A P-band full-cavity extraction relativistic magnetron

Abstract

The present invention discloses a P-band full-cavity extraction relativistic magnetron, which belongs to the field of high-power microwave technology. It includes a vacuum chamber, an anode, an axial extraction structure, and a cathode arranged inside the anode, which are connected in sequence along the axial direction; wherein the anode includes an anode shell, N large fan-shaped anode blades and N small fan-shaped anode blades, and there is a fan-shaped gap between the outer side of the small fan-shaped anode blades and the anode shell; the axial extraction structure includes a mode conversion section and a coaxial output section. The present invention proposes a P-band full-cavity extraction relativistic magnetron, which reduces the guide magnetic field compared to the relativistic backward wave tube; improves the energy conversion efficiency compared to the magnetic isolation line oscillator; and reduces the radial size and improves the compactness of the system compared to the relativistic magnetron with a traditional full-cavity extraction structure. Therefore, the full-cavity extraction relativistic magnetron of the present invention takes into account compactness, low magnetic field, and high efficiency while ensuring fundamental mode output.

Description

Technical Field

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

[0002] Relativistic magnetrons are a highly competitive high-power microwave source due to their compactness, low guidance magnetic field, and high conversion efficiency. With growing military and industrial needs, P-band (0.3-1 GHz) high-power microwaves have broad application prospects. However, research on relativistic magnetrons has primarily focused on the L, S, and C bands, and no reports on P-band relativistic magnetrons have been seen to date. This is primarily due to the large resonant system and output structure of P-band relativistic magnetrons, limiting their practical application. In recent years, scholars both domestically and internationally have proposed several P-band high-power microwave sources, but these have struggled to balance conversion efficiency and miniaturization.

[0003] In 2012, the National University of Defense Technology proposed a P-band compact coaxial backward wave oscillator, which reduced the axial size of the system by using three periodic slow wave structures with both inner and outer conductor corrugations [Liang Gao, Bao-Liang Qian, Xing-Jun Ge, Xiao-Ping Zhang, Zhen-Xing Jin; Experimental study of a compact P-band coaxial relativistic backward wave oscillator with three periods slow wave structure. Phys. Plasmas 1 August 2012; 19(8): 083113. https: / / doi.org / 10.1063 / 1.4748564]. The device operates at a frequency of 897MHz. Under the conditions of a diode voltage of 572kV and an axial guide magnetic field of 0.86T, it obtains a microwave radiation power of 1.47GW with an output efficiency of 32%. Under the conditions of a diode voltage of 997kV and an axial guide magnetic field of 1.2T, it obtains a microwave radiation power of 3.14GW, and the axial length of the device is 384mm.

[0004] In 2017, the National University of Defense Technology proposed another high-power microwave source feasible in the P-band: a magnetically isolated line oscillator. By tilting the blades of the slow-wave structure at a certain angle, the device's volume and weight were greatly reduced [Xiaoping Zhang, Fangchao Dang, Yangmei Li, Zhenxing Jin; Proposal of a novel compact P-band magnetically insulated transmission line oscillator with inclined vanes. Phys. Plasmas 1 June 2015; 22(6):063304. https: / / doi.org / 10.1063 / 1.4922897]. The device operates at a frequency of 645 MHz and achieves an output power of 4.7 GW at 700 kV, with an energy conversion efficiency of 14.9%. The device has a diameter of 240 mm.

[0005] Looking at the existing P-band high-power microwave sources, although new technologies have been used to reduce the size of devices and improve the overall compactness of the system, it is difficult to strike a balance between low guide magnetic field and high conversion efficiency. Relativistic magnetrons have the advantage of high conversion efficiency under low magnetic field conditions. Therefore, it is very necessary to design a compact and efficient relativistic magnetron in the P-band. Summary of the Invention

[0006] In view of the deficiency of the existing technology that it is difficult to achieve both low guide magnetic field and high conversion efficiency, the present invention provides a P-band full-cavity extraction relativistic magnetron.

