A design method of a slow wave circuit for improving the backoff efficiency of a traveling wave tube, a slow wave circuit and a traveling wave tube

Abstract

The application discloses a design method of a slow wave circuit for improving the backtracking efficiency of a traveling wave tube, a slow wave circuit and a traveling wave tube. b ; the slow wave circuit is divided into a first interval, a second interval, a third interval and a fourth interval along the direction of the electron beam; the phase velocities of electromagnetic waves in the four intervals are set as v p1 , v p2 , v p3 and v p4 , respectively, so that the phase velocity of the electromagnetic wave jumps from v p1 to v p2 at the end of the first interval, jumps from v p2 to v p3 at the end of the second interval, jumps from v p3 to v p4 at the end of the third interval; numerical simulation and performance verification are performed on the slow wave circuit by using simulation software until the residual energy distribution diagram of the output electron beam presents a stepped structure corresponding to the number of the collecting electrodes, and the recoverability of the residual energy of the electron beam can be improved significantly.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microwave vacuum electron devices. More particularly, it relates to a design method of a slow wave circuit for improving the backoff efficiency of a traveling wave tube, a slow wave circuit and a traveling wave tube. BACKGROUND

[0002] With the increasing demand for higher data throughput in wireless communication systems, the modulation signals currently widely used generally have a high peak-to-average ratio and spectral efficiency. In order to support the transmission of such signals, the traveling wave tube needs to work in a backoff state. However, in the prior art, the optimization design of the traveling wave tube mostly focuses on improving the saturation efficiency, and ignores the improvement of the backoff efficiency. In fact, the efficiency of the traveling wave tube in the backoff state largely determines the power consumption performance of the entire transmitter.

[0003] Currently, a common way to improve the backoff efficiency of the traveling wave tube is to use a multi-stage depressed collector. The core of this method is to recover the residual energy of the electron beam through multiple collector electrodes in stages, thereby improving the backoff efficiency. However, this solution has obvious shortcomings in the case of poor distribution of the residual energy of the electron beam. Due to the non-centralized distribution of the residual energy of the electron beam, it is difficult to effectively recover, and it is usually necessary to increase the number of stages of the collector to ensure the recovery efficiency. However, this significantly increases the complexity of the design of the traveling wave tube and the difficulty of the manufacturing process. SUMMARY

[0004] In view of the above problems, one object of the present application is to provide a design method of a slow wave circuit for improving the backoff efficiency of a traveling wave tube.

[0005] One object of the present application is to provide a slow wave circuit obtained by the above design method.

[0006] One object of the present application is to provide a traveling wave tube comprising the above slow wave circuit.

[0007] To achieve the above objects, the present application adopts the following technical solutions:

[0008] According to one aspect of the present application, there is provided a design method of a slow wave circuit for improving the backoff efficiency of a traveling wave tube, comprising:

[0009] determining the type of the slow wave circuit according to the performance indicators of the slow wave circuit of the traveling wave tube;

[0010] establishing a simulation model of the slow wave circuit using simulation software according to the performance indicators of the slow wave circuit and the category of the slow wave circuit, setting the operating voltage and current of the slow wave circuit, and determining the direct current speed v b of the electron beam according to the operating voltage;

[0011] The slow-wave circuit is divided into four interaction regions along the direction of electron beam travel: the first region, the second region, the third region, and the fourth region.

[0012] Let the phase velocities of electromagnetic waves in the first, second, third, and fourth intervals be v, respectively. p1 v p2 v p3 v p4 , where v p1 <v b ,

[0013] The phase velocity of the electromagnetic wave at the end of the first interval is caused by v p1 Negative jump to v p2 At the end of the second interval, by v p2 Positive jump to v p3 At the end of the third interval, v p3 Negative jump to v p4 ;

[0014] The slow-wave circuit was numerically simulated and its performance verified using simulation software. Based on the simulation results, the electromagnetic wave phase velocity and length of the four interaction regions of the slow-wave circuit were adjusted until the residual energy distribution of the output electron beam was stepped, corresponding to the number of collecting electrodes.

[0015] Alternatively, the method may further include:

[0016] Based on the simulation model, a cutoff zone is set in the first interval according to the electromagnetic wave propagation characteristics, energy exchange effect and electron beam aggregation state during the simulation process.

[0017] Alternatively, the cut-off region can be located at the position where the gain reaches 15-20dB within the first interval.

[0018] Alternatively, the method may further include:

[0019] A centralized attenuator is installed in the first interval, and the centralized attenuator is located on both sides of the cut-off zone.

[0020] Alternatively, the slow-wave circuit can be a spiral slow-wave circuit.

