Superconducting radio frequency cavity

Abstract

The invention discloses a superconducting radio frequency cavity, which comprises an ellipsoidal cavity and a beam tube structure with two asymmetric ends, wherein the ellipsoidal cavity comprises an ellipsoidal cavity left half bowl, a middle equator and an ellipsoidal cavity right half bowl; the beam tube structure with two asymmetric ends comprises a triangular beam tube structure and an adaptive beam tube structure; the triangular beam tube structure comprises a first transition section and a triangular beam tube; the middle equator is used for adjusting the frequency of the ellipsoidal cavity and providing convenience for welding; the adaptive beam tube structure is connected with the left half bowl of the ellipsoidal cavity through electron beam welding; the first end of the first transition section is connected with the half bowl on the right side of the ellipsoidal cavity through electron beam welding; the tail end of the triangular beam tube is connected with the second end of the first transition section through an electron beam welding flange. The invention has the advantages of low power loss, high impedance characteristic and good operation stability. The superconducting radio frequency cavity can be widely applied to the technical field of superconducting radio frequency cavities.

Description

Technical Field

[0001] The invention relates to the technical field of superconducting radio frequency cavities, and in particular to a superconducting radio frequency cavity. Background Art

[0002] In the fields of particle accelerators and synchrotron radiation sources, superconducting radio frequency cavities are widely used as core components. Superconducting radio frequency cavities are a type of electromagnetic resonant cavity that has many advantages over conventional resonant cavities, such as high quality factor, high acceleration gradient, and lower power loss.

[0003] In particle accelerators, superconducting radio frequency cavities are used to provide energy to keep particles moving in orbit. Charged particles such as electrons, protons and heavy ions can be accelerated to high energy or high speed; in synchrotron radiation sources, storage rings are used to store high-energy electron beams to produce synchrotron radiation light. However, during the movement of the beam, the beam loses energy due to the interaction between the beam and the cavity wall. In order to maintain the energy and brightness of the beam in the storage ring, a superconducting radio frequency cavity needs to be introduced into the storage ring to compensate for the energy loss. However, the design and manufacture of traditional superconducting radio frequency cavities in the high frequency range (such as 500MHz) are relatively complex and costly, and cannot meet the high requirements of acceleration performance and stability. They are also easily affected by higher-order modes, secondary electron multiplication effects and acceleration mode limitations. Summary of the invention

[0004] In order to solve the above technical problems, the object of the present invention is to provide a superconducting radio frequency cavity with low power loss, high impedance characteristics and good operation stability.

[0005] The technical solution adopted by the present invention is: a superconducting radio frequency cavity, including an ellipsoidal cavity and a beam tube structure with asymmetric ends, wherein:

[0006] The ellipsoidal cavity comprises a left half bowl of the ellipsoidal cavity, a middle equator and a right half bowl of the ellipsoidal cavity;

[0007] The asymmetric bundle tube structure at both ends includes a triangular bundle tube structure and an adaptive bundle tube structure;

[0008] The triangular bundle tube structure comprises a first transition section and a triangular bundle tube;

[0009] The middle equator is used to adjust the frequency of the ellipsoidal cavity and facilitate welding;

[0010] The adaptive beam tube structure is connected to the left half bowl of the ellipsoidal cavity by electron beam welding; the first end of the first transition section is connected to the right half bowl of the ellipsoidal cavity by electron beam welding; the end of the triangular beam tube is connected to the second end of the first transition section by an electron beam welding flange.

[0011] Furthermore, the adaptable bundle tube structure is an enlarged circular bundle tube structure, comprising an enlarged circular bundle tube and a second transition section.

[0012] Furthermore, the adaptable beam tube structure is a plum blossom-shaped beam tube structure, comprising a petal-shaped outlet and a central cylindrical beam tube.

[0013] Furthermore, the first end of the second transition section is connected to the left half bowl of the ellipsoidal cavity by electron beam welding; the second end of the second transition section is connected to the end of the enlarged circular beam tube by a welding flange.

[0014] Furthermore, the geometrical parameters of the ellipsoidal cavity are adjusted so that the cavity has a lower maximum surface peak electric field and acceleration gradient ratio, a lower maximum surface peak magnetic field and acceleration gradient ratio, and a larger high impedance characteristic value.

[0015] Furthermore, the geometrical parameters of the triangular beam tube structure are adjusted so that the triangular beam tube structure can propagate high-order modes to the maximum extent and reduce the adverse effects of secondary electron multiplication.

