Relativistic magnetron with adjustable working mode

Abstract

The invention discloses a relativistic magnetron with an adjustable working mode, and belongs to the technical field of high-power microwaves. The relativistic magnetron comprises a cathode assembly, an anode assembly, an output structure assembly and a tuning assembly, the tuning assembly comprises a tunable short circuit surface, a tuning knob and a telescopic rod. On the basis of the inherent structure of the relativistic magnetron, the position of the short circuit surface in the relativistic magnetron is mechanically adjusted, so that the purpose of switching the working mode and the output signal mode in the resonant cavity is achieved, the problem that the working mode of a traditional relativistic magnetron is single is solved, and multi-frequency-point working of the relativistic magnetron is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-power microwave, and particularly relates to a relativistic magnetron with adjustable operating modes. Background Technique

[0002] The relativistic magnetron is a high-power microwave source designed specifically for generating ultra-high-power electromagnetic waves. It is developed based on the traditional magnetron. By introducing the interaction between the electron beam at relativistic speeds and the high-frequency field, it achieves higher output power and a wider frequency range. The working principle of the relativistic magnetron is to use a cold cathode (field emission cathode) to emit electrons, and then use a strong magnetic field to constrain their movement, so that the electrons interact with the electromagnetic field of the anode resonant cavity, and efficiently convert the kinetic energy of the electron beam into high-power microwaves.

[0003] The relativistic magnetron mainly consists of a cathode, an anode, a strong magnetic field system, an electron injection device, an output coupler, a cooling system, and an insulating support structure, etc. The cathode is usually made of high-temperature resistant materials, which can carry a high current density and emit a high-current electron beam through electric field acceleration. These electrons then move along a spiral trajectory under the action of a strong magnetic field and exchange energy with the high-frequency field in the resonant cavity. In addition, the strong magnetic field system is usually provided by an external electromagnetic coil or a permanent magnet, and its magnetic field intensity is much higher than that of the traditional magnetron to constrain the electron beam at relativistic speeds. The energy extraction structure extracts microwave energy from the resonant cavity through a waveguide or an antenna. The high heat generated during the working process is dissipated through a liquid cooling or air cooling system to ensure the stable operation of the device. The support and insulation structure of the whole device uses high-voltage resistant materials, which not only provide physical support but also meet the electrical insulation requirements of the high-voltage environment. Compared with the traditional magnetron, the relativistic magnetron has the characteristics of higher output power and stronger mode conversion ability, and is one of the important devices in modern high-power microwave technology, representing the forefront direction of microwave electron technology.

[0004] The relativistic magnetron faces some technical bottlenecks in the development process, and these challenges limit its further application and performance improvement in the high-power microwave field. The relativistic magnetron can flexibly adjust the output mode and operating frequency, so that characteristics such as the spatial distribution of power density can more effectively meet the application requirements in different scenarios. Therefore, how to achieve the adjustment of the operating mode of the relativistic magnetron has become one of the key research topics at present.

[0005] In recent years, relativistic magnetrons have been widely used in fields such as radar, directed energy research, and particle accelerators. In 2010, the team led by Edl Schamiloglu at the University of New Mexico in the United States carried out research on frequency tuning and mode switching of high-power relativistic magnetrons using injection locking technology, and the research results were published in Applied Physics Letters (DOI: 10.1063 / 1.3529463). In 2012, the team led by Li Wei at the National University of Defense Technology of the Chinese People's Liberation Army achieved a change in the resonant frequency of a relativistic magnetron by introducing an electrolyte material inside the resonant cavity, and the relevant results were published in Applied Physics Letters (DOI: 10.1063 / 1.4768691). In 2022, the team led by Liu Meiqin at Xi'an Jiaotong University in China proposed to control the anode blade opening angle of a relativistic magnetron, which can achieve tuning and mode conversion of a 24-cavity relativistic magnetron (patent application number: 202210289099.6). The above research has laid a foundation for the mode transformation of relativistic magnetrons.

[0006] The current mode conversion methods mainly focus on injection locking, dielectric filling, and voltage and magnetic field regulation. However, the injection locking method requires additional equipment such as a microwave source and a circulator, increasing the system complexity and cost. The method of filling the dielectric is likely to lose its effect in GW-level high-power application scenarios, resulting in the inability to complete normal tuning and conversion work. The method of adjusting voltage and magnetic field places higher requirements on the entire system, causing a sharp increase in the implementation difficulty.

