detecting the electric field flatness of an RF cavity in a low-temperature environment is introduced.

[0076] As Figure 5 shown, the first connecting portion 9a is provided with a knife-edge flange, and is connected to the vacuum feedthrough 14 through the knife-edge flange.

[0077] The second connecting part 9b is provided with a knife-edge flange, and is connected to the acceleration cavity 1 through the knife-edge flange.

[0078] The positioning disk 21 is arranged on the side where the knife-edge flange contacts the acceleration cavity 1.

[0079] On the basis of the above embodiment, in another embodiment of the present invention, a device for detecting the electric field flatness of a radio frequency cavity in a low-temperature environment is introduced.

[0080] As Figures 4 to 6 shown, the housing structure 9 is provided with a first fixing seat 22 for fixing the driving mechanism 4. A slot is opened on the first fixing seat 22 for adjusting the position of the driving mechanism 4 in the cavity of the housing structure 9.

[0081] Furthermore, the first fixing seat 22 is further provided with a motor adapter 20 for adjusting the position of the rotating member 3 in the cavity of the housing structure 9.

[0082] Furthermore, the housing structure 9 can adopt a cubic structure. Preferably, the housing structure 9 can also adopt a cylindrical structure.

[0083] The housing structure 9 can also be arranged to be composed of a upper half and a lower half that are buckled together, so as to facilitate the installation and positioning of the driving mechanism 4. Correspondingly, the first fixing seat 22 is arranged at the bottom end of the upper half. A second fixing seat 23 is arranged at the top end of the lower half. The first fixing seat 22 and the second fixing seat 23 are butted to form the housing structure 9.

[0084] The sealing method of the housing structure 9 can adopt indium wire with good low-temperature performance.

[0085] On the basis of the above embodiment, in another embodiment of the present invention, a device for detecting the electric field flatness of a radio frequency cavity in a low-temperature environment is introduced.

[0086] The detection device further includes a liquid nitrogen cooling component for providing a low-temperature environment. The liquid nitrogen cooling component includes a liquid nitrogen tank 10 and a liquid nitrogen container 12. The liquid nitrogen tank 10 and the liquid nitrogen container 12 are connected through a pipeline.

[0087] The acceleration cavity 1 and the housing structure 9 are placed in the liquid nitrogen tank 10, and the liquid level of the liquid nitrogen is higher than the top of the acceleration cavity 1.

[0088] Furthermore, the acceleration cavity 1 is provided with a ceramic waveguide window 16 for ensuring vacuum sealing and signal transmission. The ceramic waveguide window 16 is installed at the coupler outlet of the acceleration cavity 1.

[0089] Furthermore, the detection device further includes a network analyzer 5 for acquiring frequency signals. The acceleration cavity 1 is provided with a waveguide-to-coaxial structure 17 for electrically connecting to the network analyzer 5.

[0090] The waveguide-to-coaxial structure 17 is connected to the ceramic waveguide window 16.

[0091] In addition, generally, the outlet of the coupler of the accelerating cavity 1 is a customized waveguide flange, which needs to be converted into a standard flange. Therefore, a section of transition waveguide 15 also needs to be provided at the outlet of the coupler. If a standard waveguide is used for the coupler, the transition waveguide 15 can be omitted.

[0092] Secondly, the accelerating cavity 1 is evacuated and sealed through a T-shaped waveguide. The tail end of the accelerating cavity 1 is connected to two ceramic waveguide windows 16 for vacuum sealing but without blocking signal transmission. Then, the ceramic waveguide window 16 is connected to the waveguide-to-coaxial structure 17 with a conventional unsealed structure. Finally, it is connected to the network analyzer 5 through the interface of the waveguide-to-coaxial structure 17.

[0093] Furthermore, if the beam pipe diameter of the accelerating cavity 1 is relatively large, one flange of the housing structure 9 can also be made into a tee structure for evacuation.

