A high frequency interaction system with a flower-shaped cross section and a processing method thereof

Abstract

This invention belongs to the field of vacuum electronic devices, specifically relating to vacuum electronic devices in the millimeter-wave and terahertz frequency bands. It provides a flower-shaped cross-section high-frequency interaction system and its fabrication method to address the fabrication difficulties caused by the small size, complex structure, and presence of mirror images and porous structures in the terahertz frequency band slow-wave architecture. This invention employs an integrated flower-shaped cross-section high-frequency structure composed of a stem, metal leaves, and a bud. The metal leaf structure resolves the competition problem of high-frequency, high-order modes. The integration of the high-frequency structure reduces the superposition error of reassembling each structure from a single fabrication. Furthermore, the through-type stem serves as a support structure, providing sufficient structural strength to prevent easy deformation. The combined metal shell and high-frequency structure achieve separation of the electron beam and signal field. Simultaneously, the flower-shaped cross-section high-frequency structure increases the interaction space and improves power capacity.

Description

Technical Field

[0001] This invention belongs to the field of vacuum electronic devices, and relates to vacuum electronic devices in the millimeter wave and terahertz frequency bands. Specifically, it provides a flower-shaped cross-section high-frequency interaction system and its processing method. Background Technology

[0002] With the advancement of science and technology, the development of vacuum electronic devices is rapid. Millimeter-wave and terahertz frequencies, due to their advantages of wide bandwidth, good directivity, and high spatial and temporal resolution, have broad application prospects in many fields such as broadband communication, radar systems, electronic countermeasures, biomedical imaging, and security inspection. While solid-state devices are small, operate at low voltages, and are easy to integrate, their operating frequency range is lower than that of vacuum electronic devices, and their anti-interference capability is poor, resulting in lower output power in the millimeter-wave and terahertz bands. For vacuum electronic devices, extending traditional microwave tubes to the millimeter-wave, submillimeter-wave, and terahertz frequency bands is the latest research direction.

[0003] Currently, millimeter-wave and terahertz devices based on vacuum electronics have significant advantages in output power, operating bandwidth, and electronic efficiency, making them irreplaceable in high-frequency electronic equipment and other application systems. However, as the frequency increases and the wavelength decreases, the device size becomes smaller and smaller, and the size of the high-frequency interaction system becomes smaller and smaller. Critical dimensions are reduced from the millimeter level to the micrometer level or even smaller, making device manufacturing and assembly extremely difficult. At the same time, the space and time for the interaction between the electron beam and the high-frequency field become narrower and shorter, resulting in insufficient modulation of the electron beam's speed and density, which greatly limits the device's power capacity. Furthermore, insufficient heat dissipation places very stringent requirements on the cathode and focusing system, making the development of millimeter-wave and terahertz devices one of the bottlenecks restricting system development. On the other hand, smaller size means that the processing and assembly of components are more difficult, and traditional machining techniques are hard to complete. Especially for the one-piece molded slow-wave structure in terahertz devices, in order to improve the operating frequency, output power, and expand the operating bandwidth of vacuum electronic devices, new materials, new structures, new processes, and new mechanisms must be used. In addition, there is a mode competition problem in the higher-order modes of the high-frequency field. How to set up a reasonable high-frequency interaction structure to suppress the generation of competing modes is also a problem to be solved.

[0004] In addition, terahertz devices are small in size and complex in structure, with mirror images, porous structures, etc., making overall processing difficult. Traditional processing methods mostly use mechanical connections or welding methods such as resistance welding and fusion welding, which are "ablation" connection methods. The processing will generate heat conduction, resulting in significant thermal damage and deformation. This also results in high surface loss and extremely low smoothness of the periodic metal disks of the slow wave structure, thus affecting the quality of terahertz devices. Summary of the Invention

