A high-frequency helical slow-wave structure and traveling wave tube

Abstract

The present invention discloses a high-frequency helical slow-wave structure and a traveling wave tube, comprising a tube shell and a helical wire fixed in the tube shell by a clamping rod, wherein the helical wire and the tube shell are coaxially arranged; a loading structure is arranged on the inner wall of the tube shell, wherein the loading structure is a groove body formed by a depression of the inner wall of the tube shell, wherein the groove body spirally winds around the central axis of the tube shell on the inner wall of the tube shell to form a helical structure, and extends from one end of the tube shell to the other end of the tube shell. Compared with the existing slow-wave structure, the structure provided by the present invention improves the structure of the slow-wave structure, and by processing the loading structure inside the tube shell, the coupling impedance and output power of the slow-wave structure are improved, and the interaction coupling efficiency of the electron beam and the electromagnetic wave is further improved. In addition, the processing difficulty can be reduced, and a new technical direction is provided for the high-efficiency technology of space traveling wave tubes.

Description

Technical Field

[0001] The present invention relates to the field of microwave vacuum electronic devices, and more specifically to a high-frequency helical slow-wave structure and a traveling wave tube. Background Art

[0002] The traveling wave tube is a microwave power amplifier device, which belongs to vacuum electronic devices. It has been widely used in radar, electronic countermeasures and communications. Compared with solid-state devices developed by semiconductor technology, it has more advantages in wide bandwidth and high efficiency. The traveling wave tube is mainly composed of five parts: electron gun, high-frequency slow wave structure, magnetic focusing system, input and output system, and collector.

[0003] The high-frequency slow-wave structure is the core component of the traveling wave tube. Its function is to fully exchange energy between the electron beam emitted by the electron gun and the RF microwave signal entering the high-frequency slow-wave structure of the input system to obtain a higher output energy signal. The high-frequency beam-wave interaction structure has a great influence on the efficiency, gain and bandwidth of the electron beam-microwave interaction. Its performance directly determines the performance of the entire traveling wave tube. When the satellite payload device works on the satellite platform, the power supply is limited. More and more satellite users are pursuing payload devices with higher working efficiency and wider working bandwidth. The broadband coupling characteristics of the helical high-frequency slow-wave structure and the easier to obtain higher coupling efficiency make the helical electric vacuum device more advantageous among many payload devices. Therefore, the research on the helical high-frequency slow-wave structure is particularly important. How to design a high-efficiency, wide-bandwidth slow-wave structure has become an indispensable and very important step in the development of satellite electric vacuum devices.

[0004] At present, the slow-wave structure of the traveling wave tube generally adopts the helical slow-wave structure, and its design theory and design method are quite mature, and a lot of relevant knowledge and experience have been accumulated, that is, through the three clamping rods and the helical line in the circular tube shell, the helical line is supported to keep the axis of the tube shell consistent. The phase velocity of the microwave is reduced by changing the pitch of the helical line, so that the electron beam passing through the center of the helical line can fully exchange energy with the microwave to amplify the electromagnetic wave signal.

[0005] In order to obtain higher interaction efficiency, high-efficiency helical slow-wave structures are usually designed by using two methods: gradual helical pitch and optimized clamping rod structure. However, with the development of aerospace technology, aerospace users are gradually pursuing higher efficiency and high-power amplifier devices for microwave transmitters. High-frequency slow-wave structures designed only by gradual pitch and special-shaped clamping rods can hardly meet more than 70% of broadband and high-efficiency traveling wave tube design requirements. Summary of the invention

[0006] In view of the above problems, an object of the present invention is to provide a high-frequency helical slow-wave structure capable of improving the mutual coupling efficiency between electron beams and electromagnetic waves.

