A slow wave structure and slow wave circuit suitable for high order modes

Abstract

This invention discloses a slow-wave structure and circuit suitable for high-order modes, including a housing, an upper gate extending from the top wall to the bottom wall of the housing, and a lower gate extending from the bottom wall to the top wall of the housing. Multiple upper and lower gates are staggered, defining multiple periodic vacuum cavities. The upper and lower gates have different heights along the height direction of the slow-wave structure. An electron beam channel is formed between the upper and lower gates. This invention can suppress low-order mode competition and back-wave oscillations at low operating voltages, achieving stable operation in high-order modes and achieving high output power of 100W or more with low voltage.

Description

Technical Field

[0001] This invention relates to the field of microwave vacuum electronics technology. More specifically, it relates to a slow-wave structure and slow-wave circuit suitable for higher-order modes. Background Technology

[0002] As the operating frequency of traveling wave tubes (TWTs) gradually expands towards the terahertz band, the impact of the size co-entropy effect becomes increasingly apparent with the reduction in device size. The size co-entropy effect refers to the continuous reduction in the lateral dimension of the slow-wave structure and the width of the electron beam channel as the operating frequency of the TWT increases. On the one hand, this increases the difficulty of fabrication and reduces the operating current; on the other hand, the increase in frequency accelerates the decay rate of surface waves. These surface electromagnetic waves can only be maintained on the surface of the slow-wave structure and become very weak in the electron beam flow region, resulting in a weakening of the beam-wave interaction. This leads to a very low coupling impedance of the slow-wave structure, which in turn reduces the interaction efficiency and ultimately reduces the output power.

[0003] An overmode traveling wave tube (TWT) is an electrovacuum device that transmits electromagnetic waves using higher-order modes. It features high power and wide bandwidth, and is a special type of TWT that utilizes higher-order modes to achieve higher output power and a wider operating frequency band. The main characteristic of an overmode TWT is its ability to operate at high frequencies while maintaining high power capacity and low transmission loss, making it a promising candidate for applications in terahertz and millimeter-wave technologies.

[0004] Overmode traveling wave tubes operating in higher-order modes have larger lateral dimensions due to the characteristics of the field distribution in higher-order modes, and can adapt to high voltage and high current inputs, operating in higher-order mode TE. 30 Taking a traveling wave tube (TWT) as an example, its lateral dimension is approximately three times that of a fundamental mode TWT in the same frequency band. This effectively reduces the difficulty of the manufacturing process and allows for the passage of larger currents, effectively increasing output power and higher-order TE modes. 20 The same principle applies to over-mode traveling wave tubes.

[0005] While overmode traveling wave tubes (TWTs) offer larger lateral dimensions and can accommodate high-voltage, high-current inputs, they also introduce problems such as mode competition in the low-order forward wave and back-wave oscillations, thus limiting output power and gain. Currently, common techniques for suppressing these problems in high-order mode TWTs include dielectric loading, ridge / groove loading, and adding a rectangular metal pillar in the middle of the electron beam channel to completely isolate adjacent channels.

[0006] Based on existing research, current overmode traveling wave tubes can be broadly classified into two categories. One type, while suppressing low-order modes, also limits the output power of the operating mode. The other type has higher gain and output power, but its operating voltage is as high as 50kV or more, making it difficult to implement a matching electron gun and magnetic focusing system.

[0007] Current research shows that very few overmode traveling wave tubes operate in higher-order modes, and those that do employ the method of adding metal pillars to the electron beam channel. This method, while suppressing lower-order modes, destroys the characteristics of higher-order modes, making them more similar to side-by-side multi-beam fundamental mode traveling wave tubes. Therefore, a novel slow-wave structure more suitable for higher-order mode operation is needed. Summary of the Invention

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

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

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] According to one aspect of the present invention, the present invention provides a slow wave structure suitable for higher-order modes, comprising a housing, an upper grating extending from the top wall of the housing to the bottom wall of the housing, and a lower grating extending from the bottom wall of the housing to the top wall of the housing, wherein a plurality of upper gratings and a plurality of lower gratings are staggered with each other, and each upper grating and each lower grating defines a vacuum cavity forming a plurality of periodic structures.

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

[0013] Furthermore, in a preferred embodiment, the height of the upper grating body is half the height of the slow-wave structure's inner cavity, and the height of the lower grating body is half the height of the upper grating body; the slow-wave structure includes two gratings extending from both ends of the lower grating body's top surface toward the top wall of the housing, the top surface of the gratings and the bottom surface of the upper grating body being in the same plane; a channel constituting an electron beam channel is formed between the two gratings, and the operating mode of the slow-wave structure is TE. 10 model.

