An internal field coupling structure of a microwave resonant cavity

Abstract

The invention discloses an internal field coupling structure of a microwave resonant cavity, including a resonant cavity and a beam body; the resonant cavity and the beam body are both made of conductive materials; the resonant cavity is vacuum, and a first cavity and a second cavity are arranged in the resonant cavity; the radial size of the first cavity is smaller than the radial size of the second cavity, the first cavity is connected to the second cavity, and a plurality of beam bodies are arranged in the first cavity and the second cavity along the axial direction; the beam body is provided with a narrow section and a wide section, the narrow section is arranged in the first cavity, and the wide section is arranged in the second cavity; the wide section is provided with a coupling window, and the coupling window is arranged adjacent to the narrow section; the plurality of beam bodies are all connected to the inner wall of the fixed resonant cavity, the plurality of beam bodies are arranged relatively, the working parts of the plurality of beam bodies are aligned with each other, and gaps are provided between the working parts of the plurality of beam bodies; a beam inlet is provided at the input end of the resonant cavity, and a beam outlet is provided at the output end of the resonant cavity, and the beam inlet and the beam outlet are both aligned with the gap. The invention effectively solves the problem that the existing coupling mechanism has a complex structure and cannot effectively improve the electromagnetic concentration phenomenon.

Description

Technical Field

[0001] The invention relates to the field of microwave resonance, and in particular to an internal field coupling structure of a microwave resonance cavity. Background Art

[0002] Existing resonant cavities generally have only one microwave resonant structure, while RF resonant cavities using two or more microwave resonant structures have different sizes and different electromagnetic field modes when working, which leads to electromagnetic field concentration in the matching sections of different resonant structures. This greatly increases the risk of voltage breakdown at that location, which will cause serious damage and impact on the operation of this type of resonant cavity. Therefore, electromagnetic coupling is required in the matching section to improve the electromagnetic concentration phenomenon. Therefore, a coupling structure with special design is required to improve the electromagnetic concentration phenomenon.

[0003] The existing coupling mechanisms are mainly external coupling and ground short circuit; the external coupling method is to improve the electromagnetic field distribution of the matching section by adding a larger microwave space, but this method can only suppress it to a certain extent and cannot completely avoid the electromagnetic field distortion of the matching section, nor can it effectively separate the electromagnetic field modes of the two microwave resonant structures when they are working; the ground short circuit method is to add grounding elements in the area where the electromagnetic field is concentrated, but this method will increase additional power loss and design complexity.

[0004] In addition, coupling also exists in the field of cavity filters. The prior art has disclosed a capacitive coupling structure and a cavity filter of a cavity filter. The principle is to open a coupling window of adjustable size between adjacent resonators so that the electromagnetic fields that originally did not interfere with each other can communicate, thereby adjusting the resonator frequency of the filter. However, it is not used to improve the electromagnetic concentration phenomenon, but to make the electromagnetic fields communicate, which is not the problem to be solved by this technical solution.

[0005] Therefore, it is of great significance to study a coupling structure with a simple structure that can effectively improve the electromagnetic concentration phenomenon. Summary of the invention

[0006] The object of the present invention is to provide an internal field coupling structure of a microwave resonant cavity to solve the problem that the existing coupling mechanism has a complex structure and cannot effectively improve the electromagnetic concentration phenomenon.

[0007] In order to solve the above technical problems, the present invention provides an internal field coupling structure of a microwave resonant cavity, comprising a resonant cavity and a beam body; the resonant cavity and the beam body are both made of conductive materials; the resonant cavity is vacuum, and a first cavity and a second cavity are arranged in the resonant cavity; the radial size of the first cavity is smaller than the radial size of the second cavity, the first cavity is connected to the second cavity, and a plurality of the beam bodies are arranged in the first cavity and the second cavity along the axial direction; the beam body is provided with a narrow section and a wide section, the narrow section is arranged in the first cavity, and the wide section is arranged in the second cavity; the wide section is provided with a coupling window, and the coupling window is arranged adjacent to the narrow section; the plurality of beam bodies are all connected and fixed to the inner wall of the resonant cavity, the plurality of beam bodies are arranged relatively, the working parts of the plurality of beam bodies are aligned with each other, and gaps are provided between the working parts of the plurality of beam bodies; a beam inlet is provided at the input end of the resonant cavity, a beam outlet is provided at the output end of the resonant cavity, and the beam inlet and the beam outlet are both aligned with the gap.

