Waveguide flange structure for transmitting high power microwaves

Abstract

The application discloses a waveguide flange structure for transmitting high-power microwave, and belongs to the technical field of high-power microwave transmission and emission. The waveguide flange structure is composed of a flange, blind holes and a radial sealing ring. The flange has a certain spacing between two flange surfaces. The two flange surfaces are provided with a circle of blind holes. The blind holes on one flange surface are rotationally offset from the blind holes on the other flange surface. The waveguide and the flange are sealed by engraving sealing grooves on the radial sealing ring and placing sealing rings, so that the waveguide can work in a vacuum environment. In the application, the spacing between the waveguide flange end surfaces is artificially increased, so that the tip field enhancement at the traditional flange surface is reduced, and the power capacity of the waveguide is improved. Meanwhile, the application solves the problem of increased loss caused by easy leakage of microwave at the traditional flange surface, reduces the precision requirement of the flange end surface in engineering, and greatly reduces the processing difficulty and cost.

Description

Technical Field

[0001] This invention belongs to the field of high-power microwave transmission and transmission technology, and specifically relates to a waveguide flange structure for transmitting high-power microwaves. Background Technology

[0002] Circular waveguides are commonly used both domestically and internationally to transmit high-power microwaves under vacuum conditions, such as the circular waveguide flange described in the article "Compact high-power microwave oscillators" by Philip MacInnes et al. (e.g., ...). Figure 9 As shown; the flange in the article "Cold-Test of Transverse Input-Output Microwave Circuit Components for a High-Power W-BandGyro-TWT" (IEEE ELECTRON DEVICE LETTERS, VOL.42, NO.1, JANUARY 2021) published by Russians Alexander A. Bogdashov and Sergey V. Samsonov, as shown. Figure 10 As shown; the paper "Design of a Compact Mode Converter With Periodic Metallic Octagon Structure for HPM Applications" published by Swati Varun Yadav et al. from India.

[0003] (Telecommunications and Radio Engineering 81(1):11–20(2022)) The flange in the article, such as Figure 11 As shown; the paper "A compact high-power microwave™" published by Yong-jun Hu et al. in China. 01 -TE 01 The flange mentioned in the article "mode converter" (Rev. Sci. Instrum. 92, 094703 (2021)), such as Figure 12As shown; the flange in the article "A wideband high-power microwave radiation source based on gyromagnetic nonlinear transmission line and Vlasov antenna" (Rev. Sci. Instrum. 93, 104706 (2022)) published by Yancheng Cui et al., such as Figure 13 As shown, its structure is a circular waveguide flange structure. During transmission, it inevitably encounters multiple waveguides connected by flanges to lengthen the microwave transmission path or to access other transmission or feeding devices such as mode converters or feeders. Discontinuities at the flange connections are one of the bottlenecks that increase transmission loss and limit the power capacity of the transmission waveguide. Especially in the millimeter-wave band, even micrometer-level gaps or non-parallelism at the connections will lead to microwave leakage. Furthermore, the presence of gaps will also cause field enhancement at the tip of the gap, thereby reducing the power capacity of the circular waveguide.

[0004] To minimize the presence of gaps, the requirements for perpendicularity and parallelism during flange processing are extremely high, generally requiring them to reach the micrometer level. At the same time, the requirements for flange surface roughness are also very high, generally also requiring them to reach the micrometer level. This greatly increases the processing difficulty, and the requirements for testing and installation are also correspondingly higher. Storage difficulties are also increased, leading to a higher overall cost of the waveguide. Summary of the Invention

[0005] The purpose of this invention is to propose a waveguide flange structure for transmitting high-power microwaves, thereby solving the technical problems of microwave leakage and insufficient power capacity at the waveguide connection flange for high-power microwave transmission, or high cost and engineering difficulty.

[0006] To achieve the above objectives and solve the above technical problems, the present invention provides the following technical solution: a waveguide flange structure for transmitting high-power microwaves, the waveguide flange structure comprising a flange 2, a blind hole 3, and a radial sealing ring 4;

[0007] The flange 2 is used to connect two circular waveguides 1;

[0008] The flange 2 has a ring of blind holes 3 on each of its two end faces. The positions of the blind holes 3 on the two end faces are shifted by 1 / 2 of the blind hole period to obtain an artificial high-resistivity surface, so that microwaves are in the bandgap region on the end face of the flange 2 and cannot be transmitted or leaked.

[0009] The radius of the blind hole 3 is about 1 / 4 of the microwave wavelength, and the depth is about 1 / 3 of the microwave wavelength. The blind holes 3 are distributed around the two end faces of the flange.

