Multistage depressed collector of millimeter wave communication traveling wave tube and working voltage design method

Abstract

The invention discloses a working voltage design method for a multistage depressed collector of a millimeter wave communication traveling wave tube, the collector comprises N inner collectors, N is greater than or equal to 3, and the method comprises the following steps: importing and analyzing a saturation inlet file and a linear inlet file of the collector; determining the working voltage of the first inner collector according to the voltage value of the inflection point of the saturated electron residual energy curve, determining the working voltage of the Nth inner collector according to the absolute value of the cathode voltage, and determining the voltage range of the nth inner collector according to the theoretical voltage reduction values of all levels corresponding to the saturated inlet file and the theoretical voltage reduction values of all levels corresponding to the linear inlet file, n belongs to [2, N-1]; and performing parameter scanning in the voltage range of the nth inner collector according to a joint optimization target including the collection efficiency and the reflux rate, and determining the working voltage of the nth inner collector. According to the invention, the selection of the optimal working voltage value of each stage of the collector in the saturated and linear dual modes is realized, and the efficient recovery of the depressed collector of the millimeter wave communication traveling wave tube in the dual modes is realized.

Description

Technical Field

[0001] The present invention relates to the field of microwave vacuum electron technology. More specifically, it relates to a multi-stage depressed collector and a working voltage design method for a millimeter-wave communication traveling wave tube. Background Art

[0002] As the final-stage power amplifier, traveling wave tubes are widely used in fields such as radar and electronic warfare. The depressed collector is an important part of the traveling wave tube. By setting a voltage drop, it decelerates electrons so that they hit the electrode surface, reducing the heat loss caused by electron bombardment and improving the recovery efficiency of the remaining electron energy, thereby effectively enhancing the total efficiency of the traveling wave tube.

[0003] The working state of a traveling wave tube can be divided into two types: saturated and linear. In the saturated state, the output power is large but the nonlinear effect is obvious; in the linear state, the output power is small but the linearity is high. For a long time, when a traveling wave tube is used as a power device in a system, high power and high efficiency are pursued. Correspondingly, existing depressed collectors are mostly designed for the saturated remaining electron state. However, when a millimeter-wave traveling wave tube is applied to a communication system, it mainly operates linearly and is in the saturated state for some time, and it is necessary to take into account the remaining electron states in both working modes. Figure 1 As shown in the schematic diagrams of saturated and linear remaining electron energy spectra, it can be seen that the kinetic energy distribution of saturated electrons is scattered, while most linear electrons are concentrated in the region of large kinetic energy, and design needs to be carried out comprehensively considering both states.

[0004] The electron efficiency of a millimeter-wave traveling wave tube is relatively low (5% - 10%). Taking a 71 - 76 GHz traveling wave tube with a saturated electron efficiency of 8.5% as an example, if only saturated electrons are used as the collector inlet (when designing, only considering the electron information in the saturated state), and analyzed using the microwave tube simulation studio software MTSS (Microwave Tube Simulation Studio), it is found that only a two-stage deep depressed collector is required to achieve a saturated electron recovery efficiency of 87.4%, corresponding to a total efficiency of 32%, which basically meets the usage requirements. However, under the same conditions, the recovery efficiency of linear-state electrons is 85.5%, corresponding to a total efficiency of only 14%. It can be seen that the existing technology cannot achieve high-efficiency recovery in both working modes under the same working conditions. Summary of the Invention

[0005] The present invention provides a multi-stage depressed collector and a working voltage design method for a millimeter-wave communication traveling wave tube to solve at least one of the problems existing in the prior art.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The first aspect of the present invention provides a method for designing the operating voltage of a multi-stage depressed collector for a millimeter-wave communication traveling-wave tube. The collector includes N inner collectors, where N ≥ 3. The method includes

[0008] Import and analyze the saturated inlet file and the linear inlet file of the collector;

[0009] Determine the operating voltage of the first inner collector according to the inflection point voltage value of the saturated electron residual energy curve, determine the operating voltage of the Nth inner collector according to the absolute value of the cathode voltage, and determine the voltage range of the nth inner collector according to the theoretical voltage drops at all levels corresponding to the saturated inlet file and the theoretical voltage drops at all levels corresponding to the linear inlet file, where n ∈ [2, N - 1];

[0010] Perform parameter scanning within the voltage range of the nth inner collector with a combined optimization objective including collection efficiency and reflux rate to determine the operating voltage of the nth inner collector.

