Slow-wave structure and slow-wave circuit suitable for high-order mode

Abstract

The embodiment of the invention discloses a slow wave structure and a slow wave circuit suitable for a high-order mode, and the structure comprises a housing, upper grid bodies which extend from the top wall of the housing to the bottom wall of the housing, and lower grid bodies which extend from the bottom wall of the housing to the top wall of the housing, and the plurality of upper grid bodies and the plurality of lower grid bodies are distributed in a staggered manner. A plurality of vacuum cavities with periodic structures are defined by the upper grid bodies and the lower grid bodies; in the height direction of the slow wave structure, the upper grid body and the lower grid body have different heights; an electron beam channel is formed between the upper gate body and the lower gate body. According to the invention, low-order mode competition and backward wave oscillation can be suppressed under low working voltage, high-order mode stable working is realized, and high output power of 100W and above can be realized with low voltage.

Description

Technical Field

[0001] The present invention relates to the field of microwave vacuum electronic technology, and more specifically to a slow-wave structure and a slow-wave circuit suitable for high-order modes. Background Art

[0002] In the process of the operating frequency band of the traveling wave tube gradually expanding to the terahertz band, as the size of the device decreases, the influence of the size co-transit effect becomes more and more obvious. The size co-transit effect refers to the fact that in the process of increasing the operating frequency of the traveling wave tube, the lateral size of the slow-wave structure and the width of the electron beam channel continue to decrease, which on the one hand increases the difficulty of the processing technology and reduces the working current; on the other hand, the increase in frequency accelerates the decay rate of the surface wave. This surface electromagnetic wave can only be maintained on the surface of the slow-wave structure, and becomes very weak in the electron beam flow area, resulting in a weakened degree of injection-wave interaction, resulting in a very small coupling impedance of the slow-wave structure, which leads to a decrease in interaction efficiency and ultimately a decrease in output power.

[0003] An over-moded traveling wave tube is an electric vacuum device that uses high-order modes to transmit electromagnetic waves. It has the characteristics of high power and wide bandwidth. It is a special traveling wave tube that uses high-order modes to work to achieve higher output power and wider operating frequency band. The main feature of the over-moded traveling wave tube is that it can work at high frequencies while maintaining high power capacity and low transmission loss, which makes it have broad application prospects in terahertz technology and millimeter wave technology.

[0004] The over-mode traveling wave tube working in the high-order mode has a larger lateral size due to the characteristics of the high-order mode field distribution, and can adapt to high voltage and high current input. 30 Taking the over-mode traveling wave tube as an example, its lateral size is about three times that of the fundamental mode traveling wave tube in the same frequency band, which can effectively reduce the difficulty of the processing technology and can pass a larger current to effectively increase the output power. 20 The same is true for the over-moded traveling wave tube.

[0005] Although the over-mode TWT has a large lateral size and is suitable for high voltage and high current input, it will also cause problems such as mode competition of the low-order mode forward wave and backward wave oscillation, which will limit the output power and gain. At present, the commonly used technologies to suppress the above problems in high-order mode over-mode TWTs include dielectric loading, ridge / groove loading, and adding rectangular metal columns in the middle of the electron injection channel to completely isolate adjacent channels.

[0006] According to existing research results, the existing over-mode traveling wave tubes can be roughly divided into two categories. One category suppresses low-order modes while limiting the output power of the working mode. The other category has higher gain and output power, but its working voltage is as high as 50kV or more, and it is difficult to achieve a matching electron gun and magnetic focusing system.

[0007] In the existing research results, there are very few over-mode traveling wave tubes that work in high-order modes, and all of them use the method of adding metal columns in the electron injection channel. This method destroys the characteristics of high-order modes while suppressing low-order modes, making it more similar to a side-by-side multi-injection fundamental mode traveling wave tube. Therefore, it is necessary to provide a new slow-wave structure that is more suitable for high-order mode operation. Summary of the invention

[0008] In view of the above problems, an object of the present invention is to provide a slow-wave structure suitable for high-order modes, wherein the slow-wave structure has a stable working state under high-order mode characteristics and achieves high output power under low working voltage.

[0009] Another object of the present invention is to provide a slow-wave circuit including the above-mentioned slow-wave structure.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions:

[0011] According to one aspect of the present invention, the present invention provides a slow-wave structure suitable for high-order modes, comprising a shell, an upper grid body extending from the top wall of the shell to the bottom wall of the shell, and a lower grid body extending from the bottom wall of the shell to the top wall of the shell, wherein a plurality of upper grid bodies and a plurality of lower grid bodies are staggered and distributed with each other, and each upper grid body and each lower grid body define a plurality of vacuum cavities with periodic structures;

[0012] In the height direction of the slow-wave structure, the upper grid body and the lower grid body have different heights; an electron injection channel is formed between the upper grid body and the lower grid body.

[0013] In addition, a preferred solution is that the height of the upper grid body is 1 / 2 of the height of the slow-wave structure inner cavity, and the height of the lower grid body is 1 / 2 of the height of the upper grid body; the slow-wave structure includes two grids extending from the two ends of the top surface of the lower grid body toward the top wall of the shell, and the top surface of the grid and the bottom surface of the upper grid body are located in the same plane; a channel constituting an electron injection channel is formed between the two grids, and the working mode of the slow-wave structure is TE 10 model.

