Slow wave structure and control method, control device and traveling wave tube thereof

Abstract

The application discloses a slow wave structure and a control method and device thereof and a traveling wave tube, relates to the field of vacuum electron technology, and is used for receiving an electron beam and electromagnetic waves. The control method of the slow wave structure obtains a candidate period length distribution and inputs a preset algorithm to obtain a coupling impedance and a normalized phase velocity distribution, substitutes the normalized phase velocity distribution into a differential equation to calculate a normalized amplitude distribution, combines a power equation to obtain output power, takes the output power as a reference value, iteratively updates the candidate period length distribution by using a particle swarm algorithm until convergence, and outputs an optimal non-uniform period length distribution. According to the non-uniform period length distribution, the period length of the slow wave structure is adjusted, the electromagnetic wave phase velocity is accurately controlled, the electromagnetic wave phase velocity and the electron beam motion speed are kept in an optimal synchronous state in the whole process of the interaction between the electron beam and the electromagnetic wave, the interaction efficiency between the electron beam and the electromagnetic wave is significantly improved, and the output power and the electron efficiency of the whole traveling wave tube are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of vacuum electronics technology, and in particular to a slow-wave structure and its control method, control device and traveling wave tube. Background Technology

[0002] Traveling wave tubes (TWTs), as wideband, high-gain millimeter-wave terahertz vacuum tube devices, play an irreplaceable role in high-resolution radar, electronic warfare, and satellite communication systems. Their core advantage lies in their ability to simultaneously achieve high output power and extremely wide operating bandwidth, a feat currently unattainable for solid-state devices. However, with the continuous increase in the demands of modern electronic information systems for operating range and interference capabilities, the power capacity of TWTs is facing severe technical bottlenecks. In high-frequency bands (such as W-band, H-band, and above), the output power of traditional TWTs is increasingly difficult to increase due to the physical limitations of the slow-wave structure's size. Further power increases are also significantly constrained by the declining interaction efficiency between the electron beam and the slow-wave structure. Overcoming this power bottleneck, enabling TWTs to achieve higher output power and efficiency while maintaining wideband characteristics, has become a core research focus in the current TWT field, directly impacting whether the performance of next-generation electronic systems can achieve a leapfrog development.

[0003] Currently, there are two main technical approaches in the industry to improve the overall output power and electronic efficiency of traveling wave tubes (TWTs), both of which have significant technical drawbacks: First, increasing the interaction time by extending the slow-wave circuit length to improve efficiency inevitably leads to gain saturation, exacerbates nonlinear distortion, and easily induces back-wave oscillations, affecting device stability. Second, while existing phase rematching techniques can improve output power through multiple transductions of the electron beam and electromagnetic wave, they are limited to a few periods or segmented local phase matching at the end of the slow-wave structure, failing to fully realize the potential for output power improvement. Furthermore, this local optimization method requires extensive electromagnetic simulation and iterative analysis, resulting in high computational load, time consumption, and high R&D costs. In summary, the limitations of traditional technical approaches are becoming increasingly prominent, and the need to improve the output power and electronic efficiency of TWTs is becoming increasingly urgent. A highly efficient efficiency improvement solution is urgently needed to address the shortcomings of existing technologies and meet the performance requirements of next-generation electronic systems for TWTs. Summary of the Invention

[0004] The main objective of this invention is to propose a slow-wave structure and its control method, control device, and traveling-wave tube, aiming to solve the technical problems of difficulty in improving the overall output power and electronic efficiency of existing traveling-wave tubes, as well as the technical problems of existing phase rematching technology which only performs local optimization, has a large amount of computation, is time-consuming, and has high R&D costs.

[0005] To achieve the above objectives, the present invention proposes a control method for a slow-wave structure, wherein the slow-wave structure is used to receive electron beams and electromagnetic waves, and the control method for the slow-wave structure includes: Obtain the candidate period length distribution of the slow-wave structure; The candidate period length distribution of the slow wave structure is input into a preset algorithm to obtain the coupling impedance distribution and normalized phase velocity distribution corresponding to the candidate period length distribution. Substituting the coupling impedance distribution and the normalized phase velocity distribution into the normalized differential equation, the normalized amplitude distribution of the slow wave structure along the axial direction is calculated. Based on the normalized amplitude distribution at the end of the slow wave structure and the power calculation equation, the output power of the slow wave structure under the candidate period length distribution is calculated. Using the output power as a baseline, the candidate period length distribution is iteratively updated using a particle swarm optimization algorithm until the number of iterations reaches a preset maximum number of iterations, or until the increment of the output power is lower than a preset increment threshold for a preset number of consecutive preset number of iterations before reaching the preset maximum number of iterations, and the optimal non-uniform period length distribution of the slow wave structure is output. The length of each period of the slow-wave structure is adjusted periodically according to the optimal non-uniform period length distribution so that the electromagnetic wave phase velocity and the electron beam motion velocity remain synchronized during the interaction process.

[0006] In one embodiment, the step of inputting the candidate period length distribution of the slow-wave structure into a preset algorithm to calculate the coupling impedance distribution and normalized phase velocity distribution corresponding to the candidate period length distribution is specifically calculated using the following formula: ; ; ; in, The phase constants of slow-wave structure units with different period lengths are given. This represents the phase delay of the electromagnetic wave within the corresponding period length. The period length of the slow-wave structure unit; For coupling impedance, The electric field intensity along the axial (z-direction) axis for different period lengths. The radio frequency power flow per unit time and unit length in slow wave structure units with different period lengths; This represents the normalized phase velocity of electromagnetic waves within the slow-wave structural unit. At the speed of light, The angular frequency corresponding to the preset optimized frequency point.

[0007] In one embodiment, the step of substituting the coupling impedance distribution and the normalized phase velocity distribution into the normalized differential equation to calculate the normalized amplitude distribution of the slow-wave structure along the axial direction specifically includes: Construct the normalized circuit amplitude equation and phase transformation equation in the normalized differential equation system:

[0008] ;

[0009] ; Construct the normalized electron motion equations in the normalized system of differential equations:

[0010] ; Construct the electronic phase differential equation in the normalized differential equation system: ; Where y is the normalized distance, and A(y) is the normalized amplitude distributed along the axis. The phase angle distribution is as follows: This represents the initial phase of the electron. This represents the offset of the electron's velocity relative to its initial velocity. Let be the phase change of the electron at position y relative to the initial phase, b be the injection velocity parameter determined based on the normalized phase velocity, C be the gain factor determined based on the coupling impedance distribution, and d be the loss factor. The space charge field strength; Substituting the injection velocity parameter and the gain factor into the constructed normalized differential equation system and solving them jointly yields the normalized amplitude distribution of the slow wave structure along the axial direction.

[0011] In one embodiment, the step of constructing the normalized differential equation specifically includes: Obtaining the circuit equations: ; Where z is the axial position and t is the time. The axial electric field strength is... The axial electron beam line density, Let be the phase velocity of the electromagnetic wave, d be the loss factor, and ω be the angular frequency of the electromagnetic wave. For coupling impedance, For gain factor, The direct current for electron injection, The DC voltage of the electron beam; Obtain the equation of motion for the electron: ; in, η represents the space charge field intensity; η = e / m represents the electron mass-to-charge ratio, where e is the electron charge and m is the electron mass. Obtain the normalized distance: ;

[0012] Where y is the normalized distance. The initial velocity of the electron takes into account relativistic effects; Obtain the initial phase of the electron: ; Acquisition speed of electrons: ; in, This represents the offset of the electron's velocity relative to its initial velocity; Substituting the obtained normalized distance, initial phase of the electron, and electron velocity into the circuit equations, we obtain the normalized circuit amplitude equation and the phase transformation equation, where, For injection speed parameters; Substituting the obtained normalized distance, initial phase of the electron, and electron velocity into the electron motion equation, the normalized electron motion equation is obtained. The formula for obtaining the difference between the phase angle of the electron wave and the phase angle of the electromagnetic wave is: ; in, Let y be the phase change of the electron at position y relative to the initial phase; Substituting the obtained normalized distance, initial phase of the electron, and electron velocity into the difference formula and performing differentiation, the electron phase differential equation is obtained.

[0013] In one embodiment, the calculation of the output power of the slow-wave structure under the candidate period length distribution, based on the normalized amplitude and power calculation equations of the normalized amplitude distribution at the end of the slow-wave structure, is specifically obtained using the following formula: ; Where P(y) is the output power, A(y) is the normalized amplitude distribution at the end of the slow-wave structure, is the phase angle distribution, b is the injection velocity parameter determined based on the normalized phase velocity distribution, and C is the gain factor corresponding to the slow-wave structure unit at the end of the slow-wave structure. The direct current for electron injection, The DC voltage of the electron beam.

