Design method of slow wave circuit for improving rollback efficiency of traveling wave tube, slow wave circuit and traveling wave tube

Abstract

The invention discloses a design method of a slow-wave circuit for improving the rollback efficiency of a traveling wave tube, the slow-wave circuit and the traveling wave tube. The design method comprises the following steps: determining the type of the slow-wave circuit according to the performance index of the slow-wave circuit of the traveling wave tube; establishing a simulation model of the slow-wave circuit by using simulation software, setting the working voltage and current of the slow-wave circuit, and determining the direct-current speed vb of the electron beam; the slow wave circuit is divided into a first interval, a second interval, a third interval and a fourth interval in the electron beam advancing direction; electromagnetic wave phase velocities in the four intervals are set to be vp1, vp2, vp3 and vp4 in sequence, so that the electromagnetic wave phase velocities are negatively jumped to vp2 from vp1 at the tail end of the first interval, positively jumped to vp3 from vp2 at the tail end of the second interval, and negatively jumped to vp4 from vp3 at the tail end of the third interval; simulation software is used for carrying out numerical simulation and performance verification on the slow wave circuit until an output electron beam residual energy distribution diagram is of a step-shaped structure and corresponds to the series of a collector, and the recoverability of the electron beam residual energy can be remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of microwave vacuum electronic devices, and more specifically to a design method for a slow-wave circuit for improving the back-off efficiency of a traveling wave tube, a slow-wave circuit and a traveling wave tube. Background Art

[0002] As the demand for higher data throughput in wireless communication systems continues to increase, the modulation signals currently widely used usually 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 the back-off state. However, in the prior art, the optimization design of the traveling wave tube mostly focuses on improving the saturation efficiency, while ignoring the improvement of the back-off efficiency. In fact, the efficiency of the traveling wave tube in the back-off state largely determines the power consumption performance of the entire transmitter.

[0003] At present, the common practice to improve the back-off efficiency of traveling wave tubes is to achieve it through a multi-stage step-down collector. The core of this method is to recover the residual energy of the electron beam step by step through multiple collector electrodes, thereby improving the back-off efficiency. However, this solution has obvious shortcomings when the residual energy of the electron beam is poorly distributed. Since the residual energy of the electron beam is not concentrated and difficult to recover effectively, it is usually necessary to increase the number of collector stages to ensure the recovery efficiency. But this is accompanied by a significant increase in the complexity of the traveling wave tube design and the difficulty of the manufacturing process. Summary of the invention

[0004] In view of the above problems, an object of the present invention is to provide a design method for a slow-wave circuit for improving the back-off efficiency of a traveling wave tube.

[0005] An object of the present invention is to provide a slow-wave circuit obtained by the above-mentioned design method.

[0006] An object of the present invention is to provide a traveling wave tube comprising the above-mentioned slow-wave circuit.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] According to one aspect of the present invention, a design method for a slow-wave circuit for improving the back-off efficiency of a traveling wave tube is provided, comprising:

[0009] Determine the type of slow-wave circuit according to the performance index of the traveling wave tube slow-wave circuit;

[0010] According to the performance index and category of the slow-wave circuit, the simulation model of the slow-wave circuit is established using simulation software, the working voltage and current of the slow-wave circuit are set, and the electron injection DC speed v is determined according to the working voltage. b ;

[0011] Dividing the slow-wave circuit into four interaction intervals, namely, a first interval, a second interval, a third interval and a fourth interval, along the traveling direction of the electron beam;

[0012] Set the electromagnetic wave phase velocity in the first interval, the second interval, the third interval, and the fourth interval to v 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 v p1 Negative transition to v p2 , at the end of the second interval by v p2 Positive transition to v p3 , at the end of the third interval by v p3 Negative transition to v p4 ;

[0014] The slow-wave circuit is numerically simulated and its performance is verified using simulation software. The phase velocity and length of the electromagnetic waves in the four interaction intervals of the slow-wave circuit are adjusted according to the simulation results until the residual energy distribution diagram of the output electron beam is stepped, corresponding to the order of the collecting electrode.