[0007] Another object of the present invention is to provide a traveling wave tube including the above-mentioned high-frequency helical slow-wave structure.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] According to one aspect of the present invention, there is provided a high-frequency helical slow-wave structure, comprising:

[0010] A tube shell and a helical wire fixed in the tube shell by a clamping rod, wherein the helical wire and the tube shell are coaxially arranged;

[0011] The inner wall of the tube shell is provided with a loading structure, which is a groove body formed by the inner wall depression of the tube shell. The groove body is spirally wound around the central axis of the tube shell on the inner wall of the tube shell to form a spiral structure, extending from one end of the tube shell to the other end of the tube shell.

[0012] In addition, an optional solution is that the loading structure is a multi-line spiral structure, including at least two grooves equidistantly distributed along the axial direction of the tube shell.

[0013] In addition, an optional solution is that the helix is ​​a variable pitch helix.

[0014] In addition, an optional solution is that the helix angle of the helical structure is related to the pitch of the helix line.

[0015] In addition, an optional solution is that the loading structure includes N slots:

[0016] N=

[0017] Wherein, β is the helical angle of the helical structure.

[0018] In addition, an optional solution is that the clamping rod is a T-shaped structure, including a first structure part and a second structure part, one end of the first structure part away from the second structure part is fixedly combined with the spiral line, and the surface of one end of the second structure part away from the first structure part is an arc surface, which is fixedly combined with the inner wall of the tube shell;

[0019] The width a of the first structure portion is smaller than the width b of the second structure portion.

[0020] In addition, an optional solution is that a groove width m of the groove body along the axial direction of the tube shell is smaller than a width b of the second structural portion of the clamping rod.

[0021] In addition, an optional solution is that the clamping rod includes an attenuator in the middle portion along the axial direction of the tube shell, and the length of the attenuator is greater than the length of 2-3 wavelengths of the signal transmitted by the slow-wave structure.

[0022] In addition, an optional solution is that the groove width m of the groove body along the axial direction of the tube shell is smaller than the pitch of the helix.

[0023] According to another aspect of the present invention, there is provided a traveling wave tube, comprising an electron gun, a focusing system, a collector, an input device, an output device and a high-frequency helical slow-wave structure;

[0024] The tube shell of the high-frequency helical slow-wave structure comprises an input port and an output port, and the pitch of the helical line close to the input port is greater than the pitch of the helical line close to the output port.

[0025] The beneficial effects of the present invention are as follows:

[0026] In view of the technical problems existing in the prior art, the present invention provides a high-frequency helical slow-wave structure and a traveling wave tube. By improving the structure of the slow-wave structure and processing the loading structure inside the tube shell, the coupling impedance and output power of the slow-wave structure are improved, and the mutual coupling efficiency of the electron beam and the electromagnetic wave is further improved, providing a new technical direction for the high-efficiency technology of space traveling wave tubes. Under the existing mechanical processing level, the structure provided by the present invention is easier to implement than the slow-wave structure that reduces the pitch size to improve the mutual coupling efficiency, and can reduce the processing difficulty of the helical slow-wave structure of the small-size pitch of the millimeter-wave traveling wave tube. At the same time, it can have higher output power and mutual coupling efficiency at the same size, meeting the design requirements of high-efficiency traveling wave tubes. The slow-wave structure has the advantages of simple structure and easy processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0028] Figure 1 A front view of a high-frequency helical slow-wave structure in the prior art is shown.

[0029] Figure 2 A cross-sectional view of a high-frequency helical slow-wave structure in the prior art is shown.

[0030] Figure 3 A front view of a high-frequency helical slow-wave structure provided by an embodiment of the present invention is shown.

[0031] Figure 4 Show Figure 3 Medium AA view.

[0032] Figure 5 A cross-sectional view of a high-frequency helical slow-wave structure provided by an embodiment of the present invention is shown.

[0033] Figure 6 A coupling impedance simulation comparison graph of a comparative example and an embodiment is shown.