[0014] In one embodiment, the step of using the output power as a reference value to iteratively update the candidate period length distribution using a particle swarm optimization algorithm until the number of iterations reaches a preset maximum number of iterations, or where the increment of the output power is lower than a preset increment threshold for a preset number of consecutive preset number of iterations before reaching the preset maximum number of iterations, and then outputting the optimal non-uniform period length distribution of the slow wave structure specifically includes: The vector formed by the period lengths of each slow wave structure unit of the slow wave structure is set as the position vector of the particle, and the particle swarm is initialized within the preset range of period length values. In each iteration, the fitness value of each particle after initialization is calculated based on the output power, and the historical best solution of each particle and the global historical best solution of the particle swarm are updated. The iteration velocity and position vector of each particle are updated based on the historical best solution of each particle and the global historical best solution of the particle swarm to generate the updated candidate period length distribution. If the number of iterations reaches the preset maximum number of iterations, or if the increment of the output power is lower than the preset increment threshold for a preset number of consecutive iterations before reaching the preset maximum number of iterations, the candidate period length distribution corresponding to the global historical optimal solution of the population will be output as the optimal non-uniform period length distribution.

[0015] The present invention also proposes a control device for a slow-wave structure, comprising a processor and a memory, wherein the memory stores a control program for the slow-wave structure, and when the control program for the slow-wave structure is executed by the processor, the control method for the slow-wave structure described above is implemented.

[0016] This invention also proposes a slow-wave structure, comprising: Multiple slow-wave structure units are arranged sequentially along the axial direction, and the period length of the multiple slow-wave structure units first increases and then decreases along the axial direction, then increases again and then decreases. The control device described above is electrically connected to a plurality of the slow-wave structure units.

[0017] The present invention also proposes a traveling wave tube, comprising: The slow-wave structure as described above; An electron gun is used to generate an electron beam and inject the electron beam into the slow-wave structure; An input waveguide mode is set at the input end of the slow wave structure to introduce electromagnetic waves, and the introduced electromagnetic waves are impedance matched before being input into the slow wave structure. An output waveguide mode is disposed at the output end of the slow wave structure to export the electromagnetic wave after power amplification by the slow wave structure. A dielectric attenuator is disposed on the slow-wave structure to absorb electromagnetic waves reflected from inside the slow-wave structure and block the feedback path of the electromagnetic waves, thereby suppressing self-excited oscillations and parasitic oscillations. In this process, the electron beam and the electromagnetic wave enter the slow-wave structure together to perform beam-wave interaction. The slow-wave structure is used to reduce the phase velocity of the electromagnetic wave and keep the phase velocity of the electromagnetic wave synchronized with the velocity of the electron beam during the interaction process, so as to transfer the energy of the electron beam to the electromagnetic wave for power amplification.

[0018] In one embodiment, the dielectric attenuator is positioned close to the input waveguide mode, and the distance between the dielectric attenuator and the input waveguide mode is one-third of the distance between the input waveguide mode and the output waveguide mode.

[0019] In the technical solution of this invention, the candidate period length distribution of the slow wave structure is obtained and input into a preset algorithm to obtain the corresponding coupling impedance distribution and normalized phase velocity distribution. The coupling impedance distribution and normalized phase velocity distribution are substituted into the normalized differential equation to calculate the normalized amplitude distribution of the slow wave structure along the axial direction. Based on the normalized amplitude and power calculation equation of the normalized amplitude distribution at the end of the slow wave structure, the output power of the slow wave structure under the candidate period length distribution is calculated. Using the output power as the benchmark value, the candidate period length distribution is iteratively updated using a particle swarm optimization algorithm until the number of iterations reaches the preset maximum number of iterations, or before reaching the preset maximum number of iterations, the increment of output power is continuously lower than the preset increment threshold for a preset number of times. The optimal non-uniform period length distribution of the slow wave structure is then output. The length of each period of the slow wave structure is then adjusted cycle by cycle according to the optimal non-uniform period length distribution to achieve precise control of the electromagnetic wave phase velocity. Thus, in the entire process of the interaction between the electron beam and the electromagnetic wave, the electromagnetic wave phase velocity and the electron beam velocity are always kept in the optimal synchronization state. Through the aforementioned full-cycle phase rematching strategy, the energy of the electron beam can be continuously and efficiently exchanged with the electromagnetic wave, significantly improving the interaction efficiency. This, in turn, increases the overall output power and electronic efficiency of the traveling wave tube while effectively suppressing common problems in traditional methods, such as gain saturation and nonlinear distortion. Furthermore, unlike traditional phase velocity jump techniques (which primarily rely on electromagnetic simulation software to independently optimize each cycle of the slow-wave structure), this invention combines normalized differential equations and particle swarm optimization to optimize the full-cycle length distribution of the slow-wave structure using numerical calculations. This effectively avoids the problem of easily getting trapped in local optima when optimizing the cycle length of each slow-wave structure individually, while significantly saving the computational time cost of electromagnetic simulation software. This, in turn, shortens the development cycle of the traveling wave tube and reduces development costs. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0021] Figure 1 The flowchart of the slow-wave structure control method of the present invention is as follows. Figure 1 ; Figure 2 The flowchart of the slow-wave structure control method of the present invention is as follows. Figure 2 ; Figure 3 The flowchart of the slow-wave structure control method of the present invention is as follows. Figure 3 ; Figure 4 The flowchart of the slow-wave structure control method of the present invention is as follows. Figure 4 ; Figure 5 The flowchart of the slow-wave structure control method of the present invention is as follows. Figure 5 ; Figure 6 This is a schematic diagram of the traveling wave tube structure of the present invention; Figure 7 for Figure 6 Schematic diagram of the xoz plane of a medium- and slow-wave structure; Figure 8 This is a comparison diagram of the coupling impedance and normalized phase velocity of the slow-wave structure of the present invention under different period lengths. Figure 9 This is a schematic diagram of the circuit functional modules of the control device for the slow-wave structure of the present invention; Figure 10 This is a schematic diagram of the circuit functional modules of the slow-wave structure of the present invention; Figure 11 This is a graph showing the normalized amplitude as a function of the normalized distance in this invention. Figure 12 This invention presents the optimal non-uniform period length distribution containing 103 sets of parameters obtained through the particle swarm optimization algorithm. Figure 13 This is a diagram showing the output power of the traveling wave tube of the present invention; Figure 14 This is the spectrum diagram of the traveling wave tube of the present invention; Figure 15 This is a comparison chart of the output power and electronic efficiency of the traveling wave tube of the present invention and the traveling wave tube of the prior art.

[0022] Explanation of icon numbers: 1000 Traveling wave tube; 100 Slow wave structure; 10 Slow wave structure unit; 20 Control device; 21 Processor; 22 Memory; 200 Input waveguide mode; 300 Output waveguide mode; 400 Dielectric attenuator.

[0023] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Traveling wave tubes (TWTs), as wideband, high-gain millimeter-wave terahertz vacuum tube devices, play an irreplaceable role in high-resolution radar, electronic warfare, and satellite communication systems. Their core advantage lies in their ability to simultaneously achieve high output power and extremely wide operating bandwidth, a feat currently unattainable for solid-state devices. However, with the continuous increase in the demands of modern electronic information systems for operating range and interference capabilities, the power capacity of TWTs is facing severe technical bottlenecks. In high-frequency bands (such as W-band, H-band, and above), the output power of traditional TWTs is increasingly difficult to increase due to the physical limitations of the slow-wave structure's size. Further power increases are also significantly constrained by the declining interaction efficiency between the electron beam and the slow-wave structure. Overcoming this power bottleneck, enabling TWTs to achieve higher output power and efficiency while maintaining wideband characteristics, has become a core research focus in the current TWT field, directly impacting whether the performance of next-generation electronic systems can achieve a leapfrog development.

[0026] Currently, there are two main technical approaches in the industry to improve the overall output power and electronic efficiency of traveling wave tubes (TWTs), both of which have significant technical drawbacks: First, increasing the interaction time by extending the slow-wave circuit length to improve efficiency inevitably leads to gain saturation, exacerbates nonlinear distortion, and easily induces back-wave oscillations, affecting device stability. Second, while existing phase rematching techniques can improve output power through multiple transductions of the electron beam and electromagnetic wave, they are limited to a few periods or segmented local phase matching at the end of the slow-wave structure, failing to fully realize the potential for output power improvement. Furthermore, this local optimization method requires extensive electromagnetic simulation and iterative analysis, resulting in high computational load, time consumption, and high R&D costs. In summary, the limitations of traditional technical approaches are becoming increasingly prominent, and the need to improve the output power and electronic efficiency of TWTs is becoming increasingly urgent. A highly efficient efficiency improvement solution is urgently needed to address the shortcomings of existing technologies and meet the performance requirements of next-generation electronic systems for TWTs.

[0027] This invention proposes a control method for a slow-wave structure 100.