[0005] The purpose of this invention is to address numerous problems existing in the background technology by providing a high-frequency, high-order mode interaction system and its fabrication method. The system has a cross-section with an outer ring and a central flower shape, hence the name "flower-shaped cross-section high-frequency interaction system." This invention uses a flower bud, a stem, and metal leaves to form the flower-shaped cross-section high-frequency interaction structure. The flower bud cross-section has holes for electron beam channels, and the flower bud has spaced coupling grooves along the axial direction of the electron beam channels. These coupling grooves and the high-frequency metal leaves form a longitudinal periodic structure. In this flower-shaped cross-section high-frequency interaction structure, the metal leaves effectively resolve mode competition in high-order modes, while the flower-shaped structure increases the space for beam-wave interaction, improving the power capacity of the tube. Furthermore, the structure and fabrication method of the high-frequency interaction part can solve the problems of difficult small-size fabrication, precision issues, and surface finish issues in millimeter-wave terahertz devices.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A high-frequency interaction system with a flower-shaped cross-section includes: a tubular outer shell 1, a flower stem 2, metal leaves 3, and a flower bud 4; characterized in that,

[0008] The inner wall of the tubular shell has a through groove along the direction of electron beam propagation.

[0009] The flower stem, metal leaves, and flower bud together form a high-frequency structure with a flower-shaped cross section. The top of the flower stem is connected to the flower bud, and the bottom is inserted into and fixed in a through groove. The metal leaves extend upward along both sides of the flower stem and are symmetrical about the flower stem. The metal leaves are arc-shaped and their centers overlap with the center of the flower bud. An electron injection channel is opened in the center of the flower bud, and several coupling grooves are opened at equal intervals and arranged in parallel along the axial direction of the electron injection channel.

[0010] The tubular outer shell 1 forms a wave injection interaction space through the upper cover plate 1-1 and the lower cover plate 1-2 located at both ends. The upper cover plate and the lower cover plate are respectively provided with signal input port 5 and signal output port 6 facing the electron injection channel.

[0011] Furthermore, the operating mode of the high-frequency interaction system is TM. mn According to the working mode TM mn The number of metal blades is set to n-1, and the n-1 metal blades are located sequentially at the minimum position of the electromagnetic field along the radial direction of the circular waveguide; the radian α (central angle) of the n-1 metal blades is the same: when m=0, 0<α≤2π, when m=i, α=π / i, i≥1.

[0012] Furthermore, the number of coupling grooves ranges from 3 to 200. When the depth of the coupling groove is at its minimum value, the coupling groove penetrates the flower bud; when the depth of the coupling groove is at its maximum value, it penetrates the flower bud, flower stem, and corresponding metal leaves; the depth of the coupling groove can be adjusted between the maximum and minimum values.

[0013] Furthermore, the flower bud is round or elliptical, and the corresponding electron injection channel is round.

[0014] Furthermore, the center of the flower bud may or may not coincide with the center of the tubular outer shell.

[0015] The processing method of the above-mentioned flower-shaped cross-section high-frequency interaction system is characterized by comprising the following steps:

[0016] Step 1. Using a rectangular metal block as raw material, firstly, a flower-shaped cross-sectional pattern consisting of a stem, metal leaves, and a bud is processed on any square end face of the metal block using electrochemical etching, particle beam etching, wire cutting, or laser etching processes; then, a hole is drilled along the long side of the metal block at the center of the bud in the flower-shaped cross-sectional pattern to obtain an electron beam channel; finally, based on the flower-shaped cross-sectional pattern, a linear cutting process is used to cut along the long side of the metal block to obtain an integrated flower-shaped cross-sectional high-frequency structure.

[0017] Step 2. Use electrochemical etching, particle beam etching, wire cutting or laser etching processes to create coupling grooves along the electron beam channel axis on the flower bud of the high-frequency structure with flower-shaped cross section;

[0018] Step 3. Using a circular metal column as raw material, firstly, a cylinder is cut at the center of the circular metal column to obtain a tubular outer shell; then, a through groove is formed inside the tubular outer shell by wire cutting or laser cutting.