[0007] The technical solution adopted in the present invention is:

[0008] A P-band full-cavity extraction relativistic magnetron, comprising a vacuum chamber, an anode, a cathode, and an axial extraction structure;

[0009] The anode is characterized in that: the anode includes a cylindrical anode shell, N large fan-shaped anode blades and N small fan-shaped anode blades located inside the anode shell and staggered along the circumference; wherein the inner radius of the large fan-shaped anode blade is the same as the inner radius of the small fan-shaped anode blade, the outer side surface of the large fan-shaped anode blade is in contact with the inner wall of the anode shell, and a fan-shaped gap is present between the outer side surface of the small fan-shaped anode blade and the anode shell; the fan-shaped cavity between the large fan-shaped anode blade and the small fan-shaped anode blade is a resonant cavity, and the fan-shaped gap between the small fan-shaped anode blade and the anode shell is a fan-shaped waveguide cavity;

[0010] The vacuum chamber comprises a vacuum chamber shell, one end of which is connected to the anode, and the other end of which is connected to the front-stage accelerator;

[0011] The cathode is arranged inside the anode housing and is coaxial with the anode housing;

[0012] The axial extraction structure includes a mode conversion section and a coaxial output section; wherein the mode conversion section includes a conversion section shell, a downstream annular baffle, and a conversion section inner conductor; the coaxial output section includes an output section shell and an output section inner conductor; the conversion section shell and the output section shell are axial extensions of the anode shell, and the inner radii of the three are the same; the conversion section inner conductor is a hollow frustum-shaped shell, the end with a larger radius of which is connected to the end face of the fan-shaped anode blade, and the outer radius is the same as the outer radius of the small fan-shaped anode blade; the downstream annular baffle is located at the end with a larger radius of the conversion section inner conductor, and is connected to the downstream end face of the fan-shaped anode blade, the inner radius of the downstream annular baffle is the same as the inner radius of the fan-shaped anode blade, and the outer side surface is connected to the conversion section inner conductor; the output section inner conductor is a cylindrical shell with one end closed, and the open end is connected to the conversion section inner conductor, and the inner and outer radii of the connection are the same.

[0013] Furthermore, the vacuum chamber shell includes a small cylindrical shell, an annular end cover, a large cylindrical shell, an upstream annular baffle, and a vacuum chamber annular baffle located in the axial middle position of the large cylindrical shell, which are coaxial and arranged in sequence; wherein the internal cavities of the small cylindrical shell, the annular end cover, and the large cylindrical shell are stepped cylindrical cavities; the other end of the small cylindrical shell is connected to the front-stage accelerator; the end face of the upstream annular baffle is connected to the upstream end face of the fan-shaped anode blade; the outer side surface of the upstream annular baffle is connected to the anode shell, and the inner radius is smaller than the outer radius of the small fan-shaped anode blade and larger than the inner radius of the small fan-shaped anode blade.

[0014] Furthermore, the inner radius of the output section housing is 0.135λ-0.157λ, and the outer radius of the inner conductor of the output section is 0.09λ-0.104λ.

[0015] Furthermore, the axial length of the mode conversion section is 0.03λ-0.14λ.

[0016] Furthermore, the small sector-shaped anode blades are fixed to the upstream annular baffle by screws.

[0017] Furthermore, the cathode is a transparent cathode, comprising a cathode support rod, several transparent cathode rods, and a downstream cathode end cap connected in sequence; wherein the other end of the cathode support rod is connected to the front-stage accelerator; the several transparent cathode rods are evenly distributed along the circumference; and the downstream end cap extends into the conductor in the conversion section.

[0018] Furthermore, the downstream end cap is in a stepped cylindrical shape.