[0028] Please see Figure 1 In one embodiment of the present invention, the control method of the slow-wave structure 100 includes: S100, Obtain the candidate period length distribution of the slow wave structure; S200. Input the candidate period length distribution of the slow wave structure into the preset algorithm to obtain the coupling impedance distribution and normalized phase velocity distribution corresponding to the candidate period length distribution. S300. Substitute the coupling impedance distribution and normalized phase velocity distribution into the normalized differential equation to calculate the normalized amplitude distribution of the slow wave structure along the axial direction. S400. Based on the normalized amplitude and power calculation equations at the end of the slow wave structure, the output power of the slow wave structure under the candidate period length distribution is calculated. S500: Using the output power as a baseline, the particle swarm algorithm is used to iteratively update the candidate period length distribution until the number of iterations reaches the preset maximum number of iterations, or before reaching the preset maximum number of iterations, the increment of the output power is lower than the preset increment threshold for a preset number of consecutive preset number of iterations, and the optimal non-uniform period length distribution of the output slow wave structure is output. S600. The length of each period of the slow wave structure is adjusted periodically according to the optimal non-uniform period length distribution so that the electromagnetic wave phase velocity and the electron beam motion velocity remain synchronized during the interaction process.

[0029] In this embodiment, the slow-wave structure 100 is used to receive electron beams and electromagnetic waves, and is the core interaction component in the traveling wave tube 1000 that realizes the conversion of electron beam kinetic energy into electromagnetic wave energy. The traveling wave tube 1000 is a wideband, high-gain millimeter-wave terahertz vacuum electronic device, which mainly includes an electron gun, an input waveguide modem 200, an output waveguide modem 300, and a slow-wave structure 100. The electron gun is used to emit and form an electron beam that propagates along the axial direction; the input waveguide modem 200 is used to couple externally input microwave signals into the slow-wave structure 100 to form electromagnetic waves that interact with the electron beam; the output waveguide modem 300 is used to couple the amplified electromagnetic waves in the slow-wave structure 100 to an external load; the slow-wave structure 100 is used to reduce the phase velocity of the electromagnetic waves so that the phase velocity of the electromagnetic waves keeps synchronized with the electron beam's motion speed and realizes continuous energy exchange between the electron beam and the electromagnetic waves. The working principle of the traveling wave tube 1000 is to use the electron beam generated by the electron gun to interact synchronously with the electromagnetic wave in the slow wave structure 100, so that the kinetic energy of the electron beam is continuously converted into the energy of the electromagnetic wave to achieve signal amplification.

[0030] To overcome the limitations of existing phase rematching techniques, which are restricted to a few cycles or segmented local phase matching at the end of the slow-wave structure 100, thus limiting the potential for output power improvement, and the high computational cost, time-consuming, and costly due to the reliance on extensive electromagnetic simulation iterations, the control method for the slow-wave structure 100 first obtains the candidate period length distribution. The candidate period length distribution characterizes the initial arrangement of each period length along the axial direction of the slow-wave structure 100, serving as the starting input parameter for subsequent optimization iterations. Subsequently, the candidate period length distribution of the slow-wave structure 100 is input into a pre-defined algorithm to obtain the corresponding coupling impedance distribution and normalized phase velocity distribution. The pre-defined algorithm establishes a mapping relationship between period length, coupling impedance, and normalized phase velocity based on a pre-constructed sample dataset. This allows for the rapid derivation of the coupling impedance distribution and normalized phase velocity distribution corresponding to any candidate period length distribution, thus replacing the cumbersome process of independently modeling and solving each cycle of the slow-wave structure 100 using traditional electromagnetic simulation software. This significantly reduces the time cost and computational resource consumption required to obtain the coupling impedance distribution and normalized phase velocity distribution.

[0031] After obtaining the coupling impedance distribution and normalized phase velocity distribution, these distributions are substituted into the normalized differential equation to calculate the normalized amplitude distribution along the axial direction of the slow-wave structure 100. The normalized differential equation describes the evolution of the electromagnetic wave amplitude as it propagates along the axial direction of the slow-wave structure 100. By using the coupling impedance distribution and normalized phase velocity distribution as coefficients of the equation, the variation trend of the electromagnetic wave amplitude along the entire length of the slow-wave structure 100 can be quickly solved numerically. Then, based on the normalized amplitude distribution at the end of the slow-wave structure 100 and the power calculation equation, the output power of the slow-wave structure 100 under the candidate period length distribution is calculated. The power calculation equation transforms the normalized amplitude at the end of the slow-wave structure 100 into a quantifiable output power index, enabling the performance evaluation of the candidate period length distribution to be completed instantly through lightweight numerical computation. This avoids the enormous overhead of repeatedly performing three-dimensional electromagnetic simulations of the entire period of the slow-wave structure 100, significantly saving the computational time cost of electromagnetic simulation software.

[0032] To search for the periodic arrangement scheme that maximizes output power globally, a particle swarm optimization (PSO) algorithm is used to iteratively update the candidate period length distribution, using output power as a baseline value. This continues until the maximum number of iterations is reached, or until the output power increment is below a preset increment threshold for a preset number of consecutive iterations before reaching the maximum number of iterations. This indicates that the PSO algorithm's search for the candidate period length distribution has converged and further iterations have limited effect on improving output power. The optimal non-uniform period length distribution for the output slow wave structure 100 is then determined. Here, the maximum number of iterations is the upper limit of the maximum number of iterations allowed by the PSO algorithm, for example, 400; the preset number of iterations is the minimum statistical window length required to continuously satisfy the increment condition for the output power to stabilize, for example, 30; and the preset increment threshold is the power difference limit for determining whether the change in output power between two adjacent iterations is sufficiently small, for example, 0.0001W. In other words, when the particle swarm optimization algorithm has completed 400 iterations, or when the output power increment has been less than 0.0001W for 30 consecutive iterations before completing 400 iterations, it is considered that the current search result has sufficiently approximated the better solution in the feasible region. At this point, the iteration is terminated and the corresponding optimal non-uniform period length distribution is output.

[0033] The particle swarm optimization (PSO) algorithm can perform global search and local optimization within the multidimensional solution space of candidate period length distributions, gradually approaching the optimal solution that maximizes output power. This effectively improves the situation where individual optimization of each slow-wave structure with a period length of 100 is prone to getting trapped in local optima. Furthermore, since performance evaluation in each iteration is rapidly completed using a pre-defined algorithm and normalized differential equations, rather than relying on time-consuming electromagnetic simulations, the total computation time required to find the optimal non-uniform period length distribution is significantly reduced, significantly improving optimization efficiency and lowering computational costs during the research and development process.

[0034] After obtaining the optimal non-uniform period length distribution, the length of each period of the slow-wave structure 100 is adjusted cycle-by-cycle according to the optimal non-uniform period length distribution to keep the electromagnetic wave phase velocity and the electron beam motion velocity synchronized during the interaction. This cycle-by-cycle adjustment ensures that the actual physical dimensions of the slow-wave structure 100 precisely match the optimal non-uniform period length distribution, thereby maintaining dynamic synchronization between the electromagnetic wave phase velocity and the electron beam motion velocity throughout the entire axial stroke of the electron beam-electromagnetic wave interaction. Compared to existing technologies that only perform phase rematching in a few periods at the end of the slow-wave structure 100, cycle-by-cycle adjustment achieves phase rematching throughout the entire slow-wave structure 100 period, promoting the continuous and efficient transfer of electron beam energy to the electromagnetic wave, which significantly improves the overall output power and electronic efficiency of the traveling-wave tube 1000. Simultaneously, since the process of obtaining the optimal non-uniform period length distribution eliminates the reliance on extensive electromagnetic simulation and iterative analysis, the overall development cycle is shortened, and the development cost is correspondingly reduced, thus better meeting the dual requirements of high performance and low cost for the traveling-wave tube 1000 in next-generation electronic systems.