[0015] In addition, an optional solution is that the method further comprises:

[0016] In combination with the simulation model, a cut-off zone is set in the first interval based on the electromagnetic wave propagation characteristics, energy exchange effect and electron beam clustering state in the simulation process.

[0017] In addition, an optional solution is that the cut-off area is located at a corresponding position in the first interval where the gain reaches 15-20 dB.

[0018] In addition, an optional solution is that the method further comprises:

[0019] A concentrated attenuator is arranged in the first section, and the concentrated attenuators are respectively located on both sides of the cut-off area.

[0020] In addition, an optional solution is that the type of the slow-wave circuit is a spiral slow-wave circuit;

[0021] The spiral slow-wave circuit comprises a spiral line, and the spiral line comprises a first section, a second section, a third section and a fourth section corresponding to four interaction intervals of the slow-wave circuit;

[0022] The pitch and / or radius of the first, second, third and fourth segments are adjusted respectively so that the phase velocity of the electromagnetic wave changes from v to 0 at the end of the first interval. p1 Negative transition to v p2 , at the end of the second interval by vp2 Positive transition to v p3 , at the end of the third interval by v p3 Negative transition to v p4 .

[0023] In addition, an optional solution is 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 folded waveguide units of geometric periodic structure, wherein the folded waveguide unit comprises connected straight waveguide sections and connecting waveguide sections;

[0025] Adjust the length of the straight waveguide section and / or the period length of the folded waveguide unit corresponding to the four interaction intervals so that the electromagnetic wave phase velocity changes from v to v at the end of the first interval. p1 Negative transition to v p2 , at the end of the second interval by v p2 Positive transition to v p3 , at the end of the third interval by v p3 Negative transition to v p4 .

[0026] In addition, an optional solution is 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 traveling direction of the electron beam;

[0028] Adjust the structural shape and / or geometric dimensions of the cavity corresponding to the four interaction intervals so that the phase velocity of the electromagnetic wave changes from v at the end of the first interval to p1 Negative transition to v p2 , at the end of the second interval by v p2 Positive transition to v p3 , at the end of the third interval by v p3 Negative transition to v p4 .

[0029] According to one aspect of the present invention, there is provided a slow-wave circuit, wherein the slow-wave circuit is obtained by a design method of a slow-wave circuit for improving the back-off efficiency of a traveling wave tube;

[0030] The slow wave circuit is divided into four interaction intervals, namely, a first interval, a second interval, a third interval and a fourth interval, along the traveling 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 electromagnetic waves in the first interval, the second interval, the third interval, and the fourth interval are v p1 、v p2 、v p3 、v p4 , where v p1 <vb ,

[0032] The phase velocity of the electromagnetic wave changes from v to p1 Negative transition to v p2 , at the end of the second interval by v p2 Positive transition to v p3 , at the end of the third interval by v p3 Negative transition to v p4 .

[0033] In addition, an optional solution is that the slow-wave circuit is a helical slow-wave circuit, a folded waveguide slow-wave circuit or a coupler slow-wave circuit.

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

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

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

[0037] In view of the problems existing in the prior art, the present invention provides a design method for a slow-wave circuit for improving the back-off efficiency of a traveling wave tube, a slow-wave circuit and a traveling wave tube. Through the positive and negative jumps of the phase velocity, the precise shaping of the residual energy distribution of the electron beam is effectively achieved. In the back-off working state of the traveling wave tube, the technology is used to construct a step-shaped distribution shape of the residual energy curve of the electron beam, which can significantly improve the recoverability of the residual energy of the electron beam, thereby improving the back-off efficiency of the traveling wave tube.

[0038] Through the phase velocity jump from positive to negative, the remaining energy of the electron beam is concentrated in a few narrow energy intervals, making the distribution curve of the remaining energy of the electron beam present a step-like or approximately step-like distribution, greatly reducing the number of collector levels, making the collector design more streamlined, and improving the recovery efficiency of the collector. The recovery efficiency of the three-stage collector can reach 96.8%, which is only 1% lower than that of the traditional five-stage collector, which means that the three-stage recovery can achieve an effect close to the five-stage recovery, greatly simplifying the design and process complexity of the collector.