[0011] Optionally, the importing and analyzing the saturated inlet file and the linear inlet file of the collector includes obtaining the input and output powers of the linear operating point and the saturated operating point through the MTSS software;

[0012] Obtain the saturated output result, i.e., the saturated inlet file, according to the preset frequency and the input power of the saturated operating point;

[0013] Obtain the linear output result, i.e., the linear inlet file, according to the preset frequency and the input power of the linear operating point.

[0014] Optionally, the obtaining the input and output powers of the linear operating point and the saturated operating point through the MTSS software includes

[0015] Through power scan calculation at the preset frequency, obtain the input-output power scan distribution map, so as to obtain the input and output powers corresponding to the linear operating point and the saturated operating point of the traveling-wave tube.

[0016] Optionally, the importing and analyzing the saturated inlet file and the linear inlet file of the collector further includes

[0017] Obtain the theoretical voltage drops at all levels of the collector, the currents at all levels, and the maximum collector efficiency according to the number of input electrodes and the preset voltage interval.

[0018] Optionally, the determining the voltage range of the nth inner collector according to the theoretical voltage drops at all levels corresponding to the saturated inlet file and the theoretical voltage drops at all levels corresponding to the linear inlet file includes

[0019] Select multiple frequency points at equal intervals within the working frequency band, obtain the theoretical voltage drops of the nth inner collector corresponding to the saturated input file and the linear input file at each frequency point, form a value set, and the minimum and maximum values in the set are the voltage ranges of the nth inner collector.

[0020] Optionally, the parameter scanning within the voltage range of the nth inner collector with the combined optimization objective including the collection efficiency and the reflux rate includes

[0021] Obtain the scanning results according to the voltage range of the nth inner collector and the preset voltage interval, and screen the optimal operating voltage of the nth inner collector according to the scanning results.

[0022] Optionally, the screening of the optimal operating voltage of the nth inner collector according to the scanning results includes

[0023] Taking the preset reflux rate as the screening criterion, select a set of scanning voltages with relatively better comprehensive linear collector efficiency and saturated collector efficiency as the optimal operating voltage.

[0024] A multi-stage depressed collector of a millimeter-wave communication traveling-wave tube is provided in the second aspect of the present invention. The multi-stage depressed collector includes a collector outer cylinder, N inner collectors, and insulating ceramics and lead insulating ceramics between the collector outer cylinder and the inner collector assembly, where N≥3.

[0025] The N inner collectors include N sleeves and lead ends. The N inner collectors are arranged axially in sequence for recovering the energy of the electrons after interaction. The first inner collector is a hollow cylindrical cavity. The inlet ends of the nth inner collectors are all planar structures with the same inclination direction, n∈[2,N-1]. The Nth inner collector is a conical shape. The connecting part of the nth inner collector is a hollow cylindrical structure.

[0026] Optionally, the inclination angles of the inlet ends of the nth inner collectors are θ2, θ3,..., θ in sequence within 180° along the axis. n-1 .

[0027] Optionally, the axis of the inlet end of the nth inner collector is eccentric in the same direction with respect to the axis of the inlet end of the first inner collector. Among them, the offset distances of the axis of the inlet end of the nth inner collector with respect to the axis of the inlet end of the first inner collector are d2, d3,..., d. n-1 , where d2 < d3 <... < d. n-1 .

[0028] The beneficial effects of the present invention are as follows:

[0029] Through the comprehensive design method of the collector in the saturation and linear dual modes, the present invention realizes the selection of the optimal operating voltage values for each stage of the collector, achieves the improvement of the collector efficiency and the suppression of the backflow. Correspondingly, it can comprehensively improve the overall efficiency of the millimeter-wave communication traveling-wave tube in the saturation and linear dual modes. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The following further describes in detail the specific embodiments of the present invention with reference to the accompanying drawings.

[0031] Figure 1 Shows the schematic diagrams of the energy distributions of the saturated residual electrons and the linear residual electrons;

[0032] Figure 2 Shows the schematic diagram of the engineering interface of the MTSS software injection-wave interaction of the present invention;

[0033] Figure 3 Shows the schematic diagram of the interface of the power scan calculation in the first embodiment;

[0034] Figure 4 Shows the result distribution diagram of the power scan in the first embodiment;

[0035] Figure 5 Shows the schematic diagram of the interface of the single-frequency calculation in the first embodiment;

[0036] Figure 6 Shows the schematic diagram of the saturation inlet file in the first embodiment;

