Design method of high frequency circuit of multi-gap multi-cavity klystron

Abstract

The application provides a design method of a multi-gap multi-cavity klystron high-frequency circuit, comprising the following steps: obtaining macroscopic performance parameters and initial circuit parameters of the multi-gap multi-cavity klystron high-frequency circuit, and taking the initial circuit parameters as initial model analysis parameters; performing model analysis based on the initial model analysis parameters, judging whether the result of the model analysis meets the macroscopic design index, and selecting high-frequency circuit parameters for iteration of the model analysis correspondingly. The application can quickly calculate the performance index of the multi-gap multi-cavity klystron high-frequency circuit, and meanwhile, high calculation accuracy is achieved, thereby providing a high-efficiency and accurate design method of the multi-gap multi-cavity klystron high-frequency circuit.

Description

Technical Field

[0001] This invention relates to the field of microwave and millimeter-wave vacuum electronic devices, and in particular to a design method for a high-frequency circuit of a multi-gap, multi-cavity klystron. Background Technology

[0002] Currently, low-frequency klystrons operating in the centimeter and decimeter waves typically employ re-entrant single-gap resonant cavities as the basic unit of their high-frequency circuits. Their advantages include simple cavity structure and high gap electric field strength, resulting in high electron beam modulation efficiency. However, as the operating frequency of klystrons continues to increase, the transit radiation principle they rely on requires the circuit size to be approximately on the same order of magnitude as the operating wavelength. This significantly reduces the power capacity and characteristic impedance of traditional single-gap cavities with drift heads, especially in the 30-300 GHz millimeter-wave band, where the cavity structure becomes difficult to implement and external mechanisms for frequency tuning are challenging. To meet the demands of miniaturized high-frequency klystrons for mobile platforms such as vehicles, aircraft, and satellites, distributed-effect klystrons with multi-gap, multi-cavity high-frequency circuits are receiving increasing attention. However, current design methods for multi-gap, multi-cavity klystron high-frequency circuits are complex and inaccurate. Therefore, how to quickly and accurately design compliant multi-gap, multi-cavity klystron high-frequency circuits is a pressing problem to be solved. Summary of the Invention

[0003] (I) Technical Solution

[0004] This invention provides a design method for a multi-gap multi-cavity klystron high-frequency circuit, comprising: acquiring output parameters and initial parameters of the multi-gap multi-cavity klystron high-frequency circuit, wherein the output parameters include the output power, gain, efficiency, and bandwidth of the multi-gap multi-cavity klystron high-frequency circuit, and the initial parameters include the circuit physical parameters and resonant cavity physical parameters of the multi-gap multi-cavity klystron high-frequency circuit, and using the initial parameters as initial model analysis parameters; performing model analysis based on the initial model analysis parameters, including: establishing a two-dimensional multi-gap resonant cavity model of the multi-gap multi-cavity klystron high-frequency circuit according to the initial model analysis parameters, calculating the field distribution of the resonant cavity of the multi-gap multi-cavity klystron high-frequency circuit according to the two-dimensional multi-gap resonant cavity model; establishing a one-dimensional circuit model of the multi-gap multi-cavity klystron high-frequency circuit according to the initial model analysis parameters and the field distribution, and optimizing the one-dimensional circuit model, wherein the output index of the optimized one-dimensional circuit model meets the macroscopic performance index, and outputting the first model parameters of the optimized one-dimensional circuit model; establishing a three-dimensional circuit model of the multi-gap multi-cavity klystron high-frequency circuit according to the first model parameters, and outputting the first model parameters when the output index of the three-dimensional circuit model meets the macroscopic performance index.

[0005] Optionally, if the output parameters of the three-dimensional circuit model do not meet the macroscopic performance parameters, the output parameters of the three-dimensional circuit model are analyzed and the first model parameters are improved to obtain the second model parameters. The second model parameters are then used as the initial model analysis parameters for re-simulation analysis.

[0006] Optionally, the circuit physical parameters include: electron beam voltage, electron beam current, focusing magnetic field amplitude, drift tube radius, and electron beam radius of the multi-gap multi-cavity klystron high-frequency circuit.