[0014] In addition, a preferred solution is that the slow-wave structure includes a grating extending from the top surface of the lower grating body toward the top wall of the shell, and the top surface of the grating and the bottom surface of the upper grating body are located in the same plane;

[0015] The height of the upper grid body is 1 / 2 of the height of the slow-wave structure inner cavity, and the height of the lower grid body is 1 / 2 of the height of the upper grid body.

[0016] In addition, the preferred solution is that the number of the barrier is one; two channels constituting the electron injection channel are arranged side by side on both sides of the barrier, and the working mode of the slow wave structure is high-order TE20 model.

[0017] In addition, a preferred solution is that the slow-wave structure has two electron injection channels, and the two electron injection channels have the same width in the width direction of the slow-wave structure.

[0018] In addition, a preferred solution is that the number of the grilles is two; three channels constituting electron injection channels are formed between the side wall of one side of the shell and an adjacent grille, between two grilles, and between the side wall of the other side of the shell and another adjacent grille, and the working mode of the slow wave structure is high-order TE 30 model.

[0019] In addition, a preferred solution is that the slow-wave structure has three electron injection channels, and the three electron injection channels have the same width in the width direction of the slow-wave structure.

[0020] In addition, it is preferred that the electron injection channel comprises:

[0021] an electron injection channel injection region located in the upper half of the electron injection channel, and

[0022] an electron injection channel non-injection region located in the lower half of the electron injection channel;

[0023] The channel height of the electron injection channel injection zone is 1 / 2 of the overall height of the electron injection channel.

[0024] According to another aspect of the present invention, the present invention provides a slow-wave circuit suitable for high-order modes, the slow-wave circuit comprising a slow-wave structure input section, a slow-wave structure output section, and a cut-off structure connecting the slow-wave structure input section and the slow-wave structure output section;

[0025] The slow-wave structure input section includes the slow-wave structure described above, and / or the slow-wave structure output section includes the slow-wave structure described above.

[0026] The present invention also provides a slow-wave circuit suitable for high-order modes, the slow-wave circuit comprising a slow-wave structure input section, a slow-wave structure output section, and a cut-off structure connecting the slow-wave structure input section and the slow-wave structure output section;

[0027] The slow-wave structure input section includes the slow-wave structure as described above, and / or the slow-wave structure output section includes the slow-wave structure as described above;

[0028] The cut-off structure includes a first cavity close to the input section of the slow-wave structure and a second cavity close to the output section of the slow-wave structure;

[0029] The first cavity includes a first grid, and the second cavity includes a second grid;

[0030] In the axial direction of the slow-wave structure, the projection boundary of the first grid, the projection boundary of the second grid and the projection boundary of the grating coincide with each other.

[0031] The beneficial effects of the present invention are as follows:

[0032] The premise for the high-mode traveling wave tube to work stably is to suppress the backward oscillation and mode competition of the low-order mode. One method is to reduce the coupling impedance at the intersection of the electron injection voltage line and the low-order mode, and the other method is to cut off the electric field of the low-order mode at a position where the electric field intensity is high. The slow-wave structure provided by the present invention realizes the combination of these two methods, which can suppress the low-order mode competition and backward oscillation at a low working voltage, realize the stable operation of the high-order mode, and realize a high output power of 100W or more at a low voltage. The technical effects of the present invention compared with the prior art are explained one by one in the specific embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0034] Figure 1 The conventional TE with metal pillars is shown. 30 Mode slow wave structure.

[0035] Figure 2 The dispersion curves of the higher-order modes of the conventional existing slow-wave structure with metal pillars are shown.

[0036] Figure 3 An embodiment of the present invention provides a method for applying TE 10 One of the schematic diagrams of the slow-wave structure of the mode.

[0037] Figure 4 An embodiment of the present invention provides a method for applying TE 10 The second schematic diagram of the slow-wave structure of the mode.

[0038] Figure 5a Shows the traditional existing TE 10 Energy distribution diagram of the forward wave electric field of the mode-interlaced grating slow-wave structure.

[0039] Figure 5b Shows the traditional existing TE 10 Energy distribution diagram of the return wave electric field of the mode-interleaved grating slow-wave structure.

[0040] Figure 6a An embodiment of the present invention provides a method for applying TE 10 Energy distribution diagram of the forward wave electric field of the slow wave structure of the mode.

[0041] Figure 6b An embodiment of the present invention provides a method for applying TE 10Energy distribution diagram of the return wave electric field of the slow wave structure of the mode.

[0042] Figure 7 Another embodiment of the present invention provides a TE 20 One of the schematic diagrams of the slow-wave structure of the mode.

[0043] Figure 8 Another embodiment of the present invention provides a TE 20 The second schematic diagram of the slow-wave structure of the mode.

[0044] Figure 9a Shows the traditional existing TE 20 Energy distribution diagram of the forward wave electric field of the mode-interlaced grating slow-wave structure.

[0045] Figure 9b Shows the traditional existing TE 20 Energy distribution diagram of the return wave electric field of the mode-interleaved grating slow-wave structure.

[0046] Fig.10a Another embodiment of the present invention provides a TE 20 Energy distribution diagram of the forward wave electric field of the slow wave structure of the mode.

[0047] Fig.10b Another embodiment of the present invention provides a TE 20 Energy distribution diagram of the return wave electric field of the slow wave structure of the mode.

