A high-frequency structure loaded with four-bridge all-metal supercell unit

Abstract

The application provides a high-frequency structure loaded with a four-bridge full-metal superstructure unit, and belongs to the technical field of high-power vacuum electron devices. The structure realizes miniaturization of a multi-beam klystron high-frequency structure by loading a four-bridge full-metal superstructure unit in the multi-beam klystron high-frequency structure. Meanwhile, a circular through hole is arranged in the axial center area of the four-bridge full-metal superstructure unit, and by adjusting the radius of the circular through hole and the radius of the superstructure resonant cavity, the electric field intensity distribution in the inner and outer circle electron beam channels can be effectively controlled under the premise that the working frequency of the resonant cavity basic mode electric field does not deviate, that is, the electric field in the axial center area is weakened, and electromagnetic energy is redistributed in the radial direction, so that the electric field consistency in the multi-circumference electron beam channel is effectively improved while the multi-beam klystron is miniaturized, the difference in the modulation effect of the inner and outer circle electron beams is reduced, and the electron efficiency and operation stability of the multi-beam klystron are improved.

Description

Technical Field

[0001] This invention belongs to the field of high-power vacuum electronic device technology, specifically relating to a high-frequency structure with a loaded four-bridge all-metal meta-unit. Background Technology

[0002] A klystron is a vacuum electronic device capable of power amplification in the microwave band. Due to its advantages such as high power, high gain, and high efficiency, klystrons are widely used in particle accelerators, plasma heating, radar systems, colliders, and medical accelerators, serving as a key component in large scientific facilities. As these important applications increasingly demand higher microwave output power, system efficiency, and device integration, klystrons are evolving towards higher power, higher efficiency, and miniaturization.

[0003] Under high-power operating conditions, traditional single-beam klystrons typically require high operating voltages and currents, resulting in large electron beam conductivity, significant space charge effects, and limitations on electron beam modulation and clustering processes, thus posing a challenge to improving electronic efficiency. Multi-beam klystrons, through the coordinated operation of multiple electron beams, can significantly reduce the conductivity of each electron beam channel while maintaining the same total operating voltage and current, thereby mitigating the space charge effect and improving electron beam modulation and clustering characteristics. Multi-beam klystrons are a crucial technological approach for improving the electronic efficiency and output power of klystrons. However, multi-beam klystrons require multiple electron beam channels in the lateral space, and due to size co-entropy effects, their high-frequency structure typically has a large lateral dimension. This not only increases the difficulty of device fabrication and system integration costs but also limits their application in fields with stringent size and weight requirements, such as medical devices and aerospace. Therefore, achieving miniaturization while ensuring high-power and high-efficiency performance of multi-beam klystrons has become a key issue in the development of klystrons.

[0004] To achieve miniaturization of klystrons, existing research has introduced metamaterial units (referred to as metamaterial units)—circular complementary open-circuit resonant rings (CeSRRs)—into the resonant cavity. Utilizing their subwavelength and strong resonant electromagnetic properties, significant progress has been made in the miniaturization of single-beam klystrons (Patent CN113838727B, a miniaturized high-power klystron based on a single-ridge CeSRR unit). Regarding the miniaturization of multi-beam klystrons, patent CN119673730A (a miniaturized high-efficiency multi-beam klystron based on a double-ridge porous metamaterial unit) has made some progress in multi-beam metamaterial klystrons employing a resonant cavity loaded with double-ridge porous metamaterial units. However, multi-beam klystrons based on this resonant cavity are only suitable for cases where the number of electron beams is small and the electron beams can be uniformly distributed on a single circumference. When the number of electron beams is further increased and distributed in multiple circles to meet the demand for high output power, the electric field intensity in the inner and outer electron beam channels of the metamorphic resonant cavity loaded with the double-ridged porous metamorphic unit is difficult to keep consistent. During the beam-wave interaction process, the inner electron beam modulation is too strong and the outer electron beam modulation is insufficient, which leads to a decrease in the transduction efficiency of the outer electron beam and backflow of the inner electron beam. This seriously restricts the high power output, efficiency improvement and stable operation of the multi-beam klystron.