[0039] Adjusting the distribution curve of the residual energy of the electron injection to a step-like or approximately step-like distribution shape can not only optimize the recovery efficiency of the collector, but also provide an ideal entrance condition for the collector. Since most of the electron energy is already 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 electrons can reach each electrode at a lower speed, that is, in the so-called soft landing state. This avoids 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.

[0040] By optimizing the energy distribution of the electron beam, it helps to reduce the bombardment of the collector by abnormally high-speed electrons, thereby avoiding the violent collision of too many high-energy electrons in the collector. In traditional designs, since the energy distribution of the electron beam is relatively dispersed and the recovery efficiency is low, the collector needs to withstand more bombardment of high-energy electrons. These high-speed electrons may cause local overheating and reduce the reliability of the traveling wave tube. Through the design of the present invention, the energy distribution of the electron beam is effectively shaped, the number of abnormal energy electrons is reduced, and the strong bombardment of the collector by high-energy electrons is avoided. 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 THE DRAWINGS

[0041] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

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

[0043] Figure 2 FIG. 4 is a schematic diagram showing the structure of a slow-wave circuit provided in an embodiment of the present invention.

[0044] Figure 3 The diagram shows the distribution of the electron beam residual energy when the saturation is backed off by 3 dB in the embodiment.

[0045] Figure 4 A comparison diagram of the residual energy distribution of electron beams of the embodiment and the comparative example when the saturation is backed off by 3 dB is shown. DETAILED DESCRIPTION

[0046] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0047] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" 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 directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] In the present invention, unless otherwise clearly stipulated and limited, a first feature being “on” or “under” a second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through another feature between them.

[0049] In the description of this embodiment, the terms "upper", "lower", "left", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0050] Figure 1 This is a schematic diagram of energy recovery of a four-stage step-down collector in the prior art, wherein the horizontal axis is the collector voltage and the vertical axis is the collector current. Figure 1 The area enclosed between the curve 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 the four-stage step-down collector is adopted, and the blank part in this area represents the unrecovered energy of the collector, where the recoverable energy of each collector electrode is the area of ​​the corresponding rectangle (for example, the recoverable energy of the collector electrode when the 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 you want to achieve a higher recovery efficiency, you can choose to increase the number of collector stages to fit the area enclosed by the curve, but the increase in the number of collector stages means more electrode arrangements and more complex voltage regulation, which will increase the difficulty of collector design and thus affect the reliability of the system.

[0051] From another perspective, if the distribution curve of the residual energy of the electron beam can be step-shaped or approximately step-shaped, only fewer collecting electrode levels (i.e., fewer rectangular areas) are needed to fit the area enclosed by the entire step-shaped curve. The steeper the change between the steps, the more concentrated the electron beam energy distribution, the less unrecovered energy corresponding to each collecting electrode, and the higher the overall recovery efficiency of the collecting electrode.

[0052] In view of the defects of the prior art, the present invention provides a design method for a slow-wave circuit for improving the back-off efficiency of a traveling wave tube, so as to make the distribution curve of the residual energy of the electron beam present a step-like or approximately step-like shape, thereby achieving the purpose of improving the back-off efficiency of the traveling wave tube.

[0053] Specifically, the method includes:

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

[0055] S20, using simulation software to establish a simulation model of the slow-wave circuit according to the performance index of the slow-wave circuit and the type of the slow-wave circuit, setting the working voltage and current of the slow-wave circuit, and determining the electron injection DC speed v according to the working voltage b ;

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

[0057] S40, setting the electromagnetic wave phase velocities in the first interval A, the second interval B, the third interval C, and the fourth interval D to v p1 、v p2 、v p3 、v p4 , where v p1 <v b ,

[0058] S50, the electromagnetic wave phase velocity is changed from v at the end of the first interval A. p1 Negative transition to v p2 , at the end of the second interval B, v p2 Positive transition to v p3 , at the end of the third interval C, v p3 Negative transition to v p4 ;

[0059] S60, use simulation software to perform numerical simulation and performance verification on the slow-wave circuit, and adjust the electromagnetic wave phase velocity and length parameters of the four interaction intervals of the slow-wave circuit according to the simulation results for optimization, until the output electron beam energy distribution diagram is distributed in a step-like manner, corresponding to the order of the collecting electrode.