[0010] The number and size of blind holes on both ends of the flange are the same, and the misalignment angle is set at half the spatial distance;

[0011] The radial sealing ring 4 is used to seal the flange 2 to prevent microwave leakage and keep the entire waveguide transmission channel in a sealed state, so that the waveguide transmission channel can transmit high-power microwaves in a vacuum.

[0012] The distance between the two end faces of flange 2 is increased to 1 / 4 of the microwave wavelength to reduce tip field enhancement and increase the power capacity of the waveguide.

[0013] Compared with existing technologies, the effective benefits of this invention are:

[0014] 1. This invention provides a ring of blind holes on each of the two flange faces, with the blind holes staggered on the two flange faces to create an artificially constructed high-resistivity surface, ensuring that microwaves are in the bandgap region on the flange face.

[0015] Microwave leakage is prevented, thus solving the problem of increased losses caused by microwave leakage on traditional flange surfaces.

[0016] 2. In this invention, the spacing between the waveguide flange end faces is artificially increased, thereby reducing the tip field enhancement at the traditional flange face and increasing the power capacity of the waveguide.

[0017] 3. This invention utilizes a radial sealing ring to seal the flange, which not only further prevents microwave leakage but also allows the entire waveguide transmission channel to operate in a sealed state, enabling the waveguide transmission channel to transmit high-power microwaves in a vacuum.

[0018] 4. This invention can reduce the precision requirements of the flange end face in engineering, thus greatly reducing the processing difficulty and cost. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the waveguide flange structure of the present invention;

[0020] Figure 2 This is a schematic diagram of the waveguide planar flange structure according to an embodiment of the present invention (flange gap 100μm);

[0021] Figure 3 The waveguide transmission coefficient diagram is shown for a waveguide with a planar flange (flange gap 100μm).

[0022] Figure 4 This is a schematic diagram of the electric field distribution in a cross section of a waveguide with planar flanges (flange gap 100μm).

[0023] Figure 5 A schematic diagram of the flange structure of this invention with a waveguide;

[0024] Figure 6 The transmission coefficient diagram of the flange waveguide of this invention is shown.

[0025] Figure 7 This is a schematic diagram of the electric field distribution of the flange waveguide section of the present invention;

[0026] Figure 8 Photograph of a flange used in a traditional high-power microwave transmission waveguide;

[0027] Figure 9 The flange mentioned in the text refers to Compact high-power microwave oscillators;

[0028] Figure 10 Cold-Test of Transverse Input-Output Microwave Circuit Components for a High-Power W-Band Gyro-TWT (Flange mentioned in the text);

[0029] Figure 11 The flange mentioned in the text is from the design of a Compact Mode Converter with Periodic Metallic Octagon Structure for HPM Applications.

[0030] Figure 12 A compact high-power microwaveTM 01 -TE 01 The flange mentioned in the text about mode converter;

[0031] Figure 13 A wideband high-power microwave radiation source based on a gyromagnetic nonlinear transmission line and a Vlasov antenna (the flange mentioned in the text). Detailed Implementation

[0032] The present invention will now be explained in more detail with reference to the accompanying drawings and embodiments.

[0033] High-power microwave sources typically operate in a vacuum environment, and the microwaves they generate are generally transmitted using circular waveguides. During transmission, connecting flanges are indispensable to increase transmission distance or to connect components such as mode converters, power dividers, or phase shifters. Flat flanges are commonly used, with a ring of through holes on the flange face for screw installation. One flange face has a sealing groove with a built-in rubber sealing ring. Tightening the screws connects the two flange faces, allowing the waveguide to operate in a vacuum. Figure 8 As shown. However, due to processing, installation, and other reasons, there will always be gaps between the actual flange faces, resulting in discontinuities at the flange, for example... Figure 8 There is a certain gap at the joint surface of the two flanges. The discontinuity at the joint flange is one of the bottlenecks that increases transmission loss and limits the power capacity of the transmission waveguide. Especially in the millimeter wave band, micron-level gaps or non-parallelism at the joint will lead to microwave leakage, and the presence of gaps will also lead to field enhancement at the tip of the gap, thereby reducing the power capacity of the circular waveguide.