[0014] Furthermore, in a preferred embodiment, the slow-wave structure includes a grid extending from the top surface of the lower grid body towards the top wall of the housing, wherein the top surface of the grid body and the bottom surface of the upper grid body are located in the same plane;

[0015] The height of the upper grating is half the height of the slow-wave structure cavity, and the height of the lower grating is half the height of the upper grating.

[0016] Furthermore, in a preferred embodiment, the number of septa is one; two channels forming an electron beam channel are arranged side-by-side on both sides of the septa, and the operating mode of the slow-wave structure is a high-order TE.20 model.

[0017] Furthermore, a preferred embodiment is that the slow-wave structure has two electron beam channels, and the two electron beam channels have the same width in the width direction of the slow-wave structure.

[0018] Furthermore, in a preferred embodiment, the number of grates is two; three channels constituting the electron beam channel are formed side-by-side between one sidewall of the housing and an adjacent grates, between two grates, and between the other sidewall of the housing and another adjacent grates. The operating mode of the slow-wave structure is a high-order TE. 30 model.

[0019] Furthermore, a preferred embodiment is that the slow-wave structure has three electron beam channels, and the three electron beam channels have the same width in the width direction of the slow-wave structure.

[0020] Furthermore, a preferred embodiment is that the electron injection channel includes:

[0021] The electron injection channel injection area located in the upper half of the electron injection channel, and

[0022] The non-injection zone of the electron injection channel is located in the lower half of the electron injection channel;

[0023] The channel height of the injection zone of the electron injection channel 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 including a slow-wave structure input segment, a slow-wave structure output segment, and a cut-off structure connecting the slow-wave structure input segment and the slow-wave structure output segment;

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

[0026] The present invention also provides a slow-wave circuit suitable for high-order modes, the slow-wave circuit including 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 segment includes the slow wave structure as described above, and / or the slow wave structure output segment includes the slow wave structure as described above;

[0028] The cutting 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.

[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 projected boundaries of the first grid, the second grid, and the grating coincide.

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

[0032] The stable operation of a high-mode traveling wave tube relies on suppressing back-wave oscillations and mode competition in low-order modes. One approach is to reduce the coupling impedance at the intersection of the electron beam voltage line and the low-order mode. Another approach is to cut off the electric field of the low-order mode at locations where the electric field intensity is high. This invention provides a slow-wave structure that combines these two methods, enabling the suppression of low-order mode competition and back-wave oscillations at low operating voltages, while achieving stable operation in high-order modes. This allows for high output power of 100W and above with low voltage. The technical advantages of this invention compared to existing technologies will be described in detail in the specific embodiments of this invention. Attached Figure Description

[0033] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0034] Figure 1 This illustrates a conventional TE with metal pillars. 30 Slow wave structure in mode.

[0035] Figure 2 The dispersion curves of conventional high-order modes with metal column slow-wave structures are shown.

[0036] Figure 3 This illustrates an embodiment of the invention suitable for TE 10 One of the schematic diagrams of the slow-wave structure of the mode.

[0037] Figure 4 This illustrates an embodiment of the invention suitable for TE 10 The second schematic diagram of the slow-wave structure of the mode.

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

[0039] Figure 5b Showing the traditional existing TE 10 Energy distribution diagram of the electric field of the returned wave in the slow-wave structure with interleaved grid.

[0040] Figure 6a This illustrates an embodiment of the invention suitable for TE 10 Energy distribution of forward wave electric field in the slow-wave structure of the model.

[0041] Figure 6b This illustrates an embodiment of the invention suitable for TE 10Energy distribution of the returned electric field in the slow-wave structure of the model.

[0042] Figure 7 This illustrates another embodiment of the invention suitable for TE 20 One of the schematic diagrams of the slow-wave structure of the mode.

[0043] Figure 8 This illustrates another embodiment of the invention suitable for TE 20 The second schematic diagram of the slow-wave structure of the mode.

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

[0045] Figure 9b Showing the traditional existing TE 20 Energy distribution diagram of the electric field of the returned wave in the slow-wave structure with interleaved grid.

[0046] Figure 10a This illustrates another embodiment of the invention suitable for TE 20 Energy distribution of forward wave electric field in the slow-wave structure of the model.

[0047] Figure 10b This illustrates another embodiment of the invention suitable for TE 20 Energy distribution of the returned electric field in the slow-wave structure of the model.

[0048] Figure 11 This illustrates another embodiment of the invention suitable for TE 30 One of the schematic diagrams of the slow-wave structure of the mode.