[0060] In one embodiment, the first interval A is a phase velocity uniform section of the slow wave circuit, and the phase velocity of the electromagnetic wave in the first interval A is set to v p1 , and v p1 <v b In this interval, the electromagnetic wave and the electron beam exchange initial energy, the electron beam is initially clustered, and the electromagnetic wave obtains energy and is enhanced. The length of the first interval A needs to be obtained through simulation optimization based on the required gain and the phase relationship between the beam wave.

[0061] In one embodiment, the second interval B is a phase velocity negative jump section of the slow wave circuit, and the phase velocity of the electromagnetic wave in the second interval B is set to v p2 , and v p2 <v p1 , that is, the phase velocity of the electromagnetic wave at the end of the first interval A is v p1 Negative transition 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 denser cluster, and the electromagnetic wave is further enhanced. In this process, the kinetic energy of the electron beam decreases. The length of the second interval B is generally based on the required energy exchange and the electron beam clustering shape.

[0062] In one embodiment, the third interval C is the phase velocity positive jump section of the slow wave circuit, and the phase velocity of the electromagnetic wave in the third interval C is set to v p3 , and v p3 >v p2 , that is, the phase velocity of the electromagnetic wave at the end of the second interval B is v p2 Positive transition to v p3 In addition, v p3 Can be slightly greater than, equal to, or slightly less than v p1 , which is not limited in the embodiment of the present invention. 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, fast electrons decelerate and slow electrons accelerate, which can effectively optimize the clustering quality of the high-energy electron group and form a high-energy electron cluster block with concentrated energy. The length of the third interval C needs to be determined according to the change in the energy distribution of the electrons in the cluster block so that the high-energy electron group can be effectively modulated in this interval.

[0063] In one embodiment, the fourth interval D is a phase velocity negative jump section of the slow wave circuit, and the phase velocity of the electromagnetic wave in the fourth interval D is set to v p4 , and v p4 <v p3 , that is, the electromagnetic wave phase velocity at the end of the third interval C is changed from v p3 Negative transition to v p4 In the fourth interval D, the electron beam completes the switch from the cluster state to the overpressure state, further improving the clustering quality of the low-energy electron group and forming a low-energy electron cluster block with concentrated energy. The length of the fourth interval D needs to be determined according to the required energy distribution change of the low-energy electron group, and the saturated output power requirement also needs to be considered during the design.

[0064] In a specific embodiment, in order to prevent the occurrence of self-oscillation, the design method further includes: S31, combining the simulation model, setting the cut-off area 1 in the first interval A based on the electromagnetic wave propagation characteristics, energy exchange effect and electron beam clustering state 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 a preferred example, combined with the simulation model, when the gain of the first interval A reaches 15-20dB, the cut-off zone 1 is set at this position to ensure the stability of the slow-wave circuit.

[0066] In order to avoid oscillation caused by reflection, a concentrated attenuator 2 needs to be set. In one embodiment, the design method also includes: S32, setting a concentrated attenuator 2 in the first interval A, and the concentrated attenuator is respectively located on both sides of the cut-off area 1. During the design process, the attenuation of the concentrated attenuator 2 needs to reach more than 30dB. It should be noted that, in order to facilitate calculation, the length of the concentrated attenuator 2 is usually designed to be shorter and the attenuation is larger when establishing the model. In practical applications, the specific length of the concentrated attenuator 2 can be adjusted according to the required attenuation, and this embodiment of the present invention is not limited to this.

[0067] The slow-wave circuit can be divided into an input section 3 and an output section 4 according to the cut-off area 1. The first section A and the second section B, the third section C and the fourth section B located on the side of the cut-off area 1 close to the second section B are the output section 4, and the part located on the other side of the cut-off area 1 is the input section 3.