[0007] Optionally, the physical parameters of the resonant cavity of the multi-gap multi-cavity klystron high-frequency circuit include: the position of the center of each resonant cavity along the axis of the multi-gap multi-cavity klystron high-frequency circuit, the number of gaps contained in each resonant cavity, the gap width and gap distance in each resonant cavity, the resonant frequency of each resonant cavity, the quality factor of each resonant cavity, the external quality factors of the input cavity and the output cavity, and the characteristic impedance of each resonant cavity.

[0008] Optionally, the characteristic impedance of each resonant cavity in the multi-gap multi-cavity klystron high-frequency circuit includes: establishing a three-dimensional multi-gap cavity structure model based on the number of gaps, gap width, and gap distance of each resonant cavity in the multi-gap multi-cavity klystron high-frequency circuit, and according to the formula... Calculate the characteristic impedance of each resonant cavity in a multi-gap, multi-cavity klystron high-frequency circuit. Where f is the resonant frequency of the three-dimensional multi-gap cavity, W is the average energy stored in the three-dimensional multi-gap cavity, and E z The distribution of the z-direction electric field component along the axial direction in the operating mode of a multi-gap, multi-cavity klystron high-frequency circuit.

[0009] Optionally, the operating modes of the multi-gap multi-cavity klystron high-frequency circuit include π mode or 2π mode. In π mode, the electric field direction component changes alternately in the gaps between the resonant cavities of the multi-gap multi-cavity klystron high-frequency circuit, while in 2π mode, the electric field direction component remains unchanged in the gaps between the resonant cavities of the multi-gap multi-cavity klystron high-frequency circuit.

[0010] Optionally, the two-dimensional multi-gap resonant cavity model includes an axisymmetric cylindrical cavity chain equivalent model or a planar symmetric dumbbell-shaped cavity model.

[0011] Optionally, the axisymmetric cylindrical cavity chain equivalent model is applicable to high-frequency circuits of multi-gap multi-cavity klystrons with circular electron beams and circular drift channel trapezoidal cavity structures, while the planar symmetric dumbbell-shaped cavity model is applicable to high-frequency circuits of multi-gap multi-cavity klystrons with strip electron beams and rectangular drift channel dumbbell-shaped cavity structures.

[0012] Optionally, the field distribution of the high-frequency circuit resonator of the multi-gap multi-cavity klystron is calculated based on the two-dimensional multi-gap resonator model, including the calculation of the field distribution of the two-dimensional multi-gap resonator model in the π mode and 2π mode.

[0013] Optionally, analyzing the output parameters of the three-dimensional circuit model and improving the first model parameters includes: analyzing the influence of each parameter in the first model parameters on the output parameters of the three-dimensional high-frequency circuit model, selecting key parameters in the first model parameters according to the magnitude of the influence, and improving the key parameters.

[0014] (II) Beneficial Effects

[0015] This invention presents a design method for a high-frequency circuit of a multi-gap, multi-cavity klystron. The method obtains the operating mode field distribution within each multi-gap, multi-cavity drift tube through a two-dimensional model, and substitutes the field distribution into a one-dimensional circuit model for parametric simulation calculation. This method maintains both fast calculation speed and high calculation accuracy, thus effectively simplifying the design process of the high-frequency circuit of the multi-gap, multi-cavity klystron and improving the R&D efficiency of related devices. Attached Figure Description

[0016] Figure 1 The schematic diagram illustrates a design method for a multi-gap, multi-cavity klystron high-frequency circuit according to an embodiment of the present invention.

[0017] Figure 2 The schematic diagram illustrates the process flow of model analysis provided in the embodiments of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] The present invention is described herein with respect to structural embodiments and methods. It should be understood that this is not intended to limit the invention to the specific disclosed embodiments, and the invention can be practiced using other features, elements, methods, and embodiments. Similar elements in different embodiments are typically designated with similar numbers.