[0048] Fig.11 Another embodiment of the present invention provides a TE 30 One of the schematic diagrams of the slow-wave structure of the mode.

[0049] Fig.12 Another embodiment of the present invention provides a TE 30 The second schematic diagram of the slow-wave structure of the mode.

[0050] Fig.13 Shows the traditional existing TE 30 Energy distribution diagram of the forward wave electric field of the mode-interlaced grating slow-wave structure.

[0051] Fig.14 Another embodiment of the present invention provides a TE 30 Energy distribution diagram of the forward wave electric field of the slow wave structure of the mode.

[0052] Fig.15 Shows the traditional existing TE 30 Dispersion curve of the mode-interleaved grating slow-wave structure.

[0053] Fig.16 Another embodiment of the present invention provides a TE 30Dispersion curve of the slow-wave structure of the mode.

[0054] Fig.17 Another embodiment of the present invention provides a TE 30 The coupling impedance variation curve of the slow-wave structure of the mode between the phases of 360°-720°.

[0055] Fig.18 Showing a method including Fig.11 , Fig.12 TE shown 30 Slow-wave circuit of mode slow-wave structure.

[0056] Fig.19 Show Fig.18 Schematic diagram of the slow-wave circuit cut-off structure shown.

[0057] Fig. 20 Another embodiment of the present invention provides a TE 30 Spectrum diagram of the slow-wave structure output signal of the mode after Fourier transform. DETAILED DESCRIPTION

[0058] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0059] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0060] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0061] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0062] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0063] The existing over-mode traveling wave tube slow wave structure is divided into three categories. One category suppresses the low-order mode while limiting the output power of the working mode. The saturated output power of this type of slow wave structure does not exceed 100W. Although it maintains the integrity of the high-order mode, the output power does not meet the current needs. The other category has higher gain and output power, but because it works near the 360° phase, its working voltage is as high as 50kV or more, and it is difficult to achieve a matching electron gun and magnetic focusing system.

[0064] The third type is to add a metal column 100 in the middle of the electron injection channel to completely isolate the adjacent channels. This method is used to obtain a slow-wave structure, which is widely used in the research of staggered grating and sinusoidal waveguide type over-mode slow-wave structures. Figure 1 The structure shown, Figure 1 The conventional TE with metal pillar 100 is shown. 30 The slow wave structure in the mode. From the dispersion curve, refer to Figure 2 As shown in the figure, it can be seen that the dispersion curves of the higher-order modes of this type of slow-wave structure almost coincide with the fundamental mode, where Mode1 is the dispersion curve of the fundamental mode and Mode2 is the dispersion curve of the TE mode. 20 Mode dispersion curve, Mode3 is TE 30 Mode dispersion curve. From the perspective of physical structure, the adjacent electron injection channels of this structure are completely isolated, and the rectangular metal column runs through the entire interaction circuit. The high-order mode is completely cut off at the electron injection channel, and the electric field distribution of the high-order mode can only be maintained in the slot. This type of slow-wave structure is more similar to a side-by-side fundamental mode multi-injection traveling wave tube. It does not have the over-mode characteristic of the over-mode traveling wave tube slow-wave structure where the interval between the dispersion curves of each mode increases by multiples, and loses the size advantage of the over-mode traveling wave tube. The processing technology is difficult,

[0065] The present invention is committed to improving the traditional staggered double-grid slow-wave structure from the perspective of the structure itself, and provides a new slow-wave structure suitable for high-order mode propagation and a slow-wave circuit including a cover slow-wave structure.

[0066] It should be noted that the slow wave structure of the high-order mode is divided into TE according to the different high-order working modes. 10 Mode slow wave structure, TE 20 Mode slow wave structure, TE 30 Mode slow wave structure, and TE 30 The slow-wave structure of a higher working mode above the mode, according to the purpose of the invention, the specific implementation mode of the invention will be explained from the slow-wave structures of several different working modes according to the different working modes.

[0067] Example 1:

[0068] A method for TE comprising a slow wave structure provided by the present invention 10Mode slow wave structure, in this embodiment, the present invention first provides a TE 10 The slow-wave structure of the mode is also called the fundamental mode slow-wave structure. Figure 3 , Figure 4 As shown, the slow-wave structure includes a shell 10, an upper grid body 11 extending from the top wall of the shell 10 to the bottom wall of the shell, and a lower grid body 12 extending from the bottom wall of the shell 10 to the top wall of the shell, and a plurality of upper grid bodies 11 and a plurality of lower grid bodies 12 are staggered with each other, and each upper grid body 11 and each lower grid body 12 define a vacuum cavity forming a plurality of periodic structures. As known in the art, the vacuum cavity of the slow-wave structure described in the present invention generally refers to the shell 10 and each upper grid body 11 and each lower grid body 12 in the shell 10 define a plurality of periodic structures, which are usually presented in the form of simulation. In this embodiment, the bottom surface of the upper grid body 11 and the top surface of the lower grid body 12 are both planar designs. Specifically, it is defined that the height of the upper grid body 11 refers to the height in the height direction of the slow-wave structure, represented by h1, the height of the lower grid body 12 refers to the height in the height direction of the slow-wave structure, represented by h2, and the height of the slow-wave structure cavity is represented by H. This embodiment provides a slow-wave structure. In the height direction of the slow-wave structure, the upper gate body 11 and the lower gate body 12 have different heights, wherein the height h1 of the upper gate body 11 is 1 / 2 of the height H of the slow-wave structure inner cavity, and the height h2 of the lower gate body 12 is 1 / 2 of the height h1 of the upper gate body, and an electron injection channel 13 is formed between the upper gate body 11 and the lower gate body 12.