[0005] In summary, there is an urgent need to develop a new high-frequency structure suitable for multi-beam klystrons. This structure should not only achieve miniaturization of multi-beam klystrons but also effectively improve the uniformity of electric field distribution within the multi-circular electron beam channels, enhance the energy conversion efficiency between electron beams and electromagnetic waves, and improve the operational stability of the device. This would meet the application requirements of high-power, high-efficiency, and miniaturized multi-beam klystrons. Summary of the Invention

[0006] To address the problems existing in the background technology, this invention provides a high-frequency structure with a four-bridge all-metal meta-unit. This structure achieves miniaturization of the multi-beam klystron high-frequency structure by loading a four-bridge all-metal meta-unit into the multi-beam klystron high-frequency structure. Simultaneously, by introducing a circular via of a specific radius at the center of the four-bridge all-metal meta-unit, the region is transformed from a continuous vacuum state to a vacuum-to-metal boundary condition. By adjusting the radius of the circular via and the radius of the meta-resonant cavity, the electric field intensity distribution within the inner and outer electron beam channels can be effectively controlled without shifting the operating frequency of the fundamental mode electric field of the resonant cavity. This weakens the electric field in the axial region, causing a redistribution of electromagnetic energy in the radial direction. Therefore, while ensuring the miniaturization of the multi-beam klystron, it effectively improves the electric field consistency within the multi-circular electron beam channels, reduces the difference in the modulation effect of the inner and outer ring electric fields on the electron beam, and improves the electronic efficiency and operational stability of the multi-beam klystron.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A high-frequency structure loaded with a four-bridge all-metal metacell includes a metacell input cavity, a first set of drift tubes, a first metacell intermediate cavity, a second set of drift tubes, a second metacell intermediate cavity, a third set of drift tubes, a third metacell intermediate cavity, a fourth set of drift tubes, and a metacell output cavity connected in sequence; each set of drift tubes is composed of multiple cylindrical drift tubes, and the number of drift tubes is the same as the number of electron beams;

[0009] The superstructure input cavity, the first superstructure intermediate cavity, the second superstructure intermediate cavity, the third superstructure intermediate cavity, and the superstructure output cavity are all superstructure resonant cavities loaded with four-bridge all-metal superstructure units; and the structures of the first superstructure intermediate cavity, the second superstructure intermediate cavity, and the third superstructure intermediate cavity are similar, each containing a pair of internal drift tubes and two four-bridge all-metal superstructure units, wherein the four-bridge all-metal superstructure units are respectively loaded at the center positions of the left drift tube and the right drift tube of the superstructure intermediate cavity;

[0010] The meta-input cavity is equipped with a standard coaxial energy input device, a pair of internal drift tubes, and a four-bridge all-metal meta-unit. The left drift tube in the pair of internal drift tubes is connected to the electron gun of the multi-beam meta-klystron. The four-bridge all-metal meta-unit is loaded at the center of the right drift tube in the pair of internal drift tubes.

[0011] The metamorphic output cavity is provided with a pair of standard rectangular waveguide energy output devices, a pair of internal drift tubes and two four-bridge all-metal metamorphic units, wherein the four-bridge all-metal metamorphic units are respectively loaded at the center positions of the left drift tube and the right drift tube of the metamorphic output cavity;

[0012] All four-bridge all-metal meta-units have similar structures and are centrally symmetrical. They include concentric metal outer rings and metal inner rings. The metal inner rings have multiple electron beam channels uniformly arranged on concentric circles of different radii. The metal outer rings and metal inner rings are interconnected by four metal bridges, with adjacent metal bridges spaced 90° apart. A circular through-hole is provided at the center of the metal inner ring. The circular through-hole is used to reduce the difference in electric field between the inner and outer ring electron beam channels.

[0013] Furthermore, the radius of the circular via is related to the fundamental mode electric field characteristics of the superstructure resonator of the loaded four-bridge all-metal superstructure unit. Specifically, the smaller the radius of the circular via, the greater the difference in fundamental mode electric field intensity within the inner and outer electron beam channels of the superstructure resonator; conversely, the larger the radius of the circular via, the smaller the difference in fundamental mode electric field intensity within the inner and outer electron beam channels. While ensuring that the operating frequency of the fundamental mode electric field of the superstructure resonator remains constant, the size of the circular via radius can regulate the electric field intensity within the inner and outer electron beam channels, i.e., weaken the electric field in the axial region, promote the redistribution of electromagnetic energy in the radial direction, thereby effectively improving the electric field consistency within the multi-circular electron beam channels, reducing the difference in the modulation effect of the inner and outer electric fields on the electron beam, and improving the electronic efficiency and operational stability of the multi-beam superstructure klystron.