[0020] Figure 1 The schematic diagram illustrates a design method for a multi-gap, multi-cavity klystron high-frequency circuit according to an embodiment of the present invention, including processes S110 to S150.

[0021] In S110, the macroscopic performance indicators and initial parameters of the output parameters of the multi-gap multi-cavity klystron high-frequency circuit are obtained. The output parameters include the output power, gain, efficiency and bandwidth of the multi-gap multi-cavity klystron high-frequency circuit. The initial parameters include the circuit physical parameters and resonant cavity physical parameters of the multi-gap multi-cavity klystron high-frequency circuit.

[0022] In this embodiment, the circuit physical parameters include: electron beam voltage, electron beam current, focusing magnetic field amplitude, drift tube radius, and electron beam radius of the multi-gap multi-cavity klystron high-frequency circuit.

[0023] In this embodiment, the physical parameters of the resonant cavity of the multi-gap multi-cavity klystron high-frequency circuit include: the position of the center of each resonant cavity along the axis of the multi-gap multi-cavity klystron high-frequency circuit, the number of gaps contained in each resonant cavity, the gap width and gap distance in each resonant cavity, the resonant frequency of each resonant cavity, the quality factor of each resonant cavity, the external quality factor of the input cavity and the output cavity, and the characteristic impedance of each resonant cavity.

[0024] In this embodiment, it is necessary to first calculate the axial velocity v of the electrons in the DC state based on the electron injection voltage U0. e The formula is as follows:

[0025]

[0026] Where, m e Let be the rest mass of the electron, c be the speed of light in vacuum, and v be the axial velocity of the electron. e Calculate the electron axial propagation constant β e The formula is as follows:

[0027]

[0028] f0 is the operating frequency of the klystron. This is based on the electron axial propagation constant β. e The width d of each cavity gap can be preliminarily determined. s and gap distance p s The initial values ​​of the circuit, to ensure circuit stability, typically need to satisfy the following relationship: β e ·p s ≤π or 2π, meaning the cavity gap transition angle does not exceed 90°. For π-mode and 2π-mode cavities, the gap phase shift does not exceed 180° and 360°, respectively. To improve interaction efficiency, the output cavity gap width and gap distance of practical high-frequency circuits should be smaller than the gap width and gap distance of the input cavity and intermediate cavity.

[0029] In this embodiment, a three-dimensional multi-gap cavity structure model needs to be established based on the number of gaps, gap width, and gap distance of each resonant cavity in the multi-gap multi-cavity klystron high-frequency circuit, and then according to the formula... Calculate the characteristic impedance of each resonant cavity in the multi-gap multi-cavity klystron high-frequency circuit, where f is the resonant frequency of the three-dimensional multi-gap cavity, W is the average energy stored in the three-dimensional multi-gap cavity, and E... zThis refers to the axial distribution of the z-direction electric field component in the operating mode of the multi-gap, multi-cavity klystron high-frequency circuit. The characteristic impedance value is related to the position of the selected axial integration path within the cross-section of the drift channel; in this embodiment, the value on the central axis is used as a reference.

[0030] In this embodiment, the software used to establish the three-dimensional multi-gap cavity structure model is CST-MWS. This software can be used to determine the specific structure of each multi-gap cavity and the actual high-frequency circuit form.

[0031] In this embodiment, a three-dimensional model is performed based on the specific cavity structure to obtain the resonant frequency of the working mode and the field distribution inside the drift tube contained in the cavity. Then, the integral of the absolute value of the mode electric field component along the axis and the energy stored in the cavity are calculated respectively. Subsequently, the accurate characteristic impedance value can be calculated according to the definition of characteristic impedance, which helps to improve the accuracy of the output index of the subsequent one-dimensional circuit model calculation.

[0032] In S120, model analysis is performed based on the initial model analysis parameters.

[0033] Figure 2 The schematic diagram illustrates the model analysis process provided in the embodiment of the present invention, including processes S210 to S220.

