Compact real-time frequency agility relativistic magnetron

Abstract

The invention discloses a compact real-time frequency agility relativistic magnetron, and belongs to the technical field of high-power microwave sources. The device comprises an input structure, an end space structure, an anode cavity structure, a full-cavity extraction output structure, a cathode coaxially arranged in an anode and a vacuum tuning mechanism which are sequentially arranged in the axial direction, the vacuum tuning mechanism comprises a tuning sliding block, a tuning rod and a sealing assembly. According to the invention, the vacuum tuning mechanism is designed, and the tuning rod drives the tuning slide block to move, so that the axial lengths of the coupling slot and the fan-shaped waveguide cavity are adjusted, the resonant frequency of the resonant cavity is further changed, and finally, real-time frequency agility of the device in a high vacuum state is realized; in addition, by adopting a reentrant coupling cavity structure and a full-cavity extraction structure, the compactness of the device is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-power microwave sources, and particularly relates to a compact real-time frequency-agile relativistic magnetron. Background Art

[0002] James Benford, a life fellow of the Institute of Electrical and Electronics Engineers, once predicted that future high power would be applied in the air-to-air field. It is necessary to ensure the compactness and light weight of the overall system, and it is also necessary for the high-power microwave source to achieve broadband tunability.

[0003] The relativistic magnetron is a widely used compact, high-efficiency, and stable high-power microwave source. It generates high-energy plasma on the cathode surface through a relatively high voltage (about several hundred kilovolts). The high-energy particles diffusing from the plasma interact with the resonant field inside the interaction region to achieve energy conversion, and finally form electromagnetic waves and output them through a certain extraction structure.

[0004] Traditional relativistic magnetrons can only operate at a single frequency point. Currently, there are technical solutions to achieve frequency tuning of relativistic magnetrons, but they require interrupting the vacuum state, that is, the existing technical solutions have not achieved real-time frequency agility in a high-vacuum state. Almost all of the currently proposed frequency-agile relativistic magnetrons perform frequency agility under normal atmospheric pressure, and it is necessary to break their high-vacuum working state for frequency agility operations, which limits their application environment. Moreover, using a vacuum pump for evacuation multiple times, the vacuum-breaking process will damage the vacuum pump. In actual use, due to the evacuation and vacuum-breaking links, a large amount of operation time is required, which will greatly affect the working efficiency of the relativistic magnetron.

[0005] Light weight and compactness are the current development trends of relativistic magnetrons. The existing relativistic magnetron design solutions cannot meet both the requirements of light weight and compactness. The relativistic magnetron requires an additional axial magnetic field to guide the high-energy particles in its internal interaction region to oscillate. Usually, a permanent magnet is directly installed outside the vacuum chamber of the relativistic magnetron. Under the condition of ensuring the same magnetic field strength in the uniform region, the larger the radial size of the vacuum chamber, the more the weight of the permanent magnet will increase exponentially. The radial size of the relativistic magnetron will affect its internal interaction region and energy extraction structure. Considering the compactness, complexity, and robustness requirements of the entire system ultimately, a permanent magnet is selected as the magnetic field mechanism. Compared with an electromagnetic mechanism, it does not require an additional magnetic field power supply and can maintain the stability of the magnetic field for a long time. With the continuous development of magnetic materials, the coercivity and magnetic permeability of magnetic materials have been continuously improved, but their density has been continuously reduced, which just meets our need for compactness. Therefore, to ensure the compactness and light weight of the entire system, the radial size of the relativistic magnetron must be small enough.

[0006] In the L-band frequency-agile relativistic magnetron design proposed in Technical Route 1, the outer wall radius of the external cavity is 83 mm, the outer wall radius of the output waveguide is the same as the outer cavity radius, and the frequency tuning range is 1.23 GHz to 1.7 GHz. [F. Qin, Y. Zhang, S. Xu, L.-R. Lei, B.-Q. Ju and D. Wang, "A Frequency-Agile Relativistic Magnetron With Axial Tuning," in IEEE Electron Device Letters, vol. 41, no. 5, pp. 781-783, May 2020, doi: 10.1109 / LED.2020.2984096.] The outer cavity radius of the L-band relativistic magnetron proposed in Technical Route 2 is 72 mm. The outer cavity radius designed by the two design schemes is greater than half of the working wavelength, which is not conducive to the lightweight and compact design of the relativistic magnetron.