[0068] In one embodiment, a distributed attenuator 5 may be further provided in the first interval A. Two distributed attenuators 5 are provided at the input section 3 and the output section 4, respectively. Specifically, one distributed attenuator 5 is provided approximately in the middle of the input section 3, and the other distributed attenuator 5 is provided approximately at one third of the output section 4. The specific positions need 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, which is generally 2-3 dB.

[0069] In a 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 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 changed from v to v at the end of the first interval A. p1 Negative transition to v p2 , at the end of the second interval B, v p2 Positive transition to v p3 , at the end of the third interval C, v p3 Negative transition to v p4 Through the phase velocity jump between positive and negative, the electron beam energy distribution is shaped in the beam-wave interaction, the density and energy concentration of each cluster block are improved, and a step-shaped or approximately step-shaped electron beam residual energy distribution diagram is constructed to improve the recoverability of the electron beam residual energy. On the basis of reducing the number of collecting poles, the purpose of improving the travel wave tube back-off efficiency 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 includes a plurality of folded waveguide units of geometric periodic structure, wherein the folded waveguide unit includes a connected straight waveguide segment and a connecting waveguide segment; the length of the straight waveguide segment corresponding to the four interaction intervals and / or the period length of the folded waveguide unit are adjusted so that the phase velocity of the electromagnetic wave changes from v to t at the end of the first interval A. p1 Negative transition to v p2 , at the end of the second interval B, v p2 Positive transition to v p3 , at the end of the third interval C, v p3 Negative transition to v p4 . Through the positive and negative jumps of the phase velocity, the electron beam energy distribution is shaped in the beam-wave interaction, the density and energy concentration of each cluster block are improved, and a step-shaped or approximately step-shaped distribution of the electron beam residual energy distribution diagram is constructed to improve the recoverability of the electron beam residual energy. On the basis of reducing the number of collecting poles, the purpose of improving the back-off efficiency of the traveling wave tube is achieved. Specifically, corresponding to the positions of the first interval A and the second interval B, the change of the phase velocity is mainly controlled by adjusting the period length of the folded waveguide unit; and at the positions corresponding to the third interval C and the fourth interval D, it is necessary to make more precise adjustments to the length of the straight waveguide section and the period length of the waveguide unit 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 includes a plurality of cavities arranged along the traveling direction of the electron beam, and the structural shape and / or geometric dimensions of the cavities corresponding to the four interaction intervals are adjusted so that the phase velocity of the electromagnetic wave changes from v to t at the end of the first interval A. p1 Negative transition to v p2 , at the end of the second interval B, v p2 Positive transition to v p3 , at the end of the third interval C, v p3 Negative transition to v p4 Through the phase velocity jump between positive and negative, the electron beam energy distribution is shaped in the beam-wave interaction, the density and energy concentration of each cluster block are improved, and a step-shaped or approximately step-shaped electron beam residual energy distribution diagram is constructed to improve the recoverability of the electron beam residual energy. On the basis of reducing the number of collecting poles, the purpose of improving the travel wave tube back-off efficiency is achieved.

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

[0073] The first interval A is the phase velocity uniform section of the slow wave circuit. 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 initial energy, the electron beam is initially clustered and the electromagnetic wave gains energy and is enhanced. The length of the first interval A needs to be obtained through simulation optimization based on the required gain and the phase relationship between the beam wave.

[0074] The second interval B is the phase velocity negative jump section of the slow wave circuit. 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 at the end of the first interval A is v p1 Negative transition to v p2 In the second interval B, the energy exchange between the electron beam and the electromagnetic wave is further enhanced, the electron beam forms a denser cluster, and the electromagnetic wave is further enhanced. In this process, the kinetic energy of the electron beam decreases. The length of the second interval B is generally based on the required energy exchange and the electron beam clustering shape.