[0016] Furthermore, the geometrical parameters of the enlarged circular beam tube structure are adjusted so that the beam has the best matching and coupling efficiency when it is led out of the enlarged circular beam tube structure.

[0017] Furthermore, the geometrical parameters of the plum blossom-shaped bundle tube structure and the direction of the petal-shaped outlet are adjusted to meet specific electromagnetic mode and high-order mode damping requirements.

[0018] The beneficial effects of the present invention are as follows: the superconducting radio frequency cavity designed by the present invention has low power loss, high impedance characteristics, good high-order mode propagation capability, no influence of secondary electron multiplication, and can provide high acceleration gradient and good low-temperature stability performance; in addition, the present invention also has the advantages of simple manufacturing process, easy processing and welding, high manufacturing efficiency and low manufacturing cost; the present invention uses superconducting materials to provide higher particle acceleration gradient and quality factor; the present invention adopts electron beam welding technology to ensure reliable connection between the cavity and the beam tube, and improves the vacuum degree and stability of the cavity; the adaptive beam tube structure of the present invention adopts an enlarged circular beam tube structure, which can be applied to the storage ring of the synchrotron radiation light source, used to compensate for beam energy loss, and improve the energy recovery efficiency and beam quality of the accelerator; the adaptive beam tube structure of the present invention adopts a plum blossom beam tube structure, which can be applied to a particle accelerator, used to accelerate the beam and supplement the energy lost by the beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of a superconducting radio frequency cavity of the present invention;

[0020] FIG2 is a schematic diagram of the structure of a specific embodiment of the present invention; wherein FIG2(a) is a stereoscopic view of a specific embodiment of the present invention; FIG2(b) is a front view of a specific embodiment of the present invention; FIG2(c) is a left view of a specific embodiment of the present invention; and FIG2(d) is a right view of a specific embodiment of the present invention;

[0021] FIG3 is a schematic diagram of the structure of a second specific embodiment of the present invention; wherein FIG3(a) is a stereoscopic view of the second specific embodiment of the present invention; FIG3(b) is a front view of the second specific embodiment of the present invention; FIG3(c) is a left view of the second specific embodiment of the present invention; and FIG3(d) is a right view of the second specific embodiment of the present invention;

[0022] FIG. 4 is a schematic diagram of geometric parameters of a specific embodiment of the present invention; FIG. 4( a ) is a schematic diagram of parameter symbols of a specific embodiment of the present invention; FIG. 4( b ) is a diagram of parameter size settings of a specific embodiment of the present invention;

[0023] FIG5 is a schematic diagram of geometric parameters of a second specific embodiment of the present invention; FIG5(a) is a schematic diagram of parameter symbols of the second specific embodiment of the present invention; FIG5(b) is a diagram of cavity parameter size setting of the second specific embodiment of the present invention; FIG5(c) is a diagram of plum blossom beam tube structure parameter size setting of the second specific embodiment of the present invention;

[0024] Description of the drawings: 1. Adaptive beam tube structure; 2. Left half bowl of the ellipsoidal cavity; 3. Middle equator; 4. Right half bowl of the ellipsoidal cavity; 5. First transition section; 6. Triangular beam tube; 7. Second transition section; 8. Enlarged circular beam tube; 9. Plum blossom-shaped beam tube structure. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only provided for the convenience of explanation and description, and the order between the steps is not limited in any way. The execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0026] Reference Figure 1 , a superconducting radio frequency cavity, comprising an ellipsoidal cavity and a beam tube structure with asymmetric ends, wherein:

[0027] The ellipsoidal cavity comprises a left half bowl 2 of the ellipsoidal cavity, a middle equator 3 and a right half bowl 4 of the ellipsoidal cavity;

[0028] The left half bowl 2 of the ellipsoid cavity and the right half bowl 4 of the ellipsoid cavity are symmetrical in both vertical and horizontal directions;

[0029] The asymmetric beam tube structure at both ends can effectively propagate high-order modes out of the cavity and reduce the influence of secondary electron multiplication;

[0030] The asymmetric bundle tube structure at both ends includes a triangular bundle tube structure and an adaptive bundle tube structure 1;

[0031] The triangular bundle tube structure comprises a first transition section 5 and a triangular bundle tube 6;

[0032] The middle equator 3 is used to adjust the frequency of the ellipsoidal cavity and facilitate welding;

[0033] The adaptive beam tube structure 1 is connected to the left half bowl 2 of the ellipsoidal cavity by electron beam welding; the first end of the first transition section 5 is connected to the right half bowl 4 of the ellipsoidal cavity by electron beam welding; the electron beam welding process needs to be carried out in a high vacuum environment to ensure the reliability of the welding connection and the quality of the weld, and the strength and stability of the welded joint are ensured by precisely controlling the welding parameters and welding position.