C.He et al., "Compact${L}$-BandRelativistic Magnetron With Diffraction Output of TEM Mode," in IEEETransactions on Electron Devices, vol.66, no.12, pp.5327-5332, Dec.2019, doi:10.1109 / TED.2019.2945836.

[0007] In conclusion, the current L-band relativistic magnetron design schemes cannot simultaneously achieve the three design indicators of compactness, lightness, and real-time agile frequency conversion. Summary of the invention

[0008] In view of the problems in the prior art of L-band relativistic magnetron design such as single operating frequency, inability to achieve real-time frequency agility and lack of compactness, the present invention provides a compact real-time frequency agility relativistic magnetron.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] A compact real-time frequency-agile relativistic magnetron comprises an input structure, an end space structure, an anode cavity structure, an output structure which are sequentially arranged along an axial direction, and a cathode which is coaxially arranged inside the anode;

[0011] Wherein, the input structure is a circular waveguide;

[0012] The end space structure is a cylindrical cavity with a radius greater than the inner radius of the input structure;

[0013] The anode cavity structure includes N anode blades, a fan-shaped resonant cavity is formed between adjacent anode blades, and a coupling slit is provided on the outside of the fan-shaped resonant cavity for microwave energy coupling;

[0014] Characterized in that the output structure is a full-cavity extraction output structure;

[0015] The full cavity extraction output structure comprises a coaxially arranged inner conductor, an outer conductor, an end shell, and N / 2 plug-ins; the end shell is arranged at one end of the inner and outer conductors close to the input structure, so that the annular cavity between the inner and outer conductors is isolated from the external space to form a vacuum chamber; the plug-ins are located between the inner and outer conductors and are evenly distributed along the circumference, and the length of the plug-ins is not less than the length of the anode blades, and the annular cavity between the inner and outer conductors is divided into N / 2 fan-shaped waveguide cavities, and the outer sides of two adjacent coupling slits correspond to one fan-shaped waveguide cavity, and the microwave energy is radially extracted to the fan-shaped waveguide cavity through the coupling slit, and then synthesized into one output in the coaxial cavity between the inner and outer conductors;

[0016] The relativistic magnetron also includes a vacuum tuning mechanism;

[0017] The vacuum tuning mechanism comprises a tuning slider, a tuning rod and a sealing assembly;

[0018] The tuning slider is located inside the fan-shaped waveguide cavity and matches the fan-shaped waveguide cavity;

[0019] The tuning rod is arranged parallel to the axial direction, one end of which is connected to the tuning slider, and the other end of which extends out of the vacuum chamber through a through hole arranged on the end shell;

[0020] The sealing assembly is arranged between the tuning rod and the end housing to ensure the airtightness of the vacuum chamber;

[0021] The tuning rod is moved axially so that the tuning rod drives the tuning slider to slide inside the fan-shaped waveguide cavity to adjust the axial length of the coupling gap and the fan-shaped waveguide cavity, thereby realizing the real-time frequency agility of the relativistic magnetron.

[0022] Preferably, the vacuum tuning mechanism further comprises a tuning fixed disk;

[0023] The tuning fixed disk is arranged outside the vacuum chamber, and the tuning rod passing through the end shell is fixedly connected to the tuning fixed disk. By moving the tuning fixed disk, the tuning rod drives the tuning slider to keep moving synchronously.

[0024] Preferably, the sealing assembly comprises a sealing rubber ring and a sealing stopper;

[0025] A circular hole is provided in the middle of the sealing block for the tuning rod to pass through, and matching threads are provided on the outer wall of the sealing block and the inner wall of the through hole;

[0026] The sealing rubber ring is placed at the bottom of the sealing block and is fixed by being compacted by the sealing block.

[0027] Preferably, the value of N is an even number greater than 6.

[0028] Preferably, the anode cavity structure is a coaxial cavity structure, that is, the anode blade sizes are the same.