[0049] Figure 12 This illustrates another embodiment of the invention suitable for TE 30 The second schematic diagram of the slow-wave structure of the mode.

[0050] Figure 13 Showing the traditional existing TE 30 Energy distribution of forward wave electric field in a mode-interlaced grating slow-wave structure.

[0051] Figure 14 This illustrates another embodiment of the invention suitable for TE 30 Energy distribution of forward wave electric field in the slow-wave structure of the model.

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

[0053] Figure 16 This illustrates another embodiment of the invention suitable for TE 30Dispersion curves of the slow-wave structure of the mode.

[0054] Figure 17 This illustrates another embodiment of the invention suitable for TE 30 The coupling impedance of the slow-wave structure of the mode varies with phase between 360° and 720°.

[0055] Figure 18 Showing a type including Figure 11 , Figure 12 TE shown 30 Slow-wave circuits with a mode slow-wave structure.

[0056] Figure 19 Show Figure 18 The diagram shows the slow-wave circuit cutoff structure.

[0057] Figure 20 This illustrates another embodiment of the invention suitable for TE 30 The spectrum of the output signal after Fourier transform of the slow-wave structure of the mode. Detailed Implementation

[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, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

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

[0060] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

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

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

[0063] Existing slow-wave structures for overmode traveling wave tubes (TWTs) fall into three categories. One type, while suppressing lower-order modes, also limits the output power of the operating mode; the saturated output power of this type of slow-wave structure does not exceed 100W. Although it maintains the integrity of higher-order modes, the output power does not meet current requirements. Another type offers higher gain and output power, but because it operates near a 360° phase angle, its operating voltage is as high as 50kV or more, making it difficult to implement a matching electron gun and magnetic focusing system.

[0064] The third method involves adding a metal pillar 100 in the middle of the electron beam channel to completely isolate adjacent channels. This method is widely used in the study of slow-wave structures of interleaved grids and sinusoidal waveguides, referring to... Figure 1 The structure shown is... Figure 1 The image shows a conventional TE with a metal column 100. 30 Slow-wave structure in the mode. From the dispersion curve, reference... Figure 2 As shown, it can be seen that the dispersion curves of the higher-order modes in 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 curves. From a physical structure perspective, adjacent electron beam channels in this structure are completely isolated, with rectangular metal pillars running through the entire interaction circuit. Higher-order modes are completely cut off at the electron beam channels, and the electric field distribution of higher-order modes can only be maintained in the slots. This type of slow-wave structure is more similar to a side-by-side fundamental mode multi-beam traveling wave tube. It lacks the mode-passing characteristic of the slow-wave structure of a passing-mode traveling wave tube, where the dispersion curve spacing between modes increases exponentially. Furthermore, it loses the size advantage of a passing-mode traveling wave tube and faces high manufacturing difficulty.

[0065] This invention aims to improve upon the traditional interleaved dual-gate slow-wave structure from the perspective of the structure itself, providing a novel slow-wave structure suitable for high-order mode propagation and a slow-wave circuit including a covered slow-wave structure.

[0066] It should be noted that the slow-wave structure of higher-order modes is divided into TE according to the different higher-order operating modes. 10 Mode slow wave structure, TE 20 Mode slow wave structure, TE 30 Mode slow-wave structure, and TE 30 Based on the invention's objective, the specific embodiments of this invention will be described from several different operating modes of slow-wave structures, according to the different operating modes.

[0067] Example 1,

[0068] A method suitable for TE, including the slow-wave structure provided by the present invention. 10In this embodiment, the present invention first provides a mode slow wave structure suitable for TE 10 The slow-wave structure of the mode, also known as the fundamental mode slow-wave structure, is referenced. Figure 3 , Figure 4 As shown, the slow-wave structure includes a housing 10, an upper grid body 11 extending from the top wall of the housing 10 to the bottom wall of the housing 10, and a lower grid body 12 extending from the bottom wall of the housing 10 to the top wall of the housing 10. Multiple upper grid bodies 11 and multiple lower grid bodies 12 are staggered, and each upper grid body 11 and each lower grid body 12 defines a vacuum cavity with multiple periodic structures. As is known in the art, the vacuum cavity of the slow-wave structure in this invention generally refers to the housing 10 and the multiple periodic structures defined by each upper grid body 11 and each lower grid body 12 within the housing 10, which is usually presented in a simulation form. 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, the height of the upper grid body 11 is defined as its height in the slow-wave structure height direction, denoted by h1; the height of the lower grid body 12 is defined as its height in the slow-wave structure height direction, denoted by h2; and the height of the inner cavity of the slow-wave structure is denoted by H. This embodiment provides a slow-wave structure. In the height direction of the slow-wave structure, the upper grating 11 and the lower grating 12 have different heights. The height h1 of the upper grating 11 is half of the height H of the inner cavity of the slow-wave structure, and the height h2 of the lower grating 12 is half of the height h1 of the upper grating. An electron beam channel 13 is formed between the upper grating 11 and the lower grating 12.