[0021] The spiral slow-wave circuit includes a spiral, which includes a first segment, a second segment, a third segment, and a fourth segment corresponding to the four interaction intervals of the slow-wave circuit.

[0022] Adjust the pitch and / or radius of the first, second, third, and fourth segments respectively, so that the phase velocity of the electromagnetic wave changes from v at the end of the first interval. p1 Negative jump to v p2 At the end of the second interval, by vp2 positive jump to v p3 , at the end of the third interval by v p3 negative jump to v p4 .

[0023] Further, it is optional that the type of the slow wave circuit is a folded waveguide slow wave circuit.

[0024] The folded waveguide slow wave circuit comprises a plurality of geometrically periodic folded waveguide units, the folded waveguide units comprising a straight waveguide segment and a connecting waveguide segment in communication;

[0025] The length of the straight waveguide segment and / or the period length of the folded waveguide units corresponding to the four interaction intervals are adjusted so that the phase velocity of the electromagnetic wave at the end of the first interval is v p1 negative jump to v p2 , at the end of the second interval by v p2 positive jump to v p3 , at the end of the third interval by v p3 negative jump to v p4 .

[0026] Further, it is optional that the type of the slow wave circuit is a coupled cavity slow wave circuit.

[0027] The coupled cavity slow wave circuit comprises a plurality of cavities arranged along the direction of the electron beam;

[0028] The structural shape and / or geometric size of the cavities corresponding to the four interaction intervals are adjusted so that the phase velocity of the electromagnetic wave at the end of the first interval is v p1 negative jump to v p2 , at the end of the second interval by v p2 positive jump to v p3 , at the end of the third interval by v p3 negative jump to v p4 .

[0029] According to an aspect of the present application, there is provided a slow wave circuit obtained by a design method of a slow wave circuit for improving the backoff efficiency of a traveling wave tube;

[0030] The slow wave circuit is divided into four interaction intervals of a first interval, a second interval, a third interval and a fourth interval along the direction of the electron beam, wherein the first interval is located at the initial end of the slow wave circuit;

[0031] The phase velocities of the electromagnetic wave in the first interval, the second interval, the third interval and the fourth interval are v p1 , v p2 , v p3 , v p4 , respectively, wherein v p1 <vb ,

[0032] The phase velocity of the electromagnetic wave at the end of the first interval is v p1 Negative jump to v p2 At the end of the second interval, by v p2 Positive jump to v p3 At the end of the third interval, v p3 Negative jump to v p4 .

[0033] Alternatively, the slow-wave circuit may be a spiral slow-wave circuit, a folded waveguide slow-wave circuit, or a coupler slow-wave circuit.

[0034] According to one aspect of the present invention, a traveling wave tube is provided, including a collector and a slow wave circuit;

[0035] The number of collecting electrodes corresponds to the stepped distribution of the electron beam residual energy distribution map of the slow-wave circuit.

[0036] The beneficial effects of this invention are as follows:

[0037] To address the problems existing in the prior art, this invention provides a design method for a slow-wave circuit, a slow-wave circuit, and a traveling wave tube to improve the back-off efficiency of a traveling wave tube. By switching the phase velocity between negative and positive phases, the invention effectively achieves precise shaping of the distribution of the remaining energy of the electron beam. In the back-off working state of the traveling wave tube, this technology constructs a step-like distribution shape of the remaining energy curve of the electron beam, which can significantly improve the recoverability of the remaining energy of the electron beam, thereby improving the back-off efficiency of the traveling wave tube.

[0038] By employing phase velocity abrupt changes, the remaining energy of the electron beam is concentrated within a few narrow energy ranges, resulting in a stepped or near-stepped distribution curve for the remaining energy. This significantly reduces the number of collecting electrode stages, simplifying the collecting electrode design and improving its recovery efficiency. The recovery efficiency of a three-stage collecting electrode can reach 96.8%, only 1% lower than that of a traditional five-stage collecting electrode. This means that a three-stage recovery can achieve near-five-stage recovery results, greatly simplifying the design and manufacturing complexity of the collecting electrode.

[0039] Adjusting the distribution curve of the remaining electron beam energy to a stepped or near-stepped distribution not only optimizes the recovery efficiency of the collector but also provides ideal entry conditions. Since most electron energy is concentrated within a few energy ranges, the collector only needs a small number of electrodes and a specific voltage to recover this energy. Most electrons arrive at the electrodes at a relatively low velocity, achieving a so-called soft landing. This avoids a large number of high-energy electrons bombarding the collector at high speed, reducing localized overheating and alleviating the heat dissipation burden on the collector.