[0075] The third interval C is the phase velocity positive jump section of the slow wave circuit. 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 at the end of the second interval B is v p2 Positive transition to v p3 In addition, v p3 Can be slightly greater than, equal to, or slightly less than v p1 , which is not limited in the embodiment of the present invention. 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, fast electrons decelerate and slow electrons accelerate, which can effectively optimize the clustering quality of the high-energy electron group and form a high-energy electron cluster block with concentrated energy. The length of the third interval C needs to be designed according to the change in the energy distribution of the electrons in the cluster block so that the high-energy electron group can be effectively modulated in this interval.

[0076] The fourth interval D is the phase velocity negative jump section of the slow wave circuit. The phase velocity of the electromagnetic wave in the fourth interval D is v p4 , and v p4 <v p3 , that is, the electromagnetic wave phase velocity at the end of the third interval C is changed from v p3 Negative transition to v p4In the fourth interval D, the electron beam completes the switch from the cluster state to the overpressure state, further improving the clustering quality of the low-energy electron group and forming a low-energy electron cluster block with concentrated energy. The length of the fourth interval D needs to be determined according to the required energy distribution change of the low-energy electron group, and the saturated output power requirement also needs to be considered during the design.

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

[0078] Another embodiment of the present invention provides a traveling wave tube, including a collector and a slow wave circuit provided in the above embodiment, wherein the number of collectors needs to be determined according to the distribution curve of the electron beam residual energy distribution diagram of the slow wave circuit, which is approximately a step-shaped distribution. For example, if the curve in the electron beam residual energy distribution diagram of the slow wave circuit is approximately a three-step 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 communications, especially to meet the communication needs of resource-scarce scenarios such as unmanned platforms, mobile platforms, and airborne platforms with high system cost requirements and limited power supply.

[0079] The beneficial effects of the design method of the slow-wave circuit for improving the back-off efficiency of a traveling wave tube provided by the present invention are 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 = 0.66 mm;

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

[0083] The third interval C: p3 = 0.66 mm;

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

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

[0086] During the design process, the lengths and phase velocities of the four interaction intervals are closely coordinated and jointly optimized. The first interval A is mainly used to achieve linear gain. When nonlinear injection wave interaction occurs, the length of the first interval A can be determined accordingly. The design purpose of the second interval B is to improve the back-off efficiency, make the electron clustering more dense, and adjust the injection wave phase in this area, while effectively transferring energy to the electromagnetic wave. The third interval C is dedicated to modulating the electron beam through electromagnetic waves so that the high-energy clustering block can achieve the best clustering effect. The design feature of the fourth interval D is a sudden drop in phase velocity. In this interval, electrons with lower energy will cluster, while providing higher saturation efficiency. In short, the length and phase velocity of each interval need to be repeatedly adjusted and optimized using simulation software according to specific needs, and finally the specific parameters of each area are determined.

[0087] A distributed attenuator 5 is set in the middle of the input section 3, and a distributed attenuator 5 is set near the cut-off area 1 of the output section 4 to avoid oscillation caused by reflection. The length of the distributed attenuator is determined according to the required attenuation (usually 2-3dB). On both sides near the cut-off area 1, concentrated attenuators are set, and their attenuation must reach more than 30dB. It should be noted that in order to facilitate calculation, when establishing the simulation model, the length of the concentrated attenuator is usually short and the attenuation is very large. In actual applications, the specific length of the concentrated attenuator is adjusted according to the required attenuation.

