Narrowband filter structure and high-order mode damping cavity

Abstract

The present invention discloses a narrowband filtering structure and a high-order mode damping cavity. The narrowband filtering structure includes a first cavity having an annular chamber extending through two opposing surfaces of the cavity, the inner surface of the annular chamber having an annular coupling groove coaxial with the annular chamber; an insulating ring coaxial with the annular coupling groove; and a metal ring sleeved on the insulating ring and coaxial with the insulating ring, the metal ring being disposed in the annular coupling groove to form an RLC equivalent circuit structure. In the technical solution of the present invention, since the narrowband filtering structure is equivalent to an RLC equivalent circuit structure, the rate of change of the magnetic field near the node point is reduced, effectively reducing electromagnetic field leakage in the operating mode, thereby improving the stability of the high-order mode damping cavity under high gradient conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of particle accelerators, and in particular to a narrowband filtering structure and a high-order mode damping cavity. Background Art

[0002] In synchrotron radiation sources, a particle accelerator cavity is needed to compensate for the energy loss caused by the synchrotron radiation source and inserts. At the same time, the particle accelerator cavity needs to fully suppress high-order modes to reduce multi-bunch coupling instabilities and improve beam quality.

[0003] In existing technologies, particle accelerators use TM020 as the acceleration mode, which increases the cavity volume, reduces the surface power density, and improves the cavity pressure tolerance (generally greater than 0.8 MV / cell). However, the high-gradient operation stability of the high-order mode damping cavity depends on the accuracy of the coupling slot position and wave node position on the high-order mode damping cavity. Coupling slot position deviation caused by processing, installation, thermal deformation, and mechanical stress, as well as wave node deviation caused by tuners and couplers, can cause severe electromagnetic field leakage. The leaked electromagnetic field energy is completely absorbed by the damper, but the damper can only withstand a limited thermal load, which in turn limits the high-gradient stable operation of the high-order mode damping cavity.

[0004] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a narrowband filtering structure and a high-order mode damping cavity to solve the problems in the prior art such as the coupling slot position offset caused by processing, installation, thermal deformation and mechanical stress, and the wave node offset caused by tuners, couplers, etc., which will cause serious electromagnetic field leakage. The leaked electromagnetic field energy will be completely absorbed by the damper, and the thermal load that the damper can withstand is limited, thereby limiting the high-gradient stable operation problem of the high-order mode damping cavity.

[0006] The technical solution adopted by the present invention to solve the technical problem is to provide a narrowband filtering structure, including:

[0007] A first cavity, wherein the first cavity is provided with an annular cavity penetrating two opposite surfaces of the first cavity, and an inner surface of the annular cavity is provided with an annular coupling groove coaxially arranged with the annular cavity;

[0008] an insulating ring, coaxially arranged with the annular coupling groove;

[0009] The metal ring is sleeved on the insulating ring and coaxially arranged with the insulating ring. The metal ring is arranged in the annular coupling groove to form an RLC equivalent circuit structure.

[0010] According to a further configuration of the present invention, one end of the cavity is folded back in the circumferential direction.

[0011] According to a further configuration of the present invention, one end of the cavity is folded outward along the circumferential direction; or one end of the cavity is folded inward along the circumferential direction.

[0012] According to a further configuration of the present invention, the first cavity is a cylindrical cavity, and a circular ring-shaped chamber is provided on the first cavity, which passes through the upper surface and the lower surface of the first cavity, and the circular ring-shaped chamber is the annular chamber.

[0013] According to a further configuration of the present invention, the metal ring is a circular ring, and the insulating ring is a circular ring.

[0014] According to a further configuration of the present invention, the metal ring is a copper ring or a stainless steel ring.

[0015] According to a further configuration of the present invention, the insulating ring is a ceramic ring.

[0016] The present invention also provides a high-order mode damping cavity, comprising: the narrowband filtering structure as described above.

[0017] According to a further configuration of the present invention, the high-order mode damping cavity further comprises:

[0018] The second cavity is a cylindrical cavity, and the narrowband filtering structure is respectively provided at both ends of the second cavity. One end of the first cavity is connected to the second cavity, and the other end of the first cavity extends axially away from the second cavity. The annular chamber is coaxially arranged with the second cavity.

[0019] According to a further configuration of the present invention, a coupler, a plurality of symmetrically distributed tuners, a damper, a plurality of signal extraction ports and a vacuum port are provided on the side wall of the second cavity; and a damper for absorbing waves is provided at the other end of each of the first cavities.