[0008] In one embodiment, the first cavity is a cylinder; the second cavity is also a cylinder; the axes of the two cylinders are arranged on the same resonant cavity axis.

[0009] In one embodiment, the axis of the beam inlet, the axis of the beam outlet and the axis of the gap are arranged on the same axis.

[0010] In one embodiment, the distance of the gap is equal everywhere.

[0011] In one of the embodiments, the length direction of the coupling window is arranged perpendicular to the axis of the resonant cavity.

[0012] In one of the embodiments, the edge of the coupling window and the edge of the beam body are both chamfered.

[0013] In one embodiment, the coupling window has a regular shape.

[0014] In one of the embodiments, the wall surface of the beam body and the inner wall of the resonance cavity are both smooth.

[0015] In one embodiment, both ends of the plurality of beam bodies are provided with undercut structures.

[0016] The beneficial effects of the present invention are as follows:

[0017] Since the beam body is provided with a narrow section and a wide section, the narrow section is provided in the first cavity, and the wide section is provided in the second cavity; the wide section is provided with a coupling window, and the coupling window is arranged adjacent to the narrow section, so when applied, the coupling window is arranged at the matching section of the first cavity and the second cavity. When the electromagnetic field of the first cavity and the electromagnetic field of the second cavity form an electromagnetic concentration phenomenon at the matching section, the coupling window is provided in the electromagnetic concentration area, providing an additional electromagnetic field path for the area, smoothing the field distribution in the electromagnetic field concentration area, and effectively solving the electromagnetic concentration phenomenon.

[0018] At the same time, by setting the coupling window with a simple structure between the two electromagnetic field areas, not only the possibility of spark breakdown at this location can be reduced, but also the beam transmission efficiency at this location can be increased, and beam mismatch caused by the concentration and distortion of the electromagnetic field at the matching section can be prevented. Structurally, it replaces the problem that the existing coupling mechanism needs to add a larger microwave space or increase the grounding elements to increase the design complexity, and can effectively solve the problem of complex coupling structure in the prior art.

[0019] In summary, the present invention can effectively solve the problem that the existing coupling mechanism has a complex structure and cannot effectively improve the electromagnetic concentration phenomenon. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the implementation mode will be briefly introduced below. Obviously, the drawings described below are only some implementation modes of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a schematic diagram of the overall structure provided by a preferred embodiment of the present invention;

[0022] Figure 2 It is a schematic diagram of the beam structure provided by a preferred embodiment of the present invention;

[0023] Figure 3 It is a schematic diagram of the large-scale structure of the electromagnetic field matching section provided in the preferred embodiment of the present invention;

[0024] Figure 4 is a schematic diagram of a cross-sectional structure of a coupling window provided in a preferred embodiment of the present invention;

[0025] Figure 5 is a schematic diagram of a beam envelope provided in a preferred embodiment of the present invention;

[0026] Figure 6 It is a schematic diagram of the electromagnetic field region of the matching section without a coupling window provided in a preferred embodiment of the present invention;

[0027] Figure 7 It is a schematic diagram of the electromagnetic field region of a matching section with a coupling window provided in a preferred embodiment of the present invention.

[0028] The reference numerals are as follows:

[0029] 1. Resonant cavity; 2. First cavity; 3. Second cavity; 4. Beam body; 5. Narrow section; 6. Wide section; 7. Coupling window; 8. Gap; 9. Beam entrance; 10. Beam exit; 11. Electromagnetic field matching section; 12. Electromagnetic field region of matching section without coupling window; 13. Electromagnetic field region of matching section with coupling window; 14. Beam envelope of matching section without coupling window; 15. Beam envelope of matching section with coupling window; 16. Undercut. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings.

[0031] First, the application fields and scenarios of the present application are introduced. The present invention relates to a microwave resonant cavity in the field of microwave resonance. A microwave resonant cavity is a resonant element working at microwave frequencies. A microwave resonant cavity is an area of ​​any shape surrounded by conductive walls or magnetic walls and in which electromagnetic oscillations can be formed. It is usually composed of a closed metal cavity and can be used in resonant circuits for microwave bands. A microwave resonant cavity has the characteristics of storing electromagnetic energy and selecting signals of a certain frequency, and is therefore widely used in scenarios such as particle acceleration, microwave communication, and microwave measurement.

