Relativistic magnetron and parameter determination method thereof

Abstract

The invention relates to the technical field of microwaves, and discloses a relativistic magnetron and a parameter determination method thereof, so as to improve the power conversion efficiency. The antenna is of a symmetrical structure on the whole and comprises a coaxial input structure, a resonant structure, a transition section structure and an output circular waveguide. The transition section structure is provided with a gradually-changed stepped diffraction extraction cavity protruding outwards on a circular truncated cone with hollow left and right end faces; each gradually-changed stepped diffraction extraction cavity is communicated with one fan-shaped vacuum cavity, and one fan-shaped vacuum cavity is arranged between every two adjacent gradually-changed stepped diffraction extraction cavities; a first outer table-board of the gradient step type diffraction extraction cavity is perpendicular to the outer vertical surface of the fan-shaped vacuum cavity and is positioned on the same plane with the left end surface of the circular truncated cone, a second outer table-board is parallel to the first outer table-board, and the ring surface radius of a connecting part between the first outer table-board and the second outer table-board is increased according to a linear rule from left to right; and an extension part of the fan-shaped vacuum cavity, which protrudes outwards and is not communicated with the gradient stepped diffraction extraction cavity, is arranged on the circular truncated cone.

Description

Technical Field

[0001] The invention relates to the field of microwave technology, and in particular to a relativistic magnetron and a method for determining its parameters. Background Art

[0002] High-power microwaves refer to strong electromagnetic pulses with a peak power exceeding 100MW and operating in the frequency range of 0.3 to 30GHz.

[0003] High-power microwave technology is in rapid development, and the key technologies involved mainly include primary energy technology, pulse drive source technology, high-power microwave generation technology and high-power microwave emission technology. Among them, high-power microwave generation technology is the key technology for converting high-power electrical pulse energy into high-power microwave energy, and is the core part of the entire high-power microwave technology. As one of the mature high-power microwave sources, the relativistic magnetron has the characteristics of simple and compact structure, easy processing, high power conversion efficiency, and reproducible long pulse operation. It has played an increasingly critical role in the field of high-power microwave sources and occupied an increasingly important position.

[0004] The output structure of the relativistic magnetron can be divided into a radial output structure and an axial output structure, which are used to extract and output the high-frequency field energy stored in the resonant cavity. The axial output structure can avoid the problem of high-frequency breakdown at the extraction port in the traditional radial extraction structure, and has a more stable working mode and higher power conversion efficiency. At the same time, different numbers of diffraction extraction cavities can be used to output high-power microwaves of different modes. At present, many scholars have adopted different types of extraction structures to improve the power conversion efficiency of relativistic magnetrons under different working conditions. Summary of the invention

[0005] The present invention aims to disclose a relativistic magnetron and a method for determining its parameters to improve power conversion efficiency.

[0006] To achieve the above-mentioned purpose, the relativistic magnetron disclosed in the present invention has a symmetrical structure as a whole, and includes, from left to right, a coaxial input structure, a resonance structure, a transition section structure and an output circular waveguide that are adjacently connected; the coaxial input structure includes an anode shell and a cathode inner conductor, the cathode inner conductor includes a cylindrical inner core connected to the left cathode cap, and a transmitting rod connected between the left and right cathode caps; the resonance structure includes a fan-shaped anode block and a fan-shaped vacuum cavity; the transition section structure is provided with a gradually stepped diffraction extraction cavity protruding outward on a hollow truncated cone on the left and right end faces; the output circular waveguide is a cylindrical structure with a radius that is consistent with the radius of the lower end face of the truncated cone; each of the gradually stepped diffraction extraction cavities is provided on the truncated cone with a hollow left and right end faces; The cavities are respectively connected with a fan-shaped vacuum cavity, and two adjacent gradient step diffraction extraction cavities are separated by a fan-shaped vacuum cavity, the left end face of the truncated cone is located between the two cathode caps for each of the emission rods to penetrate, and the radius of the right end face is consistent with the inner radius of the fan-shaped vacuum cavity; the first outer table surface of the gradient step diffraction extraction cavity is perpendicular to the outer facade of the fan-shaped vacuum cavity and is located in the same plane as the left end face of the truncated cone, the second outer table surface is parallel to the first outer table surface, the annular radius of the connecting part between the first outer table surface and the second outer table surface increases linearly from left to right, and an extension of the fan-shaped vacuum cavity that protrudes outward and is not connected with the gradient step diffraction extraction cavity is provided on the truncated cone.