[0019] The working process of the present invention is as follows: a high-voltage pulse from a diode accelerator enters a resonant cavity through a vacuum chamber, where an electron beam is emitted from the cathode. When the electron beam velocity matches the phase velocity of the electromagnetic wave, the electron beam begins to convert kinetic energy into high-frequency field energy. The π-mode field excited in the resonant cavity is coupled into the fan-shaped waveguide cavity between the small fan-shaped anode blades and the anode shell. Because the phases of the two adjacent resonant cavities differ by 180°, the angular components of the electric field in the fan-shaped waveguide cavity are canceled out, leaving only the radial component. TE with the same amplitude and phase is simultaneously excited in the three fan-shaped waveguide cavities. 11 mode, and propagates axially into the axial extraction structure; TE 11 The mode is converted into TEM mode through the mode conversion section and finally output through the coaxial output section.

[0020] Compared with the existing technology, the beneficial results of the present invention are:

[0021] This invention proposes a P-band full-cavity extraction relativistic magnetron. Compared to a relativistic backward wave tube, it reduces the guide magnetic field; compared to a magnetically isolated line oscillator, it improves energy conversion efficiency; and compared to traditional full-cavity extraction relativistic magnetrons, it reduces radial dimensions and improves system compactness. Therefore, the full-cavity extraction relativistic magnetron of this invention achieves compactness, low magnetic field, and high efficiency while maintaining fundamental mode output. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the overall structure of the embodiment;

[0023] Figure 2 This is a cross-sectional view of the overall structure of the embodiment along the axial direction;

[0024] Figure 3 Schematic diagram of the resonance system structure of the embodiment;

[0025] Figure 4 is a cross-sectional view of a resonant system according to an embodiment;

[0026] Figure 5 is a cross-sectional view of the axial extraction structure of the embodiment along the axial direction;

[0027] Figure 6 This is the electric field distribution diagram when the embodiment is in π mode operation;

[0028] Figure 7 This is a diagram of microwave power output when driven by a 690 kV diode voltage and a 0.38 T axial magnetic field.

[0029] Explanation of the accompanying drawings: 11. Small cylindrical shell, 12. Annular end cover, 13. Large cylindrical shell, 14. Upstream annular baffle, 15. Vacuum chamber annular baffle, 21. Anode shell, 22. Large fan-shaped anode blade, 23. Small fan-shaped anode blade, 24. Resonant cavity, 25. Fan-shaped waveguide cavity, 31. Cathode support rod, 32. Transparent cathode rod, 33. Downstream end cap, 41. Conversion section shell, 42. Downstream annular baffle, 43. Conversion section inner conductor, 44. Output section shell, 45. Output section inner conductor. DETAILED DESCRIPTION

[0030] In order to better illustrate the purpose, advantages and technical ideas of the present invention, the technical solutions of the present invention are further described below with reference to the accompanying drawings and specific examples. It should be noted that the specific examples given below are only used to illustrate the present invention, and the scope of protection of the present invention is not limited to the following.

[0031] A P-band full-cavity extraction relativistic magnetron of this embodiment, such as Figures 1-4 As shown, it includes a vacuum chamber, an anode, a cathode, and an axial extraction structure.

[0032] The vacuum chamber includes a vacuum chamber shell; the vacuum chamber shell includes a small cylindrical shell, an annular end cover, a large cylindrical shell, an upstream annular baffle, and a vacuum chamber annular baffle located in the axial middle of the large cylindrical shell, which are coaxial and arranged in sequence; wherein the internal cavities of the small cylindrical shell, the annular end cover, and the large cylindrical shell are stepped cylindrical cavities; the other end of the small cylindrical shell is connected to the front-stage accelerator; the end face of the upstream annular baffle is connected to the upstream end face of the fan-shaped anode blade; the outer side face of the upstream annular baffle is connected to the anode shell, and the inner radius is 83.5 mm.

