Slow wave structure based on moving standing wave work

Abstract

The invention belongs to the technical field of microwave vacuum electronics, and particularly provides a slow wave structure based on moving standing wave work, which is used for realizing the design targets of high power, high gain and wide bandwidth of a vacuum electronic device. According to the invention, a rectangular folded slow-wave structure which is a traveling-wave-type slow-wave line is creatively adopted to replace a distributed multi-gap structure in a traditional extended interaction klystron, and a novel resonant cavity of an upper coupled cavity / traveling-wave-type slow-wave line / lower coupled cavity is obtained, so that the novel slow-wave structure can have traveling wave characteristics and standing wave characteristics at the same time. Stronger characteristic impedance and wider bandwidth are obtained; the novel slow-wave structure is applied to a vacuum electronic device as a high-frequency structure, can achieve the design targets of high power, high gain and wide bandwidth of the vacuum electronic device, has the advantage of good cavity consistency, can effectively reduce the complexity of a cavity compared with an existing device, and improves the reliability of the vacuum electronic device. And the magnetic field distribution design difficulty and the device processing difficulty are greatly reduced.

Description

Technical Field

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

[0002] With the wide application of terahertz technology in fields such as radar, satellite remote sensing, high-speed communication, detection imaging, and biomedicine, the application demand for terahertz power sources is increasing; in the terahertz frequency band, compared with solid-state devices, vacuum electron devices have the advantages of high power, wide bandwidth, and high stability, and have been proven to be important terahertz power sources, with very important research and application values.

[0003] Among many vacuum electron devices, the extended interaction klystron uses a multi-gap distributed resonant cavity as the high-frequency structure, which has the advantages of high power, high gain, and miniaturization. Its working mode is usually standing wave, but the bandwidth is narrower than that of the traveling wave tube; while the traveling wave tube uses a section of slow-wave line as the control structure of the electron beam and the energy exchange mechanism, so that the electromagnetic field is transmitted along the slow-wave line in the form of a traveling wave, which has a relatively wide bandwidth, but the gain is generally less than that of the extended interaction klystron. Chinese invention patent with publication number CN110060911A discloses a slow-wave structure with wide bandwidth and high gain, which combines the traditional standing-wave type slow-wave structure with the traveling-wave type slow-wave structure. The traveling-wave type slow-wave structure is used as the input and output cavities, and the middle cavity is composed of a five-cavity extended interaction klystron with three resonant cavity standing-wave structures; the traveling-wave type input and output cavities are used to obtain a relatively wide bandwidth, and the resonant cavity standing-wave structure obtains high gain, so as to achieve wide bandwidth and high gain. Chinese invention patent with publication number CN117747382A discloses an extended interaction klystron based on traveling and standing wave modes, which adopts a two-cavity structure of a traveling-wave input cavity and a standing-wave output cavity. The traveling-wave input cavity is used to obtain a relatively wide transmission bandwidth, and the standing-wave output cavity obtains a relatively high characteristic impedance and high output gain, so that the extended interaction klystron obtains a relatively high power and a relatively wide working bandwidth.

[0004] In summary, the two invention patents use the traveling-wave type slow-wave structure as the input cavity or output cavity, and the resonant cavity standing-wave structure as the middle bunching cavity or output cavity, and obtain a composite extended interaction klystron with high power, high gain, and wide bandwidth; however, due to the structural differences between the traveling-wave type slow-wave structure and the resonant cavity standing-wave structure, the overall cavity structure of the klystron is relatively complex, increasing the difficulty of magnetic field distribution design and the processing difficulty of the device. Therefore, a new type of vacuum electron slow-wave structure and related devices with both the traveling-wave characteristics of the traveling-wave line and the standing-wave characteristics of the resonant cavity are still an important research direction at present. Summary of the Invention

