Relativistic magnetron for full-cavity extraction and radial output

Abstract

The invention relates to a relativistic magnetron for full-cavity extraction and radial output, and belongs to the technical field of high-power microwaves, the relativistic magnetron comprises an anode, a cathode and a magnet, the anode comprises an anode block and an anode shell, a fan-shaped waveguide and a rectangular waveguide are arranged on the periphery of the anode shell, and the rectangular waveguide is arranged in the radial direction of the anode shell; the fan-shaped waveguide is provided with two short-circuit surfaces in the axial direction of the anode shell, one end of the rectangular waveguide is connected with one short-circuit surface of the fan-shaped waveguide, and the technical problems that in the prior art, the periodic symmetry of an interaction area is poor, the inner diameter of a magnet is large, and light and small size cannot be achieved can be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of high-power microwaves, and in particular relates to a relativistic magnetron for full-cavity extraction of radial output. Background Art

[0002] High power microwave (HPM) refers to electromagnetic waves with peak power greater than 100MW and frequency between 1GHz and 300GHz. It is an interdisciplinary research field that has developed since the 1970s with the development of pulse power technology, relativistic electronics, plasma physics and other disciplines. High power microwave source is a device that mainly uses relativistic electron beams to generate high power microwave radiation and is one of the key components in high power microwave systems.

[0003] Relativistic magnetron (RM) has the advantages of simple structure, low operating magnetic field, high power and repeated pulse working ability, and is one of the most practical lightweight high-power microwave sources. At present, the research focus of relativistic magnetron is to improve power and conversion efficiency, reduce the volume and weight of the entire system, and achieve lightweight design. Among them, the output structure is the key factor affecting lightweight and miniaturization.

[0004] In the early days, relativistic magnetrons adopted a radial output structure, which coupled and output microwave energy by opening a gap axially on the outer wall of a resonant cavity. Since this output structure occupies the radial outer space of the resonant cavity, it is impossible to arrange magnets in this area. In order to ensure that the resonant cavity has a uniform axial guide magnetic field, a pair of Helmholtz coils or permanent magnets must be arranged at both ends of the resonant cavity. However, compared with a single magnet system directly arranged in the radial outer space of the resonant cavity, this magnet system is more complicated. Due to the existence of a single coupling gap, the periodic symmetry of the interaction zone is poor, which affects the working stability of the magnetron; and due to the gap breakdown threshold limitation, the output efficiency is low.

[0005] In 2006, Greenwood, Hoff and others proposed a full-cavity extraction axial output structure, which can be regarded as an improvement of the traditional radial output structure. This structure connects the coupling slots of adjacent resonant cavities to a fan-shaped rectangular waveguide in a symmetrical form along the center line. When the working mode of the magnetron is π mode, the TE11 mode will be excited in the fan-shaped rectangular waveguide and transmitted axially. Compared with the traditional radial output structure, the full-cavity extraction axial output structure has periodic symmetry and has little effect on the working state of the magnetron; and microwaves are transmitted axially, and the periphery of the fan-shaped waveguide can still be used to arrange magnets. Compared with the traditional radial output structure, the magnet structure is somewhat simplified. However, due to the existence of the fan-shaped rectangular waveguide outside the resonant cavity, the lateral size of the entire system is still larger than the outer radius of the anode, resulting in a larger inner diameter of the magnet, and the system's lightweight and miniaturization level is still limited. Summary of the invention

[0006] In view of various deficiencies in the prior art, a relativistic magnetron with full-cavity extraction of radial output is proposed to solve the technical problems of the prior art, such as poor periodic symmetry of the interaction zone, large inner diameter of the magnet, and inability to achieve lightweight and miniaturization.

[0007] To achieve the above object, the present invention provides the following technical solutions: A relativistic magnetron with full-cavity extraction radial output comprises an anode, a cathode and a magnet, wherein the anode comprises an anode block and an anode shell, a fan-shaped waveguide and a rectangular waveguide are arranged on the periphery of the anode shell, the rectangular waveguide is arranged along the radial direction of the anode shell, the fan-shaped waveguide has two short-circuit paths along the axial direction of the anode shell, and one end of the rectangular waveguide is connected to one of the short-circuit paths of the fan-shaped waveguide.