[0020] The beneficial effects of the present invention are:

[0021] The present invention discloses a narrowband filtering structure and a high-order mode damping cavity. The narrowband filtering structure includes: a cavity, wherein the cavity is provided with an annular cavity extending through two opposite surfaces of the first cavity, wherein the inner surface of the annular cavity is provided with an annular coupling groove coaxially arranged with the annular cavity; an insulating ring coaxially arranged with the annular coupling groove; and a metal ring sleeved on the insulating ring and coaxially arranged with the insulating ring, wherein the metal ring is arranged in the annular coupling groove to form an RLC equivalent circuit structure. In the technical solution of the present invention, since the narrowband filtering structure is equivalent to an RLC equivalent circuit structure, the rate of change of the magnetic field near the node point is reduced, thereby effectively reducing the electromagnetic field leakage in the working mode, thereby improving the stability of the high-order mode damping cavity under high gradient operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary personnel in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0023] Figure 1 It is a structural diagram of the narrowband filtering structure of the present invention.

[0024] Figure 2 FIG. 4 is an exploded view of a narrowband filtering structure in one embodiment of the present invention.

[0025] Figure 3 It is a cross-sectional view of a narrowband filtering structure in one embodiment of the present invention.

[0026] Figure 4 It is a partially enlarged view of the cross-section of the narrowband filtering structure in one embodiment of the present invention.

[0027] Figure 5 4 is a cross-sectional view of the first cavity in one embodiment of the present invention.

[0028] Figure 6 This is the RLC circuit structure diagram equivalent to the narrowband filter structure.

[0029] Figure 7 This is a position offset curve of the coupling slot of the high-order mode damping cavity when the electromagnetic field leakage rate is 2%.

[0030] Figure 8 It is a relationship diagram between transmission efficiency, frequency and quality factor.

[0031] Figure 9 This is a curve graph with the resonance point acting at 1.5 GHz.

[0032] Figure 10 It is a structural diagram of the high-order mode damping cavity of the present invention.

[0033] The marks in the accompanying drawings are: 101, narrowband filtering structure; 1011, first cavity; 1012, insulating ring; 1013, metal ring; 1014, annular chamber; 1015, annular coupling groove; 10, high-order mode damping cavity; 102, second cavity; 103, coupler; 104, tuner; 105, damper; 106, signal extraction port; 107, vacuum port. DETAILED DESCRIPTION

[0034] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "up", "down", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail", etc. are based on the directions or positional relationships shown in the accompanying drawings and are constructed and operated in specific directions. They are only for the convenience of describing the technical solution and do not indicate that the devices or components referred to must have specific directions. Therefore, they should not be understood as limiting the present invention.

[0035] Traditional room-temperature particle accelerators use the TM010 mode as their acceleration mode, typically leveraging the high-pass filtering characteristics of the waveguide structure to effectively suppress high-order modes and protect the operating mode (TM010 mode). Taking a 1500MHz room-temperature damped cavity as an example, the TM010 mode damped cavity typically withstands an accelerating cavity pressure of less than 0.15MV / cell. This pressure requirement must be met by increasing the number of cavities. However, as the number of cavities increases, the requirements for high-order mode suppression also increase.

[0036] Compared to the TM010 mode damping cavity, the TM020 mode damping cavity uses the TM020 mode as the acceleration mode, which increases the cavity volume, reduces the surface power density, and improves the cavity pressure tolerance (generally greater than 0.3MV / cell). At the same time, using the TM020 mode as the acceleration mode reduces its characteristic impedance (R / Q) by half. When applied to a harmonic cavity, it can effectively reduce the periodic bunch coupling instability to improve the bunch stretching efficiency and effectively increase the beam lifetime. In addition, a more prominent feature of the TM020 mode damping cavity is its unique electromagnetic field distribution, which can achieve effective damping of high-order modes and a compact structural design.

[0037] However, the high-frequency performance and high-gradient operational stability of the high-order mode damping cavity using the TM020 mode are highly dependent on the position accuracy of the coupling slot and wave node of the high-order mode damping cavity. Position deviation will cause serious electromagnetic field leakage, which needs to be fully absorbed by the damper. However, due to processing, installation, thermal stress, mechanical stress, etc., the position of the coupling slot will be offset; similarly, the introduction of couplers and tuners will disturb the electromagnetic field distribution, causing the wave node position to shift, resulting in serious electromagnetic field leakage. The leaked electromagnetic field energy will be completely absorbed by the damper, but the damper can only withstand a limited thermal load, which in turn limits the high-gradient stable operation of the high-order mode damping cavity.