[0014] Furthermore, the radius of the circular through hole is 1~2mm.

[0015] Furthermore, the electron injection channels on the inner metal ring are preferably distributed on two concentric circles with different radii.

[0016] Furthermore, the standard coaxial energy input device adopts a magnetic coupling method, including a coaxial input inner conductor and a coaxial input outer conductor; the end of the inner conductor is fixed to the inner wall of the meta-input cavity to couple microwave signals into the klystron, and the outer conductor is connected to the outer wall of the meta-input cavity.

[0017] Furthermore, the standard rectangular waveguide energy output device is used to output the amplified microwave signal, and it adopts an electrical coupling method, preferably a standard rectangular waveguide; the standard rectangular waveguide is connected to the meta-output cavity to realize the output of the microwave signal.

[0018] Furthermore, the lengths of the first, second, third, and fourth groups of drift tubes are determined by the phase modulation requirements of the electron beam wave by each stage of the meta-resonant cavity, and their radii are consistent with the radius of the electron beam channel, thereby ensuring the continuity and stability of the multiple electron beams during transmission.

[0019] Furthermore, the geometric dimensions of the superstructure input cavity, superstructure intermediate cavity, and superstructure output cavity are all determined by the operating frequency of the fundamental mode electric field of the superstructure resonant cavity. This ensures that when the electron beam enters the next superstructure resonant cavity after clustering in the drift tube, it is modulated by the fundamental mode electric field of the optimal frequency, thereby enabling the electron beam to achieve the best clustering effect in the output cavity.

[0020] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0021] 1. Significant miniaturization of the high-frequency structure of a multi-beam metamorphic klystron. This invention achieves significant miniaturization of the resonant cavity by loading four-bridge all-metal metamorphic units into the input, intermediate, and output cavities of the klystron. While maintaining the operating frequency and output power, the physical size of the multi-beam metamorphic klystron high-frequency structure is significantly reduced. The radius of the proposed multi-beam metamorphic klystron high-frequency structure is 36-38 mm, approximately 60% of the radius of a conventional multi-beam klystron high-frequency structure, effectively achieving lateral miniaturization and overall weight reduction.

[0022] 2. Significantly improves the consistency of the electric field modulation effect on the electron beam within the multi-circular electron beam channel, enhancing the electronic efficiency and operational stability of the multi-beam klystron. This invention, by setting a circular through-hole at the center of the four-bridge all-metal meta-unit, modulates the electromagnetic field in the axial region to redistribute electromagnetic energy radially, maintaining a high degree of consistency in the axial electric field component distribution within the inner and outer electron beam channels. Under the same coupling coefficient, compared to the 115.7% difference in average effective characteristic impedance between the inner and outer electron beam channels of the meta-resonant cavity loaded with a double-ridged porous meta-unit, the difference in average effective characteristic impedance between the inner and outer electron beam channels in this invention is reduced to 2.2%. This effectively avoids insufficient transduction of the outer electron beam and backflow of the inner electron beam caused by uneven modulation during beam-wave interaction, thus significantly improving the electronic efficiency and stability of the multi-beam meta-klystron.

[0023] 3. The centrally symmetric structure and high mechanical strength of the four-bridge all-metal metacell synergistically enhance electric field uniformity and power adaptability. The four-bridge all-metal metacell of this invention employs a strictly centrally symmetric structure, ensuring that the current flow path on the metacell surface is centrally symmetrically distributed, effectively avoiding electric field inconsistencies caused by asymmetrical surface current distribution. Simultaneously, the four-bridge structure of the four-bridge all-metal metacell provides higher mechanical support capabilities in both the radial and circumferential directions, effectively improving the overall structural stiffness and deformation resistance. This structure, while meeting the requirements for multi-circular electron beam channel arrangement, also satisfies the mechanical strength requirements of megawatt-level klystrons, reducing the risk of electric field distortion and local breakdown caused by structural vibration, deformation, or instability. It avoids the adverse effects of asymmetrical surface current distribution on electric field uniformity, providing a balanced beam-wave interaction environment for multi-circular electron beam channels, thereby significantly improving the electronic efficiency and operational stability of multi-beam meta-klystrons. Attached Figure Description

[0024] Figure 1 A comparison of the electric field distribution of a resonant cavity loaded with a double-ridged porous meta-unit (left) and a novel resonant cavity loaded with a four-bridge all-metal meta-unit (right) in this invention.