[0037] Figure 7 shows the schematic diagram of the interface setting (a) for importing the saturation inlet file and the schematic diagram of the interface for setting parameters (b) in the first embodiment;

[0038] Figure 8 shows the method for viewing the electron energy distribution curve at the collector inlet (a) and the result distribution diagram of the analysis and calculation of the collector inlet file (b) in the first embodiment;

[0039] Figure 9 Shows the schematic diagram of the analysis and calculation of the collector inlet file in the first embodiment;

[0040] Figure 10 Shows the schematic diagram of the preferred range of the voltage drop values for each stage of the collector in the first embodiment;

[0041] Figure 11 Shows the schematic diagram of the scan setting in the first embodiment;

[0042] Figure 12 shows the overall scan result (a) and the result of the optimal scan example (b) in the first embodiment;

[0043] Figure 13 Shows the analysis and comparison diagram of the scan results of each scan example in the first embodiment;

[0044] Figure 14 shows a schematic structural diagram of the five - stage depressed collector arranged axially in the second embodiment;

[0045] Figure 15 Figure shows a schematic diagram of equipotential lines of the five - stage depressed collector in the second embodiment;

[0046] Figure 16 Figure shows a schematic structural diagram of the five - stage depressed collector arranged perpendicular to the axis in the second embodiment. Detailed implementation manners

[0047] To illustrate the present invention more clearly, the present invention will be further described below in conjunction with preferred embodiments and the accompanying drawings. Similar components in the drawings are denoted by the same reference numerals. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0048] The present invention provides a five - stage depressed collector that can achieve efficient recovery while taking into account both saturation and linear dual - working modes, which can significantly improve the collector recovery efficiency in the linear working state, reduce the heat dissipation pressure, is applicable to millimeter - wave communication traveling - wave tubes, and is of great significance for reducing system costs.

[0049] The first aspect of the present invention provides a design method for a multi - stage depressed collector of a millimeter - wave communication traveling - wave tube. The collector includes N inner collector components, N≥3, and the method includes

[0050] Obtain the saturation inlet file and the linear inlet file of the collector:

[0051] Through the power scan calculation at a preset frequency by MTSS software, obtain the input - output power scan distribution diagram, and accordingly determine the input and output powers corresponding to the linear working point and the saturation working point of the traveling - wave tube; obtain the saturation output calculation result according to the preset frequency and the input power at the saturation working point, that is, the saturation inlet file; obtain the linear output calculation result according to the preset frequency and the input power at the linear working point, that is, the linear inlet file;

[0052] Import and analyze the saturation inlet file and the linear inlet file of the collector;

[0053] Obtain the theoretical voltage drop values of each stage of the collector, the current of each stage, and the maximum collector efficiency according to the number of input electrodes and the preset voltage interval;

[0054] Determine the working voltage of the first inner collector according to the inflection - point voltage value of the saturation electron residual energy curve, determine the working voltage of the Nth inner collector according to the absolute value of the cathode voltage, and determine the voltage range of the nth inner collector according to the theoretical voltage drop values of each stage corresponding to the saturation inlet file and the theoretical voltage drop values of each stage corresponding to the linear inlet file, n∈[2,N - 1];

[0055] Select multiple frequency points at equal intervals within the working frequency band, obtain the theoretical voltage drop values of the nth inner collector corresponding to the saturated input file and the linear input file at each frequency point, form a value set, and the minimum and maximum values in the set are the voltage ranges of the nth inner collector.

[0056] Perform parameter scanning within the voltage range of the nth inner collector with the combined optimization objective including collection efficiency and reflux ratio to determine the optimal operating voltage of the nth inner collector. Specifically: obtain the scanning results by scanning the voltage range of the nth inner collector and the preset voltage interval, and screen the optimal operating voltage of the nth inner collector according to the scanning results; use the preset reflux ratio as the screening criterion, and select the voltage value corresponding to a group of values with relatively better comprehensive linear collection efficiency and saturated collection efficiency as the optimal operating voltage; preferably use a reflux ratio of 0 as the screening criterion.