[0005] The object of the present invention is to provide a slow-wave structure based on traveling and standing waves to achieve the design goals of high power, high gain, and wide bandwidth for vacuum electronic devices. Based on the traditional high-frequency structure of extended interaction klystrons, the present invention creatively proposes to use a traveling-wave slow-wave line structure to replace the original distributed multi-gap structure, forming a new resonant cavity of an 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 possess both traveling-wave characteristics and standing-wave characteristics, obtaining a stronger characteristic impedance and a wider bandwidth. Applying the new slow-wave structure in the present invention as a high-frequency structure to vacuum electronic devices 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 as follows: A slow-wave structure based on traveling and standing waves, comprising: an upper coupling cavity, a traveling-wave slow-wave line, a lower coupling cavity, and an electron beam channel; wherein, the traveling-wave slow-wave line is connected between the upper coupling cavity and the lower coupling cavity, jointly constituting a resonant cavity short-circuited at both ends; the electron beam channel penetrates the traveling-wave slow-wave line in the vertical direction and is located at the central position of the traveling-wave slow-wave line in the cross-section.

[0007] Furthermore, the upper coupling cavity and the lower coupling cavity adopt the same structure, and the cross-sectional shape is rectangular, circular, or elliptical, preferably rectangular.

[0008] Furthermore, the traveling-wave slow-wave line is a folded waveguide slow-wave structure, an interleaved double-grid slow-wave structure, or a corrugated waveguide slow-wave structure, preferably a rectangular folded waveguide slow-wave structure.

[0009] Furthermore, the electron beam channel is a circular channel, an elliptical channel, or a strip beam channel, preferably a strip beam channel.

[0010] Furthermore, the number of electron beam channels is one, two, or more.

[0011] Based on the above technical solution, the beneficial effects of the present invention are as follows: The present invention provides a new slow-wave structure based on traveling and standing waves. By using a traveling-wave slow-wave line structure to replace the distributed multi-gap structure in traditional extended interaction klystrons, a new resonant cavity of an upper coupling cavity / traveling-wave slow-wave line / lower coupling cavity is obtained, enabling the new slow-wave structure to possess both traveling-wave characteristics and standing-wave characteristics, obtaining a stronger characteristic impedance and a wider bandwidth. Applying this new slow-wave structure as a high-frequency structure to vacuum electronic devices can achieve the design goals of high power, high gain, and wide bandwidth for vacuum electronic devices, and at the same time has the advantage of good cavity consistency. In addition, compared with the existing composite extended interaction klystrons, the present invention can effectively reduce the complexity of the cavity, greatly reducing the difficulty of magnetic field distribution design and device processing difficulty. Description of the Drawings

[0012] Figure 1 It is a schematic diagram of the vacuum model of the distributed multi-gap structure in a traditional extended interaction klystron.

[0013] Figure 2 It is a schematic diagram of the decomposition of the distributed multi-gap structure in a traditional extended interaction klystron.

[0014] Figure 3 It is a schematic diagram of the vacuum model of the slow-wave structure based on traveling and standing waves in the present invention.

[0015] Figure 4 It is a schematic diagram of the decomposition of the slow-wave structure based on traveling and standing waves in the present invention.

[0016] Figure 5 It is a dimension marking diagram of the slow-wave structure based on traveling and standing waves in the present invention.

[0017] Figure 6 It is a simulation result diagram of the characteristic impedance R / Q of the slow-wave structure based on traveling and standing waves in the present invention.

[0018] Figure 7 It is a simulation result diagram of the adjacent mode frequency interval of the slow-wave structure based on traveling and standing waves in the present invention.

[0019] Reference numerals: 1 is the upper rectangular coupling cavity, 2 is the rectangular folded waveguide slow-wave structure, 3 is the lower rectangular coupling cavity, 4 is the ribbon beam electron beam channel, and 5 is the distributed rectangular gap waveguide. Specific embodiments