[0034] In process S210, a two-dimensional multi-gap resonant cavity model of the multi-gap multi-cavity klystron high-frequency circuit is established based on the initial model analysis parameters, and the field distribution of the resonant cavity of the multi-gap multi-cavity klystron high-frequency circuit is calculated based on the two-dimensional multi-gap resonant cavity model.

[0035] In this embodiment, the software used to establish the two-dimensional multi-gap resonant cavity model is Superfish, developed by Los Alamos National Laboratory in the United States. This software can be used to calculate the field distribution within the rz section of a two-dimensional axisymmetric resonant cavity. When using the two-dimensional Superfish software to calculate the electric field distribution within the drift channel of the multi-gap cavity, the gap width d is set... s and gap distance p s (Corresponding to the s-th resonant cavity) maintains the same dimensions as the corresponding dimensions in the three-dimensional cavity structure.

[0036] In this embodiment, the two-dimensional resonant cavity model includes an axisymmetric cylindrical cavity chain equivalent model or a planar symmetric dumbbell-shaped cavity model. The axisymmetric cylindrical cavity chain equivalent model is suitable for high-frequency circuits of multi-gap multi-cavity klystrons with circular electron beams and circular drift channels and trapezoidal cavities. The planar symmetric dumbbell-shaped cavity model is suitable for high-frequency circuits of multi-gap multi-cavity klystrons with strip electron beams and rectangular drift channels and dumbbell-shaped cavities.

[0037] In this embodiment, the operating mode of the multi-gap multi-cavity klystron high-frequency circuit includes π mode or 2π mode. The π mode is in which the electric field direction component alternates in the direction of each resonant cavity gap of the multi-gap multi-cavity klystron high-frequency circuit, and the 2π mode is in which the electric field direction component remains unchanged in the resonant cavity gap of the multi-gap multi-cavity klystron high-frequency circuit.

[0038] In this embodiment, a multi-gap trapezoidal cavity calculation model equivalent to an axisymmetric, drift-head-free flat cylindrical box-shaped cavity chain is established in Superfish software. The cavity center is defined as the origin of the axial coordinate system, and the drift tube radius r is defined as... t Gap width d s , gap distance p s And the number of gaps N s Consistent with the initial values ​​of each cavity mentioned above, the field distribution calculation for the π-mode or 2π-mode is completed by setting the excitation source. The "Interpolate" command is then used to specify the coordinates of the drift channel region and the number of grids to be divided along the radial and axial directions. The program interpolates and calculates the field values ​​at the grid points and outputs the results file.

[0039] In process S220, a one-dimensional circuit model of a multi-gap, multi-cavity klystron high-frequency circuit is established and optimized based on the initial model analysis parameters and field distribution. The first model parameters of the optimized one-dimensional circuit model are then output. In this embodiment, the output index of the optimized one-dimensional circuit model satisfies the macroscopic performance index.

[0040] In this embodiment, the software used to build the one-dimensional circuit model is AJDISK. This program runs quickly and is suitable for rapidly screening high-frequency circuit parameters.

[0041] In this embodiment, the initial model analysis parameters and the field distribution of each cavity are substituted into the one-dimensional AJDISK software for calculation, with a focus on optimizing the resonant frequency f of each cavity. s and its axial arrangement position z s And adjust the characteristic impedance of the cavity appropriately. And quality factor Q 0s For input and output cavities, the external quality factor Q is also involved. es After optimization, the output power, gain, efficiency, and bandwidth of the multi-gap, multi-cavity klystron high-frequency circuit as a function of input power and frequency meet the macroscopic performance indicators. Finally, the first model parameters of the optimized one-dimensional circuit model are output.

[0042] In process S230, a three-dimensional circuit model of the multi-gap multi-cavity klystron high-frequency circuit is established based on the first model parameters, and the output index of the three-dimensional circuit model is calculated.

[0043] In this embodiment, using the first model parameter as the target value, a specific three-dimensional circuit model is established in CST software. By adjusting the cavity shape and size in the model, the resonant frequency, quality factor, and characteristic impedance are determined. The axial position and other parameters were adjusted to the target values. Under the constraint of the focusing magnetic field B0, the output power, gain, efficiency, and bandwidth after the beam-sink interaction were obtained as a function of the input power and frequency through three-dimensional particle simulation.