[0069] Furthermore, the present embodiment provides a slow-wave structure comprising two grids 14 extending from the two ends of the top surface of the lower grid body 12 toward the top wall of the shell 10, wherein the top surface of the grid 14 and the bottom surface of the upper grid body 11 are located in the same plane; a channel constituting an electron injection channel 13 is formed between the two grids 14 in the width direction of the slow-wave structure.

[0070] According to TE 10 The characteristics of the electric field distribution of the slow-wave structure in the mode. The upper part of the electron injection channel 13 is in TE 10 In the working mode, the electric field energy is high, and the lower part is in TE 10 In the working mode, the electric field energy is low and the return wave electric field energy is high, which can easily cause return wave oscillation. In the specific implementation, this embodiment provides a working mode of high-order TE 10 The electron injection channel 13 of the slow-wave structure of the mode includes: an electron injection channel injection area located in the upper half of the electron injection channel 13, and an electron injection channel non-injection area located in the lower half of the electron injection channel 13. The channel height of the injection area of ​​the electron injection channel 13 is 1 / 2 of the overall height of the electron injection channel. Therefore, in practical applications, half of the channel, that is, the upper half of the electron injection channel, is selected as the injection area of ​​the electron injection channel.

[0071] Comparative Example 1:

[0072] Figure 5a and Figure 5b are the traditional existing TE obtained by CST eigenmode solver. 10 Electric field energy distribution diagram of the mode staggered grating slow-wave structure, where Figure 5a For TE 10 Mode forward wave, Figure 5b For TE 10 Mode return wave.

[0073] Figure 6a and Figure 6b The present invention provides TE respectively obtained by CST eigenmode solver 10 Electric field energy distribution diagram of the mode slow-wave structure, where Figure 6a TE of the present invention 10 Mode slow wave structure forward wave, where Figure 6b TE of the present invention 10 Mode slow wave structure return wave.

[0074] By comparison, it can be seen from the figure that compared with the traditional existing TE 10 Mode staggered grating slow wave structure, the present invention provides TE 10 The low-order mode forward wave and backward wave electric field energy of the mode slow-wave structure is greatly reduced, and the electric field energy distribution range in the center area of ​​the mode is greatly reduced, which effectively suppresses the low-order mode backward wave oscillation, and the interaction between the electron beam and the electromagnetic wave is more stable.

[0075] According to one aspect of the present invention, based on the present invention provided above, the TE 10 The present invention also provides a slow wave structure of the TE mode. 10 The slow-wave circuit of the mode slow-wave structure, specifically, the slow-wave circuit includes a slow-wave structure input section, a slow-wave structure output section and a cut-off structure connecting the slow-wave structure input section and the slow-wave structure output section. In the slow-wave circuit structure, the slow-wave structure input section and / or the slow-wave structure output section include the TE 10 The slow-wave structure of the mode.

[0076] In this embodiment, further, the cut-off structure includes a first cavity near the input section of the slow-wave structure and a second cavity near the output section of the slow-wave structure. The first cavity includes a first grid, and the second cavity includes a second grid. The number of the first grid and the number of the second grid are respectively the same as those of the TE 10 The number of gratings in the slow-wave structure of the mode is equal, and coincides with the projection boundary of the first grating, the projection boundary of the second grating and the projection boundary of the grating in the axial direction of the slow-wave structure. Regarding the cut-off structure and the projection boundary of the first grating, the projection boundary of the second grating and the projection boundary of the grating in the axial direction of the slow-wave structure, please refer to the following including TE30 Structural diagram of the slow-wave circuit of the mode slow-wave structure.

[0077] Example 2:

[0078] A method for TE comprising a slow wave structure provided by the present invention 20 mode slow wave structure, in this embodiment, the present invention further provides a TE 20 The slow-wave structure of the mode, ref. Figure 7 , Figure 8 As shown, the slow-wave structure includes a housing 20, an upper grid body 21 extending from the top wall of the housing 20 to the bottom wall of the housing, and a lower grid body 22 extending from the bottom wall of the housing to the top wall of the housing, and a plurality of upper grid bodies 21 and a plurality of lower grid bodies 22 are staggered with each other, and each upper grid body 21 and each lower grid body 22 define a vacuum cavity with a plurality of periodic structures. As known in the art, the vacuum cavity of the slow-wave structure described in the present invention generally refers to the housing and each upper grid body and each lower grid body in the housing define a plurality of periodic structures, which are generally presented in the form of simulation.

[0079] This embodiment provides a slow-wave structure, in the height direction of the slow-wave structure, the upper grid body 21 and the lower grid body 22 have different heights, and an electron injection channel 24 is formed between the bottom surface of the upper grid body 21 and the top surface of the lower grid body 22. Specifically, it is defined that the height of the upper grid body 21 refers to the height in the height direction of the slow-wave structure, represented by h1, the height of the lower grid body 22 refers to the height in the height direction of the slow-wave structure, represented by h2, and the slow-wave structure inner cavity height is represented by H.

