A trapezoidal subwavelength hole high frequency structure extended interaction klystron

Abstract

This invention belongs to the field of microwave vacuum electronic devices, specifically providing a trapezoidal subwavelength aperture high-frequency structure for an extended interaction klystron, used to improve the power and gain of the extended interaction klystron and expand its bandwidth. This invention creatively proposes an isosceles trapezoidal subwavelength aperture with a base length proportional to the width of the resonant cavity, thereby designing the input cavity, intermediate cavity, and output cavity. This increases the beam-wave interaction area and characteristic impedance of the intermediate cavity, improving the interaction efficiency while maintaining a low quality factor and avoiding parasitic oscillations. It also increases the characteristic impedance of the input and output cavities, enhancing beam-wave interaction and reducing the input reflection coefficient S. 11 With a relatively large value and a -5dB bandwidth greater than 1GHz, the power feed and bandwidth extension capabilities are further enhanced. Compared with the traditional trapezoidal structure, the extended interaction klystron of this invention has significant advantages in terms of high power, high gain, and wide bandwidth.

Description

Technical Field

[0001] This invention belongs to the field of microwave vacuum electronic devices, specifically providing an extended interaction klystron with a trapezoidal subwavelength aperture high-frequency structure. Background Technology

[0002] With the continuous development and application of terahertz technology in fields such as communications, radar, medicine, and security inspection, there is an urgent need for terahertz radiation sources with superior performance indicators. Currently, terahertz sources mainly fall into two categories: solid-state semiconductor devices and vacuum electronic devices. In recent years, solid-state semiconductor devices have gradually replaced vacuum devices in the low-frequency band due to their small size, low cost, ease of production, and integration. However, in the high-frequency band, especially the terahertz band, the electron mobility of solid-state semiconductor devices is lower than that in a vacuum because electrons collide with each other inside the conductor. At the same time, due to the limitations of current processing materials and manufacturing processes, the output power can only approach the watt level, and it is still very difficult to reach the watt level or higher. In contrast, vacuum electronic devices can generate higher output power at high frequencies and have reliable stability. Therefore, in the terahertz band, vacuum electronic devices have greater advantages and potential and are an effective way to promote the better application of terahertz technology.

[0003] In vacuum electronic devices, klystrons possess advantages such as high power, high efficiency, high gain, small size, and good stability, leading to their wide application in civilian and military fields, including communications and radar. The high-frequency system of a klystron is composed of a resonant cavity. The presence of the resonant cavity concentrates the electromagnetic field, resulting in high output power and gain. However, the bandwidth of the klystron is relatively narrow due to its narrow bandwidth characteristic. Meanwhile, traveling wave tubes (TWTs) are vacuum devices with relatively wide bandwidth, but their gain and power are not as ideal. Based on this, the high-frequency structure of the extended interaction klystron can be viewed as both a slow-wave structure and a resonant cavity, combining the advantages of both klystrons and TWTs, resulting in a novel klystron device with a wider bandwidth.

[0004] Currently, traditional extended interaction klystrons such as Figure 1 As shown, it mainly includes: a rectangular electron beam channel, an input cavity, an intermediate cavity, an output cavity, and a drift tube. The input cavity, intermediate cavity, and output cavity all adopt a trapezoidal structure; a traditional trapezoidal structure is shown below. Figure 2As shown, the intermediate cavity consists of an upper coupled cavity, a resonant cavity, and a lower coupled cavity. The resonant cavity is connected to the upper and lower coupled cavities via a rectangular subwavelength aperture. The upper coupled cavity of the input cavity is connected to a standard rectangular waveguide via a coupling aperture, and the upper coupled cavity of the output cavity is also connected to a standard rectangular waveguide via a coupling aperture. Compared to the original holeless trapezoidal structure, the use of a rectangular subwavelength aperture in the intermediate cavity concentrates energy in the beam-wave interaction region, increases the characteristic impedance, and improves the interaction efficiency. However, its quality factor is too large, making it prone to parasitic oscillations. Although the use of rectangular subwavelength apertures in the input and output cavities slightly increases the characteristic impedance and enhances the beam-wave interaction, its input reflection coefficient S... 11 The value is still relatively small and the -5dB bandwidth is less than 1GHz, so the ability to feed in power and expand bandwidth is still relatively poor. Summary of the Invention

