A slow-wave structure based on traveling standing waves

Abstract

The present invention belongs to the field of microwave vacuum electronics technology, and specifically provides a slow-wave structure based on traveling standing waves to achieve the design goals of high power, high gain and wide bandwidth of vacuum electronic devices. The present invention creatively adopts a traveling wave type slow-wave line of a rectangular folded slow-wave structure to replace the distributed multi-gap structure in the traditional extended interaction klystron, and obtains a new resonant cavity of upper coupling cavity / traveling wave type slow-wave line / lower coupling cavity, so that the new slow-wave structure can have both traveling wave characteristics and standing wave characteristics, and obtain stronger characteristic impedance and wider bandwidth; the new slow-wave structure is applied as a high-frequency structure in vacuum electronic devices, which can achieve the design goals of high power, high gain and wide bandwidth of vacuum electronic devices, and has the advantage of good cavity consistency. Compared with existing devices, it can effectively reduce the complexity of the cavity, greatly reduce the difficulty of magnetic field distribution design and device processing difficulty.

Description

Technical Field

[0001] The present invention belongs to the field of microwave vacuum electronics technology, and specifically provides a slow-wave structure based on traveling standing waves. Background Art

[0002] With the widespread application of terahertz technology in radar, satellite remote sensing, high-speed communications, detection imaging, and biomedicine, the demand for terahertz power sources is increasing. In the terahertz frequency band, compared with solid-state devices, vacuum electronic devices have the advantages of high power, wide bandwidth, and high stability. They have been proven to be important terahertz power sources and have very important research and application value.

[0003] Among numerous vacuum electronic devices, the extended interaction klystron (EIK) utilizes a multi-gap resonant cavity as its high-frequency structure, offering advantages such as high power, high gain, and miniaturization. Its operating mode is typically standing wave, but its bandwidth is narrower than that of a traveling wave tube (TWT). A TWT, on the other hand, uses a slow-wave line as the control structure for the electron beam and the energy exchange mechanism, allowing the electromagnetic field to propagate along the line in the form of traveling waves. This results in a wider bandwidth, but the gain is generally lower than that of the EIK. Chinese invention patent publication number CN110060911A discloses a broadband, high-gain slow-wave structure that combines a traditional standing-wave slow-wave structure with a traveling-wave slow-wave structure. The five-cavity EIK consists of a traveling-wave slow-wave structure as the input and output cavities, with a three-cavity resonant standing-wave structure as the intermediate cavity. The traveling-wave input and output cavities achieve a wider bandwidth, while the resonant standing-wave structure achieves high gain, thus achieving both broadband and high gain. Chinese invention patent publication number CN117747382A discloses an extended interaction klystron operating in a traveling standing wave mode. The structure employs a dual-cavity structure consisting of a traveling wave input cavity and a standing wave output cavity. The traveling wave input cavity is used to obtain a wider transmission bandwidth, while the standing wave output cavity is used to obtain a higher characteristic impedance and high output gain, enabling the extended interaction klystron to achieve higher power and a wider operating bandwidth.

[0004] In summary, the two invention patents achieve a composite extended interaction klystron with high power, high gain, and wide bandwidth by using a traveling-wave slow-wave structure as the input or output cavity and a resonant cavity standing-wave structure as the intermediate cluster cavity or output cavity. However, due to the structural differences between the traveling-wave slow-wave structure and the resonant cavity standing-wave structure, the entire klystron cavity structure is relatively complex, increasing the difficulty of magnetic field distribution design and device processing. Therefore, new vacuum electronic slow-wave structures and related devices that simultaneously possess traveling-wave characteristics and resonant cavity standing-wave characteristics remain an important research direction. Summary of the Invention

[0005] The purpose of the present invention is to provide a slow-wave structure based on traveling standing waves to achieve the design goals of high power, high gain, and wide bandwidth for vacuum electronic devices. Based on the high-frequency structure of the traditional extended interaction klystron, the present invention creatively proposes using a traveling-wave slow-wave line structure to replace the original distributed multi-gap structure, forming a new resonant cavity of upper coupling cavity / traveling-wave slow-wave line / lower coupling cavity. The addition of the traveling-wave slow-wave line enables the new slow-wave structure to have both traveling wave characteristics and standing wave characteristics, thereby obtaining a stronger characteristic impedance and a wider bandwidth. The new slow-wave structure of the present invention is applied as a high-frequency structure in vacuum electronic devices, which can achieve the design goals of high power, high gain, and wide bandwidth for vacuum electronic devices.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A slow-wave structure based on traveling standing waves comprises an upper coupling cavity, a traveling-wave slow-wave line, a lower coupling cavity and an electron injection channel. The traveling-wave slow-wave line is connected between the upper coupling cavity and the lower coupling cavity, forming a resonant cavity with two ends short-circuited. The electron injection channel vertically penetrates the traveling-wave slow-wave line and is located at the center of the traveling-wave slow-wave line along the cross section.