[0025] Figure 2 This is a schematic diagram of the high-frequency structure of the multi-injection superstructure velocity regulator tube of the present invention.

[0026] Figure 3 This is a schematic diagram of the four-bridge all-metal metastructure unit of the present invention.

[0027] Figure 4 This is a schematic diagram of the input cavity of the four-bridge all-metal metastructure unit loaded in this invention.

[0028] Figure 5 This is a schematic diagram of the metamorphic intermediate cavity of the four-bridge all-metal metamorphic unit loaded in this invention.

[0029] Figure 6 This is a schematic diagram of the metamorphic output cavity of the four-bridge all-metal metamorphic unit loaded in this invention.

[0030] Figure 7 This is a comparison diagram of the Z-axis electric field distribution along the central axis of the inner and outer electron beam channels of the resonant cavity loaded with four-bridge all-metal meta-units (right) and the meta-resonant cavity loaded with double-ridge porous meta-units (left) in this invention.

[0031] Figure 8 This is a diagram showing the output power of the multi-injection superstructure klystron of the present invention.

[0032] Figure 9 This is a spectrum diagram of the multi-injection superstructure klystron of the present invention.

[0033] Reference numerals: 1 is the superstructure input cavity, 2 is the first superstructure intermediate cavity, 3 is the second superstructure intermediate cavity, 4 is the third superstructure intermediate cavity, 5 is the superstructure output cavity, 6 is the first group of drift tubes, 7 is the second group of drift tubes, 8 is the third group of drift tubes, 9 is the fourth group of drift tubes; 1-1 is the left drift tube wall of the superstructure input cavity, 1-2 is the right drift tube wall of the superstructure input cavity, 1-3 is the four-bridge all-metal superstructure unit loaded in the superstructure input cavity, 1-4 is the inner conductor of the standard coaxial energy input device; 1-5 is the outer conductor of the standard coaxial energy input device; 1-3-1 is the metal bridge, 1-3-2 is the outer ring electron beam channel, 1-3-3 is the inner ring electron beam channel, 1-3-4 is the metal inner... Ring, 1-3-5 is a metal outer ring, 1-3-6 is a circular through hole; 2-1 is the left drift tube wall of the first superstructure intermediate cavity, 2-2 is the right drift tube wall of the first superstructure intermediate cavity, 2-3 is a four-bridge all-metal superstructure unit loaded on the left drift tube of the first superstructure intermediate cavity, 2-4 is a four-bridge all-metal superstructure unit loaded on the right drift tube of the first superstructure intermediate cavity; 5-1 is the left drift tube wall of the superstructure output cavity, 5-2 is the right drift tube wall of the superstructure output cavity, 5-3 is a four-bridge all-metal superstructure unit loaded on the left drift tube of the superstructure output cavity, 5-4 is a four-bridge all-metal superstructure unit loaded on the right drift tube of the superstructure output cavity, 5-5 and 5-6 are both standard rectangular waveguide energy output devices. Detailed Implementation

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

[0035] The core of this invention lies in achieving a uniform radial distribution of the axial electric field in the resonant cavity of a multi-beam klystron while ensuring its miniaturization. This improves the consistency of the electric field distribution within the inner and outer electron beam channels of the klystron, reducing the difference in the modulation effect of the inner and outer electric fields on the electron beam. The basic idea is to miniaturize the klystron by loading a four-bridge all-metal meta-unit and utilizing its subwavelength characteristics. Simultaneously, by introducing a circular via of a specific radius at the center of the four-bridge all-metal meta-unit, the axial region of the meta-resonant cavity is transformed from a continuous vacuum state to a vacuum-to-metal boundary condition. This modulates the electromagnetic field distribution characteristics of the axial region, weakening the electric field and guiding the redistribution of electromagnetic energy in the radial direction. Specifically, this invention achieves the above-mentioned modulation by setting a circular via at the center of the inner metal ring of the four-bridge all-metal meta-unit, thereby altering the boundary conditions of the axial region of the meta-resonant cavity.