[0007] Preferably, the number of the gradient step diffraction extraction cavities is three.

[0008] Preferably, the opening angle of the sector-shaped anode block is 40°, and the opening angle of the sector-shaped vacuum chamber is 20°.

[0009] Preferably, the operating frequency band of the relativistic magnetron is in the S band, corresponding to TE 01 The structural dimensions of the mode are as follows: the length of the coaxial input structure is 55.5mm, the inner radius of the cylindrical anode shell is 42.6mm, the length of the cylindrical inner core is 44mm, and the radius is 10mm; the thickness of the left and right disc-shaped cathode caps is 5mm, and the radius is 18.6mm; the length of each emitting rod is 78mm, and the radius is 1.5mm; in the resonant structure, the length of the fan-shaped anode block and the fan-shaped vacuum cavity is 54.5mm, the inner radius is 22mm, and the outer radius is 42.6mm; the distance between the left and right end surfaces of the hollow truncated cone is 220mm, the radius of the left end surface is 22mm, and the radius of the right end surface is 87mm; the radial height h1 of the first outer table surface in the gradient step diffraction extraction cavity is 15mm, the gradient angle α of the annular surface of the connecting part between the first outer table surface and the second outer table surface is 13.1°, and the radial height h2 of the second outer table surface is 16.8mm; the length of the output circular waveguide is 40mm, and the radius is 87mm.

[0010] To achieve the above-mentioned purpose, the present invention also discloses a method for determining parameters of a relativistic magnetron, which is applied to the relativistic magnetron as described above. When determining the parameters of the gradient step diffraction extraction cavity, a set of initial parameters is first determined. Then, in a simulation platform, with the optimal power conversion efficiency as the goal, the optimal radius difference between the left and right end surfaces of the cone is first found based on the initial parameters of the initial diffraction length, and then the optimal diffraction length is found based on the optimal radius difference; then, the initial gradient length is kept unchanged, and the optimal gradient angle and step height between the first outer table surface and the second outer table surface are found.

[0011] The present invention has the following beneficial effects:

[0012] Based on the unique gradual step diffraction extraction cavity structure and parameter determination method of the present invention, high-efficiency extraction of high-frequency field energy of the resonant cavity can be achieved; the energy in the high-frequency field can be extracted and TE can be radiated. 01 mode microwaves, and avoid TE 11 The polarization direction of the mode is unstable or TE due to uneven processing 31 The present invention improves the power conversion efficiency of the relativistic magnetron under the condition of low magnetic field in the S band, so that it can be applied to high-power microwave system scenarios such as light and small airborne and vehicle-mounted systems.

[0013] The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0015] Figure 1 It is a schematic diagram of the segmented structure of the relativistic magnetron disclosed in the embodiment of the present invention.

[0016] Figure 2 It is a schematic diagram of an axial cross section of a relativistic magnetron disclosed in an embodiment of the present invention.

[0017] Figure 3 It is a cross-sectional schematic diagram of the high-frequency resonance structure disclosed in an embodiment of the present invention.

[0018] Figure 4 It is a two-dimensional schematic diagram of a single gradient step diffraction extraction cavity disclosed in an embodiment of the present invention.

[0019] Figure 5 The embodiment of the present invention discloses that under the condition that the transmission length ls of the diffraction cavity is constant, the output radius r of the diffraction cavity is o Schematic diagram of the relationship with device output parameters.

[0020] Figure 6 is the output radius r of the diffraction cavity disclosed in the embodiment of the present invention o Schematic diagram of the relationship between the diffraction cavity transmission length ls and the device output parameters under certain conditions.

[0021] Figure 7 It is a schematic diagram of simulation results of keeping the gradient length l unchanged and analyzing the influence of the gradient angle α on the output parameters of the magnetron under different values ​​of the first step height h1 of the gradient step transition section disclosed in an embodiment of the present invention.