[0080] In this embodiment, in the height direction of the slow-wave structure, the height of the upper grid body 21 is 1 / 2 of the height H of the inner cavity of the slow-wave structure, and the height of the lower grid body 22 is 1 / 2 of the height of the upper grid body.

[0081] To further illustrate, the slow-wave structure includes a grating 23 extending from the top surface of the lower grating body 22 toward the top wall of the shell, and the top surface of the grating 23 is located in the same plane as the bottom surface of the upper grating body 21. In this embodiment, the bottom surface of the upper grating body 21 and the top surface of the lower grating body 22 are both planes, and the top surface of the grating 23 is also designed to be plane.

[0082] The working mode of the slow wave structure provided in this embodiment is high-order TE 20 mode, the TE 20 The number of the grille 23 in the slow-wave structure of the mode is one, and the electron injection channel 24 includes two channels constituting the electron injection channel 24 formed between the side wall of one side of the shell 20 and the grille 23 and between the side wall of the other side of the shell 20 and the grille 23 and arranged side by side in the width direction of the slow-wave structure. This working mode is high-order TE 20The slow-wave structure of the mode has two electron injection channels 24. Preferably, the two electron injection channels 24 have the same width in the width direction of the slow-wave structure.

[0083] According to TE 20 The characteristics of the electric field distribution of the slow-wave structure in the mode, the upper part of the electron injection channel 24 is in TE 20 In the working mode, the electric field energy is high, and the lower part is in TE 20 In the working mode, the electric field energy is low and the return wave electric field energy is high, which can easily cause return wave oscillation. In the specific implementation, this embodiment provides a working mode of high-order TE 20 The electron injection channel 24 of the slow-wave structure of the mode includes: an electron injection channel injection area located in the upper half of the electron injection channel 24, and an electron injection channel non-injection area located in the lower half of the electron injection channel. The channel height of the electron injection channel injection area is 1 / 2 of the overall height of the electron injection channel 24. Therefore, in practical applications, half of the channel, that is, the upper half of the electron injection channel, is selected as the injection area of ​​the electron injection channel.

[0084] Comparative Example 2:

[0085] Figure 9a and Figure 9b are the traditional existing TE obtained by CST eigenmode solver. 20 Electric field energy distribution diagram of the mode staggered grating slow-wave structure, where Figure 9a For TE 20 Mode forward wave, Figure 9b For TE 20 Mode return wave.

[0086] Fig.10a and Fig.10b The present invention provides TE respectively obtained by CST eigenmode solver 20 Electric field energy distribution diagram of the mode slow-wave structure, where Fig.10a TE of the present invention 20 Mode slow wave structure forward wave, where Figure 9b TE of the present invention 20 Mode slow wave structure return wave.

[0087] By comparison, it can be seen from the figure that compared with the traditional existing TE 20 Mode staggered grating slow wave structure, the present invention provides TE 20 The low-order mode forward wave and backward wave electric field energy of the mode slow-wave structure is greatly reduced, and the electric field energy distribution range in the center area of ​​the mode is greatly reduced, which effectively suppresses the low-order mode backward wave oscillation, and the interaction between the electron beam and the electromagnetic wave is more stable.

[0088] According to one aspect of the present invention, based on the present invention provided above, the TE 20The present invention also provides a slow wave structure of the TE mode. 20 The slow wave circuit of the mode slow wave structure, specifically, the slow wave circuit includes a slow wave structure input section, a slow wave structure output section and a cut-off structure connecting the slow wave structure input section and the slow wave structure output section. The slow wave structure input section includes the TE 20 Mode slow-wave structure, and / or the slow-wave structure output section includes the TE 20 Mode slow wave structure.

[0089] In this embodiment, further, the cut-off structure includes a first cavity near the input section of the slow-wave structure and a second cavity near the output section of the slow-wave structure. The first cavity includes a first grid, and the second cavity includes a second grid. The number of the first grid and the number of the second grid are respectively the same as those of the TE 20 The number of gratings in the slow-wave structure of the mode is equal, and in the axial direction of the slow-wave structure, the projection boundary of the first grating, the projection boundary of the second grating and the projection boundary of the grating coincide. Regarding the cut-off structure and in the axial direction of the slow-wave structure, the projection boundary of the first grating, the projection boundary of the second grating and the projection boundary of the grating coincide, please refer to the following including TE 30 Structural diagram of the slow-wave circuit of the mode slow-wave structure.

[0090] Example three,

[0091] A method for TE comprising a slow wave structure provided by the present invention 30 Mode slow wave structure, in one embodiment, the present invention also provides a TE 30 The slow-wave structure of the mode, ref. Fig.11 , Fig.12 As shown, the slow-wave structure includes a housing 30, an upper grid body 31 extending from the top wall of the housing 30 to the bottom wall of the housing, and a lower grid body 32 extending from the bottom wall of the housing 30 to the top wall of the housing, and a plurality of upper grid bodies 31 and a plurality of lower grid bodies 32 are staggered with each other, and each upper grid body 31 and each lower grid body 32 define a vacuum cavity with a plurality of periodic structures. As known in the art, the vacuum cavity of the slow-wave structure described in the present invention generally refers to the housing and each upper grid body and each lower grid body in the housing define a plurality of periodic structures, which are generally presented in the form of simulation.