[0038] In view of the problems existing in the prior art, the present invention provides a narrowband filtering structure 101 that can be applied to a high-order mode damping cavity 10 using a TM020 mode. Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 and Figure 6 As shown, the narrowband filtering structure 101 may include a first cavity 1011, an insulating ring 1012 and a metal ring 1013; wherein the first cavity 1011 is provided with an annular cavity 1014 penetrating two opposite surfaces of the cavity, and the inner surface of the annular cavity 1014 is provided with an annular coupling groove 1015 coaxially arranged with the annular cavity; the insulating ring 1012 is coaxially arranged with the annular coupling groove 1015; the metal ring 1013 is sleeved on the insulating ring 1012 and coaxially arranged with the insulating ring 1012, and the metal ring 1013 is arranged in the annular coupling groove 1015 to form an RLC equivalent circuit structure (the insulating ring 1012, the metal ring 1013, the annular coupling groove 1015 and the first cavity 1011 constitute an RLC equivalent circuit structure). Figure 6 The RLC circuit structure is an equivalent circuit structure to the narrowband filtering structure 101.

[0039] Specifically, the first cavity 1011 can be configured as a cylindrical cavity, on which a circular ring-shaped chamber is formed that passes through the upper and lower surfaces of the cylindrical cavity. The circular ring-shaped chamber is the annular chamber 1014 .

[0040] An annular coupling groove 1015 is defined on the inner surface of the annular chamber. The annular coupling groove 1015 is coaxially disposed with the annular chamber. The annular chamber and the annular coupling groove 1015 can be integrally formed, i.e., the annular coupling groove 1015 is formed on the inner surface of the annular chamber during the manufacturing process. When defining the annular coupling groove 1015, its location must be considered to minimize heat loss, ensuring that the narrowband filter structure is positioned to minimize heat loss.

[0041] Further, if Figure 2 As shown, when the annular chamber 1014 is a circular chamber, the metal ring 1013 is configured as a circular ring, and the circular ring is coaxially arranged with the annular coupling groove 1015. Correspondingly, the insulating ring 1012 is also configured as a circular ring, and when the metal ring 1013 is sleeved on the insulating ring 1012, the insulating ring 1012 and the metal ring 1013 are coaxially arranged, that is, the insulating ring 1012 is also coaxially arranged with the annular coupling groove 1015.

[0042] In this embodiment, the RLC equivalent circuit structure reduces the rate of change of the magnetic field near the node, alleviates the electromagnetic field leakage caused by the offset of the coupling slot and the node position of the high-order mode damping cavity 10, and thus improves the stability of the high-order mode damping cavity 10 working under high gradient. Figure 6 As shown in FIG, the narrowband filter structure 101 is equivalent to the RLC circuit structure, wherein the role of the insulating ring 1012 is to increase the dielectric constant to increase the capacitance. It can be concluded from the simulation data that Figure 7 As shown, when the electromagnetic field leakage rate is 2%, the allowable offset of the coupling slot position of the high-order mode damping cavity 10 increases from ±0.12 mm to ±0.9 mm.

[0043] In some embodiments, as Figure 1 、 Figure 2 、 Figure 3 and Figure 5 As shown, one end of the first cavity 1011 can be folded back in the circumferential direction.

[0044] Specifically, when the narrowband filtering structure 101 is used, one end of the first cavity 1011 can be folded back along the circumferential direction. When folding back, one end of the first cavity 1011 can be folded back 90°, so that one end of the first cavity 1011 is roughly in a disc structure.

[0045] Of course, one end of the first cavity 1011 can also be folded at other angles, for example, 88°, 85°, 70°, 65°, 60°, 55°, etc. Those skilled in the art can determine the folding angle according to actual conditions, and no further restrictions are made here.

[0046] In this embodiment, the inverted design of the first cavity 1011 can reduce the occupied area in the axial direction and reduce the machining cost (an excessively long first cavity 1011 will increase the machining cost).

[0047] Further, if Figure 1 、 Figure 2As shown, one end of the first cavity 1011 can be folded outward or inward along the circumferential direction, that is, one end of the first cavity 1011 can be folded inward or outward along the circumferential direction. Those skilled in the art can determine whether the cavity is folded outward or inward according to actual conditions, and no further limitation is given here.