[0019] Step 4. Fix the flower-shaped cross-section high-frequency structure into the tubular shell by embedding the bottom of the flower stem into the through groove, and then weld the upper cover plate and the lower cover plate with the pre-set port to both ends of the tubular shell.

[0020] Furthermore, the rectangular metal block is made of oxygen-free copper, gold, silver, or stainless steel.

[0021] It should be noted that the direction of all "sections" in this invention is perpendicular to the electron beam propagation direction, and the terms "center" and "symmetry" are based on the positional description on the "section". Based on the flower-shaped cross-section high-frequency interaction system of this invention, the various parts are finally assembled into a whole using microwave vacuum electronic device technology, connected to the front-end electron gun, input module, and rear-end collector and signal output module. Then, the entire structure is vacuum-vented to ensure that an absolute vacuum environment is formed inside the entire device.

[0022] In terms of working principle:

[0023] There are infinitely many types of TM in circular waveguides. mn It is beneficial for electron injection and TM mn Energy exchange occurs within the longitudinal electric field of the mode, and different values ​​of m and n represent different modes. m represents the integer wave number distributed along the circumference of the field, and n represents the number of maximum values ​​distributed along the radius of the field. For the same type of mode, such as TM... mn By comparing the modulus, it was found that within a certain range, when n is greater than m, the larger the difference between m and n, the more the field radiation energy tends to concentrate in the center. When m = 0, the field radiation energy is concentrated at the center of the circle; when m > 1, the field radiation energy shifts from the center outwards. This is to ensure a strong longitudinal component E of the electric field near the center of the waveguide. z This allows for effective energy exchange with the electron beam moving along the axial direction, so the appropriate mode can be selected based on the actual application.

[0024] In circular waveguides, for high-frequency fields, the larger size of higher-order modes allows for greater beam-wave interaction space and facilitates device fabrication, such as TM waveguides. 03 The mode possesses a strong central field and multiple local minima, allowing for the installation of metal blades to suppress competing modes. Furthermore, the bud cross-sectional shape can be customized based on the mode's field energy distribution characteristics, enabling the selection of different operating modes, such as TM. 11 If the model is such that the cross-section of the flower bud can be set to an ellipse, which conforms to the shape of its field energy distribution, it is convenient for the electron injection through the electron channel on the flower bud to interact effectively with the electric field.

[0025] The cross-sections of the flower stem, bud, and metal leaves form a complete flower shape. The spaced coupling grooves on the bud and the metal leaves form a longitudinal periodic structure. The periodic structure can be adjusted by changing the longitudinal distance (gap) of the coupling grooves. Through the periodic slow-wave characteristics of the high-frequency interaction unit, the electron beam is velocity-modulated and density-modulated, resulting in electron clustering. As the beam-wave interaction intensifies, the modulation depth further increases. The energy of the electron beam is exchanged with the high-frequency signal field through the coupling grooves. After multiple energy exchanges, the velocity of most electrons decreases, resulting in a decrease in electron beam energy and amplification of the high-frequency signal field. Finally, the amplified signal is coupled out from the signal output port, and the electron beam enters the subsequently connected collector through the electron channel. For different working models, depending on the energy distribution of the mode field, to ensure the interaction between the electron beam and the field, the center of the electron channel may not be on the same axis as the center of the metal cylinder (outer shell).