[0040] By optimizing the energy distribution of the electron beam, the bombardment of the collector by abnormal high-speed electrons is reduced, thereby avoiding the intense collision of too many high-energy electrons on the collector. In the conventional design, due to the dispersed energy distribution of the electron beam, the recovery efficiency is low, and the collector needs to withstand more bombardment of high-energy electrons. These high-speed electrons can cause local overheating, reducing the reliability of the traveling wave tube. Through the design of the present application, the electron beam energy distribution is effectively shaped, reducing the number of abnormal energy electrons and avoiding the strong bombardment of high-energy electrons on the collector. The long-term working stability of the traveling wave tube is effectively improved, the risk of failure caused by overheating is reduced, and the reliability of the system is improved. BRIEF DESCRIPTION OF DRAWINGS

[0041] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0042] Figure 1 A schematic diagram of the energy recovery of a four-stage voltage reduction collector in the prior art is shown.

[0043] Figure 2 A schematic diagram of the structure of the slow wave circuit provided by the embodiment of the present application is shown.

[0044] Figure 3 A graph showing the residual energy distribution of the electron beam when the saturation backoff is 3dB is shown.

[0045] Figure 4 A comparison graph showing the residual energy distribution of the electron beam when the saturation backoff is 3dB between the embodiment and the comparative example is shown. DETAILED DESCRIPTION

[0046] The present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely intended to explain the present application, but not to limit the present application. In addition, it should be noted that only the parts related to the present application are shown in the drawings for ease of description, rather than all the structures.

[0047] In the description of the present application, unless otherwise explicitly specified and limited, the terms "connected", "connected", "fixed" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0048] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature can include that the first and second features are in direct contact, or can include that the first and second features are not in direct contact but are in contact through another feature between them.

[0049] In the description of the present embodiment, the terms "upper", "lower", "left", "right", and other orientation or position relationships shown in the drawings are based on the orientation or position relationships shown in the drawings, and are only for the convenience of description and simplification of operation, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0050] Figure 1 The schematic diagram of the prior art four-stage voltage reduction collector energy recovery is shown in FIG. 1. The horizontal axis is the collector voltage, and the vertical axis is the collector current. Figure 1 The area enclosed between the curve in FIG. 1 and the horizontal axis represents the total energy of the electron beam entering the collector. The shaded part in this area corresponds to the recoverable energy after using the four-stage voltage reduction collector, and the blank part in this area represents the unrecoverable energy of the collector. The recoverable energy of each collector electrode is the area of the corresponding rectangle (for example, the recoverable energy of the collector electrode whose voltage drops to the cathode potential V0 is V0*I4). The total recovery efficiency of the collector is the ratio of the recoverable energy to the total energy of the electron beam. Therefore, if a higher recovery efficiency is desired, the number of stages of the collector can be increased to fit the area enclosed by the curve, but the increase in the number of stages of the collector means more electrode arrangement and more complex voltage regulation, which increases the difficulty of designing the collector and affects the reliability of the system.

[0051] From another perspective, if the distribution curve of the residual energy of the electron beam is step-shaped or approximately step-shaped, only a small number of stages of the collector (i.e. a small number of rectangular areas) are needed to fit the area enclosed by the entire step-shaped curve, and the steeper the change between the steps, the more concentrated the energy distribution of the electron beam, and the less the unrecoverable energy of each collector electrode, and the higher the total recovery efficiency of the collector.

[0052] In view of the defects of the prior art, the present application provides a design method of a slow wave circuit for improving the backflow efficiency of a traveling wave tube, to make the distribution curve of the residual energy of the electron beam step-shaped or approximately step-shaped, to achieve the purpose of improving the backflow efficiency of the traveling wave tube.

[0053] Specifically, the method comprises:

[0054] S10, determining the type of the slow wave circuit according to the performance indicators of the traveling wave tube slow wave circuit;

[0055] S20, a simulation model of the slow wave circuit is established according to the performance index of the slow wave circuit and the category of the slow wave circuit using simulation software, working voltage and current of the slow wave circuit are set, and the direct current speed v of the electron beam is determined according to the working voltage b ;

[0056] S30, the slow wave circuit is divided into four interaction intervals of a first interval A, a second interval B, a third interval C and a fourth interval D along the direction of the electron beam, wherein the first interval A is located at the initial end of the slow wave circuit;

[0057] S40, the phase speed of the electromagnetic wave in the first interval A, the second interval B, the third interval C and the fourth interval D is set as v p1 , v p2 , v p3 , v p4 respectively, wherein v p1 < v b ,

[0058] S50, the phase speed of the electromagnetic wave is negatively jumped from v p1 to v p2 at the end of the first interval A, positively jumped from v p2 to v p3 at the end of the second interval B, and negatively jumped from v p3 to v p4 at the end of the third interval C;

[0059] S60, numerical simulation and performance verification of the slow wave circuit are performed using simulation software, the phase speed and length parameters of the four interaction intervals of the slow wave circuit are adjusted according to the simulation results for optimization until the energy distribution diagram of the output electron beam is in step distribution corresponding to the number of stages of the collector.