[0034] Based on the limitations and problems of the aforementioned connecting flanges, the design concept of this invention is described as follows: This invention employs a transmission waveguide flange structure composed of a circular waveguide, a flange, blind holes, and a radial sealing ring. There is a certain distance between the two flange faces, and each flange face has a ring of blind holes. The blind holes on one flange face are slightly misaligned with those on the other. A sealing groove is carved on the radial sealing ring to place the sealing ring, sealing the waveguide and flange together, ensuring the waveguide can operate in a vacuum environment. This structure creates an artificially constructed high-resistivity surface between the two flange end faces, placing microwaves in a bandgap region between the flange end faces, preventing transmission and leakage. Simultaneously, the radial sealing ring seals the flange, further preventing microwave leakage and ensuring the entire waveguide transmission channel operates in a sealed state, allowing for high-power microwave transmission in a vacuum. Artificially increasing the distance between the waveguide flange end faces reduces tip field enhancement and increases the waveguide's power capacity. This design also reduces the precision requirements of the flange end faces in engineering, significantly reducing processing difficulty and cost.

[0035] A waveguide flange structure for transmitting high-power microwaves includes a circular waveguide 1, a flange 2, a blind hole 3, and a radial sealing ring 4, the material of which is a conductor with good electrical conductivity.

[0036] The waveguide flange 2 has a ring of blind holes 3 on each of its two end faces. The positions of the blind holes 3 on the two flange faces are offset by half the blind hole period, creating an artificially constructed high-resistivity surface. This ensures that microwaves are in the bandgap region on the flange 2 end faces, preventing transmission and leakage. The radius of the blind holes 3 is approximately 1 / 4 of the microwave wavelength, and the depth is approximately 1 / 3 of the microwave wavelength. The blind holes 3 are distributed around the circumference of the flange. The number and size of the blind holes on each of the two end faces are consistent, and the offset angle is set to half the spatial distance, which is considered reasonable.

[0037] By using a radial sealing ring to seal the flange, not only can microwave leakage be further prevented, but the entire waveguide transmission channel can also be operated in a sealed state, and the waveguide transmission channel can transmit high-power microwaves in a vacuum.

[0038] By artificially increasing the distance between the waveguide flange ends to 1 / 4 of the wavelength, the tip field enhancement is reduced, thereby increasing the power capacity of the waveguide.

[0039] Example 1

[0040] The present invention will now be explained and described in detail with reference to the accompanying drawings and specific embodiments.

[0041] A circular waveguide for transmitting Ka-band high-power microwaves (made of a good conductor; material-related losses need not be considered in this invention) has two connecting flanges, such as... Figure 2 As shown, the circular waveguide has a radius of 7.4 mm and a length of 100 mm. When both flange faces are flat and the flange face gap is 100 μm, its transmission loss is close to 10 dB@29.16 GHz. Figure 3 As shown. Due to the presence of the gap, microwaves generate a very strong field enhancement point on the flange end face, and a large portion of the electric field overflows the flange, such as... Figure 4 As shown. The structural schematic diagram is as follows after replacing the flat flange with the waveguide flange shown in this invention. Figure 5 As shown, a hole with a radius of 2.47 mm and a depth of 3.16 mm is drilled 3.47 mm from the inner wall of the waveguide on the flange end face. One hole is drilled every 30° around the waveguide transmission direction, resulting in 12 holes in a ring on the flange end face. The holes on the opposite flange end face are the same size, and the flange is rotated and shifted 15° before installation. The gap between the two flanges is 2.3 mm. A 2 mm thick radial sealing ring is added to the outer wall of the flanges to enable the waveguide to operate in a vacuum environment. Its maximum transmission loss is 0.07 dB@29.64 GHz. Figure 6 As shown, after replacing the flange with the flange of the present invention, the electric field strength at the flange decreased by more than 8 times, and there was no electric field leakage. Figure 7 As shown.

[0042] The above description, in conjunction with specific embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A waveguide flange structure for transmitting high-power microwaves, characterized in that, The waveguide flange structure comprises a flange (2), blind holes (3) and a radial sealing ring (4); The flange (2) is used for connecting two circular waveguides (1); Each of the two end faces of the flange (2) is provided with a circle of blind holes (3), and the positions of the blind holes (3) on the two end faces are offset by 1 / 2 of the period of the blind holes, so as to obtain an artificial high-resistance surface, so that the microwave is in a forbidden band region at the end face of the flange (2) and cannot be transmitted and leaked; The radius of the blind hole (3) is 1 / 4 of the wavelength of the microwave, and the depth is 1 / 3 of the wavelength of the microwave, and the blind holes (3) are distributed on one side of the two end faces of the flange; The number and size of the blind holes of the two end faces of the flange are consistent, and the offset angle is set according to half of the space distance; The radial sealing ring (4) is used for sealing the flange (2), for preventing the microwave from leaking out and making the entire waveguide transmission channel work in a sealed state, so that the waveguide transmission channel can transmit high-power microwaves in a vacuum state; The distance between the two end faces of the flange (2) is increased to 1 / 4 of the wavelength of the microwave, for reducing the tip field enhancement and improving the power capacity of the waveguide.

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