[0008] The technical solution is further configured that the anode shell is configured to be cylindrical, a plurality of anode blocks are periodically distributed along the angular direction of the anode shell, and the cavities between adjacent anode blocks constitute a resonant cavity.

[0009] The technical solution is further configured such that the number of the anode blocks is 2N, N is a positive integer not less than 2, and the number of the resonant cavities is equal to the number of the anode blocks.

[0010] The technical solution is further configured such that an axial coupling slit extending along the axial direction of the anode shell is provided on the cavity wall of the resonant cavity, the number of the axial coupling slits is equal to the number of the resonant cavities, and all the axial coupling slits are periodically distributed along the angular direction of the anode shell.

[0011] The technical solution is further configured such that two axial coupling slots located in adjacent resonant cavities are connected to the same fan-shaped waveguide in a symmetrical manner about the central axis of the anode housing.

[0012] The technical solution is further configured that a waveguide coupling slot is provided at the junction of the fan-shaped waveguide and the rectangular waveguide, and the length of the waveguide coupling slot is not greater than the length of the wide side of the rectangular waveguide.

[0013] The technical solution is further configured such that the magnet is arranged at the periphery of the anode shell, and the inner diameter of the magnet is equal to the outer diameter of the anode shell.

[0014] The technical solution is further configured such that the magnet adopts a two-section combined structure, and the two sections of the magnet are respectively located on both sides of the fan-shaped waveguide.

[0015] The technical solution is further configured that the magnet is a permanent magnet or an electromagnet.

[0016] The technical solution is further configured as follows: the cathode includes a bottom column, a connecting rod and an end cap, the bottom column is coaxially arranged with the anode housing, two end caps are provided, and the two end caps are symmetrically arranged at both ends of the connecting rod. The beneficial effects of the present invention are: The rectangular waveguide is arranged along the radial direction of the anode shell, and one end of the rectangular waveguide is connected to a short-circuit surface of the fan-shaped waveguide. All resonant cavities participate in microwave energy extraction, and the angular periodic symmetry of the resonant cavity is almost unaffected by the output structure. At the same time, the axial length of the fan-shaped waveguide is shortened, and the magnets can be arranged on both sides of the fan-shaped waveguide, which is conducive to achieving lightweight and miniaturization; the multi-path equal-phase rectangular waveguide fundamental mode electromagnetic wave output is convenient for feeding into array antennas such as waveguide slot arrays for direct radiation, which is conducive to reducing the axial size of the magnetron. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is an axial side view of a relativistic magnetron with full cavity extraction radial output according to an embodiment of the present invention; Figure 2 A side view of a relativistic magnetron with full-cavity extraction of radial output in an embodiment of the present invention; Figure 3 for Figure 2 Middle AA section view; Figure 4 It is a front view of a relativistic magnetron with full cavity extraction radial output according to an embodiment of the present invention; Figure 5 for Figure 4 Middle BB section view; Figure 6 is a schematic diagram of a cathode in an embodiment of the present invention; Figure 7 for Figure 6 Middle CC section view; Figure 8 It is a schematic diagram of a total output power signal in a specific embodiment of the present invention; Fig. 9 It is a schematic diagram of outputting microwave spectrum in a specific embodiment of the present invention.

[0018] In the attached figure: 1, anode shell; 2, rectangular waveguide; 3, magnet; 4, anode block; 5, resonant cavity; 6, fan-shaped waveguide; 7, waveguide coupling slot; 8, bottom column; 9, end cap; 10, connecting rod. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings of the present invention. Based on the embodiments in this application, other similar embodiments obtained by ordinary technicians in this field without making creative work should all fall within the scope of protection of this application. In addition, the directional words mentioned in the following embodiments, such as "up", "down", "left", "right", etc., are only reference to the directions of the accompanying drawings. Therefore, the directional words used are used to illustrate rather than limit the invention.