[0036] Although the fundamental mode electric field of the meta-resonant cavity remains quasi-TM after the circular through-hole is set. 010 The four-bridge all-metal meta-unit significantly affects the radial electric field distribution of this mode, thereby improving the consistency of the electric field between the inner and outer rings. In the meta-resonant cavity loaded with the double-ridged porous meta-unit, the axial electric field of the fundamental mode is strongest at the central axis and decreases monotonically with increasing radius. The electromagnetic energy is highly concentrated near the axis, making the electric field at the inner electron beam channel significantly stronger than that at the outer ring, resulting in obvious radial inhomogeneity. When a circular through-hole of a specific radius is set at the center of the four-bridge all-metal meta-unit, the originally continuous vacuum electromagnetic medium at the central axis is broken, transforming into a boundary condition from vacuum to metal. The electric field is forcibly constrained by the boundary condition, leading to quasi-TM 010 The axial electric field of the mode no longer exhibits a monotonically decreasing trend with increasing radius. Instead, due to the introduction of new electromagnetic boundary conditions through the circular through-hole, the fundamental mode electric field redistributes radially to satisfy the new electromagnetic constraints and energy distribution balance. This causes the electromagnetic energy, originally concentrated at the center, to expand outwards, resulting in a weakening of the central electric field and an enhancement of the electric field in the outer radius region. The electric field distribution within the resonant cavity is as follows: Figure 1 As shown, from the field distribution pattern, although the fundamental mode electric field as a whole still maintains a quasi-TM state... 010 The basic characteristics remain the same, but the radial distribution of the axial electric field has changed from being similar to a Bessel function of the first kind to a linear combination of Bessel functions of the first and second kind, with the peak position of the electric field shifting outward. As a result, the outer electron beam channels obtain a stronger axial modulation electric field, while the excessively strong electric field in the inner circle is suppressed. This ultimately significantly reduces the difference in electric field amplitude between multiple electron beam channels, achieving electric field homogenization and reducing the difference in the modulation effect of the inner and outer electric fields on the electron beam in the multi-beam klystron. The physical essence of this process is to reconstruct the electromagnetic energy distribution within the resonant cavity by introducing new electromagnetic boundaries, while keeping the mode type unchanged.

[0037] Figure 2 This is a schematic diagram of the high-frequency structure of the multi-beam metamorphic klystron of the present invention. The core feature of this high-frequency structure is that specific four-bridge all-metal metamorphic units are loaded in multiple metamorphic resonant cavities connected sequentially along the electron beam propagation path. Specifically, the high-frequency structure of the multi-beam metamorphic klystron of the present invention includes a metamorphic input cavity 1, a first group of drift tubes 6, a first metamorphic intermediate cavity 2, a second group of drift tubes 7, a second metamorphic intermediate cavity 3, a third group of drift tubes 8, a third metamorphic intermediate cavity 4, a fourth group of drift tubes 9, and a metamorphic output cavity 5, connected sequentially.

[0038] A schematic diagram of the four-bridge all-metal meta-unit is shown below. Figure 3 As shown, it adopts a concentric double-ring structure without openings, including a concentric outer metal ring 1-3-5 and an inner metal ring 1-3-4. Multiple electron beam channels are arranged on the inner metal ring, each distributed on a concentric circle of different radii, with uniform distribution of electron beam channels on each ring. The outer and inner metal rings are interconnected by four metal bridges 1-3-1, and a circular through-hole 1-3-6 is located at the center of the inner metal ring. The four-bridge all-metal meta-unit is centrally symmetrical. The metal "four-bridge" structure not only enhances the overall mechanical strength but also, through strict central symmetry design, ensures that the current flow path on the meta-unit surface is centrally symmetrically distributed, effectively avoiding the problem of uneven electric field caused by asymmetrical distribution of surface current flow paths. Simultaneously, the multi-electron beam channel structure achieves uniform arrangement of multiple electron beams, while the "opening-free" design helps reduce the local field enhancement effect under high-power operating conditions and suppresses the risk of electric field tip discharge.