[0034] Figure 7 A comparison chart of the output power results of the comparative example and the embodiment is shown. DETAILED DESCRIPTION

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] At present, in order to improve the interaction efficiency of the slow-wave structure, the industry usually adopts the method of further compressing the inner diameter of the helix. Although it can improve the interaction efficiency to a certain extent, it will increase the operating voltage, thereby reducing the reliability and working stability of the slow-wave structure. In addition, in order to avoid the working frequency band of the slow-wave structure from being offset during design, the pitch of the helix is ​​often reduced while compressing the inner diameter of the helix. For small-sized millimeter-wave traveling wave tubes, the difficulty of process implementation will be doubled.

[0040] In view of the defects of the prior art, the present invention provides a high-frequency helical slow-wave structure, combined with Figure 3-7 As shown, the high-frequency band helical slow-wave structure includes a tube shell 1 and a helical wire 3 fixed in the tube shell 1 by n clamping rods 2, and the helical wire 3 and the tube shell 1 are coaxially arranged.

[0041] The inner wall of the tube shell 1 is provided with a loading structure 4, such as Figure 3-4 As shown, the loading structure 4 is specifically a groove body 40 formed by the inner wall depression of the tube shell 1. The groove body 40 is spirally wound around the central axis of the tube shell 1 on the inner wall of the tube shell 1 to form a spiral structure, extending from one end of the tube shell 1 to the other end of the tube shell 1.

[0042] In the radial direction of the tube shell 1, n clamping rods 2 are arranged symmetrically about the helical line 3, where n is an integer greater than or equal to 2. Figure 3 As shown, the spiral wire 3 is fixed in the tube shell 1 through three T-shaped clamping rods 2, and the three clamping rods 2 are distributed in the tube shell 1 in an axisymmetric manner of 120 degrees.

[0043] Helix 3 is, for example, a variable pitch helix, which may have a gradual pitch change and / or a pitch jump change. The pitch of helix 3 along the direction of electron beam travel between input port 11 and output port 12 presents a five-segment pitch variation form of p1-p2-p3-p4-p5, where segment p1 is the initial segment of helix 3.

[0044] In a specific example, the pitch of the helix gradually decreases from the input port to the output port: p1>p2>p3>p4>p5. The change of the pitch of the helix 3 can change the phase velocity of the electromagnetic wave, thereby improving the coupling efficiency between the electron beam and the electromagnetic wave.

[0045] In a specific embodiment, the loading structure 4 is a multi-line spiral structure, including at least two spiral tracks equidistantly distributed along the axial direction of the tube shell 1, and the inner wall of the tube shell 1 is recessed along each spiral track to form a groove body 40 to constitute a loading structure. Among them, the groove width m and groove depth t of the groove body 40 corresponding to each spiral track are the same. By arranging the loading structure 4 on the inner wall of the tube shell 1 and changing the number of spiral tracks and the size parameters of the groove body 40, the propagation speed of the electromagnetic wave in the slow-wave structure can be changed, so that the electron beam and the electromagnetic wave can fully interact with each other, thereby exchanging more energy to increase the output power of the slow-wave structure. By adjusting the helical pitch, the size of the clamping rod, the inner diameter of the tube shell, the groove width m and the groove depth t of the groove body, the coupling impedance of the high-frequency structure is calculated, and the various size parameters suitable for the millimeter wave band are determined.

[0046] The helix angle of the helical structure is related to the pitch of the helix.

[0047] In a specific embodiment, the helical angle β at each location of the helical track in the helical structure is calculated by the following formula:

[0048] β =

[0049] Wherein, r is the inner radius of the tube shell 1, p is the pitch of the spiral line corresponding to the radial direction of the spiral trajectory, and the value of p is p1, p2, p3, p4, p5.

[0050] In another embodiment, the helical angle β of the spiral track is only related to the pitch of the initial segment of the spiral line 3, and the value of p is p1. During production, the value of the helical angle β of the spiral track can be optimized according to actual needs to achieve higher coupling efficiency between the electron beam and the electromagnetic wave.

[0051] In one embodiment, the number N of spiral tracks included in the loading structure 4 can be estimated by the following formula:

[0052] N=

[0053] Where β is the helical angle of the helical trajectory.