[0069] Furthermore, this embodiment provides a slow-wave structure including two gratings 14 extending from both ends of the top surface of the lower grating body 12 toward the top wall of the housing 10, the top surface of the gratings 14 and the bottom surface of the upper grating body 11 being located in the same plane; a channel forming an electron beam channel 13 in the width direction of the slow-wave structure is formed between the two gratings 14.

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

[0071] Comparative Example 1,

[0072] Figure 5a and Figure 5b The traditional existing TE obtained by the CST eigenmode solver is respectively 10 Electric field energy distribution diagram of the mode-interlaced grating slow-wave structure, in which Figure 5a For TE 10 Mode forward wave, Figure 5b For TE 10 Pattern return wave.

[0073] Figure 6a and Figure 6b The present invention provides TEs obtained by the CST intrinsic mode solver. 10 The electric field energy distribution diagram of the slow-wave structure of the mode, where Figure 6a For the present invention TE 10 The mode slow-wave structure forward wave, in which Figure 6b For the present invention TE 10 Mode slow wave structure reflected wave.

[0074] The comparison shown in the figure reveals that, compared to the traditional existing TE... 10 The present invention provides a TE interleaved grating slow wave structure. 10 The electric field energy of the forward and backward waves of the low-order modes in the slow-wave structure is greatly reduced, and the range of electric field energy distribution in the central region of the mode is greatly reduced, effectively suppressing the backward wave oscillation of the low-order modes, and making the interaction between the electron beam and the electromagnetic wave more stable.

[0075] According to one aspect of the invention, based on the invention as provided above, applicable to TE 10 The present invention also provides a slow-wave structure of the mode, including the TE as described above. 10 A slow-wave circuit with a mode-based slow-wave structure, specifically, includes a slow-wave structure input section, a slow-wave structure output section, and a disconnection structure connecting the input section and the output section. In this slow-wave circuit structure, the slow-wave structure input section and / or the slow-wave structure output section include features as described above suitable for TE. 10 The slow-wave structure of the pattern.

[0076] In this embodiment, the cutting structure further 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 first grids and the number of second grids are respectively related to the number of grids applicable to TE. 10 The number of gratings within the slow-wave structure of the pattern is equal, and they coincide with the projected boundaries of the first grating, the second grating, and the gratings in the axial direction of the slow-wave structure. Regarding the coincidence of the cut-off structure and the projected boundaries of the first grating, the second grating, and the gratings in the axial direction of the slow-wave structure, the following can be referenced, including TE.30 A schematic diagram of the slow-wave circuit with a mode slow-wave structure.

[0077] Example 2,

[0078] A method suitable for TE, including the slow-wave structure provided by the present invention. 20 In this embodiment, the present invention further provides a mode slow-wave structure suitable for TE 20 Slow-wave structure of the mode, reference 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 towards the bottom wall of the housing, and a lower grid body 22 extending from the bottom wall of the housing towards the top wall of the housing. Multiple upper grid bodies 21 and multiple lower grid bodies 22 are staggered and distributed, with each upper grid body 21 and each lower grid body 22 defining a vacuum cavity with multiple periodic structures. As is known in the art, the vacuum cavity of the slow-wave structure in this invention typically refers to the housing and the multiple periodic structures defined by each upper grid body and each lower grid body within the housing, which is usually presented in a simulation form.

[0079] This embodiment provides a slow-wave structure in which the upper gate 21 and the lower gate 22 have different heights in the height direction of the slow-wave structure, and an electron beam channel 24 is formed between the bottom surface of the upper gate 21 and the top surface of the lower gate 22. Specifically, the height of the upper gate 21 is defined as its height in the height direction of the slow-wave structure, denoted by h1, the height of the lower gate 22 is defined as its height in the height direction of the slow-wave structure, denoted by h2, and the height of the inner cavity of the slow-wave structure is denoted by H.

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

[0081] To further illustrate, the slow-wave structure includes a grid 23 extending from the top of the lower grid body 22 toward the top wall of the housing, wherein the top surface of the grid 23 and the bottom surface of the upper grid body 21 are located in the same plane. In this embodiment, the bottom surface of the upper grid body 21 and the top surface of the lower grid body 22 are both planar, and the top surface of the grid 23 is also planar.