[0060] In one embodiment, the first interval A is a uniform phase speed section of the slow wave circuit, the phase speed of the electromagnetic wave in the first interval A is set as v p1 , and v p1 < v b In this interval, the electromagnetic wave and the electron beam preliminarily exchange energy, the electron beam preliminarily clusters, and the electromagnetic wave obtains energy and is enhanced. The length of the first interval A needs to be obtained by simulation optimization according to the required gain and the phase relationship between the beam and the wave.

[0061] In one embodiment, the second interval B is a negative jump phase speed section of the slow wave circuit, the phase speed of the electromagnetic wave in the second interval B is set as v p2 , and v p2 < v p1 , i.e. the phase speed of the electromagnetic wave is negatively jumped from v p1 to v p2In the second interval B, the energy exchange between the electron beam and the electromagnetic wave is further enhanced, the electron beam forms a more dense cluster, and the electromagnetic wave is further enhanced. In this process, the kinetic energy of the electron beam is reduced. The length of the second interval B is generally based on the required energy exchange and the electron beam cluster formation.

[0062] In one embodiment, the third interval C is a positive phase jump section of the slow wave circuit, and the phase velocity of the electromagnetic wave in the third interval C is set as v p3 , and v p3 > v p2 , that is, the phase velocity of the electromagnetic wave is positively jumped from v p2 to v p3 at the end of the second interval B. In addition, v p3 may be slightly greater than, equal to, or slightly less than v p1 , and the embodiments of the present application are not limited to this. The positive phase jump of the second interval B to the third interval C helps the electron beam to transition from the overvoltage state to the cluster state in the third interval C, in which the fast electrons are decelerated and the slow electrons are accelerated, which can effectively optimize the cluster quality of the high-energy electron group and form an energy-concentrated high-energy electron cluster. The length of the third interval C needs to be determined according to the energy distribution change of the electrons in the cluster, so that the high-energy electron group can be effectively modulated in this interval.

[0063] In one embodiment, the fourth interval D is a negative phase jump section of the slow wave circuit, and the phase velocity of the electromagnetic wave in the fourth interval D is set as v p4 , and v p4 < v p3 , that is, the phase velocity of the electromagnetic wave is negatively jumped from v p3 to v p4 at the end of the third interval C. In the fourth interval D, the electron beam completes the switching from the cluster state to the overvoltage state, further improves the cluster quality of the low-energy electron group, and forms an energy-concentrated low-energy electron cluster. The length of the fourth interval D needs to be determined according to the energy distribution change of the required low-energy electron group, and the saturation output power requirement also needs to be considered in the design.

[0064] In a specific embodiment, in order to prevent the occurrence of self-oscillation, the design method further includes: S31, in combination with the simulation model, setting a cut-off zone 1 in the first interval A based on the electromagnetic wave propagation characteristics, energy exchange effect and cluster state of the electron beam in the simulation process.

[0065] In this embodiment, the cut-off zone 1 needs to be set when the gain in the first interval A reaches the expected value. In one preferred example, in combination with the simulation model, when the gain of the first interval A reaches 15-20 dB, the cut-off zone 1 is set at this position to ensure the stability of the slow wave circuit.

[0066] To avoid the reflection induced oscillation, a lumped attenuator 2 is also needed. In one embodiment, the design method further comprises: S32, setting a lumped attenuator 2 at the first interval A, which is respectively located at both sides of the cutoff region 1. In the design process, the attenuation of the lumped attenuator 2 needs to reach more than 30dB. It should be noted that, in order to facilitate calculation, the length of the lumped attenuator 2 is usually designed to be short and the attenuation is large when establishing the model. In actual application, the specific length of the lumped attenuator 2 can be adjusted according to the required attenuation, and the embodiments of the present application do not make any limitation.

[0067] The slow wave circuit can be divided into an input section 3 and an output section 4 according to the cutoff region 1, the part of the first interval A and the second interval B, the third interval C and the fourth interval B located at the side of the second interval B of the cutoff region 1 are the output section 4, and the other side of the cutoff region 1 is the input section 3.

[0068] In one embodiment, a distributed attenuator 5 can also be set in the first interval A, two distributed attenuators 5 are respectively set in the input section 3 and the output section 4, specifically, one distributed attenuator 5 is set at the approximate middle of the input section 3, and the other distributed attenuator 5 is set at about one third of the output section 4, and the specific position needs to be optimized according to the simulation software. In actual design, the length of the distributed attenuator is usually determined according to the required attenuation, and the required attenuation is generally 2-3dB.