[0020] According to an embodiment of the present invention, a relativistic magnetron with full cavity extraction radial output is provided. Figures 1 to 7 , including an anode, a cathode and a magnet 3, the anode including an anode block 4 and an anode shell 1, the periphery of the anode shell 1 is provided with a fan-shaped waveguide 6 and a rectangular waveguide 2, the rectangular waveguide 2 is arranged along the radial direction of the anode shell 1, the fan-shaped waveguide 6 has two short-circuit surfaces along the axial direction of the anode shell 1, and one end of the rectangular waveguide 2 is connected to one of the short-circuit surfaces of the fan-shaped waveguide 6.

[0021] Preferably, the anode is made of non-magnetic stainless steel, titanium alloy or other materials; the magnet 3 is a permanent magnet made of hard magnetic material or an electromagnetic coil according to actual needs; the cathode base material is non-magnetic stainless steel, titanium alloy or other materials, and a cathode emission material is set at a certain position to emit electrons as needed, and the emission material can be graphite, velvet, etc.

[0022] It should be noted that the rectangular waveguide 2 is arranged along the radial direction of the anode shell 1, and one end of the rectangular waveguide 2 is connected to a short-circuit surface of the fan-shaped waveguide 6. All resonant cavities 5 participate in microwave energy extraction, and the angular periodic symmetry of the resonant cavity 5 is almost unaffected by the output structure. At the same time, the axial length of the fan-shaped waveguide 6 is shortened, and the magnet 3 can be arranged on both sides of the fan-shaped waveguide 6, which is conducive to achieving lightweight and miniaturization; the multi-path equal-phase rectangular waveguide fundamental mode electromagnetic wave output is convenient for feeding into array antennas such as waveguide slot arrays for direct radiation, which is conducive to reducing the axial size of the magnetron.

[0023] In this embodiment of the full cavity extraction radial output of the relativistic magnetron, see Figures 1 to 7 The anode housing 1 is set to be cylindrical, and a plurality of anode blocks 4 are periodically distributed along the angular direction of the anode housing 1 , and the cavity between adjacent anode blocks 4 constitutes a resonant cavity 5 .

[0024] Specifically, the number of the anode blocks 4 is 2N, where N is a positive integer not less than 2, and the 2N anode blocks 4 are evenly arranged around the central axis of the anode housing 1, and the 2N anode blocks 4 constitute 2N resonant cavities 5, that is, the number of the resonant cavities 5 is equal to the number of the anode blocks 4.

[0025] In this embodiment of the full cavity extraction radial output of the relativistic magnetron, see Figures 1 to 7 The cavity wall of the resonant cavity 5 is provided with axial coupling slits extending along the axial direction of the anode housing 1 , the number of the axial coupling slits is equal to the number of the resonant cavities 5 , and all the axial coupling slits are periodically distributed along the angular direction of the anode housing 1 .

[0026] It should be noted that an axial coupling slit is provided on the cavity wall of each resonant cavity 5 , and the axial coupling slit extends along the axial direction of the anode housing 1 . A total of 2N axial coupling slits are provided on the 2N resonant cavities 5 , and the 2N axial coupling slits are evenly arranged around the central axis of the anode housing 1 .

[0027] In this embodiment of the full cavity extraction radial output of the relativistic magnetron, see Figures 1 to 7 The two axial coupling slots located in adjacent resonant cavities 5 are connected to the same fan-shaped waveguide 6 in a symmetrical manner about the central axis of the anode housing 1 .

[0028] It should be noted that two adjacent axial coupling slots are connected to the same fan-shaped waveguide 6 , and 2N axial coupling slots need to be provided with N fan-shaped waveguides 6 .

[0029] In this embodiment of the full cavity extraction radial output of the relativistic magnetron, see Figures 1 to 7 A waveguide coupling slot 7 is provided at the junction of the fan-shaped waveguide 6 and the rectangular waveguide 2 , and the length of the waveguide coupling slot 7 is not greater than the length of the wide side of the rectangular waveguide 2 .