[0005] The purpose of this invention is to address the numerous problems existing in traditional trapezoidal extended interaction klystrons with extended interaction structures by providing a trapezoidal subwavelength aperture high-frequency extended interaction klystron to improve its power and gain, and expand its bandwidth. This invention creatively proposes an isosceles trapezoidal subwavelength aperture with a base length proportional to the width of the resonant cavity, thereby designing the input cavity, intermediate cavity, and output cavity to form a high-frequency extended interaction klystron. Compared with traditional trapezoidal structures and isosceles trapezoidal subwavelength aperture structures with rectangular or unequal proportions, the intermediate cavity uses an isosceles trapezoidal subwavelength aperture with equal proportions, further increasing the beam-wave interaction area, increasing the characteristic impedance, and improving the interaction efficiency, while also resulting in a smaller quality factor and avoiding parasitic oscillations. The input and output cavities also use isosceles trapezoidal subwavelength apertures with equal proportions, increasing the characteristic impedance, enhancing beam-wave interaction, and simultaneously reducing the input reflection coefficient S. 11 With a relatively large value and a -5dB bandwidth greater than 1GHz, the ability to feed energy and extend bandwidth is further improved; ultimately, the extended interaction klystron of the present invention has significant advantages in terms of high power, high gain and wide bandwidth.

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

[0007] An extended interaction klystron with a trapezoidal subwavelength aperture high-frequency structure includes: an input cavity, multiple intermediate cavities, an output cavity, a rectangular electron beam channel, and a drift tube, wherein the input cavity, multiple intermediate cavities, and output cavity are sequentially connected via the drift tube; characterized in that the input cavity, intermediate cavities, and output cavity all adopt a trapezoidal line structure, the trapezoidal line structure is composed of an upper coupling cavity, a resonant cavity, and a lower coupling cavity, the resonant cavity is connected to the upper and lower coupling cavities via an isosceles trapezoidal subwavelength aperture, the long base of the isosceles trapezoidal subwavelength aperture is proportional to the wide side of the resonant cavity, the rectangular electron beam channel extends perpendicular to the cross-section of the resonant cavity, and the upper and lower coupling cavities adopt the same structure.

[0008] Furthermore, the height of the coupling cavity in the input cavity and the output cavity is the same, and the height of the coupling cavity in the multiple intermediate cavities decreases sequentially from the input cavity to the output cavity.

[0009] Furthermore, the width and length of the coupling cavity in the input cavity, the multiple intermediate cavities, and the output cavity are all the same.

[0010] Furthermore, the dimensions of the input cavity, the multiple intermediate cavities, the resonant cavity in the output cavity, and the isosceles trapezoidal subwavelength aperture are all the same.

[0011] Furthermore, the upper coupling cavity of the input cavity is connected to a standard rectangular waveguide through a coupling hole to form the input end; the upper coupling cavity of the output cavity is connected to a standard rectangular waveguide through a coupling hole to form the output end.

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

[0013] The extended interaction klystron of the trapezoidal subwavelength aperture high-frequency structure of this invention employs an isosceles trapezoidal subwavelength aperture with a base length proportional to the width of the resonant cavity. Compared to traditional trapezoidal structures and isosceles trapezoidal subwavelength aperture structures with rectangular or unequal proportions, this design concentrates electric field energy more in the interaction region, increases the beam-wave interaction area, increases characteristic impedance, and improves interaction efficiency. Simultaneously, it results in a smaller quality factor, avoiding parasitic oscillations. The input and output cavities also utilize proportionally proportioned isosceles trapezoidal subwavelength apertures, increasing characteristic impedance and enhancing beam-wave interaction. Furthermore, it reduces the input reflection coefficient S0. 11 With a relatively large value and a -5dB bandwidth greater than 1GHz, the power feed and bandwidth extension capabilities are further enhanced. Ultimately, this results in the entire extended interaction klystron possessing the advantages of high power, high gain, and wide bandwidth. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a traditional extended interaction klystron.

[0015] Figure 2 This is a three-dimensional structural diagram of the intermediate cavity and input / output cavity of a traditional trapezoidal structure.

[0016] Figure 3 This is a three-dimensional structural schematic diagram of the extended interaction klystron of the trapezoidal subwavelength aperture high-frequency structure in this invention.

[0017] Figure 4 This is a side view of the extended interaction klystron of the trapezoidal subwavelength aperture high-frequency structure in this invention, wherein 1 is the input cavity, 2 is the first intermediate cavity, 3 is the second intermediate cavity, 4 is the third intermediate cavity, 5 is the fourth intermediate cavity, 6 is the output cavity, and 7 is the rectangular electron beam channel.

[0018] Figure 5 This is a schematic diagram of the input and output cavities in the extended interaction klystron of the trapezoidal subwavelength aperture high-frequency structure in this invention, wherein (a) is the front view, (b) is the side view, and (c) is the three-dimensional structure diagram.