[0029] Preferably, the inner conductor is a hollow cylindrical structure to reduce the weight of the magnetron.

[0030] Preferably, the tuning slider can move in the sector waveguide cavity, and the gap width between the two is less than 0.1 mm.

[0031] Preferably, the materials of the anode and the vacuum tuning mechanism are titanium alloy.

[0032] Preferably, the material of the rubber ring is a fluororubber sealing rubber ring.

[0033] The beneficial effects of the present invention are as follows:

[0034] 1. The relativistic magnetron provided by the present invention adopts a reentrant coupled cavity structure, that is, the resonant cavity and the output cavity are combined together, which greatly reduces the overall size in the radial direction and realizes the compactification of the device.

[0035] 2. The present invention adopts a full-cavity extraction structure. The microwave energy of adjacent resonant cavities is coupled into a sector waveguide cavity through a coupling slot to obtain a combined sector TE11 mode; then the sector TE11 mode is combined into a coaxial TEM mode in the coaxial cavity and transmitted to the next-stage link. Since the cut-off wavelength of the TEM mode is infinite, only the power capacity problem needs to be considered for the coaxial part, and the problem of mode cut-off does not need to be considered. Therefore, the size of the coaxial waveguide can be made very compact, that is, the compactification of the device is also realized in the axial direction.

[0036] 3. The present invention designs a vacuum tuning mechanism. The tuning slider is driven by a tuning rod to move, thereby adjusting the coupling slot and the axial length of the sector waveguide cavity; by adjusting the size parameters of the coupling slot and the sector waveguide cavity, the loaded quality factor and equivalent electrical parameters inside it, such as equivalent inductance and equivalent capacitance, etc., are changed, and then the resonant frequency of the resonant cavity jointly composed of the sector resonant cavity, the coupling slot and the sector waveguide cavity is changed, and finally the real-time frequency agility of the device in a high-vacuum state is realized. Brief Description of the Drawings

[0037] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0038] Figure 2 is a schematic diagram of the interior of the relativistic magnetron of the present invention;

[0039] Figure 3 It is a schematic diagram of the interior of the vacuum tuning mechanism of the relativistic magnetron of the present invention;

[0040] Figure 4 It is a schematic diagram of some dimensions of the relativistic magnetron of the present invention; Figure 5 It is a schematic diagram of the agile frequency conversion performance of the relativistic magnetron of the present invention.

[0041] Explanation of the reference numerals: 1. Input structure, 2. Tuning rod, 3. Tuning fixed disk, 4. Sealing block, 5. Sealing ring, 6. End space, 7. Tuning slider, 8. Anode blade, 9. Vacuum chamber, 10. Coaxial outer conductor, 11. Coaxial inner conductor, 12. Coupling slot. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and technical problem solved by the present invention clearer, the present invention is further quantitatively described below in conjunction with the accompanying drawings and specific examples.

[0043] This embodiment provides a compact real-time frequency-agile relativistic magnetron, which works in the L band, such as Figure 1 to Figure 3 As shown, the relativistic magnetron includes an input structure, an end space structure, an anode cavity structure, a full-cavity extraction output structure, a cathode coaxially arranged inside the anode, and a vacuum tuning mechanism.

[0044] Wherein, the input structure is a circular waveguide with a diameter of 44.2 mm.

[0045] The end space structure is a cylindrical cavity with a diameter Фa2 of 60 mm and a length of 30 mm.

[0046] The anode cavity structure includes 6 anode blades of the same size, with a length La of 68.7 mm, an inner diameter Фa1 of 44.6 mm, and a corresponding central angle of 40°; a fan-shaped resonant cavity is formed between adjacent anode blades, and an outer diameter Фc2 of the fan-shaped resonant cavity is 91.8 mm; a coupling slit with a length La of 68.7 mm and an angle of 20° is provided on the outside of the fan-shaped resonant cavity for microwave energy coupling.