[0094] Through the detection device in this application, the accelerating cavity 1 can be repeatedly tested at low temperature and tuned at room temperature, shortening the entire test cycle. After the detection is completed, the liquid nitrogen can be quickly drained into the liquid nitrogen tank 12 through the liquid nitrogen pipeline 13 with a on-off valve 11 at the bottom, and tuning can be carried out after the temperature returns to room temperature. In this way, the cavity can meet the requirements only by precisely tuning several times. In particular, the test support 18 can be used to support the detection device. If the tuning space is not enough, the entire system can be moved out of the liquid nitrogen tank 10 through the test support 18 for tuning without repeatedly disassembling and assembling the entire device.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0096] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A device for detecting the electric field flatness of a radio frequency cavity in a low temperature environment, characterized in that: include: A shell structure (9) is sealed and connected to the radio frequency cavity, and the cavity of the shell structure (9) is connected to the acceleration cavity (1) of the radio frequency cavity; A rotating component (3) arranged in the cavity of the housing structure (9); a driving mechanism (4), installed in the cavity of the housing structure (9) and connected to the rotating member (3), and used for driving the rotating member (3) to rotate; The two shell structures (9) are symmetrically arranged at two ends of the acceleration chamber (1); a fishing line (2) is passed through the acceleration chamber (1); two ends of the fishing line (2) are respectively wound around the rotating member (3); the driving mechanism (4) is connected to a line outside the shell structure (9) via a vacuum feedthrough (14) arranged on the shell structure (9); The fishing line (2) is provided with a micro-disturbance body which can move in the acceleration chamber (1) along with the rotation of the rotating member (3), and is used to generate disturbances in the electric field inside the acceleration chamber (1).

2. The device for detecting the electric field flatness of a radio frequency cavity in a low temperature environment according to claim 1, characterized in that: The shell structure (9) is provided with a first connection portion (9a), and the first connection portion (9a) extends upward in a vertical direction and protrudes from the top of the shell structure (9); The vacuum feedthrough (14) is arranged at the upper end of the first connecting portion (9a).

3. The device for detecting the electric field flatness of a radio frequency cavity in a low temperature environment according to claim 2, characterized in that: The shell structure (9) is provided with a second connection portion (9b), and the second connection portion (9b) extends in a horizontal direction and protrudes from a side wall of the shell structure (9); A positioning disc (21) is provided at the cantilevered end of the second connecting portion (9b) for ensuring that the fishing line (2) moves along the central axis of the acceleration chamber (1).

4. The device for detecting the electric field flatness of a radio frequency cavity in a low temperature environment according to claim 3, characterized in that: The first connecting portion (9a) is provided with a knife-edge flange and is connected to the vacuum feedthrough (14) via the knife-edge flange; The second connecting portion (9b) is provided with a knife-edge flange and is connected to the acceleration chamber (1) via the knife-edge flange; The positioning disc (21) is arranged on the side of the knife edge flange that contacts the acceleration chamber (1).

5. The device for detecting the electric field flatness of a radio frequency cavity in a low temperature environment according to claim 4, characterized in that: The housing structure (9) is provided with a first fixing seat (22) for fixing the driving mechanism (4), and a slot is provided on the first fixing seat (22) for adjusting the position of the driving mechanism (4) in the cavity of the housing structure (9).

6. The device for detecting the electric field flatness of a radio frequency cavity in a low temperature environment according to claim 5, characterized in that: The first fixing seat (22) is also provided with a motor adapter (20) for adjusting the position of the rotating component (3) in the cavity of the housing structure (9).

7. The device for detecting the electric field flatness of a radio frequency cavity in a low temperature environment according to any one of claims 1 to 6, characterized in that: Also included is a liquid nitrogen cooling assembly for providing a low-temperature environment, the liquid nitrogen cooling assembly comprising a liquid nitrogen tank (10) and a liquid nitrogen tank (12), the liquid nitrogen tank (10) and the liquid nitrogen tank (12) being connected via a pipeline; The acceleration chamber (1) and the shell structure (9) are placed in the liquid nitrogen tank (10), and the liquid level of the liquid nitrogen is higher than the top of the acceleration chamber (1).

8. The device for detecting the electric field flatness of a radio frequency cavity in a low temperature environment according to claim 7, characterized in that: The accelerating cavity (1) is provided with a ceramic waveguide window (16) for ensuring vacuum sealing and signal transmission, and the ceramic waveguide window (16) is installed at a coupler outlet of the accelerating cavity (1).

9. The device for detecting the electric field flatness of a radio frequency cavity in a low temperature environment according to claim 8, characterized in that: It also includes a network analyzer (5) for acquiring frequency signals, and the acceleration cavity (1) is provided with a waveguide-to-coaxial structure (17) for being electrically connected to the network analyzer (5); The waveguide-to-coaxial structure (17) is connected to the ceramic waveguide window (16).

10. The device for detecting the electric field flatness of a radio frequency cavity in a low temperature environment according to any one of claims 1 to 6, characterized in that: The radio frequency cavity is configured as a traveling wave cavity, and the accelerating cavity (1) is made of oxygen-free copper.

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