[0026] The use of flower-shaped metal blades can suppress mode competition. By positioning the blades, modes other than the operating mode are suppressed, allowing the center field strength mode to operate better. Furthermore, the specific operating mode influences the number and position of the blades. Specifically: for the specific operating mode TM in a circular waveguide... mn, m represents the number of standing wave periods distributed along the entire circumference, reflecting the regular variation of the field components in the angular direction; n represents the number of half-standing waves or the number of maximum values ​​distributed along the radius of the circular waveguide, reflecting the regular distribution of the field components in the radial (r-direction). For a specific operating mode, m and n are determined, and the electric field distribution can be determined, thus obtaining the minimum position of the electric field along the radial direction of the circular waveguide. The number of minimum positions is the value of n-1. The radius value corresponding to the minimum point can be obtained by finding the extreme value of the electric field distribution. Therefore, for a specific operating mode, the number of metal blades is determined by n, and the radius is determined by the minimum radius of the field along the radial direction. The radian of the metal blade (degrees relative to its center) can be set according to m. When m = 0, there is no restriction between 0 and 2π. When m = 1, the radian is π. When m = 2, the radian is π / 2, and so on down. When m = i, the radian is π / i. Furthermore, the radian of each metal blade is the same. Therefore, the metal blades can suppress other modes that exist in this working mode.

[0027] The flower bud, flower stem, and metal leaves are integrated into a single, non-assembled structure. The flower stem serves as the supporting structure, running integrally through the entire high-frequency interaction system. This provides sufficient support strength, and the all-metal support structure effectively dissipates heat. Furthermore, for high-frequency signals, the higher the frequency, the smaller the device size. The integrated design of the flower stem, flower bud, and metal leaves in this invention reduces the difficulty of small-size processing, minimizes the accumulation of errors from step-by-step processing, and ensures the overall structural rigidity and support strength, preventing easy deformation. Compared to high-frequency structures that are processed and then stacked in a single cycle or supported on one side, this integrated high-frequency structure offers significant advantages.

[0028] In summary, the beneficial effects of this invention are as follows:

[0029] Because terahertz slow-wave structures are small, with device sizes reaching the micrometer scale, and are complex, including mirror images and porous structures, their overall fabrication is challenging, especially in the fabrication of three-dimensional coupling holes in a two-dimensional direction, further increasing the difficulty of traditional fabrication methods. Therefore, this invention provides a flower-shaped cross-section high-frequency interaction system and fabrication method. It employs an integrated flower-shaped cross-section high-frequency structure composed of a flower stem, metal leaves, and a bud. The metal leaf structure resolves the competition problem of high-frequency, high-order modes. The integrated high-frequency structure reduces the superposition error of reassembling each structure from a single fabrication. The metal leaves are only on one side of the circle, making fabrication convenient. Furthermore, the high-frequency structure is embedded in a tubular shell, which further facilitates fabrication. The through-type flower stem serves as a support structure, providing sufficient support strength for the entire high-frequency structure, allowing for further extension of the tube length and ensuring overall structural rigidity, preventing easy deformation. The combined metal shell and high-frequency structure achieve separation of the electron beam and signal field. Simultaneously, using only the high-frequency support structure to support the electron channel increases the interaction space, improves power capacity, reduces mechanical complexity, improves precision, and the overall metal structure is also more conducive to heat dissipation. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of the high-frequency interaction system with a flower-shaped cross section in an embodiment of the present invention;

[0031] Figure 2 This is a detailed structural schematic diagram of the high-frequency interaction system with a flower-shaped cross section in an embodiment of the present invention;

[0032] Wherein: 1 is a tubular outer shell, 1-1 is an upper cover plate, 1-2 is a lower cover plate, 1-3 is a through groove (insertion groove), 2 is a flower stem, 3 is a metal leaf, 3-1 is the first metal leaf, 3-2 is the second metal leaf, 4 is a flower bud, 4-1 is an electron injection channel, 4-2 is a coupling groove, 5 is a signal input port, and 6 is a signal output port.