[0057] In a specific embodiment, a five-stage voltage-drop collector is selected for design, that is, N = 5. The collector input file is the remaining electron beam information after the injection-wave interaction, and the collector input file needs to be obtained through the MTSS traveling-wave tube injection-wave interaction scheme. Specifically:

[0058] I. Obtain the saturated input file and the linear input file of the collector

[0059] Open the schematic diagram of the MTSS injection-wave interaction engineering interface as shown in Figure 2 Add a calculation task on the left, click "Calculation Task", add "Task 1". After the new task is completed, the "Power Scan" interface as shown in Figure 3 appears. Set the frequency f. In this embodiment, 73 GHz is used as an example. Set the scanning range of the input power to 0.01 mW - 100 mW, and set the scanning method to logarithmic scanning. After the scanning is completed, the power scan result distribution diagram as shown in Figure 4 is obtained. In the linear amplification region, the output power increases linearly with the increase of the input power; in the non-linear amplification region, as the input power gradually increases, after the output power increases to the maximum value, that is, the saturation point, it will show a gradually decreasing trend. The linear operating point is located in the linear amplification region. Set the linear operating point to back off x dB from the saturation operating point (x is determined according to actual requirements); obtain the input power Pi_L and output power Po_L corresponding to the linear operating point, and the input power Pi_S and output power Po_S corresponding to the saturation operating point from Figure 4 through the cursor reading function.

[0060] In the MTSS injection-wave interaction engineering interface, click "Calculation Task" to add "Task 2" to obtain as shown in Figure 5For the interface shown, select "Single-frequency calculation" for the calculation type, set the frequency f and the input power Pi_S corresponding to the saturation operating point, and right-click on "3D calculation" to obtain the calculation results at the saturation input power. At this time, the "Collector input.bin" file can be found in the file path of the beam-wave interaction project. This file is the collector saturation inlet file at frequency f. The path of the "Collector input.bin" file can be "C:\E-band traveling wave tube\Beam-wave interaction 1\Task 1\Collector input.bin".

[0061] In Figure 5 the interface shown, select "Single-frequency calculation", set the frequency f and the input power Pi_L corresponding to the linear operating point, and right-click on "3D calculation" to obtain the calculation results at the linear input power, that is, the collector linear inlet file at frequency f.

[0062] The collector saturation inlet file can be opened with a text document. As Figure 6 shown, the main information included is the operating voltage of the traveling wave tube, saturation power, electron efficiency, number of electrons, and the coordinates (X, Y, Z), velocities (Vx, Vy, Vz), and charge of each electron. Among them, Figure 6 the first four data in the first row of the inlet file example represent the synchronous voltage, interaction output power, interaction structure length, and total number of macroparticles respectively. The fifth data in the first row is defaulted to 0. The first three data in the second row represent the number of axial particles, number of angular particles, and number of radial particles in the interaction respectively. The fourth and fifth data in the second row are defaulted to 0. The rest, the first column represents the X coordinate of the electron, the second column represents the Y coordinate of the electron, the third column represents the Z coordinate of the electron, the fourth column represents the velocity Vx of the electron in the X direction, the fifth column represents the velocity Vy of the electron in the Y direction, the sixth column represents the velocity Vz of the electron in the Z direction, and the seventh column represents the charge of the electron.

[0063] II. Import and analyze the collector saturation inlet file and linear inlet file

[0064] Open the MTSS collector calculation project interface, import the obtained collector inlet file, and analyze it. The specific operations are as follows:

[0065] Open the MTSS collector calculation engineering interface, click "Interface Settings" in the interface, as shown in (a) of Figure 7 below, to obtain the import entry interface shown in Figure 7(b). Click "Browse", select the path where the collector entry file is located (the example is H:\Entry Conditions\73GHz Saturation Entry.bin), and the import can be completed. After the import, you can click "Single Calculation Result" in Figure 8(a) to obtain the energy distribution map of the collector entry. At the same time, enter the number of electrodes as 4 in the "Interface Settings" interface, and the preset voltage interval is preferably 5V. Click "Calculate" to obtain the theoretical voltage drop values at each level, the current at each level, and the maximum collector efficiency calculated under the given entry file and the number of voltage reduction levels. It should be noted that the fifth electrode of the five-stage voltage reduction collector in this embodiment is at the same potential as the cathode, so the number of input electrodes is 4; if the preset voltage interval is set to 1V for individual calculations, the calculation results are accurate but the calculation amount is large and the time consumption is high. If the preset voltage interval is set to 50V for individual calculations, the calculation results are inaccurate. According to a large number of experiments, the preset voltage interval is preferably 5V.

[0066] Assume that the operating frequency band of the traveling wave tube is f1 (GHz) - f n (GHz). Generally, 1GHz is set as the operating frequency band interval. Import the saturation entry files and linear entry files at each integer frequency point respectively, calculate the theoretical voltage drop values at each level according to the above method, and summarize them.