[0054] It should be noted that, in actual production, when selecting the specific value of the number N of spiral tracks, the slot width m of the slot body 40 along the axial direction of the tube shell 1 should also be considered to avoid interference between the slot bodies 40 opened along different spiral tracks. Specifically, when the value of N is not an integer, it is necessary to combine the slot width m of the slot body 40 along the axial direction of the tube shell 1 to determine whether the value of N is the maximum integer or the minimum integer closest to the obtained value.

[0055] In one embodiment, Figure 3 As shown, the clamping rod 2 is a T-shaped structure, including a first structure part 21 and a second structure part 22. The end of the first structure part 21 away from the second structure part 22 clamps the spiral wire 3; the surface of the end of the second structure part 22 away from the first structure part 21 is an arc surface, which is close to the inner wall of the tube shell 1. Specifically, the clamping rod 2 can be connected to the tube shell 1 and the spiral wire 3 respectively by welding, spring pressing, heat shrinkage, etc., which is not limited in this embodiment.

[0056] Furthermore, the width a of the first structure portion 21 is smaller than the width b of the second structure portion 22 .

[0057] In a specific embodiment, the groove width m of the groove body 40 along the axial direction of the tube shell 1 is smaller than the width b of the second structure portion 22 of the clamping rod 2 .

[0058] In one embodiment, a carbonized attenuator 5 is provided in the middle of the clamping rod 2 along the axial direction of the tube shell 1 , and the length of the attenuator 5 needs to be greater than 2-3 wavelengths of the signal transmitted by the slow-wave structure.

[0059] In one embodiment, the groove width m of the groove body 40 along the axial direction of the tube shell 1 is smaller than the pitch of each segment of the helical line 3, that is, m <p5<p4<p3<p2<p1。

[0060] Another embodiment of the present invention provides a traveling wave tube, which includes an electron gun, a focusing system, a collector, an input device, an output device and the high-frequency helical slow-wave structure provided in the above embodiments, wherein the electron gun, the focusing system, the collector, the input device and the output device are all connected to the high-frequency helical slow-wave structure.

[0061] Specifically, the two ends of the tube shell 1 include an input port 11 and an output port 12, and the input port 11 is located at one end close to the initial section of the helix 3. The inner conductor cylinder of the input device is connected to the helix 3 through the input port 11, and the outer conductor circular hole of the input device is connected to the tube shell 1; the inner conductor cylinder of the output device is connected to the helix 3 through the output port 12, and the outer conductor circular hole of the output device is connected to the tube shell 1.

[0062] The beneficial effects of the high-frequency helical slow-wave structure provided by the present invention will be described below by way of examples:

[0063] Comparative Example

[0064] like Figure 1-2 The slow-wave structure shown is suitable for the millimeter wave band. The tube shell 1 is cylindrical, the clamping rod 2 is a T-shaped structure, including three rods, and the pitch of the helical wire 3 is p1-p2-p3-p4-p5 in the direction of electron beam travel.

[0065] Example

[0066] like Figure 3-5 The slow wave structure shown is suitable for the millimeter wave band. Based on the comparative example, a loading structure 4 is arranged on the inner wall of the tube shell 1. The helical angle of the loading structure is β, the groove depth of the groove body 40 is t, the groove width is m, and the loading structure includes 5 spiral tracks.

[0067] The coupling impedance of the slow-wave structures of the comparative example and the embodiment is calculated in the millimeter wave band. The calculation results are as follows: Figure 6 As shown, from Figure 6 It can be seen that within the frequency range of 15-40 GHz, the coupling impedance of the embodiment is significantly larger by 3Ω to 8Ω than the coupling impedance of the comparative example.