[0082] The slow-wave structure provided in this embodiment operates in a higher-order TE mode. 20 The TE pattern 20 In the slow-wave structure of the mode, there is one septum 23. The electron beam channel 24 is composed of two channels forming the electron beam channel 24, arranged side-by-side in the width direction of the slow-wave structure, formed between one sidewall of the housing 20 and the septum 23, and between the other sidewall of the housing 20 and the septum 23. This operating mode is a high-order TE. 20The slow-wave structure of the mode has two electron beam channels 24. Preferably, the two electron beam 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 half of electron beam channel 24 in TE 20 The electric field energy is relatively high in the operating mode, and the lower part is in TE 20 In the operating mode, the electric field energy is low and the returned electric field energy is high, which can easily cause returned wave oscillations. In specific implementation, this embodiment provides an operating mode of higher order TE. 20 The electron beam channel 24 of the slow wave structure includes an electron beam channel injection region located in the upper half of the electron beam channel 24 and an electron beam channel non-injection region located in the lower half of the electron beam channel. The channel height of the electron beam channel injection region is 1 / 2 of the overall height of the electron beam channel 24. Therefore, in practical applications, half of the channel, that is, the upper half of the electron beam channel, is selected as the injection region of the electron beam channel.

[0084] Comparative Example 2,

[0085] Figure 9a and Figure 9b The traditional existing TE obtained by the CST eigenmode solver is respectively 20 Electric field energy distribution diagram of the mode-interlaced grating slow-wave structure, in which Figure 9a For TE 20 Mode forward wave, Figure 9b For TE 20 Pattern return wave.

[0086] Figure 10a and Figure 10b The present invention provides TEs obtained by the CST intrinsic mode solver. 20 The electric field energy distribution diagram of the slow-wave structure of the mode, where Figure 10a For the present invention TE 20 The mode slow-wave structure forward wave, in which Figure 9b For the present invention TE 20 Mode slow wave structure reflected wave.

[0087] The comparison shown in the figure reveals that, compared to the traditional existing TE... 20 The present invention provides a TE interleaved grating slow wave structure. 20 The electric field energy of the forward and backward waves of the low-order modes in the slow-wave structure is greatly reduced, and the range of electric field energy distribution in the central region of the mode is greatly reduced, effectively suppressing the backward wave oscillation of the low-order modes, and making the interaction between the electron beam and the electromagnetic wave more stable.

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

[0089] In this embodiment, the cutting structure further 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 first grids and the number of second grids are respectively related to the number of grids applicable to TE. 20 The number of gratings within the slow-wave structure of the pattern is equal, and the projected boundaries of the first grating, the second grating, and the grating coincide in the axial direction of the slow-wave structure. Regarding the cut-off structure and the coincidence of the projected boundaries of the first grating, the second grating, and the grating in the axial direction of the slow-wave structure, the following can be referenced, including TE. 30 A schematic diagram of the slow-wave circuit with a mode slow-wave structure.

[0090] Example 3,

[0091] A method suitable for TE, including the slow-wave structure provided by the present invention. 30 In one embodiment, the present invention also provides a mode slow-wave structure suitable for TE. 30 Slow-wave structure of the mode, reference Figure 11 , Figure 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 towards the bottom wall of the housing 30, and a lower grid body 32 extending from the bottom wall of the housing 30 towards the top wall of the housing 30. Multiple upper grid bodies 31 and multiple lower grid bodies 32 are staggered and distributed, and each upper grid body 31 and each lower grid body 32 defines a vacuum cavity with multiple periodic structures. As is known in the art, the vacuum cavity of the slow-wave structure described in this invention generally refers to the housing and the multiple periodic structures defined by each upper grid body and each lower grid body within the housing, which is usually presented in a simulation form.

[0092] This embodiment provides a slow-wave structure in which the upper gate body 31 and the lower gate body 32 have different heights in the height direction of the slow-wave structure, and an electron beam channel 33 is formed between the bottom surface of the upper gate body 31 and the top surface of the lower gate body 32. Specifically, the height of the upper gate body 31 is defined as its height in the height direction of the slow-wave structure, denoted by h1, the height of the lower gate body 32 is defined as its height in the height direction of the slow-wave structure, denoted by h2, and the height of the inner cavity of the slow-wave structure is denoted by H.