[0048] In some embodiments, the metal ring 1013 is a copper ring. The metal ring 1013 may also be a stainless steel ring. Of course, the metal ring 1013 may also be a ring made of other metal materials, such as an aluminum ring, a silver ring, etc.

[0049] In some embodiments, the insulating ring 1012 is a ceramic ring. Figure 9 It can be seen that the ceramic ring increases the capacitance, making the resonance point act at 1.5GHz.

[0050] In some embodiments, as Figure 10 As shown, the present invention further provides a high-order mode damping cavity 10, which includes the narrowband filtering structure 101 as described above.

[0051] In some embodiments, the high-order mode damping cavity 10 also includes a second cavity 102, which is a cylindrical cavity. The above-mentioned narrowband filtering structure 101 is respectively provided at both ends of the cylindrical cavity. One end of the first cavity 1011 in the narrowband filtering structure 101 is connected to the second cavity 102, and the other end of the first cavity 1011 extends axially away from the second cavity 102, and the annular chamber 1014 is coaxially arranged with the second cavity 102.

[0052] Specifically, the first cavity 1011 and the second cavity 102 can be made in an integrally formed manner. The annular coupling groove 1015 on the first cavity 1011 is a coupling groove of the high-order mode damping cavity 10 .

[0053] Specifically, the first cavity 1011 can be configured as a cylindrical cavity, with a circular annular chamber extending through the upper and lower surfaces of the cylindrical cavity. The circular annular chamber is the annular chamber 1014. An annular coupling groove is defined on the inner surface of the annular chamber, and the annular coupling groove and the annular chamber are coaxially disposed. The annular chamber can be integrally formed with the annular coupling groove 1015, that is, the annular coupling groove 1015 is formed on the inner surface of the annular chamber during the processing of the annular chamber.

[0054] Furthermore, when annular chamber 1014 is a toroidal chamber, metal ring 1013 is configured as a circular ring, and the circular ring is coaxially arranged with the annular coupling groove. Correspondingly, insulating ring 1012 is also configured as a circular ring, and when metal ring 1013 is sleeved on insulating ring 1012, insulating ring 1012 and metal ring 1013 are coaxially arranged, that is, insulating ring 1012 is also coaxially arranged with the annular coupling groove.

[0055] In this embodiment, if Figure 8 As shown, the narrowband filtering structure 101 on the high-order mode damping cavity 10 is an RLC equivalent circuit structure, which achieves narrowband filtering. Specifically, resonant modes other than the TM020 mode are transmitted unimpeded through the coupling slots of the high-order mode damping cavity 10 to the damper 105 on the high-order mode damping cavity 10, while the TM020 mode is blocked. This RLC equivalent circuit structure reduces the rate of change of the magnetic field near the nodal points, lowering the sensitivity of the electromagnetic field leakage rate to the position of the coupling slots and nodal points of the high-order mode damping cavity 10, and reducing the loss of the high-order mode damping cavity 10 in the operating mode to less than 1%. The high-frequency parameters of the high-order mode damping cavity 10 for the 1500 GHz TM020 mode are listed in Table 1.

[0056] Table 1

[0057] Freq.[MHz] Q0 R / Q[Ω] Ra[MΩ] Pm / Pc[%] 1500 <![CDATA[3.56×10 4 ]]> 55.6 1.98 0.32

[0058] In some embodiments, a coupler 103, multiple symmetrically distributed tuners 104, a damper 105, multiple signal extraction ports 106 and a vacuum port 107 are provided on the side wall of the second cavity 102; a damper 105 for absorbing waves is provided at the other end of each first cavity 1011.

[0059] Specifically, three tuners 104 may be provided, and the three tuners 104 are evenly distributed on the side wall of the second cavity 102 , that is, the distances between any two adjacent groups of tuners 104 are equal.

[0060] Two signal extraction ports 106 may be provided, and the two signal extraction ports 106 are symmetrically arranged, wherein each signal extraction port 106 is arranged between two tuners 104 .

[0061] One vacuum port 107 may be provided. Specifically, the vacuum port 107 may be provided between the tuner 104 and the signal extraction port 106 .

[0062] One coupler 103 may be provided. Specifically, the coupler 103 is provided between two tuners 104 , and the coupler 103 is separated from the signal extraction port 106 by the tuner 104 .