[0019] Figure 6 This is a schematic diagram of the intermediate cavity in the extended interaction klystron of the trapezoidal subwavelength aperture high-frequency structure in this invention, wherein (a) is the front view, (b) is the side view, and (c) is the three-dimensional structure diagram.

[0020] Figure 7 The eigenmodes of the input and output cavities of the extended interaction klystron with the trapezoidal subwavelength aperture high-frequency structure in this embodiment of the invention are represented by TM. 31 -2π operating mode.

[0021] Figure 8 The input reflection coefficient S of the input and output cavities of the extended interaction klystron with the trapezoidal subwavelength aperture high-frequency structure in this embodiment of the invention is... 11 .

[0022] Figure 9 The TM of the extended interaction klystron with trapezoidal subwavelength aperture high-frequency structure in the embodiments of the present invention 31 Electric field distribution diagram of the -2π operating mode.

[0023] Figure 10 This is a peak output power diagram of the extended interaction klystron of the trapezoidal subwavelength aperture high-frequency structure in an embodiment of the present invention.

[0024] Figure 11 This is a spectrum diagram of the output signal of the extended interaction klystron of the trapezoidal subwavelength aperture high-frequency structure in an embodiment of the present invention.

[0025] Figure 12 This is a diagram showing the power and gain of the output signal of the extended interaction klystron with a trapezoidal subwavelength aperture high-frequency structure at different input frequencies in an embodiment of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0027] This embodiment provides an extended interaction klystron with a trapezoidal subwavelength aperture high-frequency structure, the structure of which is as follows: Figure 3 , Figure 4As shown, it includes: an input cavity 1, first to fourth intermediate cavities 2-5, an output cavity 6, a rectangular electron beam channel 7, and five drift tubes; wherein, the input cavity, the first to fourth intermediate cavities, and the output cavity are connected sequentially through drift tubes; the input cavity, intermediate cavities, and output cavity all adopt a trapezoidal structure, the trapezoidal structure is composed of an upper coupling cavity, a resonant cavity, and a lower coupling cavity, the resonant cavity is connected to the upper and lower coupling cavities through an isosceles trapezoidal subwavelength aperture, the long base of the isosceles trapezoidal subwavelength aperture is proportional to the wide side (x-axis direction) of the resonant cavity, the rectangular electron beam channel extends perpendicular to the cross-section of the resonant cavity, and the upper coupling cavity and the lower coupling cavity adopt the same structure; the upper coupling cavity of the input cavity is connected to a standard rectangular waveguide through a coupling aperture to form the input end; the upper coupling cavity of the output cavity is connected to a standard rectangular waveguide through a coupling aperture to form the output end.

[0028] Furthermore, the height (y-axis direction) of the coupling cavities in the input cavity and output cavity is the same, and the height (y-axis direction) of the coupling cavities in the first to fourth intermediate cavities decreases sequentially; the length (x-axis direction) and width (z-axis direction) of the coupling cavities in the input cavity, the first to fourth intermediate cavities, and the output cavity are all the same; the dimensions (height, length, and width) of the resonant cavities in the input cavity, the first to fourth intermediate cavities, the output cavity, and the isosceles trapezoidal subwavelength aperture are all the same; Figure 5 , Figure 6 As shown.

[0029] In this embodiment, the specific dimensions of the extended interaction klystron of the trapezoidal subwavelength aperture high-frequency structure are as follows: the height of the coupling cavities in the input and output cavities is the same, 1.07 mm (y-axis direction); the heights of the coupling cavities in the first to fourth intermediate cavities decrease sequentially, being 1.1 mm, 1.04 mm, 1.03 mm, and 1.02 mm (y-axis direction), respectively; the length and width of the coupling cavities in the input cavity, the first to fourth intermediate cavities, and the output cavity are all the same, with a length of 1.5 mm (z-axis direction) and a width of 0.86 mm (x-axis direction); the dimensions (height, width, and length) of the resonant cavities in the input cavity, the first to fourth intermediate cavities, and the output cavity are all the same, with a height of 0.88 mm (y-axis direction), a length of 0.84 mm (x-axis direction), and a width of 0.0 mm. The dimensions (height, width, and length) of the isosceles trapezoidal subwavelength apertures in the input cavity, the first to fourth intermediate cavities, and the output cavity are all the same: height 0.11mm (y-axis), long base 0.84mm (x-axis), short base 0.09mm (x-axis), and thickness 0.09mm (z-axis). The rectangular electron beam channel has a height of 0.8mm (y-axis), a width of 0.14mm (x-axis), and a total length of 19.83mm (z-axis). The height (y-axis) and width (x-axis) of the five drift tubes are the same as those of the electron beam channel, and the lengths of the drift tubes are 2.4mm, 2.2mm, 1.81mm, 1.85mm, and 1.18mm (z-axis), respectively.