[0093] In this embodiment, in the height direction of the slow-wave structure, the height h1 of the upper gate body 31 is half the height H of the inner cavity of the slow-wave structure, and the height h2 of the lower gate body 32 is half the height h1 of the upper gate body. The slow-wave structure includes a grid 34 extending from the top of the lower gate body 32 towards the top wall of the housing 30, and the top surface of the grid 34 and the bottom surface of the upper gate body 31 are located in the same plane. In this embodiment, the bottom surface of the upper gate body 31 and the top surface of the lower gate body 32 are both planar, and the top surface of the grid 34 is also planar.

[0094] The slow-wave structure provided in this embodiment operates in a higher-order TE mode. 30 The TE pattern 30 In the slow-wave structure of the mode, there are two gratings 34. The electron beam channel 33 is composed of three channels arranged side by side in the width direction of the slow-wave structure, which constitute the electron beam channel, between one side wall of the housing and an adjacent grating, between two gratings, and between the other side wall of the housing and another adjacent grating.

[0095] To further explain, this working mode is a high-order TE. 30 The slow-wave structure of the mode has three electron beam channels 33, preferably, the three electron beam 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 in the mode, the upper half of electron beam channel 33 in TE 30 The electric field energy is relatively high in the operating mode, and the lower part is in TE 30 In the operating mode, the electric field energy is low and the returned electric field energy is high, which can easily cause returned wave oscillations. In specific implementation, this embodiment provides an operating mode of higher order TE. 30 The electron beam channel 33 of the slow wave structure includes an electron beam channel injection region located in the upper half of the electron beam channel and an electron beam channel non-injection region located in the lower half of the electron beam channel. The channel height of the electron beam channel injection region is 1 / 2 of the overall height of the electron beam channel. Therefore, in practical applications, half of the channel, i.e., the upper half of the electron beam channel, is selected as the injection region of the electron beam channel.

[0097] Comparative Example 3,

[0098] This embodiment of the invention provides a solution applicable to TE 30 The proposed slow-wave structure not only improves upon the lateral dimension 'a' of the slow-wave structure, reducing the overall fabrication difficulty, but also exhibits cold-testing characteristics comparable to traditional TE systems. 30The interleaved-mode grating slow-wave structure differs from the conventional one, primarily in the field distribution, where the electric field energy of competing modes and the reflected wave is significantly reduced. The frequency-phase curves of each mode on the dispersion curve become more "dispersed," and the overall coupling impedance is improved, exhibiting a new characteristic. Specifically:

[0099] Figure 13 and Figure 14 The traditional existing TE obtained by the CST eigenmode solver is respectively 30 Electric field energy distribution diagram of the mode-interlaced gate slow-wave structure (TE) 30 (Mode forward wave) and the TE provided by this invention 30 Electric field energy distribution diagram of the slow-wave structure in the mode (TE) 30 (Mode forward wave). A comparison of the graphs shows that, compared to traditional existing TE... 30 Mode-interleaved grating slow-wave structure (reference) Figure 13 As shown), the present invention provides TE 30 The low-order modes and returned electric field energies of the slow-wave structure are significantly reduced, and the range of electric field energy distribution in the central region of the mode is greatly reduced (reference). Figure 14 As shown in the figure, it effectively suppresses low-order mode back-wave oscillations, stabilizes the interaction between electron beam and electromagnetic wave, and achieves the technical effect of reducing operating voltage and increasing output power in high-order modes.

[0100] Furthermore, dispersion characteristics can characterize basic information such as bandwidth, phase velocity, group velocity, and bandgap between modes of slow-wave structures. Based on dispersion characteristics, the operating mode and electron beam voltage of a traveling wave tube can be determined, which is of great significance for the simulation of slow-wave structures. Figure 15 and Figure 16 They are respectively traditional existing TE 30 Dispersion curves of the slow-wave structure with interleaved mode gratings and the TE provided by this invention 30 The dispersion curve of the slow-wave structure of the mode, Figure 15 as well as Figure 16 The red curve in the middle represents TE. 30 Dispersion curves of the slow-wave structure of the mode. (Through...) Figure 15 and Figure 16 By comparison, it can be found that the present invention provides TE 30 Although the usable bandwidth of the dispersion curves in the slow-wave structure of the modes is narrower, the distribution of dispersion curves between modes becomes more "dispersed"—fewer intersections and less interference between them. (Reference) Figure 16 As shown, this change brings two benefits:

[0101] First, the frequencies of lower-order modes and their echoes are compressed into even lower frequency bands. (The last sentence appears to be incomplete and possibly contains errors. It seems to be referring to a different topic: lower-order modes and TE...) 30There is a large distance between the operating modes, so the 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 lower-order mode is far from TE. 30 The operating point of the mode is further away, see reference. Figure 15 , Figure 16 As shown, the present invention provides TE 30 Mode slow wave structure and traditional existing TE 30 Compared to the interleaved-gate slow-wave structure, the coupling impedance at the voltage line intersection is greatly reduced, decreasing the possibility of mode competition and backwave oscillation.