[0033] The anode comprises a cylindrical anode shell, three large sector-shaped anode blades and three small sector-shaped anode blades located inside the anode shell and staggered along the circumference period; wherein the inner radius of the anode shell is R s =138mm; the inner radius of the fan-shaped anode blade is R a =83.5mm; the outer side of the large sector-shaped anode blade is in contact with the inner wall of the anode shell, and the outer radius of the small sector-shaped anode blade is R b =112mm, the small fan-shaped anode blade is fixed to the upstream circular baffle by screws; the fan-shaped cavity between the large fan-shaped anode blade and the small fan-shaped anode blade is a resonant cavity with a central angle of θ=20°, and the fan-shaped gap between the small fan-shaped anode blade and the anode shell is a fan-shaped waveguide cavity.

[0034] The cathode is a transparent cathode disposed inside the anode housing and coaxial with the anode housing, comprising a cathode support rod, three fan-shaped transparent cathode rods, and a downstream end cap connected in sequence; wherein the other end of the cathode support rod is connected to the front accelerator; the three transparent cathode cylinders are evenly distributed along the circumference, and the distance from the central axis is R c =49mm; the downstream end cap is a stepped cylindrical shape and extends into the conductor in the transition section.

[0035] The axial extraction structure includes a mode conversion section and a coaxial output section; wherein the mode conversion section includes a conversion section shell, a downstream annular baffle, and a conversion section inner conductor, and the smooth transition of the microwave signal and the mode conversion are ensured by adjusting the height of the mode conversion section; the coaxial output section includes an output section shell and an output section inner conductor; the conversion section shell and the output section shell are axial extensions of the anode shell, and the inner radius of the three is the same; the conversion section inner conductor is a hollow frustum-shaped shell, the end with a larger radius is connected to the end face of the fan-shaped anode blade, and the outer radius is the same as the outer radius of the small fan-shaped anode blade; the downstream annular baffle is located at the end with a larger radius of the conversion section inner conductor, and is connected to the downstream end face of the fan-shaped anode blade, the inner radius of the downstream annular baffle is the same as the inner radius of the fan-shaped anode blade, and the outer side is connected to the conversion section inner conductor; the output section inner conductor is a cylindrical shell with one end closed, and the open end is connected to the conversion section inner conductor, and the inner and outer radii of the connection are the same, such as Figure 5 As shown, where R t =83.5mm, R i =98mm, L t =50mm, L i =450mm.

[0036] Figure 6 The electric field distribution diagram corresponding to the PIC simulation results of the P-band full-cavity extraction relativistic magnetron of this embodiment can be seen from the figure: once the π mode is established in the resonant system (i.e., the axial region where the fan-shaped anode blades are located), the microwaves of the two adjacent resonant cavities are coupled into the fan-shaped waveguide cavity, propagate axially into the mode conversion section, and are converted into TEM mode, and finally output through the coaxial waveguide section.

[0037] Figure 7 This diagram shows the microwave power output of the P-band full-cavity relativistic magnetron used in this example, driven by a 690 kV diode voltage and a 0.38 T axial guide magnetic field. It can be seen that the established RF field reaches saturation after approximately 120 ns. The microwave power output is 3.63 GW, with a conversion efficiency of 42%.

[0038] As can be seen from the above examples, the P-band full-cavity extraction relativistic magnetron provided by the present invention, when driven by a 690kV diode voltage, has an axial magnetic field range of 0.33T-0.42T for the π-mode fundamental wave. When the relativistic magnetron operates at a magnetic field of 0.38T, the output power reaches a peak value of 3.63GW, and the conversion efficiency reaches 42%. That is, the present invention obtains GW-level microwave power under low guide magnetic field conditions, achieving fundamental mode output while taking into account the size and coupling efficiency of the device.

[0039] The example described above is only a preferred embodiment of the present invention. The protection scope of the present invention is not limited to the above embodiment. All technical solutions under the design concept of the present invention belong to the protection scope of the present invention.