[0069] In one specific embodiment, the type of the slow wave circuit determined in step S10 is a spiral slow wave circuit. The spiral slow wave circuit includes a spiral line, and the spiral line includes a first section, a second section, a third section and a fourth section corresponding to the four interaction intervals of the slow wave circuit. By adjusting the pitch and / or radius of the first section, the second section, the third section and the fourth section, the phase velocity of the electromagnetic wave is negatively jumped from v p1 to v p2 at the end of the first interval A, positively jumped from v p2 to v p3 at the end of the second interval B, negatively jumped from v p3 to v p4 at the end of the third interval C, and positively jumped from v to v . Through the negative-positive-negative phase velocity jump, the shaping of the electron beam energy distribution is completed in the beam-wave interaction, the compactness and energy concentration of each group block are improved, a stepped distribution or an approximately stepped distribution of the electron beam residual energy distribution diagram is constructed, the recyclability of the electron beam residual energy is improved, and on the basis of reducing the number of collector stages, the purpose of improving the backflow efficiency of the traveling wave tube is achieved.

[0070] In a specific embodiment, the type of the slow wave circuit determined in step S10 is a folded waveguide slow wave circuit. The folded waveguide slow wave circuit comprises a plurality of geometrically periodic folded waveguide units, each of which comprises a straight waveguide section and a connecting waveguide section; the lengths of the straight waveguide sections corresponding to the four interaction intervals are adjusted and / or the period length of the folded waveguide units is adjusted, so that the phase velocity of the electromagnetic wave at the end of the first interval A is v p1 negatively jumps to v p2 , at the end of the second interval B is v p2 positively jumps to v p3 , at the end of the third interval C is v p3 negatively jumps to v p4 . Through the negative-positive-negative jumps of the phase velocity, the shaping of the electron beam energy distribution is completed in the beam-wave interaction, the compactness and energy concentration of each group are improved, a stepped or approximately stepped electron beam residual energy distribution diagram is constructed, the recyclability of the electron beam residual energy is improved, and the purpose of improving the backflow efficiency of the traveling wave tube is achieved on the basis of reducing the number of collector stages. Specifically, the positions corresponding to the first interval A and the second interval B are mainly controlled by adjusting the period length of the folded waveguide units to control the change of the phase velocity; and at the positions corresponding to the third interval C and the fourth interval D, the lengths of the straight waveguide sections and the period lengths of the waveguide units need to be more finely adjusted to ensure the effect of the phase velocity jump.

[0071] In a specific embodiment, the type of the slow wave circuit determined in step S10 is a coupled cavity slow wave circuit. The coupled cavity slow wave circuit comprises a plurality of cavities arranged along the direction of the electron beam, the structure shape and / or geometric size of the cavities corresponding to the four interaction intervals are adjusted, so that the phase velocity of the electromagnetic wave at the end of the first interval A is v p1 negatively jumps to v p2 , at the end of the second interval B is v p2 positively jumps to v p3 , at the end of the third interval C is v p3 negatively jumps to v p4 . Through the negative-positive-negative jumps of the phase velocity, the shaping of the electron beam energy distribution is completed in the beam-wave interaction, the compactness and energy concentration of each group are improved, a stepped or approximately stepped electron beam residual energy distribution diagram is constructed, the recyclability of the electron beam residual energy is improved, and the purpose of improving the backflow efficiency of the traveling wave tube is achieved on the basis of reducing the number of collector stages.

[0072] Another embodiment of the present application provides a slow wave circuit obtained by the design method of the above-mentioned embodiments. As Figure 2As shown, the slow wave circuit is divided into four interaction intervals along the direction of the electron beam, namely a first interval A, a second interval B, a third interval C and a fourth interval D, wherein the first interval A is located at the initial end of the slow wave circuit.

[0073] The first interval A is a uniform phase velocity section of the slow wave circuit, and the phase velocity of the electromagnetic wave in the first interval A is v p1 , and v p1 < v b In this interval, the electromagnetic wave and the electron beam exchange energy preliminarily, the electron beam preliminarily clusters and the electromagnetic wave is enhanced. The length of the first interval A needs to be optimized by simulation according to the required gain and the beam-wave phase relationship.

[0074] The second interval B is a negative phase velocity jump section of the slow wave circuit, and the phase velocity of the electromagnetic wave in the second interval B is v p2 , and v p2 < v p1 , that is, the phase velocity of the electromagnetic wave is negatively jumped from v p1 to v p2 at the end of the first interval A. In the second interval B, the energy exchange between the electron beam and the electromagnetic wave is further enhanced, the electron beam forms a relatively dense cluster block, and the electromagnetic wave is further enhanced. And in this process, the kinetic energy of the electron beam is reduced. The length of the second interval B is generally considered based on the required energy exchange and the electron beam cluster shape.