[0039] A schematic diagram of the super-input cavity is shown below. Figure 4 As shown, it employs a standard coaxial energy input device with magnetic coupling (including inner conductor 1-4 and outer conductor 1-5). Inside the cavity is a pair of drift tubes, where 1-1 is the wall of the left drift tube and 1-2 is the wall of the right drift tube; the right drift tube of this pair is fixedly connected to a four-bridge all-metal metastructure unit 1-3.

[0040] The first, second, and third meta-intermediate cavities are all meta-resonant cavities loaded with four-bridge all-metal meta-units. Their structures are similar, differing only in some dimensional parameters. A schematic diagram of the meta-intermediate cavity is shown below. Figure 5 As shown, each of them contains two four-bridge all-metal meta-units 2-3 and 2-4, and a pair of drift tubes. 2-1 is the wall of the left drift tube, and 2-2 is the wall of the right drift tube. A four-bridge all-metal meta-unit 2-3 is loaded on the left drift tube, and a four-bridge all-metal meta-unit 2-4 is loaded on the right drift tube.

[0041] Figure 6This is a schematic diagram of the meta-output cavity with four-bridge all-metal meta-units loaded in this invention. The meta-output cavity contains standard rectangular waveguide energy output devices 5-5 and 5-6, two four-bridge all-metal meta-units 5-3 and 5-4, and a pair of drift tubes. 5-1 is the wall of the left drift tube, and 5-2 is the wall of the right drift tube. The right drift tube in the meta-output cavity is fixedly connected to one four-bridge all-metal meta-unit 5-4, and the left drift tube is fixedly connected to the other four-bridge all-metal meta-unit 5-3. 5-5 and 5-6 are standard rectangular waveguide energy output devices using electrical coupling.

[0042] All drift tubes are composed of multiple cylindrical tubes with the same radius as the electron beam channel to ensure continuous electron beam transmission, and their lengths are determined according to the modulation phase required by each cavity.

[0043] Example 1

[0044] Take an S-band 20-injection super-klysonic tube with a working voltage of 60kV, a single injection current of 7A, and a total current of 140A as an example.

[0045] The metal bridge width of the four-bridge all-metal meta-unit in the meta-input cavity is 4mm; the outer radius of the outer metal ring is 36.1mm, and the inner radius is 32mm; the radius of the inner metal ring is 27mm; a circular through-hole with a radius of 1mm is provided; two rings of electron beam channels are provided on the inner metal ring, with the inner ring electron beam channels distributed on a circumference with a radius of 12mm and the outer ring electron beam channels distributed on a circumference of 21mm. There are 8 electron beam channels in the inner ring and 12 electron beam channels in the outer ring, with each electron beam channel having a radius of 3.16mm; the transit gap length in the meta-input cavity, i.e., the distance between the right end face of the left drift tube and the left end face of the right drift tube in the resonant cavity, is set to 8mm; the distance between the four-bridge all-metal meta-unit and the right end face of the input cavity is 17.5mm; the distance between the two end faces of the resonant cavity is 22mm; and the radius of the resonant cavity is 36.1mm. The length of the inner conductor extending into the resonant cavity of the standard coaxial energy input device is 4mm, the length of the portion of the inner conductor parallel to the central axis of the resonant cavity is 19.3mm, and the diameter of the inner conductor is 2mm.

[0046] The outer radius of the four-bridge all-metal meta-unit in the first meta-cavity is 37.6 mm, and the inner radius is 34 mm. A circular through-hole with a radius of 1.5 mm is provided. The spacing between two four-bridge all-metal meta-units is 14 mm, the distance between the two end faces of the resonant cavity is 22 mm, and the radius of the resonant cavity is 37.6 mm. The remaining dimensions are the same as those of the four-bridge all-metal meta-unit in the meta-input cavity.

[0047] In the second meta-cavity, the outer radius of the metal outer ring of the four-bridge all-metal meta-unit is 36.1 mm, and the inner radius is 32 mm; the radius of the circular through hole is 1.5 mm; the radius of the resonant cavity is 36.1 mm; the spacing between the two four-bridge all-metal meta-units is 14 mm, the distance between the two end faces of the resonant cavity is 22 mm, and the other dimensions are the same as those of the first meta-cavity.