Claims

1. A P-band full-cavity extraction relativistic magnetron, comprising a vacuum chamber, an anode, a cathode, and an axial extraction structure; Its characteristics are: The anode comprises a cylindrical anode shell, N large fan-shaped anode blades and N small fan-shaped anode blades located inside the anode shell and staggered along a circumferential period; wherein the inner radius of the large fan-shaped anode blades is the same as the inner radius of the small fan-shaped anode blades, the outer side surfaces of the large fan-shaped anode blades are in contact with the inner wall of the anode shell, and a fan-shaped gap is formed between the outer side surfaces of the small fan-shaped anode blades and the anode shell; the fan-shaped cavity between the large fan-shaped anode blades and the small fan-shaped anode blades is a resonant cavity, and the fan-shaped gap between the small fan-shaped anode blades and the anode shell is a fan-shaped waveguide cavity; The vacuum chamber comprises a vacuum chamber shell, one end of which is connected to the anode, and the other end of which is connected to the front-stage accelerator; The cathode is arranged inside the anode housing and is coaxial with the anode housing; The axial extraction structure includes a mode conversion section and a coaxial output section; wherein the mode conversion section includes a conversion section shell, a downstream annular baffle, and a conversion section inner conductor; the coaxial output section includes an output section shell and an output section inner conductor; the conversion section shell and the output section shell are axial extensions of the anode shell, and the inner radii of the three are the same; the conversion section inner conductor is a hollow frustum-shaped shell, the end with a larger radius of which is connected to the end face of the fan-shaped anode blade, and the outer radius is the same as the outer radius of the small fan-shaped anode blade; the downstream annular baffle is located at the end with a larger radius of the conversion section inner conductor, and is connected to the downstream end face of the fan-shaped anode blade, the inner radius of the downstream annular baffle is the same as the inner radius of the fan-shaped anode blade, and the outer side surface is connected to the conversion section inner conductor; the output section inner conductor is a cylindrical shell with one end closed, and the open end is connected to the conversion section inner conductor, and the inner and outer radii of the connection are the same.

2. The P-band full-cavity extraction relativistic magnetron according to claim 1, characterized in that: The vacuum chamber shell includes a small cylindrical shell, an annular end cover, a large cylindrical shell, an upstream annular baffle, and a vacuum chamber annular baffle located in the axial middle of the large cylindrical shell, which are coaxial and arranged in sequence; wherein the internal cavities of the small cylindrical shell, the annular end cover, and the large cylindrical shell are stepped cylindrical cavities; the other end of the small cylindrical shell is connected to the front-stage accelerator; the end face of the upstream annular baffle is connected to the upstream end face of the fan-shaped anode blade; the outer side surface of the upstream annular baffle is connected to the anode shell, and the inner radius of the upstream annular baffle is smaller than the outer radius of the small fan-shaped anode blade and larger than the inner radius of the small fan-shaped anode blade.

3. A P-band full-cavity extraction relativistic magnetron according to claim 1 or 2, characterized in that: The inner radius of the output section housing is 0.135λ-0.157λ, and the outer radius of the inner conductor of the output section is 0.09λ-0.104λ.

4. The P-band full-cavity extraction relativistic magnetron according to claim 3, characterized in that: The axial length of the mode conversion section is 0.03λ-0.14λ.

5. The P-band full-cavity extraction relativistic magnetron according to claim 4, characterized in that: The small sector-shaped anode blades are fixed to the upstream circular baffle by screws.

6. The P-band full-cavity extraction relativistic magnetron according to claim 5, characterized in that: The cathode is a transparent cathode, comprising a cathode support rod, a plurality of transparent cathode rods, and a downstream cathode end cap connected in sequence; wherein the other end of the cathode support rod is connected to the front-stage accelerator; the plurality of transparent cathode rods are evenly distributed along the circumference; and the downstream end cap extends into the conductor in the conversion section.

7. The P-band full-cavity extraction relativistic magnetron according to claim 6, characterized in that: The downstream end cap is in the shape of a stepped cylinder.

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