[0035] In the technical solution of this invention, the candidate period length distribution of the slow wave structure 100 is obtained and input into a preset algorithm to obtain the corresponding coupling impedance distribution and normalized phase velocity distribution. The coupling impedance distribution and normalized phase velocity distribution are substituted into the normalized differential equation to calculate the normalized amplitude distribution of the slow wave structure 100 along the axial direction. Based on the normalized amplitude distribution at the end of the slow wave structure 100 and the power calculation equation, the output power of the slow wave structure 100 under the candidate period length distribution is calculated. Using the output power as the benchmark value, the candidate period length distribution is iteratively updated using a particle swarm optimization algorithm until the number of iterations reaches the preset maximum number of iterations, or before reaching the preset maximum number of iterations, the increment of output power is continuously lower than the preset increment threshold for a preset number of times. The optimal non-uniform period length distribution of the slow wave structure 100 is then output. The length of each period of the slow wave structure 100 is then adjusted cycle by cycle according to the optimal non-uniform period length distribution to achieve precise control of the electromagnetic wave phase velocity. Thus, in the entire process of the interaction between the electron beam and the electromagnetic wave, the electromagnetic wave phase velocity and the electron beam velocity are always kept in the optimal synchronization state. Through the aforementioned full-cycle phase rematching strategy, the energy of the electron beam can be continuously and efficiently exchanged with the electromagnetic wave, significantly improving the interaction efficiency. This, in turn, increases the overall output power and electronic efficiency of the traveling wave tube 1000 while effectively suppressing common problems in traditional methods, such as gain saturation and nonlinear distortion. Furthermore, unlike traditional phase velocity jump techniques (which primarily rely on electromagnetic simulation software to independently optimize each cycle of the slow wave structure 100), this invention combines normalized differential equations and particle swarm optimization, using numerical calculation software to optimize the full-cycle length distribution of the slow wave structure 100. This effectively avoids the problem of easily getting trapped in local optima when optimizing the cycle length of each slow wave structure 100 individually, while significantly saving the computation time cost of electromagnetic simulation software. This, in turn, shortens the development cycle of the traveling wave tube 1000 and reduces its development costs.

[0036] In one embodiment, step S200 is specifically calculated using the following formula: ; ; ; in, For slow-wave structure units with different period lengths, the phase constant is 10. This represents the phase delay of the electromagnetic wave within the corresponding period length. The period length of the slow wave structure unit 10; For coupling impedance, The electric field intensity along the axial (z-direction) axis for different period lengths. The radio frequency power flow per unit time and unit length in the slow wave structure unit 10 with different period lengths; The normalized phase velocity of the electromagnetic wave in the slow-wave structure unit 10. At the speed of light, The angular frequency corresponding to the preset optimized frequency point.

[0037] In this embodiment, by using the relationship between the phase constant, the period length, and the phase delay, a quantitative correlation can be established between the geometric dimensions of the slow wave structure unit 10 and the electromagnetic wave propagation characteristics. This allows the phase constant of the slow wave structure unit 10 with different period lengths to be accurately calculated, thereby improving the accuracy of the phase matching design of each unit in the non-uniform interlaced grating slow wave structure 100 and avoiding the cumulative effect of phase mismatch caused by changes in period length.

[0038] The formula for calculating coupling impedance correlates the axial electric field strength, phase constant, and RF power flow per unit time and unit length, enabling the beam-wave interaction efficiency of the slow wave structure unit 10 with different period lengths to be quantitatively characterized. This improves the ability to control the energy exchange distribution along the slow wave structure 100, and helps to obtain a more uniform gain distribution and higher power conversion efficiency at a preset optimized frequency.

[0039] The normalized phase velocity calculation formula, combined with the angular frequency and phase constant corresponding to the preset optimized frequency point, allows the ratio of the phase velocity of the electromagnetic wave to the speed of light in the slow wave structure unit 10 to be directly obtained. This improves the evaluation accuracy of the synchronization state between the electron beam motion velocity and the electromagnetic wave phase velocity throughout the entire cycle, which helps to reduce the beam-wave out-of-synchronization phenomenon caused by phase velocity deviation and enhances the amplification stability and output performance consistency of the traveling wave tube 1000 in the target frequency band.

[0040] like Figure 2 As shown, in one embodiment, step S300 specifically includes: S210. Construct the normalized circuit amplitude equation and phase transformation equation in the normalized differential equation system:

[0041] ;

[0042] ; Construct the normalized electron motion equations in the normalized system of differential equations:

[0043] ; S220. Construct the electronic phase differential equation in the normalized differential equation system: ; Where y is the normalized distance, and A(y) is the normalized amplitude distributed along the axis. The phase angle distribution is as follows: This represents the initial phase of the electron. This represents the offset of the electron's velocity relative to its initial velocity. Let y represent the phase change of the electron at position y relative to the initial phase, b be the injection velocity parameter determined based on the normalized phase velocity, C be the gain factor determined based on the coupling impedance distribution, and d be the loss factor. The space charge field strength; S230. Substitute the injection velocity parameter and gain factor into the constructed normalized differential equation system and solve them jointly to obtain the normalized amplitude distribution of the slow wave structure along the axial direction.

[0044] In this embodiment, the normalized differential equations describe the energy exchange and phase evolution process when the electron beam and electromagnetic wave interact in the slow-wave structure 100. The normalized circuit amplitude equation characterizes the variation of the normalized amplitude with the normalized distance, reflecting the amplitude increase or decrease characteristics of the electromagnetic wave propagating in the slow-wave structure 100 due to its interaction with the electron beam. The phase transformation equation describes the evolution of the phase angle distribution with the normalized distance, reflecting the combined influence of the electromagnetic wave phase velocity being modulated by the electron beam and the dispersion characteristics of the slow-wave structure 100 itself. The normalized electron motion equation characterizes the dynamic response of the electron velocity offset relative to its initial velocity with the normalized distance, revealing the acceleration or deceleration behavior of the electron under the action of the electromagnetic wave electric field. The electron phase differential equation further establishes the correlation between the phase change of the electron at point y relative to the initial phase and the electron velocity offset, in order to track the aggregation and divergence trends of each electron phase during the electron clustering process.

[0045] Each physical parameter in the above-mentioned normalized differential equation system has a clear physical meaning and computational source. The normalized distance, as the independent variable, transforms the actual axial length of the slow-wave structure 100 into a dimensionless quantity for numerical solution. The normalized amplitude distributed along the axial direction is a key indicator for measuring the axial variation of electromagnetic wave power. The phase angle distribution is directly related to the instantaneous phase state of the electromagnetic wave. The initial phase of the electron determines the initial phase condition when the electron enters the interaction region. The offset of the electron velocity relative to its initial velocity reflects the degree to which the electron's kinetic energy is converted into electromagnetic wave energy. The phase change of the electron at point y relative to its initial phase characterizes the cumulative phase drift effect of the electron during the interaction process. The injection velocity parameter b, determined by the aforementioned normalized phase velocity distribution, characterizes the initial mismatch between the electron beam injection velocity and the electromagnetic wave phase velocity. The gain factor C, determined by the aforementioned coupling impedance distribution, reflects the strength of the interaction between the slow-wave structure 100 and the electron beam. The loss factor d incorporates the influence of the ohmic loss of the slow-wave structure 100 itself on the electromagnetic wave amplitude. The space charge field strength takes into account the repulsive effect of the space charge effect inside the electron beam on the electron motion.

[0046] After constructing the normalized differential equation system and assigning values ​​to each parameter, the injection velocity parameter and gain factor are substituted into the constructed normalized differential equation system and solved jointly to obtain the normalized amplitude distribution of the slow-wave structure 100 along the axial direction. This joint solution process simultaneously handles the normalized circuit amplitude equation, phase transformation equation, normalized electron motion equation, and electron phase differential equation using numerical integration methods. This allows the electromagnetic wave amplitude, phase, and electron motion state to be mutually coupled and iteratively updated at each normalized distance node, thereby accurately simulating the nonlinear dynamic behavior of the electron beam and electromagnetic wave throughout the entire interaction region. The normalized amplitude distribution of the slow-wave structure 100 obtained in this way not only includes the complete evolution trajectory of the electromagnetic wave amplitude from the input end to the output end, but also lays the necessary data premise for subsequent calculation of the output power based on the normalized amplitude and power calculation equation at the end of the slow-wave structure 100. This enables the performance evaluation of the candidate period length distribution to be achieved through efficient numerical computation, rather than time-consuming three-dimensional electromagnetic simulation.

[0047] like Figure 3 As shown, in one embodiment, the steps of constructing the normalized differential equation specifically include: S000, Obtain the circuit equation: ; Where z is the axial position and t is the time. The axial electric field strength is... The axial electron beam line density, Let be the phase velocity of the electromagnetic wave, d be the loss factor, and ω be the angular frequency of the electromagnetic wave. For coupling impedance, For gain factor, The direct current for electron injection, The DC voltage of the electron beam; S010, Obtain the equation of motion for the electron: ; in, η represents the space charge field intensity; η = e / m represents the electron mass-to-charge ratio, where e is the electron charge and m is the electron mass. S020, Obtain the normalized distance: ;

[0048] Where y is the normalized distance. The initial velocity of the electron takes into account relativistic effects; S030, Obtain the initial phase of the electron: ; S040, Electron acquisition velocity: ; in, This represents the offset of the electron's velocity relative to its initial velocity; S050. Substituting the obtained normalized distance, initial phase of the electron, and electron velocity into the circuit equations, we obtain the normalized circuit amplitude equation and phase transformation equation, where, For injection speed parameters; S060. Substitute the obtained normalized distance, initial phase of the electron, and electron velocity into the electron motion equation to obtain the normalized electron motion equation. S070. The formula for obtaining the difference between the phase angle of the electron wave and the phase angle of the electromagnetic wave is: ; in, Let y be the phase change of the electron at position y relative to the initial phase; S080. Substitute the obtained normalized distance, initial phase of the electron, and electron velocity into the difference formula and perform differentiation to obtain the electron phase differential equation.

