A superconducting radio frequency cavity

Abstract

The present invention discloses a superconducting radio frequency cavity, an ellipsoidal cavity and a beam tube structure with two asymmetric ends, wherein: the ellipsoidal cavity includes a left half bowl of the ellipsoidal cavity, a middle equator and a right half bowl of the ellipsoidal cavity; the beam tube structure with two asymmetric ends includes a triangular beam tube structure and an adaptive beam tube structure; the triangular beam tube structure includes a first transition section and a triangular beam 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. The present invention has low power loss, high impedance characteristics and good operational stability. The present invention can be widely used in the field of superconducting radio frequency cavity technology.

Description

Technical Field

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

[0002] Superconducting radio frequency cavities are widely used as core components in fields such as particle accelerators and synchrotron radiation sources. Superconducting radio frequency cavities are electromagnetic resonant cavities that offer 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 high-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 includes 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 adaptive bundle tube structure is an enlarged circular bundle tube structure, comprising an enlarged circular bundle tube and a second transition section.

[0012] Furthermore, the adaptive 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 expanded circular beam tube by a welding flange.

[0014] Furthermore, 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.

[0015] Furthermore, 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 adverse effects caused by secondary electron multiplication.

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

[0017] Furthermore, the geometric 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; 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 a 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 particle accelerators, used to accelerate the beam and replenish the energy lost by the beam. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0020] FIG2 is a schematic structural diagram of a first embodiment of the present invention; FIG2(a) is a perspective view of the first embodiment of the present invention; FIG2(b) is a front view of the first embodiment of the present invention; FIG2(c) is a left side view of the first embodiment of the present invention; and FIG2(d) is a right side view of the first embodiment of the present invention;

[0021] FIG3 is a schematic structural diagram of a second specific embodiment of the present invention; FIG3(a) is a perspective 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 side view of the second specific embodiment of the present invention; and FIG3(d) is a right side view of the second specific embodiment of the present invention;

[0022] FIG4 is a schematic diagram of geometric parameters of a specific embodiment of the present invention; FIG4(a) is a schematic diagram of parameter symbols of a specific embodiment of the present invention; FIG4(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 showing the size setting of cavity parameters of the second specific embodiment of the present invention; and FIG5(c) is a diagram showing the size setting of the plum blossom-shaped bundle tube structure parameters of the second specific embodiment of the present invention.

[0024] Description of the accompanying drawings: 1. Adaptive beam tube structure; 2. Left half of the ellipsoidal cavity; 3. Middle equator; 4. Right half 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 will be further described in detail below with reference to the accompanying drawings and specific embodiments. The step numbers in the following embodiments are provided for ease of description only and do not limit the order of the steps. The order of execution of the steps in the embodiments can be adaptively adjusted based on 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 ellipsoidal cavity and the right half bowl 4 of the ellipsoidal 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 impact 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 includes 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 weld 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 must possess excellent low-temperature stability to ensure stable operation at low temperatures. It must also possess excellent superconducting properties to ensure a high quality factor, low power loss, and high acceleration gradient, enabling efficient transmission of microwave energy, thereby reducing energy loss and improving energy transfer efficiency. 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, a specific embodiment of the present invention sets the adaptive beam tube structure as an enlarged circular beam tube structure, and the enlarged circular beam tube structure includes an enlarged circular beam tube 8 and a second transition section 7, wherein the 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 the 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] Refer to Figure 4(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; 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 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 acceleration 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 adverse effects caused by secondary electron multiplication.

[0040] The geometric parameters of the expanded circular beam tube structure are adjusted to ensure optimal matching and coupling efficiency when the beam exits the expanded circular beam tube structure. Compared to the quincunx-shaped beam tube structure of Example 2, the circular beam tube superconducting cavity has the advantage of being easier to manufacture. The relatively simple structure of the circular beam tube allows for easier control of machining precision, reducing both the complexity and cost of fabrication.

[0041] The geometric parameters and sizes of the cavity and beam tube after optimization in the specific embodiment 1 of the present invention can be seen in Figure 4(b). The half length l of the cavity is set to 120.04mm; 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 radius a1 of the top circle included in the cavity is set to 89mm, and b1 is set to 89mm; the horizontal axis a2 of the cavity beam hole ellipse is set to 20mm; the vertical axis radius b2 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 d between the right half bowl 4 of the ellipsoidal cavity and the left half bowl 2 of the ellipsoidal cavity is set to 9.8mm; the ratio E of the maximum surface peak electric field to the acceleration gradient is set to 100mm. 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. This parameter is used to manufacture the superconducting RF cavity in the first embodiment of the present invention using precision machining equipment and processes. The machining process must ensure geometric accuracy and surface quality requirements. The superconducting RF cavity undergoes precise process control and quality testing to ensure consistent performance and quality of each unit produced. The manufacturing process for the cavity and beam tube structure has been optimized to achieve an efficient, precise, and repeatable manufacturing process, ensuring stability and consistency.