[0007] In different application scenarios, people have different requirements for frequency and waveform. The switching of the resonant cavity working mode and the output signal mode can enable the magnetron to operate at multiple frequency points, meeting the requirements for search, tracking, imaging, etc. Therefore, the ability of the magnetron to change frequency and working mode helps to enhance its ability to cope with complex electromagnetic environments. Summary of the Invention

[0008] In order to overcome the above technical deficiencies and meet the requirements of people in different application scenarios, based on the inherent structure of a relativistic magnetron, the present invention provides a relativistic magnetron with adjustable working modes. By changing the position of the short-circuit plane inside the relativistic magnetron, the working mode of the relativistic magnetron is changed, and then the purpose of regulating the working frequency and output mode is achieved. The present invention solves the problem of the single working mode of traditional relativistic magnetrons and realizes the multi-frequency point operation of magnetrons.

[0009] The technical solution adopted by the present invention is as follows:

[0010] A relativistic magnetron with adjustable working modes, comprising: a cathode assembly, an anode assembly, an output structure assembly, and a tuning assembly;

[0011] The cathode assembly includes a cathode impedance matching structure, a cathode connecting rod, an upper cathode end cap, a cathode electron emission section, and a lower cathode end cap, which are arranged axially from left to right in sequence;

[0012] The anode assembly includes a cylindrical outer shell, an anode cylinder, and 2N sector-shaped anode vanes;

[0013] The output structure assembly includes 2N coupling slots, N sector-shaped inserts, and a mode conversion output structure;

[0014] The tuning assembly includes an adjustable short circuit surface, a tuning knob, and a telescopic rod;

[0015] The cathode assembly is coaxially arranged inside the cylindrical outer shell, and the cathode electron emission section extends into the anode cylinder;

[0016] The anode cylinder is coaxially arranged inside the cylindrical outer shell; 2N sector-shaped anode vanes are evenly distributed along the circumference on the inner wall of the anode cylinder, and a sector-shaped resonant cavity is formed between adjacent sector-shaped anode vanes, and both ends of the sector-shaped resonant cavity are closed.

[0017] N of the sector-shaped inserts are evenly distributed between the cylindrical outer shell and the anode cylinder, dividing the annular cavity into N sector-shaped waveguide cavities;

[0018] The 2N coupling slots are arranged on the anode cylinder. The coupling slots correspond to the sector-shaped resonant cavities one by one, and the microwave energy in two sector-shaped resonant cavities is radially coupled to one sector-shaped waveguide cavity through the coupling slots, and then output after mode conversion through the mode conversion output structure;

[0019] The tuning knob is located outside the cylindrical outer shell and is connected to the adjustable short circuit surface through the telescopic rod; the adjustable short circuit surface is an annular baffle arranged between the cylindrical outer shell and the anode cylinder and close to the upper cathode end cap side. By adjusting the length of the telescopic rod with the tuning knob, the adjustable short circuit surface moves left and right along the axis, thereby changing the distance between the adjustable short circuit surface and the center point of the coupling slot, and further changing the output working mode of the relativistic magnetron.

[0020] Further, the value of N is 3, 4, or 5.

[0021] Further, the distance range between the adjustable short circuit surface and the center point of the coupling slot is 60 mm to 120 mm.

[0022] Further, the telescopic rod adopts a three-stage telescopic structure, and the advantage is that it can make the most of the adjustable space inside the magnetron.

[0023] Furthermore, a sealing component is provided between the telescopic rod and the cylindrical outer shell to ensure the vacuum degree inside the relativistic magnetron. Furthermore, the mode conversion output structure includes an inner conductor and an outer conductor arranged coaxially; the outer conductor is an axial extension of the cylindrical outer shell; the left end of the inner conductor is connected to the anode cylinder, and a cavity is provided at the connection to accommodate the lower cathode end cap, prevent electron overflow, and reduce the weight of the inner conductor.

[0024] Furthermore, the mode conversion output structure includes a first transition section, a second coaxial section, a third coaxial section, and a fourth circular waveguide section from left to right; among them, in the first transition section, the width of the sector insert decreases linearly, so that N sector waveguides TE 11 mode is converted into a coaxial TEM mode and input to the second coaxial section; the second coaxial section transmits the TEM mode to the third coaxial section; in the third coaxial section, the radius of the inner conductor gradually decreases, and the TEM mode is converted into a circular waveguide TM 01 mode or TE 11 mode and is output through the fourth circular waveguide section.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] In the present invention, by mechanically adjusting the position of the short-circuit plane through the tuning component, it is equivalent to changing the geometric dimensions of the resonant cavity (sector waveguide cavity), that is, changing the field distribution in the resonant cavity (sector waveguide cavity), and the resonance condition also changes accordingly, so that the relativistic magnetron can operate at different frequencies and different modes, and the output power does not fluctuate significantly. The present invention greatly enhances the mode control ability of the relativistic magnetron and meets the demand for flexible frequency switching in different application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a 3D structure schematic diagram of the relativistic magnetron in an embodiment of the present invention;