[0103] In addition, from Figure 16 It can also be seen that the present invention provides TE 30 The slow-wave structure in the operating mode TE 30 In modes below the 0.5 mode, the dispersion curves of each operating mode are "cut off" to varying degrees, for example, TE. 10 The pattern is less affected, remaining almost identical to traditional interleaved gates, while TE 20 The mode is significantly affected, and its dispersion curve exhibits a large band gap, TE 30 The period of modes and higher orders is reduced to half that of traditional overmode interleaved grating slow wave structures, and this also brings about changes in coupling impedance.

[0104] Furthermore, the present invention provides TE 30 The mode-based slow-wave structure also offers advantages over traditional existing TE structures in terms of voltage, operating point, and coupling impedance. 30 The mode-interlaced grating slow-wave structure has outstanding characteristics, specifically, refer to Figure 17 As shown, the present invention provides TE 30 The coupling impedance of the slow-wave structure in the 360°-720° phase range as a function of phase is shown in the following curve: Figure 17 The upper curve (black) in the figure shown represents TE. 30 Mode dispersion curve, the lower curve (blue) represents TE. 30 The mode coupling impedance varies with phase (operating point). From Figure 17 As can be seen from the diagram, in the first half (360°-450°) phase range, the present invention provides TE 30 The coupling impedance variation of the slow-wave structure conforms to the common coupling impedance of forward waves, decreasing rapidly and then stabilizing. However, in the latter half of the phase range (450°-540°), the coupling impedance initially increases slowly, then increases sharply near the 540° phase. TE 30 The mode has a high coupling impedance in the operating region, which will give TE 30Forward wave propagation offers significant advantages in mode competition, effectively suppressing low-order mode competition and backwave oscillations. Furthermore, unlike traditional existing TE... 30 The present invention provides a TE interleaved grating slow wave structure. 30 The coupling resistance of the mode slow wave structure increases between 450° and 540° phase. Operating in this phase range can greatly reduce the normalized phase velocity, thereby greatly reducing the matching voltage. This solves the problem that high-gain overmode traveling wave tubes often require high operating voltages, even when the coupling impedance increases instead of decreasing.

[0105] In other words, the traditional existing TE 30 In the first half of the phase range (360°-450°) of the interleaved-gate slow-wave structure, the coupling impedance is suppressed and decreases. To reduce the operating voltage, it needs to operate in a later phase. However, although the operating voltage can be reduced in this later phase, the coupling impedance is also low, which does not meet the operating requirements. The TE provided by this invention... 30 The operating point of the slow-wave structure can be further back (450°-540°) in the phase range. The present invention provides a slow-wave structure with high coupling impedance in this phase range, achieving high output power at low operating voltage and having a stable operating state.

[0106] According to one aspect of the invention, based on the invention as provided above, applicable to TE 30 The present invention also provides a slow-wave structure of the mode, including the TE as described above. 30 Slow-wave circuits with modal slow-wave structures, specifically, combined with Figure 18 As shown, the slow-wave circuit includes a slow-wave structure input section 35, a slow-wave structure output section 36, and a cutoff 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 structure described above. 30 The mode slow wave structure, and / or the slow wave structure output segment 36 includes the TE as described above. 30 Mode slow wave structure.

[0107] Combination Figure 19 As shown, in this embodiment, the cutting-off 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 projected boundaries of the first grid 3711, the second grid 3721, and the grating 34 coincide. The arrangement of the first and second grids can cut off the TE... 30 Low-order TE during mode operation 10 TE 20 The electric field of the mode suppresses the backward oscillation.

[0108] In one specific embodiment, the present invention TE is included. 30 The slow-wave circuit with a mode-based slow-wave structure was used for beam-wave interaction simulation of a G-band strip-beam traveling-wave tube. The dimensional parameters in the G-band are as follows.

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

[0110] p represents the slow wave structure, with a single cycle length of 0.6 mm along the propagation direction.

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

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

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

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

[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 represents the lateral width of the slow-wave structure carried by the lower grid, which is 0.09 mm. In the cross-section of the slow-wave structure, the width and height of the electron beam channels are 0.7 mm and 0.16 mm, respectively. Optionally, the widths of the individual electron beam channels can be equal or unequal, depending on the electric field distribution within the traveling wave tube's slow-wave structure.