[0092] This embodiment provides a slow-wave structure, in the height direction of the slow-wave structure, the upper grid body 31 and the lower grid body 32 have different heights, and an electron injection channel 33 is formed between the bottom surface of the upper grid body 31 and the top surface of the lower grid body 32. Specifically, it is defined that the height of the upper grid body 31 refers to the height in the height direction of the slow-wave structure, represented by h1, the height of the lower grid body 32 refers to the height in the height direction of the slow-wave structure, represented by h2, and the slow-wave structure inner cavity height is represented by H.

[0093] In this embodiment, in the height direction of the slow-wave structure, the height h1 of the upper grid body 31 is 1 / 2 of the height H of the inner cavity of the slow-wave structure, and the height h2 of the lower grid body 32 is 1 / 2 of the height h1 of the upper grid body. The slow-wave structure includes a grid 34 extending from the top surface of the lower grid body 32 toward the top wall of the shell 30, and the top surface of the grid 34 and the bottom surface of the upper grid body 31 are located in the same plane. In this embodiment, the bottom surface of the upper grid body 31 and the top surface of the lower grid body 32 are both planes, and the top surface of the grid 34 is also designed to be plane.

[0094] The working mode of the slow wave structure provided in this embodiment is high-order TE 30 mode, the TE 30 In the slow-wave structure of the mode, there are two grilles 34, and the electron injection channel 33 is composed of three channels constituting the electron injection channel, which are arranged side by side in the width direction of the slow-wave structure, between the side wall on one side of the shell and an adjacent grille, between two grilles, and between the side wall on the other side of the shell and another adjacent grille.

[0095] Further explanation: the working mode is high TE 30 The slow-wave structure of the mode has three electron injection channels 33 . Preferably, the three electron injection channels 33 have the same width in the width direction of the slow-wave structure.

[0096] According to the structure TE 30 The characteristics of the electric field distribution of the mode, the upper part of the electron injection channel 33 is in TE 30 In the working mode, the electric field energy is high, and the lower part is in TE 30 In the working mode, the electric field energy is low and the return wave electric field energy is high, which can easily cause return wave oscillation. In the specific implementation, this embodiment provides a working mode of high-order TE 30 The electron injection channel 33 of the slow-wave structure of the mode includes: an electron injection channel injection area located in the upper half of the electron injection channel, and an electron injection channel non-injection area located in the lower half of the electron injection channel. The channel height of the electron injection channel injection area is 1 / 2 of the overall height of the electron injection channel. Therefore, in practical applications, half of the channel, that is, the upper half of the electron injection channel, is selected as the injection area of ​​the electron injection channel.

[0097] Comparative Example 3:

[0098] This embodiment of the present invention provides a TE 30 The slow-wave structure of the mode not only improves the lateral dimension a of the slow-wave structure, reducing the overall processing difficulty of the slow-wave structure, but also its cold test characteristics are similar to those of the traditional existing TE 30The slow-wave structure of the interleaved mode grid is different, which is mainly reflected in the fact that the electric field energy of the competition mode and the return wave is greatly reduced in the field distribution, the frequency-phase curve of each mode on the dispersion curve becomes more "dispersed", and the coupling impedance is improved as a whole and has a new characteristic. The specific manifestations are:

[0099] Fig.13 and Fig.14 are the traditional existing TE obtained by CST eigenmode solver. 30 Electric field energy distribution diagram of the mode staggered grating slow wave structure (TE 30 mode forward wave) and the present invention provides TE 30 Electric field energy distribution diagram of the mode slow-wave structure (TE 30 mode forward wave). By comparison, it can be seen from the figure that compared with the traditional existing TE 30 Mode staggered grating slow wave structure (reference Fig.13 As shown), the present invention provides TE 30 The low-order mode and return wave electric field energy of the mode slow-wave structure is greatly reduced, and the electric field energy distribution range in the center area of ​​the mode is greatly reduced (refer to Fig.14 As shown in the figure, the low-order mode return wave oscillation is effectively suppressed, the interaction between the electron beam and the electromagnetic wave is stable, and the technical effect of reducing the operating voltage and increasing the output power in the high-order mode is achieved.

[0100] Furthermore, the dispersion characteristics can characterize the basic information of the slow-wave structure, such as bandwidth, phase velocity, group velocity, and bandgap between modes. The operating mode and electron beam voltage of the traveling wave tube can be determined based on the dispersion characteristics, which is of great significance for the simulation of the slow-wave structure. Fig.15 and Fig.16 They are the traditional existing TE 30 Mode staggered grating slow wave structure dispersion curve and the present invention provides TE 30 The dispersion curve of the mode slow-wave structure, Fig.15 as well as Fig.16 The red curve in the middle represents TE 30 The dispersion curve of the mode slow-wave structure. Fig.15 and Fig.16 By comparison, it can be found that the present invention provides TE 30 Although the available bandwidth of the dispersion curve of the mode slow-wave structure has become narrower, the distribution of the dispersion curves between the modes has become more "dispersed" - there are fewer crossover points and no interference between them. Fig.16 As shown, this change brings two benefits:

[0101] First, the frequency of the low-order mode and its return wave is suppressed to a lower regional frequency band. 30The operating modes are separated by large distances, so that low-order modes can be completely eliminated by photonic crystal loading and other frequency-selective attenuation techniques.