[0049] In this embodiment, the nonlinear theory of the traveling wave tube 1000 consists of circuit equations and electron motion equations. The circuit equations describe the evolution of the amplitude and phase of the electromagnetic wave as it propagates in the slow-wave structure 100 with respect to axial position and time. The axial electric field strength characterizes the magnitude of the field force exerted by the electromagnetic wave on the electron beam, the axial electron beam linear density reflects the charge distribution of the electron beam per unit length, the electromagnetic wave phase velocity determines the matching conditions required for synchronous interaction between the electromagnetic wave and the electron beam, the loss factor takes into account the attenuation effect of conductor loss in the slow-wave structure 100 on the electromagnetic wave energy, the angular frequency of the electromagnetic wave corresponds to the operating frequency of the traveling wave tube 1000, the coupling impedance reflects the efficiency of energy exchange between the slow-wave structure 100 and the electron beam, the gain factor is related to the interaction strength, and the DC current and DC voltage of the electron beam together determine the initial power state of the electron beam. The electron motion equation describes the dynamic behavior of electrons under the combined action of axial electric field and space charge field. The intensity of space charge field reflects the modulation effect of charge repulsion effect inside the electron beam on electron motion. The electron mass-to-charge ratio, as an inherent property of electrons, determines the electron's response sensitivity to external electric field.

[0050] To make the obtained circuit equations and electron motion equations applicable to numerical calculations and eliminate dimensional differences, a normalized distance is introduced as a new independent variable to replace the actual axial position. The normalized distance is scaled by considering the electron's initial velocity with relativistic effects, giving the obtained circuit equations and electron motion equations a universal form under different operating voltages. Simultaneously, the electron's initial phase is defined as the phase reference when the electron enters the interaction region, and the electron velocity is expressed as the offset of the electron velocity relative to its initial velocity. This offset directly reflects the degree of change in kinetic energy of the electron during its interaction with the electromagnetic wave. After substituting the obtained normalized distance, electron's initial phase, and electron velocity into the circuit equations, the original circuit equations are transformed into a normalized circuit amplitude equation and a phase transformation equation. The injection velocity parameter characterizes the initial mismatch between the electron injection velocity and the electromagnetic wave phase velocity. The normalized circuit amplitude equation is used to solve for the distribution of the normalized amplitude along the axial direction, and the phase transformation equation is used to track the cumulative change in the electromagnetic wave phase. Similarly, by substituting the obtained normalized distance, the initial phase of the electron, and the electron velocity into the electron motion equation, a normalized electron motion equation is obtained. This normalized electron motion equation describes the dynamic response of the electron velocity offset with the normalized distance in a dimensionless form.

[0051] To further describe the phase evolution characteristics during electron clustering, a formula for the difference between the phase angle of the electron wave and the phase angle of the electromagnetic wave is obtained. This difference represents the phase change of the electron at position y relative to the initial phase, reflecting the degree of lag or lead of the electron relative to the peak of the electromagnetic wave. Subsequently, the obtained normalized distance, the initial phase of the electron, and the electron velocity are substituted into the difference formula and differentially calculated to obtain the electron phase differential equation. This electron phase differential equation establishes a mathematical relationship between the electron phase change rate and the electron velocity offset. The normalized circuit amplitude equation, phase transformation equation, normalized electron motion equation, and electron phase differential equation obtained through the above steps together constitute a complete set of normalized differential equations. This set of normalized differential equations describes the entire physical process of the interaction between the electron beam and the electromagnetic wave using a unified dimensionless variable system. It lays the necessary mathematical model foundation for the subsequent joint solution of the normalized amplitude distribution along the axial direction of the slow-wave structure 100, enabling the performance evaluation of the candidate period length distribution to be completed through efficient numerical computation without relying on time-consuming three-dimensional electromagnetic simulation. It is evident that the optimal non-uniform period length distribution is obtained by combining the nonlinear theory algorithm of traveling wave tube 1000 with the particle swarm optimization algorithm, which reduces the limitations and time costs of relying on electromagnetic simulation software to calculate the wave-span interaction performance.

[0052] In one embodiment, the output power of the slow-wave structure under the candidate period length distribution is calculated using the following formula, based on the normalized amplitude and power calculation equations at the end of the slow-wave structure with normalized amplitude distribution: ; Where P(y) is the output power, A(y) is the normalized amplitude distribution at the end of the slow wave structure 100, is the phase angle distribution, b is the injection velocity parameter determined based on the normalized phase velocity distribution, and C is the gain factor corresponding to the slow wave structure unit 10 at the end of the slow wave structure 100. The direct current for electron injection, The DC voltage of the electron beam.

[0053] In this embodiment, the power calculation equation is used to transform the normalized amplitude distribution obtained from the aforementioned joint solution into an output power value with practical physical meaning. The normalized amplitude distribution at the end of the slow-wave structure 100 characterizes the final amplitude state of the electromagnetic wave after amplification through the entire interaction region of the slow-wave structure 100, and is the core variable determining the output power. The phase angle distribution reflects the instantaneous phase of the electromagnetic wave at the end of the slow-wave structure 100, and together with the normalized amplitude, it determines the complex amplitude characteristics of the electromagnetic wave. The injection velocity parameter is determined by the normalized phase velocity distribution, reflecting the influence of the matching degree between the electron beam injection velocity and the electromagnetic wave phase velocity during the interaction process on the energy conversion efficiency. The gain factor corresponding to the slow-wave structure unit 10 at the end of the slow-wave structure 100 characterizes the interaction strength between the local region at the end of the slow-wave structure 100 and the electron beam. This gain factor is determined by the coupling impedance distribution derived from the candidate period length distribution by the aforementioned preset algorithm. The DC current and DC voltage of the electron beam are used as input operating parameters of the traveling wave tube 1000, which together determine the total initial kinetic energy carried by the electron beam. The power calculation equation achieves accurate conversion from dimensionless normalized amplitude to actual output power by comprehensively calculating the normalized amplitude, phase angle distribution, injection velocity parameter, gain factor, and the DC current and DC voltage of the electron beam.

[0054] After obtaining the output power of the slow-wave structure 100 under the candidate period length distribution through the aforementioned power calculation equation, this output power can be used as a key indicator to evaluate the performance of the current candidate period length distribution. Since the normalized amplitude distribution is obtained by quickly obtaining the coupling impedance distribution and normalized phase velocity distribution by inputting the candidate period length distribution into a preset algorithm, and then jointly solving the normalized differential equations, the entire process avoids the cumbersome process of independently modeling and solving each period of the slow-wave structure 100 in traditional electromagnetic simulation software. Therefore, the output power obtained based on the power calculation equation can be calculated in a very short time. This allows for efficient evaluation of the output power corresponding to a large number of different candidate period length distributions during the optimization iteration process. Thus, without significantly increasing computational resource consumption, the potential for improving output power through phase rematching technology is fully explored, effectively overcoming the problem that existing technologies are limited to only a few periods at the end of the slow-wave structure 100 or segmented local phase matching, resulting in limited output power improvement.

[0055] like Figure 4 As shown, in one embodiment, step S500 specifically includes: S510. Set the vector formed by the period lengths of each slow wave structure unit of the slow wave structure as the position vector of the particle, and initialize the particle swarm within the preset period length range. S520. In each iteration, calculate the fitness value of each particle after initialization based on the output power, and update the historical best solution of each particle and the global historical best solution of the particle swarm. S530. Update the iteration velocity and position vector of each particle based on the historical best solution of each particle and the global historical best solution of the particle swarm to generate the updated candidate period length distribution. S540. When the number of iterations reaches the preset maximum number of iterations, or when the increment of the output power is lower than the preset increment threshold for a preset number of consecutive iterations before reaching the preset maximum number of iterations, the candidate period length distribution corresponding to the global historical optimal solution of the group is output as the optimal non-uniform period length distribution.

[0056] In this embodiment, a particle swarm optimization algorithm is used to optimize the period length of each periodic unit of the slow-wave structure 100. The vector formed by the period lengths of each periodic unit of the slow-wave structure 100 is set as the position vector of the particles, so that each particle represents a specific candidate period length distribution scheme. The particle swarm is initialized within a preset period length value range, thereby generating an initial set of candidate period length distributions within a feasible engineering parameter space. The preset period length value range limits the fabrication feasibility of the physical dimensions of the slow-wave structure 100 and the effective range of its electromagnetic performance, avoiding the search process from getting stuck in meaningless parameter regions.