[0088] The distribution of the residual energy of the electron beam in the slow-wave circuit obtained by the design method provided by the embodiment of the present invention (hereinafter referred to as the embodiment) when the saturation is backed off by 3 dB is as follows: Figure 3 The horizontal axis is the collector voltage, and the vertical axis is the collector circuit. The comparison diagram of the electron beam residual energy distribution when the embodiment is saturated backed off by 3dB and the electron beam residual energy distribution when the prior art slow wave circuit (hereinafter referred to as comparative example) is shown in the figure below. Figure 4 As shown. Combined Figure 3 and Figure 4 It can be seen that the electron beam residual energy distribution curve can be constructed into a step-shaped or approximately step-shaped distribution through the design method provided in the embodiment of the present invention, such as Figure 3The residual energy of the electron beam of the embodiment shown is distributed in approximately three steps, corresponding to the number of collectors. The residual energy of the electron beam of the embodiment is recovered by three collectors. Specifically, the recovery efficiency of the three collectors is greater than 96.8%, while the residual energy of the electron beam of the comparative example is also recovered by three collectors, and its recovery efficiency is only 93.3%. The recovery efficiency of the embodiment is improved by 3% compared with the comparative example. Even if the comparative example adopts five collectors for recovery, the recovery efficiency of the embodiment is only 1% lower than that of the comparative example. It can be seen that the design method of the slow-wave circuit provided in the embodiment of the present invention significantly reduces the requirements for the number of collectors, and can reduce the process complexity and design difficulty of the collectors while improving the back-off efficiency of the traveling wave tube. Therefore, the design method of the slow-wave circuit for improving the back-off efficiency of the traveling wave tube provided in the embodiment of the present invention can be used as a practical solution to achieve high back-off efficiency of the traveling wave tube.

[0089] The embodiments of the present invention provide a design method for a slow-wave circuit for improving the back-off efficiency of a traveling wave tube, a slow-wave circuit, and a traveling wave tube. The invention effectively realizes the precise shaping of the distribution of the residual energy of an electron beam by changing the phase velocity from positive to negative. In the back-off working state of the traveling wave tube, the technology is used to construct a step-shaped distribution of the residual energy curve of the electron beam, which can significantly improve the recoverability of the residual energy of the electron beam, thereby improving the back-off efficiency of the traveling wave tube.

[0090] Through the phase velocity jump from positive to negative, the remaining energy of the electron beam is concentrated in a few narrow energy intervals, making the distribution curve of the remaining energy of the electron beam present a step-like or approximately step-like distribution, which greatly reduces the number of collector levels, makes the collector design more streamlined, and improves the recovery efficiency of the collector. The recovery efficiency of the three-stage collector can reach 96.8%, which is only 1% lower than that of the traditional five-stage collector, which means that the three-stage recovery can achieve an effect close to the five-stage recovery, greatly simplifying the design and process complexity of the collector.

[0091] Adjusting the distribution curve of the residual energy of the electron injection to a step-like or approximately step-like distribution shape can not only optimize the recovery efficiency of the collector, but also provide an ideal entrance condition for the collector. Since most of the electron energy is already 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 electrons can reach each electrode at a lower speed, that is, in the so-called soft landing state. This avoids 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, it helps to reduce the bombardment of the collector by abnormally high-speed electrons, thereby avoiding the violent collision of too many high-energy electrons in the collector. In traditional designs, since the energy distribution of the electron beam is relatively dispersed and the recovery efficiency is low, the collector needs to withstand more high-energy electrons. These high-speed electrons may cause local overheating and reduce the reliability of the traveling wave tube. Through the design of the present invention, the energy distribution of the electron beam is effectively shaped, the number of abnormal energy electrons is reduced, and the strong bombardment of the collector by high-energy electrons is avoided. 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 invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A design method for a slow-wave circuit for improving the back-off efficiency of a traveling wave tube, characterized in that: The method includes: Determine the type of 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 using simulation software, the working voltage and current of the slow wave circuit are set, and the electron beam DC speed v is determined according to the working voltage. b ; Dividing the slow-wave circuit into four interaction intervals, namely, a first interval, a second interval, a third interval and a fourth interval, along the traveling direction of the electron beam; Set the electromagnetic wave phase velocity in the first interval, the second interval, the third interval, and the fourth interval to v p1 、v p2 、v p3 、v p4 , where v p1 <v b , The phase velocity of the electromagnetic wave at the end of the first interval is v p1 Negative transition to v p2 , at the end of the second interval by v p2 Positive transition to v p3 , at the end of the third interval by v p3 Negative transition to v p4 ; The slow-wave circuit is numerically simulated and its performance is verified using simulation software. The phase velocity and length of the electromagnetic waves in the four interaction intervals of the slow-wave circuit are adjusted according to the simulation results until the output electron beam residual energy distribution diagram presents a step-like distribution, corresponding to the order of the collecting electrode.