[0102] Second, the intersection of the voltage line and the low-order mode is TE 30 The mode operating point is further away, refer to Fig.15 , Fig.16 As shown, the present invention provides TE 30 Mode slow wave structure and traditional existing TE 30 Compared with the mode-interleaved gate slow-wave structure, the coupling impedance at the intersection of the voltage lines is greatly reduced, reducing the possibility of mode competition and return wave oscillation.

[0103] In addition, from Fig.16 It can also be seen that the present invention provides TE 30 Mode slow wave structure, in working mode TE 30 In the modes below the TE mode, the dispersion curves of each working mode are "cut off" to varying degrees, such as 10 The mode is less affected and is almost the same as the conventional staggered gate, while the TE 20 The mode is significantly affected, and its dispersion curve produces a large bandgap, TE 30 The period of the mode and its higher-order modes is reduced to half of that of the traditional over-mode staggered-gate slow-wave structure, and brings about changes in the coupling impedance.

[0104] Furthermore, the present invention provides TE 30 The mode slow-wave structure is also superior to the traditional TE in terms of voltage, working point, and coupling impedance. 30 The mode staggered grating slow-wave structure has outstanding characteristics. Specifically, refer to Fig.17 As shown, the present invention provides TE 30 The coupling impedance of the mode slow-wave structure varies with the phase between 360° and 720°, as shown in Fig.17 The upper curve (black) in the figure shown represents TE 30 Modal dispersion curves, the lower curve (blue) represents TE 30 Mode coupling impedance changes with phase (operating point). Fig.17 It can be seen that in the first half (360°-450°) of the phase interval, the present invention provides TE 30 The variation law of the coupling impedance of the mode slow-wave structure conforms to the common coupling impedance of the forward wave, which decreases rapidly and then stabilizes. However, in the second half (450°-540°) phase range, the coupling impedance first increases slowly and then increases sharply when approaching the 540° phase. 30 mode has a high coupling impedance in the working area, which will give TE 30The forward wave of the mode brings great advantages in mode competition and is more conducive to suppressing low-order mode competition and return wave oscillation. In addition, unlike the traditional existing TE 30 Mode staggered grating slow wave structure, the present invention provides TE 30 The coupling resistance of the mode slow-wave structure shows an upward trend between the phases of 450°-540°. Working in this phase range can greatly reduce the normalized phase velocity, thereby greatly reducing the matching voltage. This solves the problem that high-gain over-mode traveling wave tubes often require high operating voltage when the coupling impedance increases instead of decreases.

[0105] In other words, the traditional existing TE 30 The coupling impedance of the interlaced gate slow wave structure is suppressed and decreased in the first half (360°-450°) of the phase interval. If you want to reduce the working voltage, you need to work in the later phase. However, although the work can be reduced at this time, the coupling impedance is also low, which does not meet the working requirements. 30 The operating point of the mode slow-wave structure can be further back in the phase interval (450°-540°). The slow-wave structure provided by the present invention has high coupling impedance in this phase interval, achieves high output power under low operating voltage, and has a stable working state.

[0106] According to one aspect of the present invention, based on the present invention provided above, the TE 30 The present invention also provides a slow wave structure of the TE mode. 30 The slow wave circuit of the mode slow wave structure, specifically, combined with Fig.18 As shown, the slow wave circuit includes a slow wave structure input section 35, a slow wave structure output section 36, and a cut-off structure 37 connecting the slow wave structure input section 35 and the slow wave structure output section 36. The slow wave structure input section 35 includes the TE 30 mode slow-wave structure, and / or the slow-wave structure output section 36 includes the TE 30 Mode slow wave structure.

[0107] Combination Fig.19 As shown, in this embodiment, the cutting structure 37 includes a first cavity 371 near the slow-wave structure input section 35 and a second cavity 372 near the slow-wave structure output section 36. The first cavity 371 includes a first grid 3711, and the second cavity 372 includes a second grid 3721. In the axial direction of the slow-wave structure, the projection boundary of the first grid 3711, the projection boundary of the second grid 3721, and the projection boundary of the grating 34 coincide. The setting of the first grid and the second grid can cut off the TE 30 Low TE when working in mode 10 ,TE 20 mode, suppressing the backward oscillation.

[0108] In one embodiment, the TE of the present invention is included 30 The slow-wave circuit of the mode slow-wave structure is used for the simulation of the injection-wave interaction of the G-band strip injection traveling wave tube. The size parameters in the G-band are as follows:

[0109] a is the structural width on the cross section of the slow-wave structure, and the size of a is 2.28 mm.

[0110] p is the length of a single period of the slow-wave structure along the propagation direction, which is 0.6 mm.

[0111] t is the length of the single-sided grid along the propagation direction, that is, the length of the upper grid body, the lower grid body and the grid on the lower grid body along the propagation direction. The size of t is 0.12 mm.

[0112] The length dimension of the height h1 of the upper grid body is 0.65 mm.

[0113] The length dimension of the height dimension h2 of the lower grid body is 0.325 mm.

[0114] The length dimension of the height dimension h3 of the upper grid of the lower grid body is 0.325 mm.

[0115] d is the dimension of the channel in the width direction of the slow-wave structure, and the dimension of d is 0.7 mm.