[0008] Furthermore, the upper coupling cavity and the lower coupling cavity have the same structure, and the cross-sectional shape is rectangular, circular or elliptical, preferably rectangular.

[0009] Furthermore, the traveling wave type slow wave line is a folded waveguide slow wave structure, an interlaced double-grating slow wave structure or a corrugated waveguide slow wave structure, preferably a rectangular folded waveguide slow wave structure.

[0010] Furthermore, the electron injection channel is a circular channel, an elliptical channel or a strip-shaped injection channel, preferably a strip-shaped injection channel.

[0011] Furthermore, the number of the electron injection channels is one, two or more.

[0012] Based on the above technical solution, the beneficial effects of the present invention are:

[0013] The present invention provides a novel slow-wave structure based on traveling standing waves. A traveling-wave slow-wave line structure is adopted to replace the distributed multi-gap structure in a conventional extended interaction klystron, thereby obtaining a novel resonant cavity of an upper coupled cavity / traveling-wave slow-wave line / lower coupled cavity. This enables the novel slow-wave structure to have both traveling-wave and standing-wave characteristics, thereby obtaining a stronger characteristic impedance and a wider bandwidth. The novel slow-wave structure is applied as a high-frequency structure in vacuum electronic devices, thereby achieving the design goals of high power, high gain, and wide bandwidth of the vacuum electronic devices, while having the advantage of good cavity consistency. Furthermore, compared with the existing composite extended interaction klystron, the present invention can effectively reduce the complexity of the cavity, greatly reducing the difficulty of magnetic field distribution design and device processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the vacuum model of the distributed multi-gap structure in the traditional extended interaction klystron.

[0015] Figure 2 Schematic diagram of the decomposition of the distributed multi-gap structure in the traditional extended interaction klystron.

[0016] Figure 3 Schematic diagram of the vacuum model of the slow-wave structure based on traveling standing waves in the present invention.

[0017] Figure 4 This is a schematic diagram of the decomposition of the slow-wave structure based on traveling standing waves in the present invention.

[0018] Figure 5 This is a dimensioned diagram of the slow-wave structure based on traveling standing waves in the present invention.

[0019] Figure 6 This is a simulation result diagram of the characteristic impedance R / Q of the slow-wave structure based on traveling standing wave in the present invention.

[0020] Figure 7 This is a simulation result diagram of the frequency interval between adjacent modes of the slow-wave structure based on traveling standing waves in the present invention.

[0021] Reference numerals: 1 is an upper rectangular coupled cavity, 2 is a rectangular folded waveguide slow-wave structure, 3 is a lower rectangular coupled cavity, 4 is a strip-shaped electron injection channel, and 5 is a distributed rectangular gap waveguide. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and beneficial effects of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0023] The distributed multi-gap high frequency structure in the traditional extended interaction klystron is as follows Figure 1 and Figure 2 As shown, Figure 1 From left to right in the figure are the main view, side view and three-dimensional structure diagram. Figure 2Schematic diagram of decomposition; specifically, it includes: an upper rectangular coupling cavity 1, a lower rectangular coupling cavity 3, a strip electron injection channel 4 and a distributed rectangular gap waveguide 5. Multiple distributed rectangular gap waveguides are arranged side by side between the upper rectangular coupling cavity and the lower rectangular coupling cavity. The distributed rectangular gap waveguide is arranged along the xoy plane. The strip electron injection channel penetrates the distributed rectangular gap waveguide along the vertical direction (z-axis) of the cross section (xoy plane), and the strip electron injection channel is located at the center of the distributed rectangular gap waveguide. The distributed multi-gap high-frequency structure is composed of a resonant cavity with short circuits at both ends. The electromagnetic field energy is more concentrated, but the only remaining standing wave mode makes its bandwidth narrower.