[0028] Figure 2 is a multi-angle schematic diagram of the 3D structure of the relativistic magnetron in an embodiment of the present invention;

[0029] Figure 3 is a cross-sectional annotation diagram of the y-z plane of the relativistic magnetron in an embodiment of the present invention;

[0030] Figure 4 is a cross-sectional annotation diagram of the x-y plane of the relativistic magnetron in an embodiment of the present invention;

[0031] Figure 5 is a field distribution diagram in the resonant cavity of the relativistic magnetron when the output mode is TM 01 mode in an embodiment of the present invention;

[0032] Figure 6 In the embodiment of the present invention, when the output mode is TM 01 mode, the output time-domain signal diagram of the relativistic magnetron;

[0033] Figure 7 In the embodiment of the present invention, when the output mode is TM 01 mode, the anode current curve of the relativistic magnetron;

[0034] Figure 8 In the embodiment of the present invention, when the output mode is TM 01 mode, the phase space diagram of the relativistic magnetron;

[0035] Figure 9 In the embodiment of the present invention, when the output mode is TM 01 mode, the normalized spectrum diagram of the relativistic magnetron;

[0036] Figure 10 In the embodiment of the present invention, the field distribution diagram of the relativistic magnetron when the output port mode is TM 01 mode;

[0037] Figure 11 In the embodiment of the present invention, when the output mode is TE 11 mode, the field distribution diagram in the resonant cavity of the relativistic magnetron;

[0038] Figure 12 In the embodiment of the present invention, when the output mode is TE 11 mode, the output signal diagram of the relativistic magnetron;

[0039] Figure 13 In the embodiment of the present invention, when the output mode is TE 11 mode, the anode current curve of the relativistic magnetron;

[0040] Figure 14 In the embodiment of the present invention, when the output mode is TE 11 mode, the normalized spectrum diagram of the relativistic magnetron;

[0041] Figure 15 In the embodiment of the present invention, the field distribution diagram of the relativistic magnetron when the output port mode is TE 11 mode.

[0042] Description of the attached reference numerals: 11. Cathode impedance matching structure, 12. Cathode connecting rod, 13. Upper cathode end cap, 14. Cathode electron emission section, 15. Lower cathode end cap; 21. Cylindrical outer shell, 22. Anode cylinder, 23. Sector anode blade; 31. Coupling slot, 32. Sector insert, 33. First transition section, 34. Second coaxial section, 35. Third coaxial section, 36. Fourth circular waveguide section; 41. Tunable short circuit surface, 42. Telescopic rod, 43. Tuning knob. Detailed implementation

[0043] In order to more clearly illustrate the purpose, features and advantages of the present invention, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0044] This embodiment provides a relativistic magnetron with adjustable operating modes, with an operating voltage of 245 kV and an axial magnetic field of 0.25 T. As Figure 1-4 shown, the relativistic magnetron includes: a cathode assembly, an anode assembly, an output structure assembly, and a tuning assembly.

[0045] The cathode assembly includes a cathode impedance matching structure, a cathode connecting rod, an upper cathode end cap, a cathode electron emission section, and a lower cathode end cap arranged axially from left to right in sequence. Among them, the radius of the cathode impedance matching structure is 100 mm, and the axial length is 197 mm; the radius R2 of the upper and lower cathode end caps is 42.5 mm, and the axial length is 19 mm; the radius R1 of the cathode connecting rod is 24 mm, and the axial length is 271 mm; the inner radius R1 of the cathode electron emission section is 24 mm, and the axial length is 203 mm; the upper and lower cathode end caps are symmetrically arranged at both ends of the electron emission section to suppress more electrons from escaping from the interaction region and improve the energy conversion efficiency of the high-frequency system to a certain extent.

[0046] The anode assembly includes a cylindrical outer shell, an anode cylinder, and 8 sector anode blades.

[0047] The output structure assembly includes 8 coupling slots, 4 sector inserts, and a mode conversion output structure.

[0048] The tuning assembly includes a tunable short circuit surface, a tuning knob, and a three-section telescopic rod.

[0049] The cathode assembly is coaxially arranged inside the cylindrical outer shell, and the cathode electron emission section extends into the anode cylinder.