[0075] The third interval C is a positive phase velocity jump section of the slow wave circuit, and the phase velocity of the electromagnetic wave in the third interval C is v p3 , and v p3 > v p2 , that is, the phase velocity of the electromagnetic wave is positively jumped from v p2 to v p3 at the end of the second interval B. In addition, v p3 may be slightly greater than, equal to, or slightly less than v p1 , which is not limited by the embodiments of the present application. The positive jump of the phase velocity from the second interval B to the third interval C helps the electron beam to transition from the overpressure state to the cluster state in the third interval C. In this interval, the fast electrons are decelerated and the slow electrons are accelerated, which can effectively optimize the cluster quality of the high-energy electron group and form an energy-concentrated high-energy electron cluster block. The length of the third interval C needs to be designed according to the energy distribution change of the electrons in the cluster block, so that the high-energy electron group is effectively modulated in this interval.

[0076] The fourth interval D is a negative phase velocity jump section of the slow wave circuit, and the phase velocity of the electromagnetic wave in the fourth interval D is v p4 , and v p4 < v p3 , that is, the phase velocity of the electromagnetic wave is negatively jumped from v p3 to v p4In the fourth interval D, the electron beam completes the switching from the bunching state to the overvoltage state, further improves the bunching quality of the low-energy electron bunch, and forms a low-energy electron bunch block with concentrated energy. The length of the fourth interval D needs to be determined according to the required energy distribution of the low-energy electron bunch, and the saturation output power requirement also needs to be considered in the design.

[0077] In one specific embodiment, the slow wave circuit can be a helical line slow wave circuit, a folded waveguide slow wave circuit, or a coupled cavity slow wave circuit.

[0078] Another embodiment of the present application provides a traveling wave tube, including a collector and the slow wave circuit provided in the above embodiments, wherein the number of stages of the collector needs to be determined according to the distribution curve of the approximate step-shaped distribution of the electron beam residual energy distribution map of the slow wave circuit, for example, if the curve in the electron beam residual energy distribution map of the slow wave circuit is approximately a three-stage step-shaped distribution, a three-stage collector is selected to collect the electron beam residual energy. The traveling wave tube can be used as a system final power amplifier, and can be widely used in the field of high-speed wireless communication, especially in the communication demand of resource scarce scenes such as unmanned platforms, mobile platforms, airborne platforms, etc. which require high system cost and limited power supply.

[0079] The beneficial effects of the design method of the slow wave circuit provided by the present application for improving the backoff efficiency of the traveling wave tube will be described below with reference to examples.

[0080] The slow wave circuit is a folded waveguide slow wave circuit. The working voltage is 14kV, and the working current is 50mA. The phase velocity distribution is determined by changing the parameter p (the half-period length of the folded waveguide unit), and the value of p is as follows:

[0081] First interval A: p1=0.66mm;

[0082] Second interval B: p2=0.65mm;

[0083] Third interval C: p3=0.66mm;

[0084] Fourth interval D: p4=0.62mm.

[0085] Wherein the length of the first interval A exceeds the position of the set-off zone 1, and the phase velocity on the side of the set-off zone 1 remains unchanged.

[0086] During the design process, the lengths and phase velocities of the four interaction zones are closely coordinated and jointly optimized. The first zone, A, is primarily used to achieve linear gain; its length can be determined based on this when nonlinear beam-wave interaction occurs. The design purpose of the second zone, B, is to improve backoff efficiency, making electron clusters more compact, adjusting the beam-wave phase in this region, and effectively transferring energy to the electromagnetic wave. The third zone, C, aims to modulate the electron beam through electromagnetic waves, achieving optimal clustering of high-energy clusters. The fourth zone, D, is characterized by a sudden drop in phase velocity, where lower-energy electrons cluster, while also providing high saturation efficiency. In summary, the lengths and phase velocities of each zone need to be repeatedly adjusted and optimized using simulation software according to specific requirements to ultimately determine the specific parameters for each region.

[0087] A distributed attenuator 5 is installed in the middle of input segment 3 and near the cutoff zone 1 in output segment 4 to prevent oscillations caused by reflections. The length of the distributed attenuator is determined based on the required attenuation (typically 2-3 dB). Concentrated attenuators are installed on both sides near the cutoff zone 1, with attenuation levels exceeding 30 dB. It should be noted that, for ease of calculation, the concentrated attenuator is typically shorter and has a very large attenuation in the simulation model. In practical applications, the specific length of the concentrated attenuator is adjusted according to the required attenuation.