[0057] In each iteration, the fitness value of each particle is calculated based on the output power. This output power is obtained by solving the aforementioned normalized differential equations, accurately reflecting the beam-wave interaction performance under the corresponding candidate period length distribution. By comparing the fitness values ​​of each particle, the historical optimal solution of each particle and the global historical optimal solution of the particle swarm are updated. The historical optimal solution of each particle records the candidate period length distribution with the highest output power during its own search process, while the global historical optimal solution records the candidate period length distribution with the highest output power in the current and all previous iterations of the entire particle swarm. Subsequently, the iteration velocity and position vector of each particle are updated based on the historical optimal solution of each particle and the global historical optimal solution of the particle swarm, causing the particles to move closer to their own historical optimal position and the global optimal position, thereby generating an updated candidate period length distribution and achieving adaptive adjustment of the search direction from random exploration to the high output power region.

[0058] If the number of iterations reaches the preset maximum of 400 iterations, and the increment of output power does not exceed the preset increment threshold of 0.0001W for 30 consecutive preset number of iterations, the output power is determined to meet the preset convergence condition, and the candidate period length distribution corresponding to the global historical optimal solution of the population is output as the optimal non-uniform period length distribution. For example, if the actual output power is 100W in a certain iteration, 100.00005W in the next iteration, and 100.00008W in the iteration after that, and the output power increment of the two adjacent iterations does not exceed 0.0001W, then the output power is determined to have stabilized, and continuing the iteration has limited effect on improving the output power of the slow wave structure 100. This optimal non-uniform period length distribution is the period arrangement scheme that makes the output power of the slow wave structure 100 reach a better level within the preset period length range. The entire optimization process uses the collaborative search mechanism of the particle swarm optimization algorithm to efficiently locate the high-performance non-uniform period length distribution without traversing all parameter combinations, thereby improving the efficiency and performance ceiling of the slow wave structure 100 design.

[0059] Compared to other optimization algorithms such as genetic algorithms and dragonfly swarm optimization, particle swarm optimization (PSO) demonstrates stronger global search capabilities and faster computation speed in the full-cycle phase velocity jump optimization problem of the traveling wave tube 1000, and can more effectively avoid getting trapped in local optima. Addressing the shortcomings of traditional phase rematching techniques, this invention combines normalized differential equations with PSO for full-cycle phase rematching of the traveling wave tube 1000, which significantly reduces the simulation computation time for beam-wave interaction, shortens the development cycle of the traveling wave tube 1000, and lowers development costs.

[0060] like Figure 5 As shown, in one embodiment, the construction steps of the preset algorithm specifically include: S090. Obtain the coupling impedance and normalized phase velocity of the slow wave structure at different period lengths, and establish a mapping dataset between period length, coupling impedance, and normalized phase velocity. S0100. Based on the mapping dataset, perform interpolation fitting and construct a preset algorithm.

[0061] In this embodiment, the preset algorithm aims to establish a continuous functional relationship between the geometric parameters and electromagnetic characteristic parameters of the slow-wave structure 100. When obtaining the coupling impedance and normalized phase velocity of the slow-wave structure 100 at different period lengths, multiple discrete sampling points within the preset period length range need to be covered to ensure that the subsequent fitting accuracy meets engineering requirements. The established mapping dataset between period length, coupling impedance, and normalized phase velocity contains discrete input-output correspondences, where period length is the independent variable and coupling impedance and normalized phase velocity are the dependent variables. This mapping dataset provides original data samples for interpolation fitting.

[0062] When performing interpolation fitting based on a mapped dataset, an appropriate interpolation algorithm is selected to smooth the discrete data points, thereby constructing a pre-defined algorithm that can continuously output the corresponding coupling impedance and normalized phase velocity based on any given period length. This pre-defined algorithm replaces the process of repeatedly calling 3D electromagnetic simulation software to calculate the coupling impedance and normalized phase velocity in each iteration. This allows the required coupling impedance and normalized phase velocity values ​​to be quickly obtained by querying the pre-defined algorithm when the particle swarm optimization algorithm evaluates the performance of each candidate period length distribution. The pre-defined algorithm constructed in this way significantly reduces the time overhead of beam-wave interaction performance calculation while ensuring the accuracy of electromagnetic parameter acquisition, enabling large-scale optimization iterations to be completed within a reasonable time.

[0063] like Figure 6 As shown, the present invention also proposes a control device 20 for a slow-wave structure 100. The control device 20 for the slow-wave structure 100 includes a processor 21 and a memory 22. The memory 22 stores a control program for the slow-wave structure 100. When the control program for the slow-wave structure 100 is executed by the processor 21, the control method for the slow-wave structure 100 described above is implemented. The specific structure of the control method for the slow-wave structure 100 is as described in the above embodiments. Since the control device 20 for the slow-wave structure 100 adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0064] like Figure 7 and Figure 8 As shown, the present invention also proposes a slow wave structure 100, which includes a plurality of slow wave structure units 10 and a control device 20. The specific structure of the control device 20 is as described in the above embodiments. Since the slow wave structure 100 adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0065] Among them, multiple slow wave structure units 10 are arranged sequentially along the axial direction, and the period length of the multiple slow wave structure units 10 first increases and then decreases along the axial direction, then increases and then decreases again. The control device 20 is electrically connected to multiple slow-wave structure units 10.

[0066] It is understandable that existing slow-wave structures with fixed period lengths have a constant electromagnetic wave phase velocity. During the interaction between the electron beam and the electromagnetic wave, the electron beam gradually relinquishes energy, causing its velocity to decrease, thereby disrupting the beam-wave synchronization condition, reducing energy conversion efficiency, or even preventing it from continuing, ultimately limiting output power. This invention employs a non-uniform interlaced grid slow-wave structure 100, using full-cycle phase velocity jump technology to solve the above problems. Figure 8As shown, the traveling wave tube 1000 of the present invention is characterized in that the period length of the slow wave structure 100 is non-uniformly distributed, that is, the period length of the slow wave structure 100 satisfies P1≠P2≠P m ≠P m+1 ≠P n ≠P n+1 For details, please see Figure 9 Each slow-wave structure unit 10 has a different phase velocity, which can be synchronized with the movement velocity of the electron beam, thereby maximizing energy conversion.

[0067] This invention is based on a uniform period length interlaced grid slow-wave structure and utilizes full-cycle phase velocity jump technology to improve efficiency. While keeping other structural dimensions unchanged, only the period length L of the slow-wave structure 100 is optimized, with a value ranging from 0.486 mm to 0.836 mm. Specifically, the height of the upper and lower cavities and upper and lower grid teeth of the uniform period length interlaced grid slow-wave structure is 0.295 mm, the width of the upper and lower cavities, upper and lower grid teeth, and electron beam channel is 0.842 mm, the electron beam channel height is 0.162 mm, the period length of the slow-wave structure 100 is 0.626 mm, and the thickness of the upper and lower grid teeth is 0.112 mm. Simulation conditions are: operating voltage 29.8 kV, operating current 0.15 A, input signal power 0.1 W, and background material with a conductivity of 1.57 × 10⁻⁶. 7 Lossless metals with a phase velocity (S / m). The intrinsic mode solver of electromagnetic simulation software was used to simulate structures with different period lengths within this range, obtaining the coupling impedance and normalized phase velocity corresponding to a 100-period length for each slow-wave structure. For example... Figure 10 As shown, a set of corresponding coupling impedances and normalized phase velocities are calculated for every 0.01 mm change in period length. The collected simulation data is then imported into the aforementioned pre-built algorithm to provide data for subsequent iterative optimization of structural parameters.

[0068] This optimization simulation targeted an operating frequency of 200 GHz. Throughout the simulation, the operating current, operating voltage, and input signal power of the traveling wave tube 1000 were kept consistent with the electromagnetic simulation software settings. The aforementioned particle swarm optimization algorithm was used to iteratively optimize the 100-cycle length of the slow-wave structure of the traveling wave tube 1000, with a maximum iteration count of 500. The iterative optimization results are as follows: Figure 11 As shown, after multiple rounds of iterative convergence, the normalized amplitude A(y) obtained by solving the aforementioned normalized circuit amplitude equation reaches its global maximum of 1.96. Combined with the aforementioned power calculation equation, numerical verification shows that the corresponding optimized theoretical output power can reach 443 W. This calculation uses the average coupling impedance of all non-uniform periods. Based on the iterative convergence results of this particle swarm optimization algorithm, a non-uniform period length distribution sequence containing 103 sets of parameters is finally obtained. The specific period length distribution pattern is as follows... Figure 12 As shown.