[0022] Figure 8 It is a schematic diagram of the cross section and electromagnetic field distribution of the transition section structure 3 disclosed in the embodiment of the present invention.

[0023] Fig. 9 It is a schematic diagram of the cross section and electromagnetic field distribution of the circular waveguide output structure 4 disclosed in the embodiment of the present invention.

[0024] Fig.10 It is a schematic diagram of input power simulation results disclosed in an embodiment of the present invention.

[0025] Fig.11 It is a schematic diagram of simulation results of instantaneous output power and average output power disclosed in an embodiment of the present invention.

[0026] Fig.12 It is a schematic diagram of the output microwave power spectrum simulation structure disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0028] Example 1

[0029] This embodiment discloses a relativistic magnetron with a gradient step diffraction structure, such as Figure 1 As shown, the overall structure is symmetrical, and includes, from left to right, a coaxial input structure 1, a resonant structure 2, a transition section structure 3, and an output circular waveguide 4 that are adjacently connected.

[0030] The coaxial input structure comprises an anode shell and a cathode inner conductor, wherein the cathode inner conductor comprises a cylindrical inner core connected to a left cathode cap and an emission rod connected between the left and right cathode caps.

[0031] The resonant structure includes a fan-shaped anode block and a fan-shaped vacuum chamber.

[0032] The transition section structure is provided with a gradually stepped diffraction extraction cavity protruding outward on a hollow truncated cone with left and right end faces; the output circular waveguide is a cylindrical structure with a radius consistent with the radius of the lower end face of the truncated cone; each gradually stepped diffraction extraction cavity is respectively connected to a fan-shaped vacuum cavity, and two adjacent gradually stepped diffraction extraction cavities are separated by a fan-shaped vacuum cavity, the left end face of the truncated cone is located between the two cathode caps for each of the emitting rods to penetrate, and the radius of the right end face is consistent with the inner radius of the fan-shaped vacuum cavity; the first outer table surface of the gradually stepped diffraction extraction cavity is perpendicular to the outer facade of the fan-shaped vacuum cavity and is located in the same plane as the left end face of the truncated cone, the second outer table surface is parallel to the first outer table surface, the annular radius of the connecting part between the first outer table surface and the second outer table surface increases linearly from left to right, and the truncated cone is provided with an extension of the fan-shaped vacuum cavity protruding outward that is not connected to the gradually stepped diffraction extraction cavity.

[0033] A schematic diagram of the axial cross section of a compact relativistic magnetron with high efficiency output in a specific S-band TE01 mode is shown in FIG. Figure 2 As shown, the coaxial input structure 1 includes a cylindrical anode shell 1-1 with a length of 55.5 mm and an inner radius of 42.6 mm and a cathode inner conductor 1-2, wherein the cathode inner conductor 1-2 includes a cylindrical inner core 1-2-1 with a length of 44 mm and a radius of 10 mm, a left disc-shaped cathode cap 1-2-2 with a thickness of 5 mm and a radius of 18.6 mm, three emitting rods 1-2-3 with a length of 78 mm and a radius of 1.5 mm, and a right disc-shaped cathode cap 1-2-4 with a thickness of 5 mm and a radius of 18.6 mm. The cross section of the high-frequency resonant structure is shown in FIG. Figure 3 As shown, the high-frequency resonant structure 2 includes six opening angles θ a =40° sector-shaped anode block 2-1 and six opening angles θ c =20°, the length of the sector-shaped anode block 2-1 and the sector-shaped vacuum cavity 2-2 is 54.5mm, the inner radius is 22mm, and the outer radius is 42.6mm. The transition section structure 3 includes a hollow truncated cone 3-1 and three gradient step-type diffraction extraction cavities 3-2, wherein the distance between the left and right end faces of the hollow truncated cone 3-1 is 220mm, the radius of the left end face is 22mm, and the radius of the right end face is 87mm. The first radial height h1 of the three gradient step-type diffraction extraction cavities 3-2 is 15mm, the gradient angle α=13.1°, and the second radial height h2 is 16.8mm. The three gradient step-type diffraction extraction cavities 3-2 are connected to the sector-shaped vacuum cavity 2-2 in the high-frequency resonance structure 2, and are symmetrically distributed with one sector-shaped vacuum cavity 2-2 between them. The circular band output structure 4 is composed of a cylinder 4-1 with a length of 40mm and a radius of 87mm.