[0032] The application scenario of the present invention is a particle acceleration scenario. By setting up a radio frequency resonant cavity with two or more microwave resonant structures in a microwave resonant cavity, the beam is accelerated, and a coupling structure needs to be set between the two or more microwave resonant structures. However, the current coupling structure has various problems, such as the voltage breakdown phenomenon caused by electromagnetic concentration, the inability to separate the electromagnetic field modes of different microwave resonant structures, and the complex structure. These defects of the coupling structure affect the safe operation of the microwave resonant cavity. Therefore, an embodiment of the present application provides an internal field coupling structure of a microwave resonant cavity. The coupling structure adopts a relatively simple structural design, combined with a coupling window design to provide an additional electromagnetic field path to achieve an improvement in the electromagnetic concentration phenomenon.

[0033] Next, a preferred embodiment of the internal field coupling structure of the microwave resonant cavity 1 provided in the present application will be introduced in conjunction with the accompanying drawings.

[0034] Please refer to Figure 1As shown in the schematic diagram of the overall structure, the microwave resonant cavity 1 is provided with a resonant cavity 1, a beam body 4 and a coupling window 7. The resonant cavity 1 is used to set different resonant fields to accelerate the beam, the beam body is used to provide support and power supply for the electrode, and the coupling window is used to provide an additional path for the intersection electromagnetic field of the electromagnetic field matching section 11. The core idea is that when the different resonant fields of the resonant cavity 1 accelerate the beam in the gap 8 of the beam body 4, the coupling window 7 on the beam body 4 in the resonant cavity 1 is used to couple the electromagnetic concentration phenomenon in the resonant cavity 1.

[0035] For resonant cavity 1, see Figures 1 to 4 As shown, the resonant cavity 1 is made of conductive material, the inner wall of the resonant cavity 1 is smooth, the resonant cavity 1 is vacuum, the input end of the resonant cavity 1 is provided with a beam inlet 9, and the output end of the resonant cavity 1 is provided with a beam outlet 10; and the resonant cavity 1 is provided with a first cavity 2 and a second cavity 3, the first cavity 2 is connected to the second cavity 3, the radial dimension of the first cavity 2 is smaller than the radial dimension of the second cavity 3, the first cavity 2 and the second cavity 3 are both cylindrical resonant cavities 1, and the axes of the cylinders of the two are arranged on the same axis of the resonant cavity 1.

[0036] It should be pointed out that the first cavity 2 and the second cavity 3 are arranged on the same axis so that the beam can be continuously accelerated linearly; and the reason why the first cavity 2 and the second cavity 3 both adopt the cylindrical resonant cavity 1 structure is that the cylindrical resonant cavity 1 has the advantages of high quality factor, no field change along the angular direction and non-polarized degenerate mode. Therefore, in this embodiment, the first cavity 2 and the second cavity 3 preferably both use the cylindrical resonant cavity 1.

[0037] The purpose of the smooth inner wall of the resonance cavity 1 and the vacuum in the resonance cavity 1 is to reduce the energy loss of particles.

[0038] It should be pointed out that evacuating the resonant cavity 1 can reduce the problems of particle loss and beam performance deterioration caused by the collision of the beam with residual air during movement; the smooth inner wall of the resonant cavity 1 can also reduce the energy loss when the beam contacts the inner wall of the resonant cavity 1.

[0039] The arrangement of the first cavity 2 in the resonant cavity 1 is as follows: Figure 1 As shown, the first cavity 2 is used to arrange the radio frequency quadrupole microwave resonance area, the radio frequency quadrupole microwave resonance structure is a four-wing type, and its working mode is a quadrupole mode TE 210 Mode (TE 210 mode, that is, the electric field fluctuates twice in the x direction and once in the y direction), and the high-frequency quadrupole field generated by the wavy electrode simultaneously realizes the lateral focusing, longitudinal bunching and acceleration of the beam.

[0040] It should be pointed out that the radio frequency quadrupole field resonance structure is used to accelerate the ion beam in the low energy region, and the beam transmission efficiency is high. Therefore, the radio frequency quadrupole field resonance structure is usually used as the first-stage acceleration structure after the ion source.