2. The method for designing a slow-wave circuit for improving the back-off efficiency of a traveling wave tube according to claim 1, characterized in that: The method further comprises: In combination with the simulation model, a cut-off zone is set in the first interval based on the electromagnetic wave propagation characteristics, energy exchange effect and electron beam clustering state in the simulation process.

3. The design method of a slow-wave circuit for improving the back-off efficiency of a traveling wave tube according to claim 2, characterized in that: The cut-off area is located at a corresponding position in the first interval where the gain reaches 15-20 dB.

4. The design method of a slow-wave circuit for improving the back-off efficiency of a traveling wave tube according to claim 2, characterized in that: The method further comprises: A concentrated attenuator is arranged in the first section, and the concentrated attenuators are respectively located on both sides of the cut-off area.

5. The design method of a slow-wave circuit for improving the back-off efficiency of a traveling wave tube according to claim 1, characterized in that: The type of the slow-wave circuit is a helical slow-wave circuit; The spiral slow-wave circuit comprises a spiral line, and the spiral line comprises a first section, a second section, a third section and a fourth section corresponding to four interaction intervals of the slow-wave circuit; The pitch and / or radius of the first, second, third and fourth segments are adjusted respectively so that the phase velocity of the electromagnetic wave changes from v to 0 at the end of the first interval. p1 Negative transition to v p2 , at the end of the second interval by v p2 Positive transition to v p3 , at the end of the third interval by v p3 Negative transition to v p4 .

6. The design method of a slow-wave circuit for improving the back-off efficiency of a traveling wave tube according to claim 1, characterized in that: The type of the slow-wave circuit is a folded waveguide slow-wave circuit; The folded waveguide slow-wave circuit comprises a plurality of folded waveguide units of geometric periodic structure, wherein the folded waveguide unit comprises connected straight waveguide sections and connecting waveguide sections; Adjust the length of the straight waveguide section and / or the period length of the folded waveguide unit corresponding to the four interaction intervals so that the electromagnetic wave phase velocity changes from v to v at the end of the first interval. p1 Negative transition to v p2 , at the end of the second interval by v p2 Positive transition to v p3 , at the end of the third interval by v p3 Negative transition to v p4 .

7. The design method of a slow-wave circuit for improving the back-off efficiency of a traveling wave tube according to claim 1, characterized in that: The type of the slow-wave circuit is a coupled cavity slow-wave circuit; The coupled cavity slow-wave circuit comprises a plurality of cavities arranged along the traveling direction of the electron beam; Adjust the structural shape and / or geometric dimensions of the cavity corresponding to the four interaction intervals so that the phase velocity of the electromagnetic wave changes from v at the end of the first interval to p1 Negative transition to v p2 , the end of the second interval is v p2 Positive transition to v p3 , at the end of the third interval by v p3 Negative transition to v p4 .

8. A slow wave circuit, characterized in that: The slow-wave circuit is obtained by the design method according to any one of claims 1 to 4; The slow wave circuit is divided into four interaction intervals, namely, a first interval, a second interval, a third interval and a fourth interval, along the traveling direction of the electron beam, wherein the first interval is located at the initial end of the slow wave circuit; The phase velocities of electromagnetic waves in the first interval, the second interval, the third interval, and the fourth interval are v p1 、v p2 、v p3 、v p4 , where v p1 <v b , The phase velocity of the electromagnetic wave changes from v to p1 Negative transition to v p2 , at the end of the second interval by v p2 Positive transition to v p3 , at the end of the third interval by v p3 Negative transition to v p4 .

9. The slow-wave circuit according to claim 8, characterized in that: The slow-wave circuit is a helical slow-wave circuit, a folded waveguide slow-wave circuit or a coupled cavity slow-wave circuit.

10. A traveling wave tube, characterized in that: It comprises a collector and a slow-wave circuit as claimed in any one of claims 8 to 9; The number of the collecting electrodes corresponds to the step-shaped distribution of the electron beam residual energy distribution diagram of the slow-wave circuit.

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