[0067] III. Determine the preferred voltage range for each level of the collector

[0068] Determine the operating voltage of the first inner collector according to the inflection point voltage value of the saturated electron residual energy curve, that is, the operating voltage of the first inner collector is the inflection point voltage of saturation; determine the operating voltage of the fifth inner collector according to the absolute value of the cathode voltage, that is, the operating voltage of the fifth inner collector is the cathode voltage U k ,

[0069] Determine the voltage ranges at which the second inner collector, the third inner collector, and the fourth inner collector operate according to the theoretical voltage drop values at each level corresponding to the saturation entry file and the theoretical voltage drop values at each level corresponding to the linear entry file;

[0070] According to the above operating frequency band interval, for the operating frequency band of frequency f1, through the above method, the theoretical voltage drop values at each level corresponding to the saturation entry under four-stage voltage reduction can be obtained, denoted as U 1-1S 、U 2-1S 、U 3-1S 、U 4-1S , and the theoretical voltage drop values at each level of the linear entry are denoted as U 1-1L 、U 2-1L 、U 3-1L 、U 4-1L . For the operating frequency band of frequency f2 - f nAt the same time, two sets of theoretical step-down values under saturation and linearity can also be obtained, and the collected data are summarized in Table 1 as follows.

[0071] Table 1 Summary Table of Theoretical Step-Down Values at Different Frequency Points of the Collector

[0072]

[0073] (1) The voltage of the first inner collector takes the minimum value in the set {U 1-1S , U 1-2S … U 1-nS}, denoted as U1;

[0074] (2) The upper and lower limits of the voltage range of the second inner collector are the maximum and minimum values in the set {U 2-1S , U 2-2S … U 2-nS , U 2-1L , U 2-2L … U 2-nL}, denoted as U 2max and U 2min ;

[0075] (3) The upper and lower limits of the voltage range of the third inner collector are the maximum and minimum values in the set {U 3-1S , U 3-2S … U 3-nS , U 3-1L , U 3-2L … U 3-nL}, denoted as U 3max and U 3min ;

[0076] (4) The upper and lower limits of the voltage range of the fourth inner collector are the maximum and minimum values in the set {U 4-1S , U 4-2S … U 4-nS , U 4-1L , U 4-2L … U 4-nL}, denoted as U 4max and U 4min ;

[0077] (5) The voltage of the fifth inner collector is equal to the cathode voltage, U5 = U k .

[0078] Figure 10 is a schematic diagram of the preferred range of step-down values for each stage of the collector.

[0079] IV. Determine the Optimal Operating Voltage for Each Stage of the Collector

[0080] Parameter scanning is performed within the voltage ranges of the second inner collector, the third inner collector, and the fourth inner collector with the combined optimization objective of including collection efficiency and reflux rate to determine the optimal operating voltage of the nth inner collector.

[0081] According to the preferred voltage ranges of each stage of the collector, the operating voltages of the first inner collector and the fifth inner collector are uniquely determined, and the operating voltages (u2, u3, and u4) of the second inner collector, the third inner collector, and the fourth inner collector determine the preferred voltage range. Further, with u2, u3, and u4 as variables and the collector efficiency and reflux rate as the optimization objectives, parameter scanning is carried out to obtain the optimal operating voltages of each stage of the collector. Specifically:

[0082] As Figure 11 shown, in the MTSS collector calculation engineering interface, click "Scan Settings", input the start value, end value, and interval of u2, u3, and u4, and then right-click at "Scan Settings" to perform "Scan Calculation"; after the scan calculation is completed, click "Scan Calculation Results" to view the reflux rate and the scan curves of the collector efficiency, as shown in Fig. 12(a), or view the specific calculation results of each scan case, as shown in Fig. 12(b).

[0083] Open the MTSS collector calculation project, click "Interface Settings" in the interface, and import the linear and saturated inlets of the center frequency from "Browse" respectively to perform scan calculation. The calculation results are shown in Fig. 12(a). In this embodiment, it is preferably to use a reflux rate of 0 as the screening criterion, and it is sufficient that the linear collector efficiency and the saturated collector efficiency are relatively optimal. From Figure 13 it can be obtained that scan cases 6, 22, and 23 all meet the requirements. Among the above three scan results, when the reflux rate is 0, the linear collector efficiency and the saturated collector efficiency of scan case 6 are higher than those of scan case 22 and scan case 23. Therefore, the u2, u3, and u4 corresponding to scan case 6 are selected as the optimal operating voltages of the second inner collector, the third inner collector, and the fourth inner collector, and Fig. 12(b) is the result of the operating voltage values of scan case 6.