[0044] Returning to process S130, it is determined whether the model analysis results meet the macroscopic performance indicators. In this embodiment, the model analysis results are the output indicators of the three-dimensional circuit model and the first model parameters.

[0045] In process S140, if the output indicators of the three-dimensional circuit model meet the macroscopic design indicators, the results of the model analysis are output.

[0046] In process S150, the results of the model analysis are improved to obtain the second model analysis parameters, which are then used as the initial model analysis parameters.

[0047] In this embodiment, when the output performance of the three-dimensional circuit model does not meet the macroscopic design performance, the influence of each parameter in the first model parameters on the output performance of the three-dimensional high-frequency circuit model is analyzed. Based on the magnitude of the influence, key parameters in the first model parameters are selected and improved to ensure the continuity and stability of the entire calculation iteration process.

[0048] In this embodiment, after using the second model analysis parameters as the initial model analysis parameters, a new iterative calculation is performed based on the initial model analysis parameters.

[0049] In this embodiment, a Ka-band distributed klystron high-frequency circuit can be designed. The macroscopic performance parameters and initial parameters of the output parameters of this high-frequency circuit can be obtained. The electron beam voltage in the initial parameters is 25kV, the operating frequency is 35GHz, and the electron axial propagation constant can be calculated to be 2345.07m. -1 The width of each resonant cavity gap is taken as 0.5 mm, and the gap distance is taken as 1.2 mm. Taking a three-gap intermediate cavity used in a high-frequency circuit as an example, a three-dimensional circuit model is established in CST-MWS. According to the simulation results of the three-dimensional circuit model, the working mode of the three-gap cavity is π mode, and the working frequency is 35.2918 GHz. Further calculation of the integral of the absolute value of the cavity gap electric field along the axis is performed. Substituting it into the characteristic impedance calculation formula, the R / Q value of the cavity is obtained as 100.53. The initial parameters of this high-frequency circuit are used as the initial model analysis parameters.

[0050] Based on the initial model analysis parameters, a two-dimensional three-gap resonant cavity model equivalent to a drift-head-less flat plate cylindrical box cavity chain was established in the two-dimensional Superfish software, and its field distribution was calculated.

[0051] Substitute the initial model analysis parameters and field distribution of the klystron high-frequency circuit into the one-dimensional AJDISK program to obtain a one-dimensional circuit model. By changing the excitation and frequency sweep calculation, the performance of the one-dimensional high-frequency circuit is analyzed. If the obtained output indicators can meet the macroscopic design indicators, further verification can be performed using three-dimensional CST software. Otherwise, the initial model analysis parameters and the axial arrangement of each cavity can be further optimized to obtain the first model parameters that meet the requirements of the interaction performance.

[0052] Based on the first model parameters, a three-dimensional high-frequency circuit model is established in CST software. The performance of the actual circuit is evaluated through particle simulation to determine whether macroscopic indicators such as output power, efficiency, gain, and bandwidth meet the design requirements. If they do, the first model parameters can be output. If they do not meet the design requirements, the direction of circuit parameter adjustment needs to be analyzed based on the beam-wave interaction state in the high-frequency circuit. For example, the number of gaps, the number of cavities, and characteristic impedance can be changed to obtain the second model parameters. The second model parameters are then used as the initial model analysis parameters to re-analyze the model.