[0047] The full cavity extraction output structure includes a coaxially arranged inner conductor, outer conductor, end shell, and three plug-in plates. The interior of the inner conductor is set as a cavity structure to reduce the weight of the magnetron; the end shell is set at one end of the inner and outer conductors close to the input structure, so that the annular cavity between the inner and outer conductors is isolated from the external space to form a vacuum chamber, the inner diameter Φc2 of the vacuum chamber is 91.8mm, the outer diameter is 96mm, and the length is 330mm; the plug-in plate is located between the inner and outer conductors and evenly distributed along the circumference, the length of the plug-in plate is 70.7mm, slightly larger than the length of the anode blade, and the annular cavity between the inner and outer conductors is divided into three fan-shaped waveguide cavities, and the corresponding central angle of the fan-shaped waveguide cavity is 80°; the outer sides of two adjacent coupling slits correspond to a fan-shaped waveguide cavity, and the microwave energy is radially extracted to the fan-shaped waveguide cavity through the coupling slit, and the fan-shaped TE11 mode is merged; the fan-shaped TE11 mode is transmitted in the output direction, and is merged into the coaxial TEM mode in the coaxial cavity, and transmitted to the next level link.

[0048] The vacuum tuning mechanism comprises a tuning slider, a tuning rod, a sealing component and a tuning fixing plate.

[0049] The tuning slider is located inside the fan-shaped waveguide and matches the fan-shaped waveguide, with a length of 20 mm. In order to ensure that the tuning slider can move relatively smoothly under the control of the tuning rod in a high vacuum state, and also to ensure that the tuning slider and the inner and outer conductors have good electrical contact and are tightly connected, the gap between the tuning slider and the fan-shaped waveguide is set to 0.05 mm.

[0050] The tuning rod is arranged parallel to the axial direction, has a radius of 2.5 mm, one end of the tuning rod is connected to the tuning slider, and the other end extends out of the vacuum chamber through a through hole arranged on the end shell.

[0051] The sealing component comprises a sealing rubber ring and a sealing stopper.

[0052] A circular hole for the tuning rod to pass through is arranged in the middle of the sealing block, and matching threads are arranged on the outer wall of the sealing block and the inner wall of the through hole.

[0053] The sealing rubber ring is a fluororubber ring, which is placed at the bottom of the sealing block and fixed by the sealing block. The sealing rubber ring serves as a partition between the high vacuum state and the external atmospheric pressure state. The sealing rubber ring uses its own characteristic of being deformed by the high vacuum suction force to fill the gap between the tuning rod and the through hole to ensure that the high vacuum state inside the vacuum chamber will not be affected by the movement of the tuning rod.

[0054] The tuning fixed plate is an annular structure arranged outside the vacuum chamber. The tuning rod passing through the end shell is fixedly connected to the tuning fixed plate. By moving the tuning fixed plate, the tuning rod drives the tuning slider to keep moving synchronously.

[0055] Thereby, the axial length of the coupling slot and the fan-shaped waveguide cavity is adjusted; by adjusting the size parameters of the coupling slot and the fan-shaped waveguide cavity, the loaded quality factor and equivalent electrical parameters inside, such as equivalent inductance and equivalent capacitance, are changed, thereby changing the resonant frequency of the resonant cavity composed of the fan-shaped resonant cavity, the coupling slot and the fan-shaped waveguide cavity, and finally realizing the real-time agile frequency change of the relativistic magnetron.

[0056] In order to further reduce the weight of the device, the anode and vacuum tuning mechanism are made of titanium alloy.

[0057] The relativistic magnetron provided in this embodiment adopts a reentrant coupling cavity structure, which greatly reduces the overall size in the radial direction, from about 80 mm to 48 mm, and the radial size is compressed by more than 30%. And through the lightweight design of the structure, including the selection of low-density, high-strength material titanium alloy, the overall weight of the relativistic magnetron is only 5 kg.

[0058] like Figure 5 As shown, in a vacuum state, by axially moving the tuning slider from 0mm to 20mm (i.e. adjusting the length of the coupling gap), the tuning range is 1.86GHz to 2.44GHz, and the band output power is greater than 100MW. In addition, when the relativistic magnetron operates in the π mode, the phase difference of each sector resonant cavity is 180°, and a sector TE11 mode can be obtained by merging adjacent resonant cavities. Then, by merging the three anode ridges, the three sector TE11 modes are merged into a coaxial TEM mode and transmitted to the next link. Since the TEM mode cutoff wavelength is infinite, the coaxial part only needs to consider the power capacity problem, and does not need to consider the mode cutoff problem, so the size of the coaxial waveguide can be made very compact.