[0020] To make the objectives, technical solutions and beneficial effects of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0021] The distributed multi-gap high-frequency structure in a traditional extended interaction klystron is as Figure 1 and Figure 2 shown. Figure 1 In Figure 2 , from left to right are the front view, side view and three-dimensional structure diagram in sequence, which is a decomposition schematic diagram; specifically including: the upper rectangular coupling cavity 1, the lower rectangular coupling cavity 3, the ribbon beam electron beam channel 4 and the distributed rectangular gap waveguide 5. A plurality of 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, and the ribbon beam electron beam channel penetrates the distributed rectangular gap waveguide along the vertical direction (z-axis) of the cross-section (xoy plane), and the ribbon beam electron beam channel is located at the central position of the distributed rectangular gap waveguide; the distributed multi-gap high-frequency structure is composed of resonant cavities short-circuited at both ends, and the electromagnetic field energy is more concentrated, but the existing standing wave mode makes its bandwidth narrow.

[0022] In view of the above problems, the present invention provides a novel slow-wave structure based on traveling standing waves. Taking the 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 shown. Figure 3 From left to right in the figure are the front view, side view and three-dimensional structure diagram, Figure 4 which is a decomposition schematic diagram; specifically including: upper rectangular coupling cavity 1, rectangular folded waveguide slow-wave structure 2, lower rectangular coupling cavity 3 and strip electron beam channel 4. The rectangular folded waveguide slow-wave structure is connected between the upper rectangular coupling cavity and the lower rectangular coupling cavity, and both ends (input end and output end) of the rectangular folded waveguide slow-wave structure are short-circuited, thus forming a novel resonant cavity with both ends short-circuited of the upper coupling cavity / traveling-wave type slow-wave line / lower coupling cavity; the strip electron beam channel penetrates the rectangular folded waveguide slow-wave structure along the vertical direction (z-axis) and is located at the center position of the rectangular folded waveguide slow-wave structure along the cross-section (xoy plane).

[0023] In Figure 1 and Figure 2 shown distributed multi-gap high-frequency structure, the present invention uses the rectangular folded waveguide slow-wave structure, a traveling-wave type slow-wave line, to replace the distributed multi-gap structure, thus obtaining Figure 3 and Figure 4 shown novel resonant cavity with a traveling-wave type slow-wave line. The electromagnetic field realizes the component tuning of traveling waves and standing waves in this novel resonant cavity, exists in the form of standing waves in the two end rectangular coupling cavities, and is transmitted in the form of traveling waves in the middle rectangular folded waveguide slow-wave structure, so that the novel high-frequency structure in the present invention has both traveling-wave characteristics and standing-wave characteristics at the same time, obtains a stronger characteristic impedance and a wider bandwidth, realizes the design goals of high power, high gain and wide bandwidth of vacuum electronic devices, and at the same time has the advantage of good cavity consistency. Compared with the existing composite extended interaction klystron, it can effectively reduce the complexity of the whole cavity, greatly reduce the difficulty of magnetic field distribution design and device processing difficulty.

[0024] The beneficial effects of the present invention will be described in detail below in combination with simulation tests.

[0025] In a preferred embodiment, the upper rectangular coupling cavity and the lower rectangular coupling cavity have the same structure. The rectangular folded waveguide slow-wave structure 2 is composed of distributed rectangular gap waveguides and rectangular connecting waveguides connected. A plurality of rectangular connecting waveguides are arranged between the upper rectangular coupling cavity and the lower rectangular coupling cavity, and adjacent distributed rectangular gap waveguides are cross-connected in the x-axis direction, so that the rectangular connecting waveguides and the distributed rectangular gap waveguides are connected in sequence to form the rectangular folded waveguide slow-wave structure, and then a slow-wave structure based on traveling standing waves is formed. Its dimension markings are as Figure 5As shown in the figure, 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. Among them, a is the width of the upper rectangular coupling cavity, the lower rectangular coupling cavity, and the distributed rectangular slot 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 slot waveguide; e is the length of the rectangular connecting waveguide; f is the length of the distributed rectangular slot waveguide 6; g is the height of the sheet electron beam channel; h is the width of the sheet electron beam channel; and w is the width of the rectangular connecting waveguide.

[0026] The above slow-wave structure based on traveling and standing waves operates in the 140 GHz frequency band. The 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, and the unit is: mm.