[0117] Simulation results from PIC show that, under operating conditions of 26kV voltage and two 150mA strip beams, the TE of this invention, with a cycle length of 60 cycles, achieves the desired performance. 30 The slow-wave circuit with a modal slow-wave structure achieves a power output of 103.5W at 217GHz with a gain of 19.6dB. Spectrum analysis results indicate stable operation without oscillation. (See attached reference.) Figure 20 As shown, the spectrum of the output signal after Fourier transform only has a peak at the frequency range of 217 GHz in the operating mode.

[0118] A method suitable for TE, including the slow-wave structure provided by the present invention. 30 The above higher-mode slow-wave structures, specifically, are applicable to TE 30 In the above higher-mode slow-wave structures, the number of electron beam channels divided by the grating corresponds to the number of electron beam channels required for that mode. In other words, in applications suitable for TE... 10The slow-wave structure in operating mode, excluding the septum structure, has one electron beam channel. (Applicable to TE) 20 The slow-wave structure in operating mode includes a septum and two electron beam channels. (Applicable to TE) 30 The slow-wave structure in the operating mode includes two septa and three electron beam channels, and so on. The slow-wave structures in each of the above operating modes have the technical effect of suppressing low-order mode competition and back-wave oscillation under low operating voltage, achieving stable operation of high-order modes, and high output power.

[0119] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0120] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0121] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in 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 intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A slow-wave structure suitable for higher-order modes, characterized in that, It includes a shell, an upper grid extending from the top wall of the shell to the bottom wall of the shell, and a lower grid extending from the bottom wall of the shell to the top wall of the shell. Multiple upper grids and multiple lower grids are distributed alternately, and each upper grid and each lower grid defines a vacuum cavity with multiple periodic structures. In the height direction of the slow-wave structure, the upper grating and the lower grating have different heights; an electron beam channel is formed between the upper grating and the lower grating; The slow-wave structure includes a grid extending from the top of the lower grid body towards the top wall of the housing, wherein the top surface of the grid body and the bottom surface of the upper grid body are located in the same plane; The height of the upper grating is half the height of the slow-wave structure cavity, and the height of the lower grating is half the height of the upper grating.

2. The slow-wave structure according to claim 1, characterized in that, The number of said gratings is two; two gratings extend from the top surface of the lower grating body to the top wall of the shell; a channel is formed between the two gratings to form an electron beam channel, and the working mode of the slow wave structure is TE 10 mode.

3. The slow-wave structure according to claim 1, characterized in that, The number of septa is one; two channels forming the electron beam channel are arranged side by side on both sides of the septa, and the operating mode of the slow wave structure is a high-order TE. 20 model.

4. The slow-wave structure according to claim 3, characterized in that, The slow-wave structure has two electron beam channels, and the two electron beam channels have the same width in the width direction of the slow-wave structure.

5. The slow-wave structure according to claim 1, characterized in that, The number of septa is two; three channels constituting the electron beam channel are formed side by side between one sidewall of the housing and an adjacent septa, between the two septa, and between the other sidewall of the housing and another adjacent septa. The operating mode of the slow-wave structure is a high-order TE. 30 model.

6. The slow-wave structure according to claim 5, characterized in that, The slow-wave structure has three electron beam channels, and the three electron beam channels have the same width in the width direction of the slow-wave structure.

7. The slow-wave structure according to any one of claims 1 to 6, characterized in that, The electronic injection channel includes: The electron injection channel injection area located in the upper half of the electron injection channel, and The non-injection zone of the electron injection channel is located in the lower half of the electron injection channel; The channel height of the injection zone of the electron injection channel is 1 / 2 of the overall height of the electron injection channel.

8. A slow-wave circuit suitable for higher-order modes, characterized in that, The slow-wave circuit includes a slow-wave structure input section, a slow-wave structure output section, and a disconnection structure connecting the slow-wave structure input section and the slow-wave structure output section. The slow-wave structure input segment includes the slow-wave structure as described in claim 1, and / or the slow-wave structure output segment includes the slow-wave structure as described in claim 1.

9. A slow-wave circuit suitable for higher-order modes, characterized in that, The slow-wave circuit includes a slow-wave structure input section, a slow-wave structure output section, and a disconnection structure connecting the slow-wave structure input section and the slow-wave structure output section. The slow wave structure input segment includes the slow wave structure as described in any one of claims 2 to 6, and / or the slow wave structure output segment includes the slow wave structure as described in any one of claims 2 to 6; The cutting 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. In the axial direction of the slow wave structure, the projected boundaries of the first grid, the second grid, and the grating coincide.

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