[0053] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A design method for a multi-gap, multi-cavity klystron high-frequency circuit, characterized in that, include: The output parameters and initial parameters of the multi-gap multi-cavity klystron high-frequency circuit are obtained. The output parameters include the output power, gain, efficiency and bandwidth of the multi-gap multi-cavity klystron high-frequency circuit. The initial parameters include the circuit physical parameters and resonant cavity physical parameters of the multi-gap multi-cavity klystron high-frequency circuit. The initial parameters are used as the initial model analysis parameters. Model analysis is performed based on the initial model analysis parameters, including: A two-dimensional resonant cavity model of the multi-gap multi-cavity klystron high-frequency circuit is established based on the initial model analysis parameters, and the field distribution of the resonant cavity of the multi-gap multi-cavity klystron high-frequency circuit is calculated based on the two-dimensional resonant cavity model. Based on the initial model analysis parameters and the field distribution, a one-dimensional circuit model of the multi-gap multi-cavity klystron high-frequency circuit is established, and the one-dimensional circuit model is optimized. After optimization, the output power, gain, efficiency, and bandwidth of the multi-gap multi-cavity klystron high-frequency circuit with respect to the input power and frequency meet the macroscopic performance indicators, and the first model parameters of the optimized one-dimensional circuit model are output. A three-dimensional circuit model of the multi-gap, multi-cavity klystron high-frequency circuit is established based on the first model parameters. If the output parameters of the three-dimensional circuit model meet the macroscopic performance indicators, the first model parameters are output. If the output parameters of the three-dimensional circuit model do not meet the macroscopic performance indicators, the influence of each parameter in the first model parameters on the output parameters of the three-dimensional circuit model is analyzed. Based on the magnitude of the influence, key parameters in the first model parameters are selected and improved to obtain second model parameters. The second model parameters are then used as the initial model analysis parameters for re-simulation analysis.

2. The method according to claim 1, characterized in that, The circuit physical parameters include: electron beam voltage, electron beam current, focusing magnetic field amplitude, drift tube radius, and electron beam radius of the multi-gap multi-cavity klystron high-frequency circuit.

3. The method according to claim 1, characterized in that, The physical parameters of the resonant cavities in the multi-gap multi-cavity klystron high-frequency circuit include: the position of the center of each resonant cavity along the axis, the number of gaps contained in each resonant cavity, the gap width and gap distance in each resonant cavity, the resonant frequency of each resonant cavity, the quality factor of each resonant cavity, the external quality factors of the input cavity and the output cavity, and the characteristic impedance of each resonant cavity.

4. The method according to claim 3, characterized in that, Obtaining the characteristic impedance of each resonant cavity in the multi-gap, multi-cavity klystron high-frequency circuit includes: A three-dimensional multi-gap cavity structure model is established based on the number of resonant cavities and the number of gaps in each cavity of the multi-gap multi-cavity klystron high-frequency circuit. According to the formula Calculate the characteristic impedance of each resonant cavity in the multi-gap, multi-cavity klystron high-frequency circuit. Where f is the resonant frequency of the three-dimensional multi-gap cavity, and W is the average energy stored in the three-dimensional multi-gap cavity. This refers to the axial distribution of the z-direction electric field component in the operating mode of the multi-gap, multi-cavity klystron high-frequency circuit.

5. The method according to claim 4, characterized in that, The operating modes of the multi-gap multi-cavity klystron high-frequency circuit include π mode or 2π mode. In the π mode, the electric field direction component changes alternately in the gaps between the resonant cavities of the multi-gap multi-cavity klystron high-frequency circuit. In the 2π mode, the electric field direction component remains constant in the gaps between the resonant cavities of the multi-gap multi-cavity klystron high-frequency circuit.

6. The method according to claim 1, characterized in that, The two-dimensional resonant cavity model includes an axisymmetric cylindrical cavity chain equivalent model or a planar symmetric dumbbell-shaped cavity model.

7. The method according to claim 6, characterized in that, The axisymmetric cylindrical cavity chain equivalent model is applicable to high-frequency circuits of multi-gap multi-cavity klystrons with circular electron beams and circular drift channel trapezoidal cavity structures, while the planar symmetric dumbbell-shaped cavity model is applicable to high-frequency circuits of multi-gap multi-cavity klystrons with strip electron beams and rectangular drift channel dumbbell-shaped cavity structures.

8. The method according to claim 5, characterized in that, The calculation of the field distribution of the high-frequency circuit resonator of the multi-gap multi-cavity klystron based on the two-dimensional resonator model includes calculating the field distribution of the operating mode of the two-dimensional resonator model in the π mode and the 2π mode.

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