[0068] The output power of the comparative example and the embodiment is calculated and compared by using simulation software. Under the working conditions of working frequency 20.2 GHz, working voltage 8 kV, and current 50 mA, the input power of the input port 11 of the comparative example and the embodiment is 0.06 W (as shown in FIG. Figure 7 As shown in curve 1 in FIG. 1 ), the output port 12 of the embodiment is at 20 ns later, as shown in FIG. Figure 7 As shown in curve 3 in the figure, the output power finally stabilizes at a state greater than 113W, and the mutual coupling efficiency between the electron beam and the electromagnetic wave is 28.2%; while the output port 12 of the comparative example is Figure 7As shown in Curve 2, the output power is finally stabilized at a state greater than 75 W, and the mutual coupling efficiency between the electron beam and the electromagnetic wave is only 18.7%. By comparing Curve 2 and Curve 3, it can be clearly seen that the mutual coupling efficiency between the electron beam and the electromagnetic wave is significantly improved in the embodiment compared with the comparative example.

[0069] The high-frequency helical slow-wave structure and traveling wave tube provided in the embodiment of the present invention improve the structure of the slow-wave structure and process the loading structure inside the tube shell to improve the coupling impedance and output power of the slow-wave structure, further improve the mutual coupling efficiency of the electron beam and the electromagnetic wave, and provide a new technical direction for the high-efficiency technology of space traveling wave tubes. Under the existing mechanical processing level, the structure provided by the present invention is easier to implement than the slow-wave structure that reduces the pitch size to improve the mutual coupling efficiency, and can reduce the processing difficulty of the helical slow-wave structure of the small-size pitch of the millimeter-wave traveling wave tube. At the same time, it can have higher output power and mutual coupling efficiency at the same size, meeting the design requirements of high-efficiency traveling wave tubes. The slow-wave structure has the advantages of simple structure and easy processing.

[0070] 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 high-frequency helical slow-wave structure, characterized in that: It comprises a tube shell and a helical wire fixed in the tube shell by a clamping rod, wherein the helical wire and the tube shell are coaxially arranged; The inner wall of the tube shell is provided with a loading structure, which is a groove body formed by the inner wall depression of the tube shell, and the groove body spirally winds around the central axis of the tube shell on the inner wall of the tube shell to form a spiral structure, extending from one end of the tube shell to the other end of the tube shell; The loading structure is a multi-line spiral structure, comprising at least two slots equidistantly distributed along the axial direction of the tube shell; The helical line is a variable pitch helical line.

2. The high-frequency helical slow-wave structure according to claim 1, characterized in that: The helix angle of the helical structure is related to the pitch of the helix.

3. The high-frequency helical slow-wave structure according to claim 1, characterized in that: The loading structure includes N slots: N= Wherein, β is the helical angle of the helical structure.

4. The high-frequency helical slow-wave structure according to claim 1, characterized in that: The clamping rod is a T-shaped structure, comprising a first structure part and a second structure part, wherein one end of the first structure part away from the second structure part is fixedly combined with the spiral line, and one end surface of the second structure part away from the first structure part is an arc surface, which is fixedly combined with the inner wall of the tube shell; The width a of the first structure portion is smaller than the width b of the second structure portion.

5. The high-frequency helical slow-wave structure according to claim 4, characterized in that: A groove width m of the groove body along the axial direction of the tube shell is smaller than a width b of the second structure portion of the clamping rod.

6. The high-frequency helical slow-wave structure according to claim 1, characterized in that: The clamping rod comprises an attenuator in the middle portion along the axial direction of the tube shell, and the length of the attenuator is greater than 2-3 wavelengths of the signal transmitted by the slow-wave structure.

7. The high-frequency helical slow-wave structure according to claim 1, characterized in that: The groove width m of the groove body along the axial direction of the tube shell is smaller than the pitch of the helix.

8. A traveling wave tube, characterized in that: It comprises an electron gun, a focusing system, a collector, an input device, an output device and a high-frequency helical slow-wave structure as claimed in any one of claims 1 to 7; The tube shell of the high-frequency helical slow-wave structure comprises an input port and an output port, and the pitch of the helical line on the side close to the input port is greater than the pitch on the side close to the output port.

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