[0024] In view of the above problems, the present invention provides a novel slow-wave structure based on traveling standing waves. Taking a rectangular folded waveguide slow-wave structure as an example, the novel slow-wave structure based on traveling standing waves is as follows: Figure 3 and Figure 4 As shown, Figure 3 From left to right in the figure are the main view, side view and three-dimensional structure diagram. Figure 4 Figure 2 is a decomposition diagram; it specifically includes: an upper rectangular coupled cavity 1, a rectangular folded waveguide slow-wave structure 2, a lower rectangular coupled cavity 3 and a strip injection channel 4. The rectangular folded waveguide slow-wave structure is connected between the upper and lower rectangular coupled cavities, and the two ends (input and output) of the rectangular folded waveguide slow-wave structure are short-circuited, thus forming a new type of resonant cavity with the upper coupled cavity / traveling wave type slow-wave line / lower coupled cavity short-circuited at both ends; the strip injection electron channel penetrates the rectangular folded waveguide slow-wave structure along the vertical direction (z-axis) and is located at the center of the rectangular folded waveguide slow-wave structure along the cross section (xoy plane).

[0025] exist Figure 1 、 Figure 2 Based on the distributed multi-gap high frequency structure shown in FIG, the present invention adopts a rectangular folded waveguide slow wave structure as a traveling wave type slow wave line to replace the distributed multi-gap structure, thereby obtaining Figure 3 、 Figure 4 The new resonant cavity with a traveling wave type slow wave line shown in the figure realizes the component tuning of traveling wave and standing wave in the electromagnetic field of the new resonant cavity, exists in the form of standing wave in the rectangular coupled cavities at both ends, and is transmitted in the state of traveling wave in the middle rectangular folded waveguide slow wave structure, so that the new high-frequency structure in the present invention has both traveling wave characteristics and standing wave characteristics, obtains stronger characteristic impedance and wider bandwidth, realizes the design goals of high power, high gain and wide bandwidth of vacuum electronic devices, and has the advantage of good cavity consistency. Compared with the existing composite extended interaction klystron, it can effectively reduce the complexity of the entire cavity, greatly reduce the difficulty of magnetic field distribution design and device processing difficulty.

[0026] The beneficial effects of the present invention are described in detail below in conjunction with simulation tests.

[0027] In a preferred embodiment, the upper rectangular coupling cavity and the lower rectangular coupling cavity adopt the same structure, and the rectangular folded waveguide slow-wave structure 2 is composed of a distributed rectangular gap waveguide and a rectangular connecting waveguide. A plurality of rectangular connecting waveguides are arranged between the upper rectangular coupling cavity and the lower rectangular coupling cavity, and the adjacent distributed rectangular gap waveguides are staggered in the x-axis direction, so that the rectangular connecting waveguide and the distributed rectangular gap waveguide are connected in sequence to form a rectangular folded waveguide slow-wave structure, thereby forming a slow-wave structure based on traveling standing waves. Its dimensions are marked as follows: Figure 5 As shown, the dimension in the x-axis direction is defined as the width, the dimension in the z-axis direction is defined as the length, and the dimension in the y-axis direction is defined as the height, wherein a is the width of the upper rectangular coupling cavity, the lower rectangular coupling cavity, and the distributed rectangular gap waveguide, b is the length of the upper rectangular coupling cavity and the lower rectangular coupling cavity, c is the height of the upper rectangular coupling cavity and the lower rectangular coupling cavity, d is the height of the rectangular connecting waveguide and the distributed rectangular gap waveguide, e is the length of the rectangular connecting waveguide, f is the length of the distributed rectangular gap waveguide 6, g is the height of the strip electron injection channel, h is the width of the strip electron injection channel, and w is the width of the rectangular connecting waveguide.

[0028] The above-mentioned slow-wave structure based on traveling standing waves operates in the 140 GHz frequency band, and its specific dimensions are: a=0.87, b=1.5, c=1.07, d=1.1, e=0.21, f=0.09, g=0.8, h=0.14, w=0.18, all in units of mm.