[0030] Specifically, in this embodiment, the wide side of the rectangular waveguide 2 is aligned with the short-circuit surface of the right end of the fan-shaped waveguide 6, and along the angular direction of the anode housing 1, the rectangular waveguide 2 and the fan-shaped waveguide 6 are distributed one by one, that is, N fan-shaped waveguides 6 are provided with N rectangular waveguides 2, and N waveguide coupling slots 7 are provided at the connection between the N rectangular waveguides 2 and the N fan-shaped waveguides 6. The 2N axial coupling slots couple the energy in the resonant cavity 5 to the N fan-shaped waveguides 6 and the N rectangular waveguides 2 in sequence in the radial direction, and the output direction of the rectangular waveguide 2 is parallel to the central axis of the anode housing 1.

[0031] In this embodiment of the full cavity extraction radial output of the relativistic magnetron, see Figures 1 to 7 The magnet 3 is arranged on the periphery of the anode housing 1 , and the inner diameter of the magnet 3 is equal to the outer diameter of the anode housing 1 .

[0032] Specifically, the magnet 3 adopts a two-section combined structure, and the two sections of the magnet 3 are respectively located on both sides of the fan-shaped waveguide 6 .

[0033] It should be noted that the radial coupling extraction structure of the rectangular waveguide 2 shortens the axial length of the fan-shaped waveguide 6. The magnets 3 can be arranged on both sides of the fan-shaped waveguide 6. The radius of the magnets 3 is equal to the outer diameter of the anode housing 1, which is conducive to realizing the lightweight and miniaturization of the system.

[0034] In this embodiment of the full cavity extraction radial output of the relativistic magnetron, see Figures 1 to 7 The cathode includes a bottom column 8, a connecting rod 10 and an end cap 9. The bottom column 8 is coaxially arranged with the anode housing 1. Two end caps 9 are provided, and the two end caps 9 are symmetrically arranged at both ends of the connecting rod 10.

[0035] Preferably, the cathode emission material is arranged between two end caps 9 .

[0036] The working principle of the relativistic magnetron with full-cavity extraction radial output of the present invention is: when the magnetron works in the π mode, there is a 180° phase difference between the electric field and the magnetic field between adjacent resonant cavities 5; the adjacent resonant cavities 5 excite the fan-shaped TE11 mode in the corresponding fan-shaped waveguide 6 through the axial coupling slot, and then at the short-circuit surface at the right end of the fan-shaped waveguide 6, the rectangular waveguide 2 TE10 mode is excited through the waveguide coupling slot 7 to further output outward; N TE10 mode electromagnetic waves are equal in amplitude and phase. Specific embodiment: Six anode blocks 4 are uniformly arranged around the cathode periphery in the angular direction, close to the anode housing 1, and form six resonant cavities 5. The inner radius of the anode block 4 is 32 mm, the outer radius is 60 mm, the axial length is 80 mm, and the opening angle is 40°; the length of the axial coupling gap is 53 mm, and the angle is 20°.

[0038] The cathode is a transparent cathode, consisting of three parts, namely a base column 8, an end cap 9 and 6 cylinders of the same size (as connecting rods 10); the base column 8 is a cylinder with a radius of 15mm and a length of 80mm; the end caps 9 are two cylinders with a radius of 24mm and a thickness of 20mm; the cross-sectional radius of the 6 cylinders is 5mm, the length of the column is 120mm, of which only 3 are emitting, and the length of the emitting area is 50mm.

[0039] There are three waveguide coupling slots 7 , which are respectively located on the common wall connecting the three 85° fan-shaped waveguides 6 and the three rectangular waveguides 2 ; the width of the waveguide coupling slot 7 is 16 mm, and its length is equal to the wide side length of the rectangular waveguide 2 .

[0040] There are three fan-shaped waveguides 6, with an inner radius of 68 mm, an outer radius of 91 mm, an opening angle of 85°, and an axial length of 94 mm. The three rectangular waveguides 2 radially connected to the three fan-shaped waveguides 6 have a wide side length of 110 mm, a narrow side length of 32 mm, and a radial length of 80 m.