[0041] The arrangement of the second cavity 3 in the resonant cavity 1 is as follows: Figure 1 As shown, the second cavity 3 is used to arrange the drift tube microwave resonance region, and the drift tube resonance structure works in TE mode. 110 Mode (TE 110 The electric field between the drift tubes is used to accelerate the beam, and the beam is in an electromagnetic shielding state when it enters the microwave resonance region of the drift tube. It is restrained by the magnet installed in the microwave resonance region of the drift tube to achieve lateral focusing.

[0042] It should be pointed out that the drift tube resonance structure has a better effect on beam acceleration in the mid-energy region and is usually installed behind the RF quadrupole field resonance structure to cooperate with the RF quadrupole field resonance structure for overall beam acceleration.

[0043] It is particularly pointed out that the TE mode refers to a propagation mode in which the longitudinal component of the electric field in the propagation direction of the electromagnetic wave is zero and the longitudinal component of the magnetic field is not zero; in practice, there are three waveguide forms: transverse electromagnetic wave (TEM mode), transverse electric wave (TE mode), and transverse magnetic wave (TM mode); the resonant cavity 1 of the present invention operates in the TE mode, but operates in different sub-modes of the TE mode respectively, and the TE subscript numbers are represented by letters m, n and p, which respectively represent the number of times the field intensity fluctuates along the x, y and z coordinates. Of course, the coordinate dimensions are not unique, including but not limited to two-dimensional and three-dimensional, and one fluctuation refers to one and a half cycles of the sinusoidal electric field; different acceleration structures need to work in different modes, so two modes are set to work and operate.

[0044] It should be understood that since the resonant cavity 1 contains two RF microwave resonance zones with different working modes and electrode structures, namely the RF quadrupole microwave resonance zone and the drift tube microwave resonance zone, in order to make the resonant cavity 1 work at the same frequency, the capacitance of each resonance structure must be adjusted, and the electrode of the drift tube microwave resonance zone structure is more complex than the electrode of the RF quadrupole microwave resonance zone structure. Therefore, the radius of the first cavity 2 where the RF quadrupole microwave resonance zone is set is smaller than the radius of the second cavity 3 where the drift tube microwave resonance zone is set, which can effectively meet the structural characteristics of different microwave resonance zones, thereby accelerating the beam.

[0045] In addition, the conductive material of the resonant cavity 1 includes but is not limited to conductive or magnetic materials. In this embodiment, the conductive material is preferably copper, and those skilled in the art can choose according to their own needs.

[0046] For beam 4, please refer to Figure 1 and Figure 2As shown, the two beam bodies 4 are made of conductive materials, the surfaces of the two beam bodies 4 are smooth, and the edges of the beam bodies 4 are chamfered, while the structure of the beam bodies 4 is generally processed as one piece with the shell, so the connection between the beam bodies 4 and the shell cannot be chamfered; the two beam bodies 4 are arranged in the first cavity 2 and the second cavity 3 along the axial direction of the resonance cavity 1, and the beam bodies 4 are provided with a narrow section 5 and a wide section 6, the narrow section 5 is arranged in the first cavity 2, and the wide section 6 is arranged in the second cavity 3; the two beam bodies 4 are connected and fixed on the inner wall of the resonance cavity 1, the two beam bodies 4 are arranged opposite to each other, the working parts of the two beam bodies 4 are aligned with each other, and a gap 8 is provided between the working parts of the two beam bodies 4.

[0047] It should be understood that the smooth inner wall of the beam body 4 can reduce the energy loss when the beam contacts the inner wall of the resonant cavity 1, and the chamfering treatment of the edge of the beam body 4 can effectively reduce the maximum surface electric field around the corners, thereby preventing the risk of tip voltage breaking through the edge of the beam body 4.

[0048] The arrangement of the two beam bodies 4 in the resonant cavity 1 is as follows: Figure 1 , Figure 2 and Figure 4 As shown, the function of the beam body 4 in the resonant cavity 1 is to provide support and power supply for the electrode. Since the radio frequency quadrupole microwave resonance zone and the drift tube microwave resonance zone are set in the resonant cavity 1, the capacitance and electrodes of the two microwave resonance zones are different, which makes the radius of the first cavity 2 and the second cavity 3 different, and finally leads to different volumes and structures of the beam body 4 in different microwave resonance zones. Therefore, the beam body 4 needs to be set as a narrow section 5 and a wide section 6, and the narrow section 5 corresponds to the first cavity 2 with the radio frequency quadrupole microwave resonance zone, and the wide section 6 corresponds to the second cavity 3 with the drift tube microwave resonance zone.