[0084] The second aspect of the present invention provides a multi-stage depressed collector for a millimeter-wave communication traveling-wave tube. The multi-stage depressed collector includes a collector outer cylinder, N inner collectors, and insulating ceramics and lead insulating ceramics between the collector outer cylinder and the inner collectors, where N≥3.

[0085] The N inner collector assemblies include N sleeves and lead ends with a voltage-reducing function. The N inner collectors are arranged axially in sequence for recovering the energy of the electrons after interaction; the first inner collector is a hollow cylindrical cavity, and the inlet ends of the nth inner collector are all plane structures with the same inclination direction, and the inclination angles are θ2, θ3,..., θ within 180° along the axis. n-1, where \(n\in[2,N - 1]\); the \(N\)th inner collector is conical; the connecting part of the \(n\)th inner collector has a hollow cylindrical structure.

[0086] The axis of the inlet end of the \(n\)th inner collector is eccentric in the same direction with respect to the axis of the inlet end of the 1st inner collector; among them, the offset distance of the axis of the inlet end of the \(n\)th inner collector relative to the axis of the inlet end of the 1st inner collector is \(d_2, d_3,\cdots, d\) n-1 , where \(d_2\lt d_3\lt\cdots\lt d\) n-1 .

[0087] In a specific embodiment, the five - stage step - down collector structure is shown in Figure 14, including a collector outer cylinder 1, and five inner collectors 3 are axially distributed in sequence. There are insulating ceramics 2 and lead insulating ceramics 4 between the collector outer cylinder 1 and the inner collectors 3.

[0088] The collector outer cylinder 1 adopts a hollow cylindrical structure, and the material is preferably oxygen - free copper or kovar. A limit boss for positioning the insulating ceramic 2 is provided on the collector outer cylinder 1, and a semi - circular groove for placing brazing solder is provided on the side wall of the collector outer cylinder 1 in contact with the insulating ceramic 2, and the material is selected as oxygen - free copper with high temperature deformation resistance and good thermal conductivity.

[0089] The insulating ceramic 2 can be a complete cylinder or \(M\) evenly distributed sector - shaped insulating ceramics, and \(M\) is preferably 2 or 3. Figure 14(a) shows that the insulating ceramic is a complete cylindrical structure, and Figure 14(b) shows that the insulating ceramic is a structure of 3 evenly distributed sectors; the thickness of the insulating ceramic 2 meets the withstand voltage requirements between the inner and outer collectors, and a position for the lead end to pass through is reserved on the insulating ceramic 2. The material is preferably alumina, aluminum nitride, beryllium oxide, etc. with more than 95% good insulation performance and thermal conductivity. In this embodiment, the insulating ceramic 2 is 3 evenly distributed sector - shaped ceramic parts, and the sector angle of the ceramic parts is preferably \(100\pm10^{\circ}\), designed according to the withstand voltage requirement value, and the material is selected as alumina with more than 95% good insulation performance and thermal conductivity.

[0090] The inner collector 3 includes a hollow cylindrical structure, and on the side facing the electron beam incidence, it includes the 1st inner collector 31, the 2nd inner collector 32, the 3rd inner collector 33, the 4th inner collector 34, and the 5th inner collector 35 axially distributed in sequence, as Figure 16 shown. Each stage of the inner collector includes a sleeve and a lead end brazed thereto. An annular groove is provided on the outside of the inner collector 3 for placing brazing solder. The material of the inner collector is selected as oxygen - free copper with good thermal conductivity, and the material of the lead end is selected as kovar.

[0091] The first inner collector 31 is a hollow cylindrical cavity. The entrance diameter is generally taken as 2-3 times the diameter of the electron beam after interaction, and the entrance is extended, which can prevent the secondary electrons from flowing back to the interaction region to a certain extent; the structures of the second inner collector 32, the third inner collector 33, and the fourth inner collector 34 are similar. The entrance ends of the second inner collector 32, the third inner collector 33, and the fourth inner collector 34 are all inclined planes. As shown in the attached Figure 16 figures, they are all inclined in the counterclockwise direction, and the inclination angles are θ2, θ3, and θ4 respectively, achieving the effect of deflecting electrons downward; eccentric circular openings are opened on the inclined planes, and the distances from the axis are d2, d3, and d4 in sequence. Among them, d2 < d3 < d4, and d2 = 0. The distance from the axis is related to the inclination angle. The larger the inclination angle, the stronger the electric field deflection effect, the greater the radial travel distance of the electrons, and the corresponding distance from the axis needs to be increased to better accommodate all electrons to pass through. The second inner collector 32, the third inner collector 33, and the fourth inner collector 34 include a protruding part and a connecting part. The protruding parts of the second inner collector 32, the third inner collector 33, and the fourth inner collector 34 are located in the inner cavity of the previous inner collector, forming a deflection electric field to prevent electrons from escaping between the stages; the connecting parts are all hollow cylindrical structures, and the transition between the protruding part and the connecting part is a right-angle structure; the fifth inner collector 35 is a sharp cone, and the electric field formed by it is conducive to electron divergence, shortening the travel length of the electrons, and is conducive to the miniaturization of the axial direction of the collector. The electrode potentials of each inner collector are selected according to the method in Embodiment 1 of the present invention.