[0034] The end of the triangular beam tube 6 is connected to the second end of the first transition section 5 through an electron beam welding flange to achieve a seamless transition with the cryogenic system, ensuring efficient beam energy transmission and minimal loss.

[0035] Furthermore, the material of the superconducting RF cavity has good low-temperature stability to ensure that the cavity operates stably at low temperatures; it also needs to have excellent superconducting properties to ensure that the superconducting cavity has a high quality factor, low power loss and high acceleration gradient, and can effectively transmit microwave energy, thereby reducing energy loss and improving energy transfer efficiency. The selected materials include but are not limited to Nb, Nb3Sn, and Cu-Nb.

[0036] 2(a), 2(b), 2(c) and 2(d), in order to adapt the superconducting radio frequency cavity of the present invention to the storage ring of a synchrotron radiation light source, in a specific embodiment of the present invention, the adaptive beam tube structure is configured as an enlarged circular beam tube structure, wherein the enlarged circular beam tube structure comprises an enlarged circular beam tube 8 and a second transition section 7, wherein a first end of the second transition section 7 is connected to the left half bowl 2 of the ellipsoidal cavity by electron beam welding; and a second end of the second transition section 7 is connected to the end of the enlarged circular beam tube 8 by a welding flange.

[0037] Referring to FIG4(a), l represents half the length of the cavity; Req represents the equatorial radius of the cavity; Riris represents the radius of the cavity beam hole; a1 and b1 represent the radius of the top circle contained in the cavity; a2 and b2 represent the radii of the horizontal axis and the vertical axis of the cavity beam hole ellipse, respectively; α represents the angle between the right half bowl 4 of the ellipsoidal cavity and the first transition section 5; d represents the length between the right half bowl 4 of the ellipsoidal cavity and the left half bowl 2 of the ellipsoidal cavity; E p / Eacc represents the ratio of the maximum surface peak electric field to the acceleration gradient; H p / E acc It represents the ratio of the maximum surface peak magnetic field to the accelerating gradient.

[0038] The geometric parameters and dimensions of the ellipsoidal cavity are precisely calculated and optimized to achieve a fundamental mode resonance mode with a target frequency of 500 MHz, and have a lower maximum surface peak electric field and acceleration gradient ratio, a lower maximum surface peak magnetic field and acceleration gradient ratio, and a larger high impedance characteristic value.

[0039] The geometric parameters of the triangular beam tube structure are adjusted so that the triangular beam tube structure can propagate high-order modes to the maximum extent and reduce the adverse effects caused by secondary electron multiplication.

[0040] The geometric parameters of the enlarged circular beam tube structure are adjusted so that the beam has the best matching and coupling efficiency when it is led out of the enlarged circular beam tube structure. Compared with the plum blossom-shaped beam tube structure of Example 2, the advantage of the circular beam tube superconducting cavity is that it is more convenient to process. The structure of the circular beam tube is relatively simple, and it is easy to control the processing accuracy, reducing the process difficulty and cost in the preparation process.

[0041] The geometric parameters and sizes of the optimized cavity and beam tube in the specific embodiment 1 of the present invention can be referred to FIG4(b). The half length l of the cavity is set to 120.04 mm; the equatorial radius Req of the cavity is set to 269.2 mm; the radius Riris of the cavity beam hole is set to 120 mm; the radius a1 of the top circle included in the cavity is set to 89 mm, and b1 is set to 89 mm; the horizontal axis a2 of the cavity beam hole ellipse is set to 20 mm; the longitudinal axis radius b2 of the cavity beam hole ellipse is set to 40 mm; the angle α between the right side half bowl 4 of the ellipsoidal cavity and the first transition section 5 is set to 80°; the length d between the right side half bowl 4 of the ellipsoidal cavity and the left side half bowl 2 of the ellipsoidal cavity is set to 9.8 mm; the ratio E of the maximum surface peak electric field to the acceleration gradient p / E acc Set to 2.16; the ratio of the maximum surface peak magnetic field to the acceleration gradient H p / E acc Set to 4.92. The superconducting RF cavity in the first specific embodiment of the present invention is manufactured using precision machining equipment and processes using this parameter. The machining process needs to ensure the accuracy of the geometric shape and the surface quality requirements. The superconducting RF cavity is ensured to have consistent performance and quality of each unit produced through precise process control and quality inspection. The manufacturing process of the cavity and beam tube structure is optimized to achieve an efficient, accurate and repeatable manufacturing process to ensure stability and consistency.