[0069] Table 1 shows the specific values ​​of the aforementioned 103 sets of parameters:

[0070] Table 1 in accordance with Figure 12 The 103 sets of non-uniform period length distribution parameters shown complete the overall structural modeling of the non-uniform period length staggered grid traveling wave tube 1000. Electromagnetic simulation verification was performed using simulation conditions identical to those of the aforementioned uniform period length staggered grid traveling wave tube, ensuring the comparability and effectiveness of the simulation results before and after optimization. Simulation results are as follows: Figure 13 As shown, this non-uniform period length interleaved gate traveling wave tube 1000 can achieve a stable output power of 426.3 W at a target operating frequency of 200 GHz, and the signal output duration can reach 200 ns, demonstrating long-term operational stability. The corresponding spectral characteristics are as follows... Figure 14 As shown, the operating spectrum of this non-uniform period length interleaved grid traveling wave tube 1000 has an effective signal peak only at the target operating frequency of 200 GHz, without the generation of spurious signals, harmonic oscillations, or parasitic oscillations, resulting in high overall spectral purity. This verifies that the non-uniform period length interleaved grid traveling wave tube 1000 designed in this invention will not cause problems such as electromagnetic wave reflection and spurious harmonic excitation due to mismatch caused by the difference in period length between adjacent slow wave structures 100.

[0071] like Figure 15 As shown, the in-band amplification performance of a uniform period length interleaved-gate traveling wave tube (TWT) and a non-uniform period length interleaved-gate TWT 1000 are compared and analyzed under the same simulation conditions. The uniform period length interleaved-gate TWT achieves stable signal amplification in the 186 GHz to 210 GHz operating frequency band, with an output power range of 16.8 W to 144.5 W and a corresponding electronic efficiency range of 0.38% to 3.23%. The non-uniform period length interleaved-gate TWT 1000, employing the non-uniform period length interleaved-gate slow-wave structure 100 of this invention, achieves an output power of 269.1 W to 541.2 W in the same 186 GHz to 210 GHz frequency band, with a corresponding electronic efficiency improvement of 6.02% to 12.11%. The in-band performance comparison shows that, compared to the traditional uniform period length interleaved-gate TWT, the non-uniform period length interleaved-gate TWT 1000 proposed in this invention achieves more than twice the in-band electronic efficiency and a significant increase in output power. Simulation results show that the full-cycle phase-jumping technology proposed in this invention can effectively enhance the beam-wave interaction of the traveling wave tube 1000 and has a significant effect on improving the output power and electronic efficiency of the traveling wave tube 1000.

[0072] like Figure 8As shown, the present invention also proposes a traveling wave tube 1000, which includes a slow wave structure 100, an electron gun, an input waveguide modem 200, an output waveguide modem 300, and a dielectric attenuator 400. The specific structure of the slow wave structure 100 is as described in the above embodiments. Since the present traveling wave tube 1000 adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0073] An electron gun is used to generate an electron beam and inject the electron beam into the slow-wave structure 100. The input waveguide mode 200 is set at the input end of the slow wave structure 100 to introduce electromagnetic waves, and the introduced electromagnetic waves are input into the slow wave structure 100 after impedance matching. The output waveguide mode 300 is set at the output end of the slow wave structure 100 to export the electromagnetic wave after power amplification by the slow wave structure 100. The dielectric attenuator 400 is disposed on the slow wave structure 100 to absorb electromagnetic waves reflected inside the slow wave structure 100 and block the feedback path of electromagnetic waves in order to suppress self-excited oscillation and parasitic oscillation. In this process, the electron beam and the electromagnetic wave enter the slow-wave structure 100 together to perform beam-wave interaction. The slow-wave structure 100 is used to reduce the phase velocity of the electromagnetic wave and keep the phase velocity of the electromagnetic wave and the motion velocity of the electron beam synchronized during the interaction process, so as to transfer the energy of the electron beam to the electromagnetic wave for power amplification.

[0074] In this embodiment, the electron beam generated by the electron gun is injected into the slow-wave structure 100. Simultaneously, the input waveguide modem 200 introduces external electromagnetic waves and, after impedance matching, sends them into the slow-wave structure 100, allowing the electron beam and electromagnetic waves to propagate together and interact within the slow-wave structure 100. The slow-wave structure 100 reduces the phase velocity of the electromagnetic waves through the aforementioned non-uniform period length distribution, and keeps the phase velocity of the electromagnetic waves synchronized with the electron beam's motion velocity throughout the entire period of the slow-wave structure 100, thereby continuously transferring the energy of the electron beam to the electromagnetic waves to achieve power amplification. The electromagnetic waves, after being amplified by the slow-wave structure 100, are exported by the output waveguide modem 300, completing the signal amplification function of the traveling wave tube 1000.

[0075] The dielectric attenuator 400 is disposed on the slow-wave structure 100 to absorb the reverse-transmitted electromagnetic waves generated within the slow-wave structure 100 due to impedance discontinuities or end-face reflections, thereby blocking the feedback path of the electromagnetic waves and suppressing the occurrence of self-excited oscillations and parasitic oscillations. The placement and attenuation of the dielectric attenuator 400 need to be adapted according to the gain distribution and reflection characteristics of the slow-wave structure 100 to avoid excessive loss of the forward-transmitting electromagnetic waves and to effectively eliminate feedback signals that may cause unstable operation. Through the synergistic cooperation between the dielectric attenuator 400 and the aforementioned non-uniform period length interlaced grid slow-wave structure 100, the traveling wave tube 1000 achieves high output power while maintaining operational stability and spectral purity.

[0076] The overall workflow of the traveling wave tube 1000 is as follows: an electron gun generates an electron beam and injects it into a slow-wave structure 100. An input waveguide modem 200 introduces electromagnetic waves, and after impedance matching, the waves are input into the slow-wave structure 100. The electron beam and electromagnetic waves interact within the slow-wave structure 100, with the electron beam energy being transferred to the electromagnetic waves. A dielectric attenuator 400 absorbs internally reflected electromagnetic waves to suppress self-excited oscillations and parasitic oscillations. An output waveguide modem 300 outputs the amplified electromagnetic waves. The functional integration of these components enables the traveling wave tube 1000 to achieve efficient power amplification in strip-beam or circular-beam form across multiple frequency bands in the millimeter-wave and terahertz ranges, including X, Ku, Ka, W, D, and G. This verifies the applicability and effectiveness of the aforementioned slow-wave structure 100 design within the complete traveling wave tube 1000 system.

[0077] like Figure 8 As shown, in one embodiment, the dielectric attenuator 400 is positioned close to the input waveguide mode 200, and the distance between the dielectric attenuator 400 and the input waveguide mode 200 is one-third of the distance between the input waveguide mode 200 and the output waveguide mode 300.

[0078] In this embodiment, the dielectric attenuator 400 is positioned approximately one-third of the total length of the non-uniform interlaced gate slow wave structure 100 from the input end. This position corresponds to a specific implementation where the distance between the dielectric attenuator 400 and the input waveguide modem 200 is one-third of the distance between the input waveguide modem 200 and the output waveguide modem 300. Its core function is primarily to block the feedback path to suppress self-excited oscillations. Since the non-uniform period length interlaced gate traveling wave tube 1000 has high gain characteristics, even small reflections or parasitic couplings in the slow wave structure 100 can satisfy the feedback condition and trigger self-excited oscillations, severely disrupting the normal operation of the device. By introducing distributed loss, the dielectric attenuator 400 can effectively cut off the feedback link between the input and output ends, increasing the oscillation threshold and thus enabling the traveling wave tube 1000 to maintain stable operation in a high-gain state.

[0079] Another key function of the dielectric attenuator 400 is to absorb reflected waves caused by impedance mismatch to prevent re-excitation. Because the period length of the non-uniform interlaced slow-wave structure 100 is non-uniformly distributed along the axial direction, the characteristic impedance along the line varies, easily causing signal reflection. The dielectric attenuator 400 can effectively absorb reflected echoes caused by impedance mismatch, preventing the reflected echoes from propagating in the opposite direction and coherently superimposing with the forward traveling wave, thereby eliminating standing wave components and the risk of possible secondary oscillations. By placing the dielectric attenuator 400 at approximately one-third of the total length of the slow-wave structure 100 from the input end, it can effectively attenuate the reverse-propagating electromagnetic wave before the interaction between the electron beam and the electromagnetic wave reaches saturation. This avoids disturbances to the impedance matching state at the input waveguide mode 200 at the input end caused by reflected waves and reduces interference to the beam-wave interaction process in the subsequent slow-wave structure 100.