[0088] The electron beam residual energy distribution of the slow-wave circuit (hereinafter referred to as the embodiment) obtained by the design method provided in this invention at 3dB saturation back-off is as follows: Figure 3 As shown, the horizontal axis represents the collector voltage, and the vertical axis represents the collector circuit. A comparison graph of the electron beam residual energy distribution at 3dB saturation fallback in the embodiment and the residual energy distribution of the electron beam at 3dB saturation fallback in the prior art slow-wave circuit (hereinafter referred to as the comparative example) under the same operating conditions is shown below. Figure 4 As shown. Combined with Figure 3 and Figure 4 It can be seen that the design method provided by the embodiments of the present invention can construct the electron beam residual energy distribution curve into a step-like or approximately step-like distribution, such as... Figure 3The residual energy of the electron beam of the embodiment is distributed in an approximate three-step form, corresponding to the number of stages of the collector, and the residual energy of the electron beam of the embodiment is recovered by using three-stage collectors, and the recovery efficiency of the three-stage collectors is greater than 96.8 %, while the residual energy of the electron beam of the comparative example is also recovered by using three-stage collectors, and the recovery efficiency of the three-stage collectors is only 93.3 %, and the recovery efficiency of the embodiment is improved by 3 % compared with the comparative example. Even if the five-stage collectors are used in the comparative example, the recovery efficiency of the embodiment is only 1 % lower than that of the comparative example, so it can be seen that the design method of the slow wave circuit provided in the embodiment of the application significantly reduces the requirement for the number of stages of the collector, and can improve the recovery efficiency of the traveling wave tube while reducing the process complexity and design difficulty of the collector, so the design method of the slow wave circuit for improving the recovery efficiency of the traveling wave tube provided in the embodiment of the application can be used as a practical solution for realizing high recovery efficiency of the traveling wave tube.

[0089] The design method of the slow wave circuit for improving the recovery efficiency of the traveling wave tube, the slow wave circuit and the traveling wave tube provided in the embodiment of the application effectively realize the accurate shaping of the residual energy distribution of the electron beam by the phase velocity negative-positive-negative jump, and the step-shaped distribution form of the residual energy curve of the electron beam is constructed under the recovery working state of the traveling wave tube, so that the recoverability of the residual energy of the electron beam can be significantly improved, and the recovery efficiency of the traveling wave tube is improved.

[0090] By the phase velocity negative-positive-negative jump, the residual energy of the electron beam is concentrated in a small number of narrow energy intervals, so that the distribution curve of the residual energy of the electron beam presents a step-shaped or approximate step-shaped distribution, so that the number of stages of the collector can be greatly reduced, the design of the collector is more simplified, and the recovery efficiency of the collector can be improved. The recovery efficiency of the three-stage collector can reach 96.8 %, and compared with the traditional five-stage collector, the recovery efficiency is only 1 % lower, which means that the three-stage recovery can achieve an effect close to the five-stage recovery, and the design and process complexity of the collector are greatly simplified.

[0091] Adjusting the distribution curve of the residual energy of the electron beam to a step-shaped or approximate step-shaped distribution form not only optimizes the recovery efficiency of the collector, but also provides an ideal inlet condition for the collector. Since most of the electron energy is concentrated in a few energy intervals, the collector only needs to design a small number of electrodes and use a specific voltage to recover the energy of these electrons. Most of the electrons reach each electrode at a low speed, i.e. in a so-called soft landing state. Avoiding a large number of high-energy electrons bombarding the collector at high speed reduces the phenomenon of local overheating and reduces the heat dissipation burden of the collector.

[0092] By optimizing the energy distribution of the electron beam, the bombardment of the collector by abnormal high-speed electrons is reduced, thereby avoiding the intense collision of too many high-energy electrons on the collector. In a conventional design, due to the dispersed energy distribution of the electron beam, the recovery efficiency is low, and the collector needs to withstand more high-energy electrons. These high-speed electrons can cause local overheating, reducing the reliability of the traveling wave tube. Through the design of the present application, the energy distribution of the electron beam is effectively shaped, reducing the number of abnormal energy electrons and avoiding the intense bombardment of high-energy electrons on the collector. The long-term working stability of the traveling wave tube is effectively improved, the risk of failure caused by overheating is reduced, and the reliability of the system is improved.

[0093] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. For those skilled in the art, on the basis of the above description, other different forms of changes or variations can also be made, and it is impossible to enumerate all the embodiments here. Any obvious changes or variations derived from the technical solutions of the present application are still within the protection scope of the present application.