Claims

1. A compact real-time frequency-agile relativistic magnetron, comprising an input structure, an end space structure, an anode cavity structure, an output structure, and a cathode coaxially arranged inside the anode; in, The input structure is a circular waveguide; The end space structure is a cylindrical cavity with a radius greater than the inner radius of the input structure; The anode cavity structure includes N anode blades, a fan-shaped resonant cavity is formed between adjacent anode blades, and a coupling slit is provided on the outside of the fan-shaped resonant cavity for microwave energy coupling; Characterized in that the output structure is a full-cavity extraction output structure; The full cavity extraction output structure comprises a coaxially arranged inner conductor, an outer conductor, an end shell, and N / 2 plug-ins; the end shell is arranged at one end of the inner and outer conductors close to the input structure, so that the annular cavity between the inner and outer conductors is isolated from the external space to form a vacuum chamber; the plug-ins are located between the inner and outer conductors and are evenly distributed along the circumference, and the length of the plug-ins is not less than the length of the anode blades, and the annular cavity between the inner and outer conductors is divided into N / 2 fan-shaped waveguide cavities, and the outer sides of two adjacent coupling slits correspond to one fan-shaped waveguide cavity, and the microwave energy is radially extracted to the fan-shaped waveguide cavity through the coupling slit, and then synthesized into one output in the coaxial cavity between the inner and outer conductors; The relativistic magnetron also includes a vacuum tuning mechanism; The vacuum tuning mechanism comprises a tuning slider, a tuning rod and a sealing assembly; The tuning slider is located inside the fan-shaped waveguide cavity and matches the fan-shaped waveguide cavity; The tuning rod is arranged parallel to the axial direction, one end of which is connected to the tuning slider, and the other end of which extends out of the vacuum chamber through a through hole arranged on the end shell; The sealing assembly is arranged between the tuning rod and the end housing to ensure the airtightness of the vacuum chamber; The tuning rod is moved axially so that the tuning rod drives the tuning slider to slide inside the fan-shaped waveguide cavity to adjust the axial length of the coupling gap and the fan-shaped waveguide cavity, thereby realizing the real-time frequency agility of the relativistic magnetron.

2. A compact real-time frequency-agile relativistic magnetron as claimed in claim 1, characterized in that: The vacuum tuning mechanism also includes a tuning fixed disk; The tuning fixed disk is arranged outside the vacuum chamber, and the tuning rod passing through the end shell is fixedly connected to the tuning fixed disk. By moving the tuning fixed disk, the tuning rod drives the tuning slider to keep moving synchronously.

3. A compact real-time frequency-agile relativistic magnetron as claimed in claim 2, characterized in that: The tuning slider can move in the fan-shaped waveguide cavity, and the gap width between the two is less than 0.1 mm.

4. A compact real-time frequency-agile relativistic magnetron as claimed in claim 3, characterized in that: The sealing assembly comprises a sealing rubber ring and a sealing stopper; A circular hole is provided in the middle of the sealing block for the tuning rod to pass through, and matching threads are provided on the outer wall of the sealing block and the inner wall of the through hole; The sealing rubber ring is placed at the bottom of the sealing stopper and is compacted and fixed by the sealing stopper.

5. A compact real-time frequency-agile relativistic magnetron as claimed in claim 4, characterized in that: The material of the rubber ring is a fluorine rubber sealing rubber ring.

6. A compact real-time frequency-agile relativistic magnetron as claimed in claim 4 or 5, characterized in that: The value of N is an even number greater than 6.

7. A compact real-time frequency-agile relativistic magnetron as claimed in claim 6, characterized in that: The inner conductor is a hollow cylindrical structure to reduce the weight of the magnetron.

8. A compact real-time frequency-agile relativistic magnetron as claimed in claim 7, characterized in that: The anode cavity structure is a same cavity structure.

9. A compact real-time frequency-agile relativistic magnetron according to any one of claims 8, characterized in that: The material of the anode and the vacuum tuning mechanism is titanium alloy.

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