[0042] The manufactured superconducting RF cavity is quality inspected to ensure that its performance and quality meet the requirements. The quality inspection includes strength testing of welded joints, measuring geometric dimensions using precision measuring equipment, and testing superconducting performance. The purpose of quality inspection is to ensure the consistency of performance and quality of each production unit to meet the design requirements.

[0043] The manufactured superconducting RF cavity is assembled and initially debugged. During the assembly process, the correct installation and connection of each component is ensured. During the debugging process, the performance of the superconducting RF cavity is tested and adjusted to optimize its working state and performance.

[0044] Superconducting radio frequency cavities have good low temperature stability to maintain performance at low temperature working temperature. Finally, superconducting radio frequency cavities are widely used in the storage ring of synchrotron radiation sources to compensate for beam energy loss and improve the energy recovery efficiency and beam quality of accelerators.

[0045] Through the above-mentioned specific implementation details, a superconducting radio frequency cavity that meets the requirements of the present invention and is widely used in the storage ring of a synchrotron radiation source can be manufactured. The precise control and quality inspection of each step ensure the performance and reliability of the superconducting radio frequency cavity. The optimized design and process selection during the manufacturing process enable the superconducting radio frequency cavity to have low power loss, high impedance characteristics and good propagation performance. In addition, the simplification of the manufacturing process and the selection of materials also greatly reduce the production cost and improve the manufacturing efficiency.

[0046] 3(a), 3(b), 3(c) and 3(d), in order to apply the superconducting radio frequency cavity of the present invention to a particle accelerator, in the second specific embodiment of the present invention, the adaptive beam tube structure is set as a plum blossom-shaped beam tube structure 9, including a petal-shaped outlet and a central cylindrical beam tube.

[0047] When in use, the specific embodiment 2 of the present invention enters the superconducting cavity from the triangular beam tube 6 and the first transition section 5 through the right half bowl 4, the middle equator 3 and the left half bowl 2 of the ellipsoidal cavity; the function of the triangular beam tube 6 is mainly to reduce the secondary electron multiplication, and the function of the first transition section 5 is to ensure that the right half bowl 4 and the triangular beam tube 6 of the ellipsoidal cavity are seamlessly welded; the function of the right half bowl 4, the middle equator 3 and the left half bowl 2 of the ellipsoidal cavity is to establish an electromagnetic field therein, and use the TM010 mode of the electromagnetic field to accelerate the beam, and then propagate to the vacuum box of the beam through the plum blossom-shaped beam tube structure 9.

[0048] Refer to Figure 5(a), where: l represents half the length of the cavity; Req represents the equatorial radius of the cavity; Riris represents the radius of the cavity beam hole; A and B represent the radius of the top circle contained in the cavity respectively; a and b represent the radii of the horizontal and vertical axes of the cavity beam hole ellipse respectively.

[0049] The geometric parameters of the triangular beam tube structure are adjusted so that the triangular beam tube structure can propagate high-order modes to the maximum extent and reduce the adverse effects of secondary electron multiplication. The height of the regular triangle of the triangular beam tube structure of the second specific embodiment of the present invention is 180 mm, and the superconducting radio frequency cavity of the specific embodiment of the present invention can be installed with a high-power input coupler at the plane position of the triangle when in use, so as to achieve the purpose of feeding power into the cavity.

[0050] The geometric parameters and dimensions of the ellipsoidal cavity are precisely calculated and optimized, and have lower maximum surface peak electric field and acceleration gradient ratio, lower maximum surface peak magnetic field and acceleration gradient ratio, and larger high impedance characteristic value.

[0051] The geometric parameters of the plum blossom beam tube structure and the direction of the petal-shaped outlet are adjusted to meet specific electromagnetic modes and high-order mode damping requirements. The design of the plum blossom beam tube structure shortens the length of the entire superconducting cavity, saving the occupation of the accelerator linear section, thereby achieving that the superconducting cavity of the plum blossom beam tube can more effectively propagate high-order modes, thereby reducing energy loss and the impact of secondary electron multiplication, and improving superconductivity and performance stability; when in use, the flange at the end of the plum blossom beam tube structure is welded and connected to the tuner, and the purpose of frequency tuning is achieved by stretching or squeezing the cavity. In addition, the direction of the petal-shaped outlet can be reversed and adjusted to effectively propagate high-order modes and improve superconductivity and performance stability.