[0050] The anode cylinder is coaxially arranged inside the cylindrical shell. Eight sector-shaped anode vanes are evenly distributed along the circumference on the inner wall of the anode cylinder. The space between adjacent sector-shaped anode vanes forms a sector-shaped resonant cavity, and both ends of the sector-shaped resonant cavity are closed. Among them, the inner radius R5 of the cylindrical shell is 182 mm, the inner radius R3 of the anode cylinder is 93.5 mm, the outer radius R4 is 100 mm, the inner radius R2 of the sector-shaped anode vane is 42.5 mm, the leaf gap ratio μ = 2, and the axial length of the sector-shaped anode vane and the anode cylinder is 100 mm.

[0051] Four sector-shaped inserts are evenly distributed between the cylindrical shell and the anode cylinder, dividing the annular cavity into four sector-shaped waveguide cavities with a central angle of 65°. The axial length of the sector-shaped insert is 230 mm, and the distance between the left end face and the left end face of the anode cylinder is 60 mm, which is used to place the tunable short circuit surface.

[0052] Eight coupling slots are arranged on the anode cylinder. The coupling slots correspond to the sector-shaped resonant cavities one by one, and the microwave energy in two sector-shaped resonant cavities is radially coupled to one sector-shaped waveguide cavity through the coupling slots and synthesized into the sector-shaped waveguide TE 11 mode, and then output after the mode is converted by the mode conversion output structure; the axial length of the coupling slot is 100 mm and the width is 16 mm.

[0053] The mode conversion output structure includes an inner conductor and an outer conductor arranged coaxially. The outer conductor is the axial extension of the cylindrical shell; the left end of the inner conductor is connected to the anode cylinder, and a cavity is provided at the connection to accommodate the lower cathode end cap, prevent electron overflow and reduce the weight of the inner conductor.

[0054] The mode conversion output structure is successively the first transition section, the second coaxial section, the third coaxial section, and the fourth circular waveguide section from left to right, with lengths L1 = 70 mm, L2 = 279 mm, L3 = 350 mm, and L4 = 200 mm respectively; among them, in the first transition section, the width of the sector-shaped insert decreases linearly, that is, the right side of the sector-shaped insert is a wedge-shaped structure, so that the four sector-shaped waveguide TE 11 mode is converted into a coaxial TEM mode and input to the second coaxial section; the radii of the inner and outer conductors in the second coaxial section remain unchanged, and the TEM mode is transmitted to the third coaxial section; in the third coaxial section, the radius of the inner conductor gradually decreases to 40 mm, and the TEM mode is converted into a circular waveguide TM 01 mode or TE 11 mode and output through the fourth circular waveguide section.

[0055] The tuning knob is located outside the cylindrical housing and is connected to the tunable short - circuit plane through a three - section telescopic rod; the tunable short - circuit plane is an annular baffle located between the cylindrical housing and the anode cylinder on the left side, with an inner radius of 100 mm, an outer radius of 182 mm, and a thickness of 20 mm. By adjusting the length of the telescopic rod with the tuning knob, the tunable short - circuit plane can be moved left and right along the axis, thereby changing the distance between the tunable short - circuit plane and the center point of the coupling gap, and further changing the output operating mode of the relativistic magnetron. In this embodiment, the adjustable range of the distance between the tunable short - circuit plane and the center point of the coupling gap is 60 mm to 120 mm.

[0056] A sealing component is provided between the telescopic rod and the cylindrical housing to ensure the vacuum degree inside the relativistic magnetron.

[0057] When the distance between the tunable short - circuit plane and the center point of the coupling gap is adjusted to 80 to 120 mm, as Figure 5 shown, the resonant - cavity field distribution can determine that the magnetron operates in the π mode. Among them, when the distance between the tunable short - circuit plane and the center point of the coupling gap is 100 mm, the operating stability of the relativistic magnetron is the highest. As Figure 6 shown, in this embodiment, the output power of the relativistic magnetron in the π mode is higher than 300 MW. As Figure 7 shown, the anode - collision current is about 2800 A. From Figure 8 the phase - space diagram, a 4 - corner star - shaped spoke can be clearly seen. As Figure 9 shown, the normalized spectrum of the relativistic magnetron is shown, and the operating frequency of the magnetron is 0.976 GHz. As Figure 10 shown, the field mode at the output port of the relativistic magnetron operating in the π mode is TM 01 mode.

[0058] At the same time, when changing the position of the short - circuit plane and adjusting the distance between the tunable short - circuit plane and the center point of the coupling gap to 60 to 80 mm, as Figure 11 shown, the resonant - cavity field distribution can determine that the magnetron operating mode switches to the 3π / 4 mode. Among them, when the distance between the tunable short - circuit plane and the center point of the coupling gap is 70 mm, the operating stability of the relativistic magnetron is the highest. As Figure 12 shown, the output power of the relativistic magnetron in the 3π / 4 mode is higher than 200 MW. As Figure 13 shown, the anode - collision current is about 3850 A. As Figure 14 shown, the operating frequency of the relativistic magnetron becomes 1.001 GHz. As Figure 15 shown, the field mode at the output port of the relativistic magnetron operating in the 3π / 4 mode is TE 11 mode.