[0048] The outer radius of the metal outer ring of the four-bridge all-metal meta-unit in the third meta-cavity is 36.07 mm, the inner radius is 33 mm, and the radius of the circular through hole is 1.5 mm; the radius of the resonant cavity is 36.07 mm, and the other dimensional parameters are the same as those of the first meta-cavity.

[0049] The outer radius of the metal outer ring of the four-bridge all-metal meta-unit in the meta-output cavity is 37mm, and the inner radius is 33mm; the radius of the circular through hole is 2mm; the gap length in the meta-output cavity is set to 10mm; the spacing between the four-bridge all-metal meta-units loaded on the left and right drift tubes is 19mm; the distance between the two end faces of the resonant cavity is 32mm; the radius of the resonant cavity is 37mm; and the other dimensional parameters are the same as those of the first meta-intermediate cavity.

[0050] All four-bridge all-metal metacells have a thickness of 2 mm.

[0051] Under the aforementioned structural parameters, a comparative simulation study was conducted on two types of meta-resonant cavities: one loaded with a double-ridged porous meta-unit, and the other with a four-bridge all-metal meta-unit as described in this invention. The results show that within the same resonant cavity, the electric field strength between the inner and outer electron beam channels is similar; however, when using the double-ridged porous meta-unit, there is a significant difference in the electric field strength between the inner and outer rings. To compare this difference, the Z-axis electric field distribution along the central axis of the inner and outer electron beam channels at corresponding positions in the two resonant cavities is plotted as follows: Figure 7 As shown. The results indicate that the electric field strengths in the inner and outer electron beam channels of the metamorphic resonant cavity of this invention are similar. To further quantify the differences in electric field strength, the effective characteristic impedance M, commonly used in klystrons, is employed. 2 R / Q is used to characterize the modulation effect of the electric field established within the electron beam channel of the resonant cavity on the electron beam, where M is the ratio of the modulation voltage experienced by the electron beam as it passes through the transit gap to the actual modulation voltage established on the transit gap. R / Q is the sum of the squares of the axial integral of the electric field on the transit gap of the resonant cavity. The ratio, angular frequency, The total cavity energy characterizes the magnitude of the electric field established within the electron beam channel under the condition of a fixed energy storage and resonant frequency in the resonant cavity. Based on simulation data, calculations show that, under the same coupling coefficient, the average effective characteristic impedance difference between the inner and outer electron beam channels of the metaresonant cavity loaded with double-ridged porous metaunits reaches as high as 115.7% (MTM_RRC), while the average effective characteristic impedance difference between the inner and outer electron beam channels of the metaresonant cavity loaded with four-bridge all-metal metaunits in this invention is only 2.2% (MTM_CRC).

[0052] The high-frequency structure of the present invention, which incorporates a four-bridge all-metal metastructure, was simulated in CST. Based on this invention, the multi-beam metastructure klystron achieved significant beam-wave interaction enhancement under operating conditions of 60kV, single-beam current of 7A, and total current of 140A, with a peak output power reaching 5.76MW. Figure 8 As shown, the corresponding electronic efficiency is 68%, and the gain reaches 54.6 dB. The spectrum of the multi-beam superklysonic klystron output signal is shown below. Figure 9 As shown, the amplitude of the higher harmonics of the output signal is more than 30 dB smaller than that of the fundamental wave, and the output signal spectrum is clean. For comparison, a high-frequency structure loaded with a double-ridged porous metastructure was simulated in CST. Under the conditions of an operating voltage of 60 kV, a single-beam current of 7 A, and a total current of 140 A, with the same resonant cavity position and frequency, the peak output power reached 4.62 MW, corresponding to an electronic efficiency of 55% and a gain of 56.6 dB.

[0053] Simulation results further demonstrate that the high-frequency structure of the present invention maintains high output power and gain while taking into account high electronic efficiency and good working stability. It verifies the feasibility and superiority of the proposed high-frequency structure of a multi-beam metamorphic klystron with a four-bridge all-metal metamorphic unit with a circular through-hole in solving the inconsistency of electric field in the inner and outer electron bead channels of the klystron and further improving the electronic efficiency of the multi-beam metamorphic klystron.