[0033] Figure 3 This is a schematic diagram of the processing steps of the high-frequency interaction system with flower-shaped cross-section in an embodiment of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0035] This embodiment provides a high-frequency interaction system based on a cold cathode with a flower-shaped cross-section, the structure of which is as follows: Figure 1 , Figure 2As shown, it includes: a tubular outer shell 1, a flower stem 2, metal leaves 3, and a flower bud 4; wherein, the inner wall of the tubular outer shell has through grooves 1-3 along the electron beam propagation direction; the flower stem, metal leaves, and flower bud together form a flower-shaped cross-section high-frequency structure, the top of the flower stem is connected to the flower bud, and the bottom is inserted into and fixed in the through groove; the first metal leaf 3-1 and the second metal leaf 3-2 are formed by extending upwards along both sides of the flower stem and are symmetrical about the flower stem, the metal leaves are arc-shaped, and the center of the arc overlaps with the center of the flower bud; an electron beam channel is opened in the center of the flower bud. The tube 1 has M equally spaced parallel coupling slots 4-2 along the electron beam propagation direction. The tube 1 forms a beam-wave interaction space through the upper cover plate 1-1 and the lower cover plate 1-2 located at both ends. Signal input port 5 and signal output port 6 are respectively opened on the upper cover plate and the lower cover plate facing the electron beam channel. The signal input and output ports are sealed to the external input and output windows to form an information input and output module. The material of the input and output windows is a medium, which does not affect the transmission of electromagnetic waves while maintaining the vacuum inside the device.

[0036] Furthermore, the processing method of the above-mentioned flower-shaped cross-section high-frequency interaction system is as follows: Figure 3 As shown, it includes the following steps:

[0037] Step 1. Using a rectangular metal block as raw material, firstly, a flower-shaped cross-sectional pattern consisting of a flower stem, metal leaves, and flower bud is processed on any square end face of the metal block using electrochemical etching, particle beam etching, wire cutting, or laser etching processes, as shown below. Figure 3 As shown in (a); then, a hole is made along the long side of the metal block at the center of the flower bud in the flower-shaped cross-section pattern to obtain an electron injection channel; finally, based on the flower-shaped cross-section pattern, a linear cutting process is used to cut along the long side of the metal block to obtain an integrated flower-shaped cross-section high-frequency structure, as shown in (a). Figure 3 As shown in (b);

[0038] Step 2. Using electrochemical etching, particle beam etching, wire cutting, or laser etching processes, coupling grooves are created along the axial direction of the electron beam channel on the flower-shaped cross-section high-frequency structure, such as... Figure 3 As shown in (c);

[0039] Step 3. Using a circular metal column as raw material, firstly, a cylinder is cut at the center of the circular metal column to obtain a tubular outer shell; then, a through groove is formed inside the tubular outer shell by wire cutting or laser cutting.

[0040] Step 4. Fix the flower-shaped cross-section high-frequency structure into the tubular shell by embedding the bottom of the flower stem into the through groove, and then weld the upper cover plate and the lower cover plate with the pre-set port to both ends of the tubular shell.

[0041] Furthermore, in this embodiment, the inner diameter of the metal tubular outer shell 1 is 20 mm, the outer diameter is 22 mm, the center is (0,0,0), the length is 10.6 mm, and the material is non-magnetic stainless steel. In order to embed the high-frequency wave injection interaction structure, a metal rectangular strip with an inner angle of 10°, a thickness of 0.5 mm, and a length of 10.6 mm is cut off from the inner wall of the metal tubular outer shell to form a through groove 1-3. The upper cover plate 1-1 is a metal disk with an inner diameter of 4.1 mm, an outer diameter of 22 mm, and a thickness of 0.5 mm, and the lower cover plate 1-2 is the same as the upper cover plate. For the flower-shaped cross-section high-frequency structure, the two axes of the tubular outer shell 1 and the electron injection channel 4-1 do not coincide, and the distance is 0.4mm; the inner diameter of the electron injection channel 4-1 is 2mm, the center is (0,-0.4,0), the outer diameter is 6mm, the length is 10m, and the distance between it and the front and rear metal cover plates is 0.3mm; the coupling groove 4-2 has an angle of 300 degrees, a length of 0.5mm, a cutting depth of 6mm, and M=9; the inner radius of the first metal blade 3-1 is 9.4mm, the outer radius is 11.4mm, the arc is 60°, the center is (0,-0.4,0), and the length is 10mm; the inner radius of the second metal blade 3-2 is 15.4mm, the outer radius is 17.4mm, the angle is 60°, the center is (0,-0.4,0), and the length is 10mm.