[0049] It should be pointed out that the narrow section 5 and the wide section 6 of the beam body 4 are both on the same beam body 4 , that is, the beam body 4 in the first cavity 2 part and the second cavity 3 part are integral and are the same beam body 4 .

[0050] The arrangement of the gap 8 in the resonant cavity 1 is as follows: Figure 1 , Figure 3 and Figure 4 As shown, the two beam bodies 4 are arranged opposite to each other up and down, that is, they are arranged on the upper and lower sides of the resonant cavity 1, and are arranged symmetrically along the same plane, so that the electrode structure can be prevented from being offset, thereby reducing the beam divergence loss, and the bottom of the beam body 4 arranged at the upper part of the resonant cavity 1 is an accelerating wall, and the top of the beam body 4 arranged at the lower part of the resonant cavity 1 is also an accelerating wall. The accelerating walls of the two beam bodies 4 are aligned with each other to form a gap 8, and the distance of the gap 8 is the same everywhere, the gap 8 is aligned with the beam inlet 9 and the beam outlet 10, and the axis of the beam inlet 9, the axis of the beam outlet 10 and the axis of the gap 8 are on the same axis, so that the beam can be accelerated in the gap 8 between the two accelerating walls.

[0051] It should be pointed out that, through such an arrangement, the beam enters the gap 8 from the beam inlet 9, and is accelerated in the gap 8 through the RF quadrupole microwave resonance zone and the drift tube microwave resonance zone, and finally the appropriately accelerated beam leaves the microwave resonant cavity 1 through the beam outlet 10. The same distance of the gap 8 ensures that when the beam is accelerated, there will be no beam divergence loss due to the offset of the gap 8 structure. The distance of the gap 8 is determined by the size of the electrode structure, and those skilled in the art can determine it according to their own needs.

[0052] It should be understood that the shapes and structures of the two beam bodies 4 may be slightly different. The difference mainly lies in the undercut 16 structure set at both ends of the beam structure. The undercut 16 structure is a rectangular notch at both ends of the beam body 4, which is used to increase the electric field peak value at both ends and can better adjust the field distribution at both ends. The rest of the beam body 4 has the same shape, and the two beam bodies 4 must be arranged relative to each other. Otherwise, if the two beam bodies 4 are placed asymmetrically, it will cause the electrode structure to shift, and ultimately cause beam divergence loss.

[0053] In addition, the conductive material of the beam body 4 includes but is not limited to conductive or magnetic materials. In this embodiment, the conductive material is preferably copper, and those skilled in the art can choose according to their own needs.

[0054] For coupling window 7, please refer to Figure 1 and Figure 2 As shown, the coupling window 7 is arranged in the wide section 6 of the two beam bodies 4 and is adjacent to the narrow section 5; the length direction of the coupling window 7 is arranged perpendicular to the axial direction of the resonant cavity 1; the shape of the coupling window 7 is a regular shape, and the edges of the coupling window 7 are chamfered.

[0055] It should be pointed out that the processing principle of setting chamfers on the edges of the coupling window 7 is consistent with the principle of setting chamfers on the beam body 4. Both of them can effectively reduce the maximum surface electric field around the edges by setting chamfers, thereby preventing the risk of tip voltage breaking through the edge of the beam body 4.

[0056] The coupling window 7 is arranged at a position as follows: Figure 2 As shown, two coupling windows 7 are respectively arranged in the electromagnetic field matching sections 11 of the two beam bodies 4, and the two coupling windows 7 are both connected through the beam body 4 and the vacuum in the resonant cavity 1, that is, an additional electromagnetic field path is arranged in the electromagnetic field matching section 11 between the electromagnetic field of the RF quadrupole microwave resonance zone and the electromagnetic field of the drift tube microwave resonance zone, so that the electromagnetic field that originally can only communicate through the gap 8 is connected. Coupling windows 7 are arranged on the beam bodies 4 on both sides to provide additional electromagnetic field paths, thereby improving the electromagnetic concentration phenomenon.