[0116] w is the lateral width dimension of the grid-carrying slow-wave structure on the lower grid body in the width direction, and the dimension of w is 0.09 mm. On the cross section of the slow-wave structure, the width and height of the electron injection channel are 0.7 mm and 0.16 mm, respectively. Optionally, the widths of the multiple electron injection channels can be equal or unequal, in accordance with the electric field distribution in the traveling wave tube slow-wave structure.

[0117] The PIC simulation results show that under the working conditions of 26kV voltage and two 150mA strip injections, the 60-cycle length of the TE 30 The slow-wave circuit of the mode slow-wave structure can obtain a power output of 103.5W at 217GHz, with a gain of 19.6dB. The spectrum analysis results show that the operation is stable and no oscillation occurs. Fig. 20 As shown, the spectrum diagram of the output signal after Fourier transformation has a peak only in the frequency range of 217 GHz in the working mode.

[0118] A method for TE comprising a slow wave structure provided by the present invention 30 The above higher mode slow wave structures, specifically, are suitable for TE 30 In the above higher mode slow wave structure, the number of electron injection channels divided by the grating is equal to the number of electron injection channels required in this mode. 10The slow-wave structure in the working mode does not include the grating structure, which has an electron injection channel. 20 The slow-wave structure in the working mode includes a grating and two electron injection channels. 30 The slow-wave structure in the working mode includes two grids, three electron injection channels, and so on. The slow-wave structures in the above working modes all have the technical effect of suppressing low-order mode competition and return wave oscillation under the low working voltage of the present invention, realizing stable operation of high-order modes and large output power.

[0119] 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 a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection 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.

[0120] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0121] 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.

[0122] 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 slow-wave structure suitable for high-order modes, characterized in that: It comprises a shell, an upper grid body extending from the shell top wall to the shell bottom wall, and a lower grid body extending from the shell bottom wall to the shell top wall, wherein a plurality of upper grid bodies and a plurality of lower grid bodies are staggered and distributed with each other, and each upper grid body and each lower grid body define a plurality of vacuum cavities of periodic structure; In the height direction of the slow-wave structure, the upper grid body and the lower grid body have different heights; an electron injection channel is formed between the upper grid body and the lower grid body.

2. The slow-wave structure according to claim 1, characterized in that: The height of the upper grid body is 1 / 2 of the height of the slow-wave structure inner cavity, and the height of the lower grid body is 1 / 2 of the height of the upper grid body; The slow wave structure comprises two grids extending from the two ends of the top surface of the lower grid body toward the top wall of the shell, and the top surface of the grid and the bottom surface of the upper grid body are located in the same plane; a channel constituting an electron injection channel is formed between the two grids, and the working mode of the slow wave structure is TE 10 model.

3. The slow-wave structure according to claim 1, characterized in that: The slow-wave structure comprises a partition grid extending from the top surface of the lower grid body toward the top wall of the housing, and the top surface of the partition grid and the bottom surface of the upper grid body are located in the same plane; The height of the upper grid body is 1 / 2 of the height of the slow-wave structure inner cavity, and the height of the lower grid body is 1 / 2 of the height of the upper grid body.

4. The slow-wave structure according to claim 3, characterized in that: The number of the grid is one; two channels constituting the electron injection channel are arranged side by side on both sides of the grid, and the working mode of the slow wave structure is high-order TE 20 model.

5. The slow-wave structure according to claim 4, characterized in that: The slow-wave structure has two electron injection channels, and the two electron injection channels have the same width in the width direction of the slow-wave structure.

6. The slow-wave structure according to claim 3, characterized in that: The number of the grilles is two; three channels constituting electron injection channels are formed between the side wall of one side of the shell and an adjacent grille, between two grilles, and between the side wall of the other side of the shell and another adjacent grille. The working mode of the slow wave structure is high-order TE 30 model.

7. The slow-wave structure according to claim 6, characterized in that: The slow-wave structure has three electron injection channels, and the three electron injection channels have the same width in the width direction of the slow-wave structure.

8. The slow-wave structure according to any one of claims 1 to 7, characterized in that: The electron injection channels include: an electron injection channel injection region located in the upper half of the electron injection channel, and an electron injection channel non-injection region located in the lower half of the electron injection channel; The channel height of the electron injection channel injection zone is 1 / 2 of the overall height of the electron injection channel.

9. A slow wave circuit suitable for high-order modes, characterized in that: The slow wave circuit comprises a slow wave structure input section, a slow wave structure output section and a cut-off structure connecting the slow wave structure input section and the slow wave structure output section; The slow-wave structure input section includes the slow-wave structure as claimed in claim 1, and / or the slow-wave structure output section includes the slow-wave structure as claimed in claim 1.

10. A slow wave circuit suitable for high-order modes, characterized in that: The slow wave circuit comprises a slow wave structure input section, a slow wave structure output section and a cut-off structure connecting the slow wave structure input section and the slow wave structure output section; The slow-wave structure input section comprises the slow-wave structure according to any one of claims 2 to 7, and / or the slow-wave structure output section comprises the slow-wave structure according to any one of claims 2 to 7; The cut-off structure includes a first cavity close to the input section of the slow-wave structure and a second cavity close to the output section of the slow-wave structure; The first cavity includes a first grid, and the second cavity includes a second grid; In the axial direction of the slow-wave structure, the projection boundary of the first grid, the projection boundary of the second grid and the projection boundary of the grating coincide with each other.

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