[0092] A negative high voltage is applied to the inner collector 3 through the lead end, forming a decelerating electric field between it and the grounded tube body. The potentials of each stage decrease sequentially along the axis. Electrons with small kinetic energy hit the previous stage, and electrons with large kinetic energy hit the subsequent stage, realizing the classified recovery of electrons carrying different energies. Among them, the lower limit of the value range of the absolute value of the negative high voltage is the inflection point voltage value of the saturated electron residual energy curve; the upper limit is the absolute value of the cathode voltage U k .

[0093] The lead insulator 4 is a hollow cylindrical structure, and the lead end passes through the hollow position. It is sealed with the outer cylinder 1 of the collector and the lead end through a transition structure of a kovar material to ensure the sealing performance of the collector. The materials are preferably alumina, aluminum nitride, beryllium oxide, etc. with more than 95% good insulation performance and thermal conductivity. There are various possibilities for the structure of the lead insulator 4 and its sealing method with the outer cylinder 1 of the collector and the lead end. Those skilled in the art can design it according to their own needs. In this embodiment, the lead insulator material is selected as alumina ceramic with more than 95% good insulation performance.

[0094] Brazing is carried out between the outer surface of the inner collector 3 and the inner surface of the insulating porcelain 2, and between the inner surface of the outer cylinder 1 of the collector and the outer surface of the insulating porcelain 2, so as to improve the heat transfer efficiency of the inner collector to the outside. The brazing filler metal is preferably gold-silver-copper and silver-copper with good fluidity.

[0095] Brazing is carried out between the outer cylinder 1 of the collector and the lead insulating porcelain 4, and between the lead insulating porcelain 4 and the lead end, so as to ensure the sealing performance of the collector. The brazing filler metal is preferably gold-silver-copper and silver-copper with good fluidity.

[0096] In this embodiment, a structure for suppressing backflow is also provided. Figure 16 It is a schematic diagram of the structure for suppressing backflow, and the structure for suppressing backflow can be selected as needed.

[0097] Taking the E-band 71-76 GHz traveling wave tube as an example in this embodiment, the frequency f is set to 73 GHz. In the existing scheme, the obtained saturated electron recovery efficiency is 8.5%, and the linear electron recovery efficiency is 3.4%. The saturated electron collector recovery efficiency obtained by using the method of the five-stage step-down collector proposed by the present invention reaches 90.2%, and the corresponding total efficiency of the traveling wave tube can reach 37%, and the backflow rate is reduced to 0.39%. Under the same working conditions, the linear electron collector recovery efficiency reaches 93.2%, and the corresponding total efficiency of the traveling wave tube can reach 24%, and the backflow rate is 0. The comparison of the main indicators between the technical solution of the present invention and the existing technical solution is shown in Table 2. The collector recovery efficiency and the total efficiency are greatly improved in both the saturated working state and the linear working state, and the efficient recovery of linear electrons and saturated electrons can be realized simultaneously in both the linear and saturated dual modes.

[0098] Table 2 Comparison of main indicators between the technical solution of the present invention and the existing technical solution

[0099] Saturation state Electron efficiency Collector recovery efficiency Total collector power consumption Total efficiency Recirculation rate Current solution 8.5％ 87.4％ 58W 32％ 1.17％ This solution 8.5％ 90.2％ 40W 37％ 0.39％ Difference — +2.8％ -18W +5％ -0.78％ Linear state Electron efficiency Collector recovery efficiency Total collector power consumption Total efficiency Recirculation rate Current solution 3.4％ 85.5％ 88W 14％ 0.78％ This solution 3.4％ 93.2％ 38W 24％ 0 Difference — +7.7％ -50W +10％ -0.78％