[0034] The two-dimensional schematic diagram of a single gradient step diffraction extraction cavity in this embodiment is shown in FIG. Figure 4As shown, it is mainly composed of the first radial height h1, the gradient angle α, the second radial height h2 and the tilt angle β. Among them, the tilt angle β of the diffraction extraction cavity, the first step height h1, the gradient angle α and the second radial height h2 are important factors for improving the power conversion efficiency of the device. First, the tilt angle β of the diffraction extraction cavity needs to be determined. Since the tilt angle β of the diffraction extraction cavity is related to the diffraction length ls and the output radius r of the diffraction extraction cavity, o Related; Figure 5 It shows that under the condition that the transmission length ls of the diffraction cavity is constant, the output radius r of the diffraction cavity o The relationship between the device output parameters and the output radius is determined by optimizing the output radius through simulation. o =87mm; Figure 6 shows the output radius r of the diffraction cavity o Under certain conditions, the relationship between the diffraction cavity transmission length ls and the device output parameters is optimized by simulation, and the transmission length ls = 220 mm is determined. Therefore, the tilt angle β can be determined to be 21.6°.

[0035] The key structure of this embodiment is the gradual step structure composed of the first radial height h1, the gradual angle α, and the second radial height h2. Keeping the gradual length l unchanged, the influence of the gradual angle α on the output parameters of the magnetron under different values ​​of the first step height h1 of the gradual step transition section is analyzed, as shown in FIG. Figure 7 As shown, from the simulation results, it can be seen that when the gradient length l remains unchanged, as the first step height h1 increases, the gradient angle α required for the device to achieve the optimal conversion efficiency becomes smaller; when the device reaches the optimal conversion efficiency, the first step height h1 of the gradient step transition section is 15 mm, the gradient angle α is 13.1°, and the second step height h2 is 16.8 mm.

[0036] In this embodiment, the gradient step diffraction extraction cavity 3-2-1, the gradient step diffraction extraction cavity 3-2-2 and the gradient step diffraction extraction cavity 3-2-3 are respectively distributed at 120° intervals to extract high-frequency field energy. The cross-section and electromagnetic field distribution of the transition section structure 3 are as follows: Figure 8 As shown, the cross section and electromagnetic field distribution of the circular waveguide output structure 4 are as follows Fig. 9 It can be found that the microwave energy in the transition section structure 3 is gradually converted into the TE in the circular waveguide output structure 4. 01 mold.

[0037] According to the above structure, the full electromagnetic particle simulation calculation is performed, which shows that the output power of the relativistic magnetron of this embodiment is 218MW under the conditions of working voltage 220kV and magnetic field 0.25T, the power conversion efficiency is 71%, the working frequency is 2.375GHz, and the output mode is TE 01The model is relatively pure, among which the input power simulation results are as follows Fig.10 As shown, the simulation results of instantaneous output power and average output power are shown in Fig.11 The output microwave power spectrum simulation results are shown as Fig.12 shown.

[0038] Example 2

[0039] Corresponding to the above-mentioned embodiment, the present embodiment discloses a method for determining parameters of a relativistic magnetron, which is applied to the relativistic magnetron as described in the above-mentioned embodiment. When determining the parameters of the gradient step diffraction extraction cavity, a set of initial parameters is first determined. Then, in a simulation platform, with the optimal power conversion efficiency as the goal, the optimal radius difference between the left and right end surfaces of the cone is first found based on the initial parameters of the initial diffraction length, and then the optimal diffraction length is found based on the optimal radius difference; then, the initial gradient length is kept unchanged, and the optimal gradient angle and step height between the first outer table surface and the second outer table surface are found.