[0063] When the damper 105 is set, one end of the first cavity 1011 can be folded back in the circumferential direction. When folding, one end of the first cavity 1011 can be folded back outward in the circumferential direction, or it can be folded back inward in the circumferential direction, so that one end of the first cavity 1011 is designed in the shape of an end cap. When folding, it can be folded back 90°; of course, one end of the first cavity 1011 can also be folded back at other angles, for example, 88°, 85°, 70°, 65°, 60°, 55° and other angles. Those skilled in the art can determine the folding angle according to actual conditions, and no further restrictions are made here. The damper 105 is set at the end face formed after the other end of the first cavity 1011 is folded back, wherein, at the damper 105, wave absorption is performed by the damper 105. Among them, when the end of the first cavity 1011 away from the second cavity 102 is bent, the end of any first cavity 1011 on the second cavity 102 away from the second cavity 102 can be folded back, or the ends of the two first cavities 1011 away from the second cavity 102 can be folded back. Those skilled in the art can determine the number of first cavities 1011 that need to be folded back according to actual conditions.

[0064] In this embodiment, the first cavity 1011 is folded back to form an end cap shape, which facilitates the installation of the damper 105 .

[0065] In some embodiments, the damper 105 may be a ferrite absorbing material or a silicon carbide absorbing material.

[0066] It should be noted that the description of the embodiment of the high-order mode damping cavity 10 is similar to the description of the embodiment of the narrowband filter structure 101, and has similar beneficial effects as the high-order mode damping cavity 10. For technical details not disclosed in the embodiment of the high-order mode damping cavity 10, please refer to the description of the embodiment of the narrowband filter structure 101 of the present invention for an understanding.

[0067] In summary, the present invention provides a narrowband filtering structure 101 and a high-order mode damping cavity 10, which have the following beneficial effects:

[0068] Since the narrowband filtering structure 101 is equivalent to an RLC equivalent circuit structure, the magnetic field change rate near the wave node is reduced, the electromagnetic field leakage in the working mode is effectively reduced, and the stability of the high-order mode damping cavity 10 working under high gradient is improved.

[0069] It is understandable that the above embodiments only express the preferred implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can be made, all of which fall within the scope of protection of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should fall within the scope of coverage of the claims of the present invention.

Claims

1. A narrowband filtering structure, characterized in that: include: A first cavity, wherein the first cavity is provided with an annular cavity penetrating two opposite surfaces of the first cavity, and an inner surface of the annular cavity is provided with an annular coupling groove coaxially arranged with the annular cavity; an insulating ring, coaxially arranged with the annular coupling groove; The metal ring is sleeved on the insulating ring and is coaxial with the insulating ring. The metal ring is arranged in the annular coupling groove to form an RLC equivalent circuit structure.

2. The narrowband filtering structure according to claim 1, wherein: One end of the first cavity is folded back along the circumferential direction.

3. The narrowband filtering structure according to claim 2, characterized in that: One end of the first cavity is folded outward along the circumferential direction; or one end of the first cavity is folded inward along the circumferential direction.

4. The narrowband filtering structure according to any one of claims 1 to 3, characterized in that: The first cavity is a cylindrical cavity, and a circular ring-shaped cavity penetrating the upper surface and the lower surface of the first cavity is opened on the first cavity, and the circular ring-shaped cavity is the annular cavity.

5. The narrowband filtering structure according to claim 4, characterized in that: The metal ring is a circular ring, and the insulating ring is a circular ring.

6. The narrowband filtering structure according to claim 5, characterized in that: The metal ring is a copper ring or a stainless steel ring.

7. The narrowband filtering structure according to claim 5, characterized in that: The insulating ring is a ceramic ring.

8. A high-order mode damping cavity, characterized in that: include: The narrowband filtering structure according to any one of claims 1 to 7.

9. The high-order mode damping cavity according to claim 8, characterized in that: The high-order mode damping cavity further includes: The second cavity is a cylindrical cavity, and the narrowband filtering structure is respectively provided at both ends of the second cavity. One end of the first cavity is connected to the second cavity, and the other end of the first cavity extends axially away from the second cavity. The annular chamber is coaxially arranged with the second cavity.

10. The high-order mode damping cavity according to claim 9, characterized in that: The side walls of the second cavity are provided with a coupler, a vacuum port, a plurality of symmetrically distributed tuners, a plurality of symmetrically distributed dampers and a plurality of signal extraction ports; the other end of each first cavity is provided with a damper for absorbing waves.

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