[0029] The above-mentioned slow-wave structure based on traveling standing wave is simulated to obtain its characteristic impedance R / Q, the resonant frequency of the working mode TM11-2π and the frequency interval between adjacent modes; Figure 6 The figure shows the simulation results of the characteristic impedance R / Q of the slow wave structure based on the traveling standing wave in this embodiment; Figure 7 The figure shows the simulation results of the frequency intervals of adjacent modes of the slow-wave structure based on traveling standing waves in this embodiment. The working mode of the slow-wave structure based on traveling standing waves is TM11-2π. The hollow column represents the frequency interval between the resonant frequency of the working mode TM11-2π and the previous mode, and the slash column represents the frequency interval between the resonant frequency of the working mode TM11-2π and the next mode. In addition, it should be noted that Figure 6 and Figure 7 The horizontal coordinates are all the width w of the rectangular connected waveguides. When w=0, it is the distributed multi-rectangular gap structure in the traditional extended interaction klystron.

[0030] from Figure 6 and Figure 7It can be seen that the characteristic impedance R / Q of the distributed multi-rectangular gap structure in the traditional extended interaction klystron is relatively small, and the injection wave interaction strength is weak; moreover, the frequency interval between the resonant frequency of the working mode and the previous mode is very small, only 2.05GHz, and the small mode separation is prone to mode competition, resulting in a reduction in the working bandwidth, which is also not conducive to the stable output of the entire cavity. However, the characteristic impedance R / Q of the slow-wave structure based on traveling standing wave operation in the present invention gradually increases with the width w of the rectangular connecting waveguide, and the injection wave interaction strength also gradually increases; moreover, the frequency interval between the resonant frequency of the working mode and the previous mode increases significantly, especially when w=0.18mm, the resonant frequency of the working mode and the frequency intervals of the previous mode and the next mode are both large, specifically 6.82GHz and 6.51GHz, thereby avoiding mode competition, which is beneficial to the improvement of the working bandwidth and the stable output of the entire cavity. It can be seen that compared with the traditional distributed multi-gap structure, the new slow-wave structure based on traveling standing wave proposed in the present invention can obtain a larger characteristic impedance R / Q, a more uniform and larger working mode frequency separation, which is conducive to obtaining higher power, higher gain, wider bandwidth and more stable vacuum electronic devices.

[0031] The above description is only a specific embodiment of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes; all disclosed features, or all steps in the methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A slow-wave structure based on traveling standing waves, comprising: An upper coupling cavity, a traveling-wave slow-wave line, a lower coupling cavity, and an electron injection channel; characterized in that the traveling-wave slow-wave line is connected between the upper coupling cavity and the lower coupling cavity, together forming a resonant cavity with two ends short-circuited; the electron injection channel vertically penetrates the traveling-wave slow-wave line and is located at the center of the traveling-wave slow-wave line along the cross section; The upper coupling cavity and the lower coupler both adopt rectangular coupling cavities, the traveling wave slow wave line adopts a rectangular folded waveguide slow wave structure, the electron injection channel adopts a strip injection channel, and the number of electron injection channels is one; The rectangular folded waveguide slow-wave structure is composed of a distributed rectangular gap waveguide and a rectangular connecting waveguide. A plurality of rectangular connecting waveguides are arranged between the upper rectangular coupling cavity and the lower rectangular coupling cavity, and the adjacent distributed rectangular gap waveguides are staggered in the x-axis direction, so that the rectangular connecting waveguide and the distributed rectangular gap waveguide are connected in sequence to form a rectangular folded waveguide slow-wave structure; wherein, a is the width of the upper rectangular coupling cavity, the lower rectangular coupling cavity, and the distributed rectangular gap waveguide, b is the length of the upper rectangular coupling cavity and the lower rectangular coupling cavity, and c is the upper rectangular coupling cavity. The heights of the rectangular coupling cavity and the lower rectangular coupling cavity, d is the height of the rectangular connecting waveguide and the distributed rectangular gap waveguide, e is the length of the rectangular connecting waveguide, f is the length of the distributed rectangular gap waveguide 6, g is the height of the strip electron injection channel, h is the width of the strip electron injection channel, w is the width of the rectangular connecting waveguide, a=0.87, b=1.5, c=1.07, d=1.1, e=0.21, f=0.09, g=0.8, h=0.14, w=0.18, all in mm; The resonant frequency of the slow-wave structure based on traveling standing wave operation in the working mode is 6.82 GHz and the frequency intervals between the previous mode and the next mode are 6.51 GHz.

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