[0057] It should be pointed out that, since the copper beam 4 is a conductive material, it can conduct electricity and generate a magnetic field, thereby generating a magnetic field shield, so that the electromagnetic field cannot penetrate the copper beam 4. The setting of the coupling window 7 increases the electromagnetic field flux of the electromagnetic field matching section 11. On the one hand, Figure 6 As shown in FIG. 1 , when the coupling window 7 is not provided, the electromagnetic field of the matching section is concentrated in the center of the cavity, which may cause spark breakdown, such as Figure 7 As shown, when the coupling window 7 is set, the electromagnetic field of the matching section can be coupled to the periphery of the resonant cavity 1 through the electromagnetic field at the center of the resonant cavity 1 through the coupling window 7. The electromagnetic field can directly connect the magnetic field lines at both ends of the beam body 4 through the coupling window 7, sharing the number of magnetic field lines connected through the acceleration gap. The electric field line is relieved from the original closed loop at the acceleration center to a closed loop through the coupling window, which alleviates the spark breakdown phenomenon that may be caused by the concentration of the electromagnetic field in the center of the cavity, plays a role in adjusting the field distribution, so as to reduce the concentration of the electromagnetic field in the center, reduce the electric field peak at the center, make the electric field peak uniform, and optimize the flatness of the central electric field, effectively distinguishing the electromagnetic field modes of the two microwave resonant structures; on the other hand, Figure 5 As shown, the beam envelope conditions of the matching section electromagnetic field region 12 without the coupling window 7 and the matching section electromagnetic field region 13 with the coupling window 7 can be clearly compared. The divergence of the matching section beam envelope 15 with the coupling window 7 is less affected than that of the matching section beam envelope 14 without the coupling window 7. Therefore, the additional coupling window 7 can increase the beam transmission efficiency at this location, is more conducive to beam acceleration, reduces beam divergence and loss, and generally improves the safety and performance of various microwave resonant cavities 1.

[0058] The arrangement direction of the coupling window 7 is as follows: Figures 1 to 4 As shown, the length direction of the coupling window 7 is arranged perpendicular to the axial direction of the resonant cavity 1. Through such an arrangement, as many coupling paths as possible can be arranged in the vertical area where the electromagnetic field is concentrated in the electromagnetic field matching section 11 to alleviate the phenomenon of electromagnetic field concentration.

[0059] The coupling window 7 has a regular shape, which can provide enough space to form an electromagnetic path to alleviate the electromagnetic concentration phenomenon.

[0060] It should be pointed out that the shape of the coupling window 7 includes but is not limited to rectangle, circle and ellipse. In this embodiment, the shape of the coupling window 7 is preferably rectangle, and the length and width parameters of the shape are determined according to the size of the electrode structure. Therefore, technicians in this field can choose the shape and size of the coupling window 7 according to their own needs.

[0061] As described above, compared with the coupling structure in the prior art, the present technical solution increases the electromagnetic field path of the electromagnetic matching section in different microwave resonance areas by designing a coupling window 7 with a simple structure in the beam body 4 of the electromagnetic field matching section 11 without introducing additional high-frequency components and electromagnetic field losses, thereby reducing the peak electric field and the average electric field there and smoothing the electric field distribution, effectively reducing the risk of voltage breakdown caused by electromagnetic field concentration at the matching section, and well separating the electromagnetic field modes of different microwave resonance structures, thereby ultimately improving the safety and stability of the resonant cavity 1 containing different microwave resonance structures, thereby improving the beam transmission efficiency.

[0062] In addition to the above, it should be particularly noted that in the field of filter technology, the resonator of the cavity filter is also provided with a coupling window 7, but the principle of its coupling window 7 is different from the principle of the coupling window 7 of the present technical solution.