[0040] In summary, the relativistic magnetron and its parameter determination method disclosed in the embodiments of the present invention can realize the high-efficiency extraction of high-frequency field energy of the resonant cavity based on the unique gradual step diffraction extraction cavity structure and parameter determination method of the present invention; it can extract the energy in the high-frequency field and radiate TE 01 mode microwaves, and avoid TE 11 The polarization direction of the mode is unstable or TE due to uneven processing 31 The present invention improves the power conversion efficiency of the relativistic magnetron under the condition of low magnetic field in the S band, so that it can be applied to high-power microwave system scenarios such as light and small airborne and vehicle-mounted systems.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A relativistic magnetron, characterized in that: The overall structure is symmetrical, and from left to right, it includes adjacently connected coaxial input structure, resonance structure, transition section structure and output circular waveguide in sequence; the coaxial input structure includes an anode shell and a cathode inner conductor, the cathode inner conductor includes a cylindrical inner core connected to the left cathode cap, and a transmitting rod connected between the left and right cathode caps; the resonance structure includes a fan-shaped anode block and a fan-shaped vacuum cavity; the transition section structure is provided with a gradient step-type diffraction extraction cavity protruding outward on a hollow truncated cone on the left and right end faces; the output circular waveguide is a cylindrical structure with a radius consistent with the radius of the lower end face of the truncated cone; each of the gradient step-type diffraction extraction cavities is respectively connected to a fan-shaped vacuum cavity. The cavities are interconnected, and there is a fan-shaped vacuum cavity between two adjacent gradient step diffraction extraction cavities, the left end face of the truncated cone is located between the two cathode caps for each of the emission rods to penetrate, and the radius of the right end face is consistent with the inner radius of the fan-shaped vacuum cavity; the first outer table surface of the gradient step diffraction extraction cavity is perpendicular to the outer facade of the fan-shaped vacuum cavity and is located in the same plane as the left end face of the truncated cone, the second outer table surface is parallel to the first outer table surface, the annular radius of the connecting part between the first outer table surface and the second outer table surface increases linearly from left to right, and an extension of the fan-shaped vacuum cavity that protrudes outward and is not connected to the gradient step diffraction extraction cavity is provided on the truncated cone.

2. The relativistic magnetron according to claim 1, characterized in that: The number of the gradient step diffraction extraction cavities is three.

3. The relativistic magnetron according to claim 2, characterized in that: The opening angle of the sector-shaped anode block is 40°, and the opening angle of the sector-shaped vacuum chamber is 20°.

4. The relativistic magnetron according to any one of claims 1 to 3, characterized in that: The operating frequency band of the relativistic magnetron is in the S band, corresponding to TE 01 The structural dimensions of the modes are: The length of the coaxial input structure is 55.5mm, the inner radius of the cylindrical anode shell is 42.6mm, the length of the cylindrical inner core is 44mm, and the radius is 10mm; the thickness of the left and right disc-shaped cathode caps is 5mm, and the radius is 18.6mm; the length of each emission rod is 78mm, and the radius is 1.5mm; In the resonant structure, the length of the fan-shaped anode block and the fan-shaped vacuum chamber is 54.5 mm, the inner radius is 22 mm, and the outer radius is 42.6 mm; The distance between the left and right end surfaces of the hollow truncated cone is 220 mm, the radius of the left end surface is 22 mm, the radius of the right end surface is 87 mm, the radial height h1 of the first outer table surface in the gradient step diffraction extraction cavity is 15 mm, the gradient angle α of the annular surface of the connecting part between the first outer table surface and the second outer table surface is 13.1°, and the radial height h2 of the second outer table surface is 16.8 mm; The length of the output circular waveguide is 40 mm and the radius is 87 mm.

5. A method for determining parameters of a relativistic magnetron, applied to the relativistic magnetron as claimed in any one of claims 1 to 4, characterized in that: When determining the parameters of the gradient step diffraction extraction cavity, a set of initial parameters is first determined. Then, in the simulation platform, with the optimal power conversion efficiency as the goal, the optimal radius difference between the left and right end surfaces of the cone is first found based on the initial parameters of the initial diffraction length, and then the optimal diffraction length is found based on the optimal radius difference; then, the initial gradient length is kept unchanged, and the optimal gradient angle and step height between the first outer table surface and the second outer table surface are found.

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