[0052] The optimized geometric parameters of the second specific embodiment of the present invention can be referred to Figure 5(b) and Figure 5(c); the half length l of the cavity is set to 120mm; the equatorial radius Req of the cavity is set to 269.2mm; the radius Riris of the cavity beam hole is set to 120mm; the top circle radii A and B included in the cavity are both set to 88.83mm; the horizontal axis a of the cavity beam hole ellipse is set to 20mm; the longitudinal axis radius b of the cavity beam hole ellipse is set to 40mm; the angle α between the right half bowl 4 of the ellipsoidal cavity and the first transition section 5 is set to 80°; the length of the plum bouquet tube is set to 260mm; the chamfer radius of the plum bouquet tube is set to 15mm; the petal diameter w above the plum bouquet tube is set to 60mm; the petal diameter h on the side of the plum bouquet tube is set to 63mm; the above optimized parameters are used to perform precise process control and strict quality inspection to achieve an efficient, accurate and repeatable manufacturing process for the superconducting cavity to ensure stability and consistency.

[0053] The thickness of the ellipsoidal cavity in the second specific embodiment of the present invention is more than 3 mm to ensure that the cavity has certain mechanical properties and does not undergo mechanical deformation after being assembled to the cryostat, thereby ensuring that the beam can be normally accelerated when passing through the cavity.

[0054] The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A superconducting radio frequency cavity, characterized in that: It includes an ellipsoidal cavity and a beam tube structure with two asymmetric ends, wherein: The ellipsoidal cavity comprises a left half bowl of the ellipsoidal cavity, a middle equator and a right half bowl of the ellipsoidal cavity; The asymmetric bundle tube structure at both ends includes a triangular bundle tube structure and an adaptive bundle tube structure; The triangular bundle tube structure comprises a first transition section and a triangular bundle tube; The middle equator is used to adjust the frequency of the ellipsoidal cavity and facilitate welding; The adaptive beam tube structure is connected to the left half bowl of the ellipsoidal cavity by electron beam welding; the first end of the first transition section is connected to the right half bowl of the ellipsoidal cavity by electron beam welding; the end of the triangular beam tube is connected to the second end of the first transition section by an electron beam welding flange.

2. A superconducting radio frequency cavity according to claim 1, characterized in that: The adaptable bundle tube structure is an enlarged circular bundle tube structure, comprising an enlarged circular bundle tube and a second transition section.

3. A superconducting radio frequency cavity according to claim 1, characterized in that: The adaptable beam tube structure is a plum blossom-shaped beam tube structure, comprising a petal-shaped outlet and a central cylindrical beam tube.

4. A superconducting radio frequency cavity according to claim 2, characterized in that: The first end of the second transition section is connected to the left half bowl of the ellipsoidal cavity through electron beam welding; the second end of the second transition section is connected to the end of the expanded circular beam tube through a welding flange.

5. The superconducting radio frequency cavity according to claim 1, characterized in that: The geometric parameters of the ellipsoidal cavity are adjusted so that the cavity has a lower maximum surface peak electric field and acceleration gradient ratio, a lower maximum surface peak magnetic field and acceleration gradient ratio, and a larger high impedance characteristic value.

6. The superconducting radio frequency cavity according to claim 1, characterized in that: The geometric parameters of the triangular beam tube structure are adjusted so that the triangular beam tube structure can propagate high-order modes to the maximum extent and reduce the adverse effects caused by secondary electron multiplication.

7. A superconducting radio frequency cavity according to claim 2, characterized in that: The geometric parameters of the enlarged circular beam tube structure are adjusted so that the beam has the best matching and coupling efficiency when it is led out of the enlarged circular beam tube structure.

8. The superconducting radio frequency cavity according to claim 3, characterized in that: The geometrical parameters of the plum blossom-shaped bundle tube structure and the direction of the petal-shaped outlet are adjusted to meet specific electromagnetic mode and high-order mode damping requirements.

9. The superconducting radio frequency cavity according to claim 1, characterized in that: The material of the superconducting radio frequency cavity has superconducting properties and low-temperature stability.

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