[0059] By mechanically regulating the distance between the short circuit surface and the center of the coupling slot, the present invention can switch the working mode in the relativistic magnetron resonant cavity and the output signal mode, and can also change the operating frequency of the magnetron. The technical solution of the present invention can flexibly switch the working mode of the relativistic magnetron resonant cavity, realize the mode transformation of the output signal of the relativistic magnetron and the multi-frequency operation of the magnetron. At the same time, the structural modification is small, it is easy to implement, and it has certain engineering practical value.

Claims

1. A relativistic magnetron with adjustable working mode, characterized in that: include: Cathode assembly, anode assembly, output structure assembly, tuning assembly; The cathode assembly includes a cathode impedance matching structure, a cathode connecting rod, an upper cathode end cap, a cathode electron emission section, and a lower cathode end cap, which are arranged in sequence from left to right along the axial direction; The anode assembly includes a cylindrical shell, an anode cylinder, and 2N fan-shaped anode blades; The output structure assembly includes 2N coupling slots, N fan-shaped inserts, and a mode conversion output structure; The tuning assembly includes an adjustable short circuit path, a tuning knob, and a telescopic rod; The cathode assembly is coaxially arranged inside the cylindrical shell, and the cathode electron emission section extends into the anode cylinder; The anode cylinder is coaxially arranged inside the cylindrical shell; 2N fan-shaped anode blades are evenly distributed along the circumference on the inner wall of the anode cylinder, and a fan-shaped resonant cavity is formed between adjacent fan-shaped anode blades, and both ends of the fan-shaped resonant cavity are closed; N sector-shaped inserts are evenly distributed between the cylindrical shell and the anode cylinder, dividing the annular cavity into N sector-shaped waveguide cavities; 2N coupling slots are provided on the anode cylinder, the coupling slots correspond to the fan-shaped resonant cavities one by one, and the microwave energy in the two fan-shaped resonant cavities is radially coupled to a fan-shaped waveguide cavity through the coupling slots, and then converted into a mode by the mode conversion output structure before being output; The tuning knob is located outside the cylindrical shell and is connected to the tunable short-circuit board via the telescopic rod. The tunable short-circuit board is an annular baffle arranged between the cylindrical shell and the anode cylinder and close to the side of the upper cathode end cap. The length of the telescopic rod is adjusted by the tuning knob to move the tunable short-circuit board left and right along the axis, thereby changing the distance between the tunable short-circuit board and the center point of the coupling gap, and further changing the output working mode of the relativistic magnetron.

2. A relativistic magnetron with adjustable working mode according to claim 1, characterized in that: The value of N is 3, 4, or 5.

3. The relativistic magnetron with adjustable working mode according to claim 2, characterized in that: The distance between the adjustable short-circuit surface and the center point of the coupling gap ranges from 60 mm to 120 mm.

4. The relativistic magnetron with adjustable working mode according to claim 3, characterized in that: A sealing component is provided between the telescopic rod and the cylindrical shell to ensure the vacuum degree inside the relativistic magnetron.

5. The relativistic magnetron with adjustable working mode according to claim 4, characterized in that: The telescopic rod adopts a three-section telescopic structure.

6. A relativistic magnetron with adjustable working mode according to claim 3 or 4, characterized in that: The mode conversion output structure includes a coaxially arranged inner conductor and outer conductor; the outer conductor is an axial extension of the cylindrical shell; the left end of the inner conductor is connected to the anode cylinder, and a cavity is provided at the connection to accommodate the lower cathode end cap, prevent electron overflow and reduce the weight of the inner conductor.

7. The relativistic magnetron with adjustable working mode according to claim 6, characterized in that: The mode conversion output structure is composed of the first transition section, the second coaxial section, the third coaxial section, and the fourth circular waveguide section from left to right. In the first transition section, the width of the fan-shaped insert decreases linearly, so that the N fan-shaped waveguides TE 11 The mode is converted into a coaxial TEM mode and input into the second coaxial segment; the second coaxial segment transmits the TEM mode to the third coaxial segment; in the third coaxial segment, the inner conductor radius gradually decreases, converting the TEM mode into a circular waveguide TM 01 Mode or TE 11 mode and outputted through the fourth circular waveguide segment.

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