[0041] The magnet 3 is divided into two sections with a spacing of 100 mm. The material selected is 1.4T NdFeB with an inner radius of 63 mm. Both sections are radially magnetized with an outer radius of 109 mm and an axial length of 82 mm.

[0042] The particle simulation software was used to calculate the relativistic magnetron with full cavity extraction radial output under the above structural dimensions under the conditions of feed voltage of about 630kV and guide magnetic field of about 0.36T. The results are as follows Figure 8 He Ru Fig. 9 As shown: an L-band microwave output with a resonant frequency of 1.556 GHz, an output power of 1.8 GW, and a power conversion efficiency of 56.7% was obtained, and the total weight of the magnet was about 32.04 kg. This shows that under lower guiding magnetic field conditions, the invention can maintain a relatively high beam conversion efficiency and can be applied to high-power microwave systems with strict requirements on lightness and miniaturization.

[0043] The present invention has been described in detail above. The above description is only a preferred embodiment of the present invention and should not limit the scope of implementation of the present invention. That is, all equivalent changes and modifications made within the scope of this application should still fall within the scope of the present invention.

Claims

1. A relativistic magnetron with full-cavity extraction radial output, comprising an anode, a cathode and a magnet, wherein the anode comprises an anode block and an anode shell, and a fan-shaped waveguide and a rectangular waveguide are arranged on the periphery of the anode shell, characterized in that: The rectangular waveguide is arranged along the radial direction of the anode shell, the fan-shaped waveguide has two short-circuit paths along the axial direction of the anode shell, and one end of the rectangular waveguide is connected to one of the short-circuit paths of the fan-shaped waveguide.

2. A relativistic magnetron with full cavity extraction radial output according to claim 1, characterized in that: The anode shell is set to be cylindrical, and a plurality of anode blocks are periodically distributed along the angular direction of the anode shell, and the cavity between adjacent anode blocks constitutes a resonant cavity.

3. A relativistic magnetron with full cavity extraction radial output according to claim 2, characterized in that: The number of the anode blocks is 2N, where N is a positive integer not less than 2, and the number of the resonant cavities is equal to the number of the anode blocks.

4. A relativistic magnetron with full cavity extraction radial output according to claim 2 or 3, characterized in that: Axial coupling slits extending along the axial direction of the anode shell are provided on the cavity wall of the resonance cavity. The number of the axial coupling slits is equal to the number of the resonance cavities, and all the axial coupling slits are periodically distributed along the angular direction of the anode shell.

5. A relativistic magnetron with full cavity extraction radial output according to claim 4, characterized in that: Two axial coupling slots located in adjacent resonant cavities are connected to the same fan-shaped waveguide in a symmetrical manner about the central axis of the anode shell.

6. A relativistic magnetron with full cavity extraction radial output according to claim 1, characterized in that: A waveguide coupling slot is provided at the junction of the fan-shaped waveguide and the rectangular waveguide, and the length of the waveguide coupling slot is not greater than the length of the wide side of the rectangular waveguide.

7. A relativistic magnetron with full cavity extraction radial output according to claim 1, characterized in that: The magnet is arranged on the periphery of the anode shell, and the inner diameter of the magnet is equal to the outer diameter of the anode shell.

8. A relativistic magnetron with full cavity extraction radial output according to claim 7, characterized in that: The magnet adopts a two-section combined structure, and the two sections of the magnet are respectively located on both sides of the fan-shaped waveguide.

9. A relativistic magnetron with full cavity extraction radial output according to claim 7 or 8, characterized in that: The magnet is a permanent magnet or an electromagnet.

10. A relativistic magnetron with full cavity extraction radial output according to claim 1, characterized in that: The cathode comprises a bottom column, a connecting rod and an end cap. The bottom column is coaxially arranged with the anode housing. Two end caps are provided, and the two end caps are symmetrically arranged at both ends of the connecting rod.

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