Claims

1. A method of designing a slow wave circuit for improving the backoff efficiency of a traveling wave tube, characterized by, The method comprises: determining the type of the slow wave circuit according to the performance index of the traveling wave tube slow wave circuit; According to the performance index of the slow wave circuit and the determined type of the slow wave circuit, a simulation model of the slow wave circuit is established by using simulation software, the working voltage and current of the slow wave circuit are set, and the direct current speed v of the electron beam is determined according to the working voltage b ; dividing the slow wave circuit into four interaction intervals, i.e., a first interval, a second interval, a third interval and a fourth interval along the direction of the electron beam; The electromagnetic wave phase velocities in the first interval, the second interval, the third interval and the fourth interval are set to be v p1 , v p2 , v p3 , and v p4 , respectively, where v p1 <v b , the electromagnetic wave phase velocity is increased from v p1 to v p2 at the end of the second interval from v p2 to v p3 at the end of the third interval from v p3 to v p4 ; using simulation software to perform numerical simulation and performance verification on the slow wave circuit, and adjusting the phase velocity and length of the electromagnetic wave of the four interaction intervals of the slow wave circuit according to the simulation result until the residual energy distribution diagram of the output electron beam is in step-shaped distribution corresponding to the number of stages of the collector; the type of the slow wave circuit is: a helical line slow wave circuit; wherein the helical line slow wave circuit comprises a helical line, and the helical line comprises a first segment, a second segment, a third segment and a fourth segment corresponding to the four interaction intervals of the slow wave circuit; adjusting the pitch and / or radius of the first, second, third and fourth segments respectively, such that the phase velocity of the electromagnetic wave jumps from v p1 at the end of the first interval to v p2 at the end of the second interval, and from v p2 at the end of the third interval to v p3 at the end of the fourth interval. p3 p4 ;​ or a folded waveguide slow wave circuit; wherein the folded waveguide slow wave circuit comprises a plurality of geometric periodic structure folded waveguide units, and the folded waveguide units comprise a straight waveguide segment and a connecting waveguide segment; adjusting the length of the straight waveguide section corresponding to the four interaction regions and / or the period length of the folded waveguide unit, so that the phase velocity of the electromagnetic wave is v p1 negatively jumps to v p2 at the end of the second region v p2 positively jumps to v p3 at the end of the third region v p3 negatively jumps to v p4 ; or a coupled cavity slow wave circuit; wherein the coupled cavity slow wave circuit comprises a plurality of cavities arranged along the direction of the electron beam; adjusting the structure shape and / or the geometric dimensions of the cavities corresponding to the four interaction intervals, so that the phase velocity of the electromagnetic wave goes from v p1 to v p2 at the end of the first interval with a negative jump, from v p2 to v p3 at the end of the second interval with a positive jump, from v p3 to v p4 at the end of the third interval with a negative jump.

2. The method of designing a slow wave circuit to boost the efficiency of a traveling wave tube as recited in claim 1, wherein, the method further comprises: combining the simulation model, and setting a cut-off zone in the first interval based on the electromagnetic wave propagation characteristics, energy exchange effect and group state of the electron beam in the simulation process.

3. The method of designing a slow wave circuit to boost the efficiency of a traveling wave tube as recited in claim 2, wherein, The cut-off zone is located at a corresponding position where the gain reaches 15-20 dB in the first interval.

4. The method of designing a slow wave circuit to boost the efficiency of a traveling wave tube as recited in claim 2, wherein, the method further comprises: setting a concentrated attenuator in the first interval, and the concentrated attenuator is located on both sides of the cut-off zone.

5. A slow wave circuit, characterized by The slow wave circuit is obtained by the design method of any one of claims 1-4; the slow wave circuit is divided into four interaction intervals, i.e., a first interval, a second interval, a third interval and a fourth interval along the direction of the electron beam, wherein the first interval is located at the initial end of the slow wave circuit; The electromagnetic wave phase velocities in the first interval, second interval, third interval, fourth interval are v p1 , v p2 , v p3 , v p4 , respectively, wherein v p1 <v b , The electromagnetic wave phase velocity ends the first interval by v p1 negatively jumps to v p2 at the end of the second interval by v p2 positively jumps to v p3 at the end of the third interval by v p3 negatively jumps to v p4 .

6. The slow wave circuit of claim 5, wherein, the slow wave circuit is a helical line slow wave circuit, a folded waveguide slow wave circuit or a coupled cavity slow wave circuit.

7. A traveling wave tube, characterized by, comprising a collector and the slow wave circuit of any one of claims 5-6; the number of stages of the collector corresponds to the step-shaped distribution of the residual energy distribution diagram of the electron beam of the slow wave circuit.

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