[0042] The various components of the wave-beam interaction structure are assembled and welded into a whole using microwave vacuum device technology, including the terahertz high-frequency system, as well as the input and output waveguides, electron gun and collector connected to it; and vacuum exhaust is performed to create an absolute vacuum environment inside the entire device.

[0043] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A high-frequency interaction system with a flower-shaped cross-section, comprising: A tubular outer shell (1), a flower stem (2), metal leaves (3), and a flower bud (4); characterized in that, The inner wall of the tubular shell has a through groove along the direction of electron beam propagation. The flower stem, metal leaves, and flower bud together form an integrated flower-shaped cross-section high-frequency structure. The top of the flower stem is connected to the flower bud, and the bottom is inserted into and fixed in a through groove. The metal leaves extend upward along both sides of the flower stem and are symmetrical about the flower stem. The metal leaves are arc-shaped and their centers overlap with the center of the flower bud. An electron injection channel is opened in the center of the flower bud, and several coupling grooves are opened at equal intervals and arranged in parallel along the axial direction of the electron injection channel. The tubular shell forms a wave injection interaction space through the upper and lower cover plates located at both ends. The upper and lower cover plates are respectively provided with signal input port (5) and signal output port (6) facing the electron injection channel. The operating mode of the high-frequency interaction system is TM. mn According to the working mode TM mn The number of metal blades is set to n-1, and these n-1 metal blades are located sequentially at the minimum positions of the electromagnetic field along the radial direction of the circular waveguide; the radians α of the n-1 metal blades are the same: when m=0, 0<α≤2π, m= i When α=π / i , i ≥1; The flower buds are round or oval, and the corresponding electron injection channels are round.

2. The high-frequency interaction system with a flower-shaped cross-section according to claim 1, characterized in that, The number of coupling grooves is 3 to 200. When the depth of the coupling groove is at its minimum value, the coupling groove penetrates the flower bud; when the depth of the coupling groove is at its maximum value, it penetrates the flower bud, flower stem and its connected metal leaves.

3. The high-frequency interaction system with a flower-shaped cross-section according to claim 1, characterized in that, The center of the flower bud may or may not coincide with the center of the tubular outer shell.

4. The processing method of the high-frequency interaction system with flower-shaped cross-section according to claim 1, characterized in that, Includes the following steps: Step 1. Using a rectangular metal block as raw material, firstly, a flower-shaped cross-sectional pattern consisting of a stem, metal leaves, and a bud is processed on any square end face of the metal block using electrochemical etching, particle beam etching, wire cutting, or laser etching processes; then, a hole is drilled along the long side of the metal block at the center of the bud in the flower-shaped cross-sectional pattern to obtain an electron beam channel; finally, based on the flower-shaped cross-sectional pattern, a linear cutting process is used to cut along the long side of the metal block to obtain an integrated flower-shaped cross-sectional high-frequency structure. Step 2. Use electrochemical etching, particle beam etching, wire cutting or laser etching processes to create coupling grooves along the electron beam channel axis on the flower bud of the high-frequency structure with flower-shaped cross section; Step 3. Using a circular metal column as raw material, firstly, a cylinder is cut at the center of the circular metal column to obtain a tubular outer shell; then, a through groove is formed inside the tubular outer shell by wire cutting or laser cutting. Step 4. Fix the flower-shaped cross-section high-frequency structure into the tubular outer shell by embedding the bottom of the flower stem into the through groove. Then, the upper and lower cover plates with pre-set ports are welded to both ends of the tubular outer shell.

5. The processing method of the high-frequency interaction system with flower-shaped cross-section according to claim 4, characterized in that, The rectangular metal block is made of oxygen-free copper, gold, silver, or stainless steel.

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