[0080] The dielectric attenuator 400 is typically introduced into the slow-wave structure 100 in a single-segment configuration, with a length generally selected to be approximately five slow-wave cycles. The design should avoid excessive length of the dielectric attenuator 400 or the use of a multi-segment structure. This is because the dielectric attenuator 400 is inherently a dissipative component; an excessively long attenuation path will over-absorb high-frequency signal energy, while multiple segments will increase the total loss and may introduce additional reflection discontinuities. Both of these situations will significantly reduce the gain and output power of the traveling wave tube 1000, degrading the overall amplification performance. Therefore, the length and number of segments of the dielectric attenuator 400 need to be optimized with a trade-off between oscillation suppression and gain maintenance. This ensures that the dielectric attenuator 400 effectively blocks the feedback path and absorbs reflected waves while minimizing its adverse effects on the forward amplification performance of the traveling wave tube 1000, ensuring that the traveling wave tube 1000 achieves efficient and stable power amplification in strip-beam or circular-beam configurations across multiple millimeter-wave and terahertz frequency bands.

[0081] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A control method for a slow-wave structure, characterized in that, The slow-wave structure is used to receive electron beams and electromagnetic waves, and the control method of the slow-wave structure includes: Obtain the candidate period length distribution of the slow-wave structure; The candidate period length distribution of the slow wave structure is input into a preset algorithm to calculate the coupling impedance distribution and normalized phase velocity distribution corresponding to the candidate period length distribution. Substituting the coupling impedance distribution and the normalized phase velocity distribution into the normalized differential equation, the normalized amplitude distribution of the slow wave structure along the axial direction is calculated. Based on the normalized amplitude distribution at the end of the slow wave structure and the power calculation equation, the output power of the slow wave structure under the candidate period length distribution is calculated. Using the output power as a baseline, the candidate period length distribution is iteratively updated using a particle swarm optimization algorithm until the number of iterations reaches a preset maximum number of iterations, or until the increment of the output power is lower than a preset increment threshold for a preset number of consecutive preset number of iterations before reaching the preset maximum number of iterations, and the optimal non-uniform period length distribution of the slow wave structure is output. The length of each period of the slow-wave structure is adjusted periodically according to the optimal non-uniform period length distribution so that the electromagnetic wave phase velocity and the electron beam motion velocity remain synchronized during the interaction process.

2. The control method for the slow-wave structure as described in claim 1, characterized in that, The step of inputting the candidate period length distribution of the slow wave structure into a preset algorithm to calculate the coupling impedance distribution and normalized phase velocity distribution corresponding to the candidate period length distribution is specifically calculated using the following formulas: ； ； ； in, The phase constants of slow-wave structure units with different period lengths are given. This represents the phase delay of the electromagnetic wave within the corresponding period length. The period length of the slow-wave structure unit; For coupling impedance, The electric field intensity along the axial (z-direction) axis for different period lengths. The radio frequency power flow per unit time and unit length in slow wave structure units with different period lengths; This represents the normalized phase velocity of electromagnetic waves within the slow-wave structural unit. At the speed of light, The angular frequency corresponding to the preset optimized frequency point.

3. The control method for the slow-wave structure as described in claim 1, characterized in that, The step of substituting the coupling impedance distribution and the normalized phase velocity distribution into the normalized differential equation to calculate the normalized amplitude distribution of the slow-wave structure along the axial direction specifically includes: Construct the normalized circuit amplitude equation and phase transformation equation in the normalized differential equation system: ； ； Construct the normalized electron motion equations in the normalized system of differential equations: ； Construct the electronic phase differential equation in the normalized differential equation system: ； Where y is the normalized distance, and A(y) is the normalized amplitude distributed along the axis. The phase angle distribution is as follows: This represents the initial phase of the electron. This represents the offset of the electron's velocity relative to its initial velocity. Let be the phase change of the electron at position y relative to the initial phase, b be the injection velocity parameter determined based on the normalized phase velocity, C be the gain factor determined based on the coupling impedance distribution, and d be the loss factor. The space charge field strength; Substituting the injection velocity parameter and the gain factor into the constructed normalized differential equation system and solving them jointly yields the normalized amplitude distribution of the slow wave structure along the axial direction.

4. The control method for the slow-wave structure as described in claim 3, characterized in that, The steps for constructing the normalized differential equation specifically include: Obtaining the circuit equations: ； Where z is the axial position and t is the time. The axial electric field strength is... The axial electron beam line density, Let be the phase velocity of the electromagnetic wave, d be the loss factor, and ω be the angular frequency of the electromagnetic wave. For coupling impedance, For gain factor, The direct current for electron injection, The DC voltage of the electron beam; Obtain the equation of motion for the electron: ； in, η represents the space charge field intensity; η = e / m represents the electron mass-to-charge ratio, where e is the electron charge and m is the electron mass. Obtain the normalized distance: ； Where y is the normalized distance. The initial velocity of the electron takes into account relativistic effects; Obtain the initial phase of the electron: ； Acquisition speed of electrons: ； in, This represents the offset of the electron's velocity relative to its initial velocity; Substituting the obtained normalized distance, initial phase of the electron, and electron velocity into the circuit equations, we obtain the normalized circuit amplitude equation and the phase transformation equation, where, For injection speed parameters; Substituting the obtained normalized distance, initial phase of the electron, and electron velocity into the electron motion equation, the normalized electron motion equation is obtained. The formula for obtaining the difference between the phase angle of the electron wave and the phase angle of the electromagnetic wave is: ； in, Let y be the phase change of the electron at position y relative to the initial phase; Substituting the obtained normalized distance, initial phase of the electron, and electron velocity into the difference formula and performing differentiation, the electron phase differential equation is obtained.

5. The control method for the slow-wave structure as described in claim 1, characterized in that, The output power of the slow-wave structure under the candidate period length distribution is calculated using the following formula, based on the normalized amplitude and power calculation equations at the end of the slow-wave structure according to the normalized amplitude distribution: ； Where P(y) is the output power, A(y) is the normalized amplitude distribution at the end of the slow-wave structure, is the phase angle distribution, b is the injection velocity parameter determined based on the normalized phase velocity distribution, and C is the gain factor corresponding to the slow-wave structure unit at the end of the slow-wave structure. The direct current for electron injection, The DC voltage of the electron beam.

6. The control method for the slow-wave structure as described in claim 1, characterized in that, The step of using the output power as a reference value and employing a particle swarm optimization algorithm to iteratively update the candidate period length distribution until the number of iterations reaches a preset maximum number of iterations, or until the increment of the output power is lower than a preset increment threshold for a preset number of consecutive preset number of iterations before reaching the preset maximum number of iterations, and then outputting the optimal non-uniform period length distribution of the slow wave structure specifically includes: The vector formed by the period lengths of each slow wave structure unit of the slow wave structure is set as the position vector of the particle, and the particle swarm is initialized within the preset range of period length values. In each iteration, the fitness value of each particle after initialization is calculated based on the output power, and the historical best solution of each particle and the global historical best solution of the particle swarm are updated. The iteration velocity and position vector of each particle are updated based on the historical best solution of each particle and the global historical best solution of the particle swarm to generate the updated candidate period length distribution. If the number of iterations reaches the preset maximum number of iterations, or if the increment of the output power is lower than the preset increment threshold for a preset number of consecutive iterations before reaching the preset maximum number of iterations, the candidate period length distribution corresponding to the global historical optimal solution of the population will be output as the optimal non-uniform period length distribution.

7. A control device for a slow-wave structure, characterized in that, The device includes a processor and a memory, wherein the memory stores a control program for a slow-wave structure, and when the processor executes the control program for the slow-wave structure, it implements the control method for the slow-wave structure as described in any one of claims 1 to 6.

8. A slow-wave structure, characterized in that, include: Multiple slow-wave structure units are arranged sequentially along the axial direction, and the period length of the multiple slow-wave structure units first increases and then decreases along the axial direction, then increases again and then decreases. The control device as described in claim 7 is electrically connected to the plurality of the slow-wave structure units.

9. A traveling wave tube, characterized in that, include: The slow-wave structure as described in claim 8; An electron gun is used to generate an electron beam and inject the electron beam into the slow-wave structure; An input waveguide mode is set at the input end of the slow wave structure to introduce electromagnetic waves, and the introduced electromagnetic waves are impedance matched before being input into the slow wave structure. An output waveguide mode is disposed at the output end of the slow wave structure to export the electromagnetic wave after power amplification by the slow wave structure. A dielectric attenuator is disposed on the slow-wave structure to absorb electromagnetic waves reflected from inside the slow-wave structure and block the feedback path of the electromagnetic waves, thereby suppressing self-excited oscillations and parasitic oscillations. In this process, the electron beam and the electromagnetic wave enter the slow-wave structure together to perform beam-wave interaction. The slow-wave structure is used to reduce the phase velocity of the electromagnetic wave and keep the phase velocity of the electromagnetic wave synchronized with the velocity of the electron beam during the interaction process, so as to transfer the energy of the electron beam to the electromagnetic wave for power amplification.

10. The traveling wave tube as described in claim 9, characterized in that, The dielectric attenuator is positioned close to the input waveguide mode, and the distance between the dielectric attenuator and the input waveguide mode is one-third of the distance between the input waveguide mode and the output waveguide mode.

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