[0042] The manufactured superconducting RF cavities undergo quality inspection to ensure that their performance and quality meet the requirements. This inspection includes strength testing of welded joints, measuring geometric dimensions using precision measuring equipment, and testing superconducting properties. The goal of quality inspection is to ensure that the performance and quality of each production unit are consistent and meet design requirements.

[0043] The completed superconducting RF cavity is assembled and initially debugged. During the assembly process, the correct installation and connection of all components are ensured. During the debugging process, the performance of the superconducting RF cavity is tested and adjusted to optimize its operating state and performance.

[0044] Superconducting radio frequency cavities have excellent low-temperature stability, maintaining performance at low operating temperatures. Finally, superconducting radio frequency cavities are widely used in the storage rings of synchrotron radiation sources to compensate for beam energy loss and improve the energy recovery efficiency and beam quality of the accelerator.

[0045] Through the above-described specific implementation details, a superconducting RF cavity meeting the requirements of the present invention can be manufactured for widespread use in the storage rings of synchrotron radiation sources. Precise control and quality inspection at each step ensure the performance and reliability of the superconducting RF cavity. Optimized design and process selection during the manufacturing process ensure that the superconducting RF cavity exhibits low power loss, high impedance, and excellent propagation performance. Furthermore, the simplified manufacturing process and selected materials significantly reduce production costs and improve manufacturing efficiency.

[0046] 3(a), 3(b), 3(c) and 3(d), in order to adapt 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 to a plum blossom-shaped beam tube structure 9, including a petal-shaped outlet and a central cylindrical beam tube.

[0047] When in use, the second specific embodiment of the present invention enters the superconducting cavity from the triangular beam tube 6 and the first transition section 5, passes 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 through the plum blossom-shaped beam tube structure 9 to the vacuum box of the beam.

[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; 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 to maximize propagation of higher-order modes and minimize the adverse effects of secondary electron multiplication. In a second embodiment of the present invention, the height of the regular triangle of the triangular beam-tube structure is 180 mm. Furthermore, when in use, the superconducting radio frequency cavity of this embodiment of the present invention can be equipped with a high-power input coupler in the plane of the triangle to feed 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 quincunx beam tube structure and the orientation of the petal-shaped outlet are adjusted to meet specific electromagnetic mode and higher-order mode damping requirements. The quincunx beam tube design shortens the length of the entire superconducting cavity, saving space on the accelerator's linear sections. This allows the superconducting cavity of the quincunx beam tube to more effectively propagate higher-order modes, thereby reducing energy loss and the effects of secondary electron multiplication, and improving superconductivity and performance stability. During operation, a flange is welded to the end of the quincunx beam tube structure and connected to a tuner, achieving frequency tuning by stretching or squeezing the cavity. Furthermore, the orientation of the petal-shaped outlet can be reversed to effectively propagate higher-order modes, improving superconductivity and performance stability.

[0052] The optimized geometric parameters of the second specific embodiment of the present invention can be referred to Figures 5(b) and 5(c); the half length l of the cavity is set to 120 mm; the cavity equatorial radius Req is set to 269.2 mm; the cavity beam hole radius Riris is set to 120 mm; the top circle radii A and B included in the cavity are both set to 88.83 mm; the horizontal axis a of the cavity beam hole ellipse is set to 20 mm; the longitudinal axis radius b of the cavity beam hole ellipse is set to 40 mm; 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 260 mm; the chamfer radius of the plum bouquet tube is set to 15 mm; the petal diameter w above the plum bouquet tube is set to 60 mm; the petal diameter h on the side of the plum bouquet tube is set to 63 mm; 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 and ensure stability and consistency.

[0053] The thickness of the ellipsoidal cavity in the second embodiment of the present invention is greater than 3 mm to ensure that the cavity has certain mechanical properties and does not deform mechanically after being assembled in a 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 can 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 bundled tube structure with 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 includes 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 adaptive bundle tube structure is an enlarged circular bundle tube structure, comprising an enlarged circular bundle tube and a second transition section.

3. The 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. The 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 adverse effects caused by secondary electron multiplication.

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

8. The superconducting radio frequency cavity according to claim 3, characterized in that: The geometric 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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