[0063] The principle of the coupling window 7 in the resonator of the filter is that since the resonator regions that do not interfere with each other require separate tuning operations, which increases the difficulty of tuning, a coupling window 7 can be opened between the two resonators that do not interfere with each other. The purpose of the coupling window 7 of the cavity filter is to make the electromagnetic fields between the resonators that originally do not interfere with each other communicate, and then adjust the capacitance between the components through a single operation, and finally achieve the capacitive coupling adjustment of the frequency. The specific method is that the filter coupling window 7 is opened in the area between the two resonators, which can make the electromagnetic fields of the two areas achieve the above-mentioned purpose of communication. An adjustable frequency tuning rod is provided in the coupling window 7. The capacitive coupling amount of the cavity is tuned by simply adjusting the depth of the frequency tuning rod inserted into the coupling window 7, that is, adjusting the cavity capacitance. Generally speaking, the deeper the insertion depth of the frequency tuning rod, the smaller the capacitance of the cavity and the larger the cavity frequency; the shallower the insertion depth of the frequency tuning rod, the larger the capacitance of the cavity and the smaller the cavity frequency. Therefore, the opening of the coupling window 7 in the cavity filter can make the tuning of the cavity capacitance simple, and finally play a frequency tuning role, similar to the frequency tuner of the accelerator cavity.

[0064] The principle of the coupling window 7 of the present technical solution is to provide an additional path for the electromagnetic fields of the two microwave resonant field matching segments, so as to alleviate the spark breakdown phenomenon that may be caused by the concentration of the electromagnetic field in the center of the cavity, and play a role in adjusting the field distribution. It cannot affect or adjust the overall capacitance of the cavity, and has little effect on the frequency in the cavity.

[0065] In short, the purpose of the coupling window 7 in the filter is to make the electromagnetic fields that were originally not connected to each other connected, because the two electromagnetic fields were originally not connected to each other, by opening the coupling window 7, the capacitance of the two electromagnetic fields is adjusted, thereby affecting the frequency of the resonator; and the purpose of the coupling window 7 of the accelerator is to provide an additional path for the electromagnetic field in addition to the gap 8 where the electromagnetic field originally communicates, so as to alleviate the electromagnetic field concentration phenomenon. In summary, the principle of the coupling window 7 of the filter is significantly different from the principle of the coupling window 7 of the technical solution.

[0066] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. An internal field coupling structure of a microwave resonant cavity, characterized in that: It includes a resonant cavity and a beam body; The resonant cavity and the beam body are both made of conductive materials; The resonant cavity is vacuum, and a first cavity and a second cavity are provided in the resonant cavity; The radial dimension of the first cavity is smaller than the radial dimension of the second cavity, the first cavity is connected to the second cavity, and a plurality of beams are arranged in the first cavity and the second cavity along the axial direction; The beam body is provided with a narrow section and a wide section, the narrow section is provided in the first cavity, and the wide section is provided in the second cavity; the wide section is provided with a coupling window, and the coupling window is arranged adjacent to the narrow section; The plurality of beam bodies are all connected and fixed to the inner wall of the resonant cavity, the plurality of beam bodies are arranged relatively, the working parts of the plurality of beam bodies are aligned with each other, and gaps are provided between the working parts of the plurality of beam bodies; A beam inlet is provided at the input end of the resonant cavity, and a beam outlet is provided at the output end of the resonant cavity. Both the beam inlet and the beam outlet are aligned with the gap.

2. The internal field coupling structure of a microwave resonant cavity according to claim 1, characterized in that: The first cavity is a cylinder; The second cavity is also a cylinder; The axes of the two cylinders are arranged on the same resonance cavity axis.

3. The internal field coupling structure of a microwave resonant cavity according to claim 1, characterized in that: The axis of the beam inlet, the axis of the beam outlet and the axis of the gap are all arranged on the same axis.

4. The internal field coupling structure of a microwave resonant cavity according to claim 1, characterized in that: The distance of the gap is equal everywhere.

5. The internal field coupling structure of a microwave resonant cavity according to claim 1, characterized in that: The length direction of the coupling window is arranged perpendicular to the axis of the resonant cavity.

6. The internal field coupling structure of a microwave resonant cavity according to claim 1, characterized in that: The edge of the coupling window and the edge of the beam body are both chamfered.

7. The internal field coupling structure of a microwave resonant cavity according to claim 1, characterized in that: The coupling window has a regular shape.

8. The internal field coupling structure of a microwave resonant cavity according to claim 1, characterized in that: The wall surface of the beam body and the inner wall of the resonance cavity are both smooth.

9. The internal field coupling structure of a microwave resonant cavity according to claim 1, characterized in that: Both ends of the plurality of beam bodies are provided with undercut structures.

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