[0054] 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 structure loaded with a four-bridge all-metal meta-unit, characterized in that, It includes a superstructure input cavity, a first set of drift tubes, a first superstructure intermediate cavity, a second set of drift tubes, a second superstructure intermediate cavity, a third set of drift tubes, a third superstructure intermediate cavity, a fourth set of drift tubes, and a superstructure output cavity, which are connected in sequence; each set of drift tubes consists of multiple cylindrical drift tubes, and the number of drift tubes is the same as the number of electron beams; The superstructure input cavity, the first superstructure intermediate cavity, the second superstructure intermediate cavity, the third superstructure intermediate cavity, and the superstructure output cavity are all superstructure resonant cavities loaded with four-bridge all-metal superstructure units; and the structures of the first superstructure intermediate cavity, the second superstructure intermediate cavity, and the third superstructure intermediate cavity are similar, each containing a pair of internal drift tubes and two four-bridge all-metal superstructure units, wherein the four-bridge all-metal superstructure units are respectively loaded at the center positions of the left drift tube and the right drift tube of the superstructure intermediate cavity; The meta-input cavity is equipped with a standard coaxial energy input device, a pair of internal drift tubes, and a four-bridge all-metal meta-unit. The left drift tube in the pair of internal drift tubes is connected to the electron gun of the multi-beam meta-klystron. The four-bridge all-metal meta-unit is loaded at the center of the right drift tube in the pair of internal drift tubes. The metamorphic output cavity is provided with a pair of standard rectangular waveguide energy output devices, a pair of internal drift tubes and two four-bridge all-metal metamorphic units, wherein the four-bridge all-metal metamorphic units are respectively loaded at the center positions of the left drift tube and the right drift tube of the metamorphic output cavity; All four-bridge all-metal meta-units have similar structures and are centrally symmetrical. They include concentric metal outer rings and metal inner rings. The metal inner rings have multiple electron beam channels uniformly arranged on concentric circles of different radii. The metal outer rings and metal inner rings are interconnected by four metal bridges, with adjacent metal bridges spaced 90° apart. A circular through-hole is provided at the center of the metal inner ring. The circular through-hole is used to reduce the difference in electric field between the inner and outer ring electron beam channels.

2. The high-frequency structure as described in claim 1, characterized in that, The radius of the circular through-hole is related to the fundamental mode electric field characteristics of the superstructure resonator of the loaded four-bridge all-metal superstructure unit. Specifically, the smaller the radius of the circular through-hole, the greater the difference in fundamental mode electric field intensity in the electron beam channels of the inner and outer rings of the superstructure resonator; the larger the radius of the circular through-hole, the smaller the difference in fundamental mode electric field intensity in the electron beam channels of the inner and outer rings of the superstructure resonator.

3. The high-frequency structure as described in claim 2, characterized in that, The radius of the circular through hole is 1~2mm.

4. The high-frequency structure as described in claim 1, characterized in that, The electron beam channels on the inner metal ring are distributed on two concentric circles with different radii.

5. The high-frequency structure as described in claim 1, characterized in that, The standard coaxial energy input device adopts a magnetic coupling method and includes a coaxial input inner conductor and a coaxial input outer conductor. The end of the inner conductor is fixed to the inner wall of the meta-input cavity and is used to couple microwave signals into the klystron. The outer conductor is connected to the outer wall of the meta-input cavity.

6. The high-frequency structure as described in claim 1, characterized in that, The pair of standard rectangular waveguide energy output devices are used to output amplified microwave signals, and are electrically coupled, both being standard rectangular waveguides; the standard rectangular waveguides are connected to the metamaterial output cavity to realize the output of microwave signals.

7. The high-frequency structure as described in claim 1, characterized in that, The lengths of the first, second, third, and fourth groups of drift tubes are determined by the phase modulation requirements of the electron beam wave in each stage of the meta-resonant cavity, and their radii are consistent with the radius of the electron beam channel, thereby ensuring the continuity and stability of multiple electron beams during transmission.

8. The high-frequency structure as described in claim 1, characterized in that, The geometric dimensions of the superstructure input cavity, superstructure intermediate cavity, and superstructure output cavity are all determined by the operating frequency of the fundamental mode electric field of the superstructure resonant cavity. This ensures that when the electron beam enters the next superstructure resonant cavity after clustering in the drift tube, it is modulated by the fundamental mode electric field of the optimal frequency, thereby enabling the electron beam to achieve the best clustering effect in the output cavity.

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