[0030] For the input and output cavities, an isosceles trapezoidal subwavelength aperture with equal proportions is used, and the operating mode is TM. 31 -2π, characteristic impedance is 234.14Ω, beam-wave interaction is enhanced, eigenmodes are as follows Figure 7 As shown; Input reflection coefficient S 11 With a relatively large value and a -5dB bandwidth of 1.03GHz, which is greater than 1GHz, the ability to feed in energy and extend bandwidth is further improved, and the input reflection coefficient S 11 like Figure 8 As shown.

[0031] For the intermediate cavity, an isosceles trapezoidal subwavelength aperture with equal proportions is used, which improves the characteristic impedance, increases the beam-wave interaction area, and improves the interaction efficiency. Simultaneously, it results in a smaller quality factor and avoids parasitic oscillations. The operating mode is TM. 31 -2π Figure 9 As shown.

[0032] Simulation tests were conducted on the extended interaction klystron with the aforementioned trapezoidal subwavelength aperture high-frequency structure. For the six-cavity trapezoidal subwavelength aperture high-frequency structure extended interaction klystron, when the electron beam voltage was 15.1 kV, the electron beam current was 0.3 A, the magnetic induction intensity used to focus the electron beam was 0.35 T, and the input signal was 0.02 W, the peak output power of the amplified signal was 171.25 W, and the electronic efficiency was 3.78%. Figure 10 As shown; the Fourier transform of the output signal yields the signal's spectrum, which is very clean, with a frequency of 230.56 GHz and no other noise signals, as shown. Figure 11 As shown; at different input signal frequencies, the maximum output power is 171.25W, the gain is 39.3dB, and the -3dB bandwidth exceeds 1.1GHz, as... Figure 12 As shown.

[0033] In summary, this invention provides an extended interaction klystron with a trapezoidal subwavelength aperture high-frequency structure, which effectively achieves high power, high gain, and wide bandwidth in the terahertz band. It solves the disadvantages of traditional trapezoidal klystrons in the terahertz band and provides a new design idea for the research of other subwavelength aperture structures in vacuum electronic devices.

[0034] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A trapezoidal subwavelength aperture high-frequency structure extended interaction klystron, comprising: The system comprises an input cavity, multiple intermediate cavities, an output cavity, a rectangular electron beam channel, and a drift tube, wherein the input cavity, multiple intermediate cavities, and output cavity are sequentially connected via the drift tube. The system is characterized in that the input cavity, intermediate cavities, and output cavity all adopt a trapezoidal structure, which consists of an upper coupling cavity, a resonant cavity, and a lower coupling cavity. The resonant cavity is connected to the upper and lower coupling cavities via an isosceles trapezoidal subwavelength aperture. The long base of the isosceles trapezoidal subwavelength aperture is connected to the resonant cavity, and the short base of the isosceles trapezoidal subwavelength aperture is connected to the upper and lower coupling cavities. The long base of the isosceles trapezoidal subwavelength aperture has the same dimension as the wide side of the resonant cavity. The rectangular electron beam channel extends perpendicular to the cross-section of the resonant cavity, and the upper and lower coupling cavities adopt the same structure. The dimensions of the resonant cavity and the isosceles trapezoidal subwavelength aperture in the input cavity, multiple intermediate cavities, and output cavity are all identical.

2. The extended interaction klystron with the trapezoidal subwavelength aperture high-frequency structure according to claim 1, characterized in that, The height of the coupling cavity in the input cavity and the output cavity is the same, and the height of the coupling cavity in the multiple intermediate cavities decreases sequentially from the input cavity to the output cavity.

3. The extended interaction klystron with the trapezoidal subwavelength aperture high-frequency structure according to claim 1, characterized in that, The width and length of the input cavity, the multiple intermediate cavities, and the coupling cavity in the output cavity are all the same.

4. The extended interaction klystron with the trapezoidal subwavelength aperture high-frequency structure according to claim 1, characterized in that, The upper coupling cavity of the input cavity is connected to a standard rectangular waveguide through a coupling hole to form the input end; the upper coupling cavity of the output cavity is connected to a standard rectangular waveguide through a coupling hole to form the output end.

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