[0100] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention. Unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0101] It should also be noted that in the description of the present invention, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variation thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0102] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to enumerate all implementation manners here. Any obvious changes or modifications derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for designing the operating voltage of a multi-stage depressed collector of a millimeter-wave communication traveling-wave tube, characterized in that, The collector includes N inner collectors, where N≥3, and the method includes importing and analyzing the saturation inlet file and the linear inlet file of the collector; determining the operating voltage of the first inner collector according to the inflection point voltage value of the saturation electron residual energy curve, determining the operating voltage of the Nth inner collector according to the absolute value of the cathode voltage, and determining the voltage range of the nth inner collector according to the theoretical voltage drops at all levels corresponding to the saturation inlet file and the theoretical voltage drops at all levels corresponding to the linear inlet file, where n∈[2,N-1]; performing parameter scanning within the voltage range of the nth inner collector with a combined optimization objective including collection efficiency and reflux rate to determine the operating voltage of the nth inner collector.

2. The operating voltage design method according to claim 1, characterized in that, The importing and analyzing the saturation inlet file and the linear inlet file of the collector includes obtaining the input and output powers of the linear operating point and the saturation operating point through MTSS software; obtaining the saturation output calculation result, i.e., the saturation inlet file, according to the preset frequency and the input power of the saturation operating point; obtaining the linear output calculation result, i.e., the linear inlet file, according to the preset frequency and the input power of the linear operating point.

3. The operating voltage design method according to claim 2, characterized in that, The obtaining the input and output powers of the linear operating point and the saturation operating point through MTSS software includes obtaining the input-output power scan distribution map through power scan calculation at the preset frequency, so as to obtain the input and output powers corresponding to the linear operating point and the saturation operating point of the traveling wave tube.

4. The operating voltage design method according to claim 1, characterized in that, The importing and analyzing the saturation inlet file and the linear inlet file of the collector further includes obtaining the theoretical voltage drops at all levels, the currents at all levels, and the maximum collector efficiency of the collector according to the number of input electrodes and the preset voltage interval.

5. The operating voltage design method according to claim 1, characterized in that, The determining the voltage range of the nth inner collector according to the theoretical voltage drops at all levels corresponding to the saturation inlet file and the theoretical voltage drops at all levels corresponding to the linear inlet file includes selecting multiple frequency points at equal intervals within the operating frequency band, obtaining the theoretical voltage drops of the nth inner collector corresponding to the saturation inlet file and the linear inlet file at each frequency point, forming a value set, and the minimum and maximum values in the set are the voltage range of the nth inner collector.

6. The operating voltage design method according to claim 1, characterized in that, The performing parameter scanning within the voltage range of the nth inner collector with a combined optimization objective including collection efficiency and reflux rate includes obtaining the scan result according to the voltage range of the nth inner collector and the preset voltage interval, and screening the optimal voltage drop of the nth inner collector according to the scan result.

7. The operating voltage design method according to claim 6, characterized in that, The screening the optimal voltage drop of the nth inner collector according to the scan result includes using the preset reflux rate as the screening criterion, and selecting a set of scan voltages with relatively better comprehensive linear collector efficiency and saturation collector efficiency as the optimal operating voltage.

8. A multi-stage depressed collector of a millimeter-wave communication traveling-wave tube, characterized in that, The multi-stage voltage-drop collector includes a collector outer cylinder, N inner collectors, and insulating ceramics and lead insulating ceramics between the collector outer cylinder and the inner collectors, where N≥3, the N inner collectors include N sleeves and lead ends, the N inner collectors are arranged axially in sequence for recovering the energy of the electrons after interaction; the first inner collector is a hollow cylindrical cavity; the inlet ends of the nth inner collectors are all plane structures with the same inclination direction, where n∈[2,N-1]; the Nth inner collector is a sharp cone; the connection part of the nth inner collector is a hollow cylindrical structure.

9. The multi-stage depressed collector according to claim 8, characterized in that, The inclination angles of the inlet ends of the nth inner collector are successively θ2, θ3,..., θ along the axial direction within 180° n-1 .

10. The multi-stage depressed collector according to claim 8, characterized in that, The axis of the inlet end of the nth inner collector is eccentric in the same direction with respect to the axis of the inlet end of the first inner collector; wherein, the offset distances of the axis of the inlet end of the nth inner collector with respect to the axis of the inlet end of the first inner collector are d2, d3,..., d n-1 , where d2 < d3 <... < d n-1 .

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