[0027] The above slow-wave structure based on traveling and standing waves is simulated, and its characteristic impedance R / Q, the resonant frequency of the operating mode TM11-2π, and the adjacent mode frequency interval are obtained; as Figure 6 shown is the simulation result of the characteristic impedance R / Q of the slow-wave structure based on traveling and standing waves in this embodiment; as Figure 7 shown is the simulation result of the adjacent mode frequency interval of the slow-wave structure based on traveling and standing waves in this embodiment. The operating mode of the slow-wave structure based on traveling and standing waves is TM11-2π. The hollow column represents the frequency interval between the resonant frequency of the operating mode TM11-2π and the previous mode, and the slanted column represents the frequency interval between the resonant frequency of the operating mode TM11-2π and the next mode; in addition, it should be noted that Figure 6 and Figure 7 the abscissas in both are the width w of the rectangular connecting waveguide. When w = 0, it is the distributed multi-rectangular slot structure in the traditional extended interaction klystron.

[0028] From Figure 6 and Figure 7It can be seen that in the traditional extended interaction klystron, the characteristic impedance R / Q of the distributed multi-rectangular gap structure is relatively small, and the beam-wave interaction strength is weak. Moreover, the frequency interval between the resonant frequencies of the working modes and the previous mode is very small, only 2.05 GHz, and the small mode separation is prone to mode competition, resulting in a reduction in the working bandwidth and also being unfavorable for the stable output of the entire cavity. In the present invention, however, the characteristic impedance R / Q of the slow-wave structure based on the traveling and standing wave operation gradually increases with the width w of the rectangular connecting waveguide, and the beam-wave interaction strength also gradually increases. Moreover, the frequency interval between the resonant frequencies of the working modes and the previous mode increases significantly. Especially when w = 0.18 mm, the frequency intervals between the resonant frequencies of the working mode and the previous mode and the subsequent mode are both large, specifically 6.82 GHz and 6.51 GHz, thus avoiding mode competition and being beneficial to the improvement of the working bandwidth and the stable output of the entire cavity. Therefore, compared with the traditional distributed multi-gap structure, the novel slow-wave structure based on the traveling and standing wave operation proposed in the present invention can obtain a larger characteristic impedance R / Q, a more uniform and larger frequency separation of the working modes, thereby being beneficial to obtaining a higher-power, higher-gain, wider-bandwidth, and more stable vacuum electronic device.

[0029] As described above, the above are only specific embodiments of the present invention. Any feature disclosed in this specification, unless specifically stated, can be replaced by other equivalent or features with similar purposes; all the features disclosed, or all the steps in any method or process, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A slow wave structure based on traveling standing wave operation, comprising: An upper coupling cavity, a traveling-wave type slow-wave line, a lower coupling cavity and an electron injection channel; characterized in that the traveling-wave type slow-wave line is connected between the upper coupling cavity and the lower coupling cavity, and together constitutes a resonant cavity with two ends short-circuited; the electron injection channel penetrates the traveling-wave type slow-wave line in a vertical direction, and is located at the center of the traveling-wave type slow-wave line along the cross section.

2. The slow wave structure based on traveling standing wave according to claim 1, characterized in that: The upper coupling cavity and the lower coupling cavity adopt the same structure, and the cross-section shape is rectangular, circular or elliptical.

3. The slow wave structure based on traveling standing wave according to claim 1, characterized in that: The traveling wave type slow wave line is a folded waveguide slow wave structure, an interlaced double-grid slow wave structure or a corrugated waveguide slow wave structure.

4. The slow wave structure based on traveling standing wave according to claim 3, characterized in that: The traveling wave type slow wave line is a rectangular folded waveguide slow wave structure.

5. The slow wave structure based on traveling standing wave according to claim 1, characterized in that: The traveling wave type slow wave line electron injection channel is a circular channel, an elliptical channel or a strip injection channel.

6. The slow wave structure based on traveling standing wave according to claim 1, characterized in that: The number of electron injection channels is one, two or more.

Images