Interdigital line-loaded meander waveguide slow wave structure and traveling wave tube

Abstract

The application discloses a staggered grid distributed loading meander waveguide slow wave structure and a traveling wave tube, and belongs to the field of microwave vacuum electron technology. The structure of the application comprises a bent waveguide section and a straight waveguide section. The bent waveguide section and the straight waveguide section are connected end to end, and an electron beam channel is arranged on the central axis symmetry line of the straight waveguide section. Staggered grid structures are arranged on both sides of the electron beam channel of the straight waveguide section, the transmission path of electromagnetic waves in the slow wave structure is lengthened, and the phase velocity of electromagnetic waves in the slow wave structure is reduced. Based on the traditional meander waveguide slow wave structure, staggered grid structures are arranged on both sides of the electron beam channel of the straight waveguide section, the transmission path of electromagnetic waves in the slow wave structure is lengthened, the phase velocity and the group velocity of electromagnetic waves in the slow wave structure are reduced, more energy is concentrated near the electron beam channel region, the longitudinal electric field distribution in the electron beam channel region is effectively enhanced, and the problem of low coupling impedance of the traditional meander waveguide slow wave structure is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of microwave vacuum electron technology, and particularly relates to a staggered grid distributed loading meander waveguide slow wave structure applied to a traveling wave tube. BACKGROUND

[0002] The terahertz (THz) band has received increasing attention from academia and industry, such as electronic warfare, high data rate communication and biomedical imaging, but the lack of high-performance terahertz sources limits the further development of applications. Solid-state circuit devices and vacuum electron devices are the most widely used as millimeter wave radiation sources. However, the development of the former is limited by heat loss and breakdown effects. Therefore, vacuum electron devices have become the best choice for terahertz (THz) band power amplifiers.

[0003] The traveling wave tube (TWT) has become an important vacuum electron device due to its outstanding performance in saturation power, gain, electron efficiency and operating bandwidth. Among the various components of the traveling wave tube, the slow wave structure, which is the main place for electromagnetic waves and electron beams to exchange energy, greatly determines the amplification performance of the traveling wave tube.

[0004] One of the functions of the slow wave structure is to generate a longitudinal electric field, which is a prerequisite for energy exchange between electromagnetic waves and electron bunches. In the slow wave structure, a small number of electrons fall into the acceleration region, and a large number of electrons fall into the deceleration region. The decelerated electrons exchange energy with the electromagnetic waves; the second function is to reduce the phase velocity of the electromagnetic wave. When the phase velocity of the electromagnetic wave is slightly greater than the velocity of the electron beam, the electromagnetic wave interacts with the electron beam bunch, and the electron beam exchanges energy with the electromagnetic wave, thereby achieving the purpose of amplifying the electromagnetic wave.

[0005] Coupling impedance, as one of the important high-frequency characteristics in the slow wave structure, is mainly used to measure the effective energy exchange degree between the electron beam and the electromagnetic wave. The greater the coupling impedance, the more sufficient the energy exchange, and the higher the conversion efficiency of the beam-wave interaction. In recent years, new slow wave structure research has mainly focused on meander waveguides, staggered double grids and sinusoidal waveguides. Among them, the meander waveguide has become the most attractive choice for wide bandwidth and high power traveling wave tubes due to its structure with high coupling impedance.

[0006] However, when working in the terahertz frequency band, the size of the traditional meander waveguide slow wave structure is reduced due to the size coherence effect, and the electron beam cross-sectional area and current capacity are limited. Therefore, it is extremely critical to improve the conversion efficiency of the beam-wave interaction, and how to further improve the coupling impedance of the meander waveguide has become one of the current research directions. SUMMARY

[0007] In order to solve the problems of weak longitudinal electric field and low coupling impedance of the traditional zigzag waveguide slow wave structure, the application provides a staggered gate distributed loaded zigzag waveguide slow wave structure and a traveling wave tube.

[0008] The application is realized by the following technical scheme:

[0009] The staggered gate distributed loaded zigzag waveguide slow wave structure comprises a bent waveguide section and a straight waveguide section; the bent waveguide section and the straight waveguide section are connected end to end, and an electron beam channel is arranged on the central axis symmetry line of the straight waveguide section; staggered gate structures are arranged on both sides of the electron beam channel of the straight waveguide section, the transmission path of electromagnetic waves in the slow wave structure is prolonged, and the phase velocity and group velocity of the electromagnetic waves in the slow wave structure are reduced.

[0010] Based on the traditional zigzag waveguide slow wave structure, the staggered gate structures are arranged on both sides of the electron beam channel of the straight waveguide section, the transmission path of electromagnetic waves in the slow wave structure is prolonged, the phase velocity and group velocity of the electromagnetic waves in the slow wave structure are reduced, more energy is concentrated near the electron beam channel area, and thus the longitudinal electric field distribution in the electron beam channel area is effectively enhanced, and the problem of low coupling impedance of the traditional zigzag waveguide slow wave structure is solved.

[0011] As a preferred embodiment, the application can adopt a single-period staggered gate structure, that is, one metal gate is arranged on each side of a single straight waveguide section to form a group of staggered gate structures.

[0012] As a preferred embodiment, the application can also adopt a two-period or multi-period staggered gate structure, that is, at least two groups of staggered gate structures are arranged along a single straight waveguide section.

[0013] As a preferred embodiment, the staggered gate structure of the application can adopt but is not limited to a rectangular shape, a semicircular shape or a polygonal shape.

[0014] As a preferred embodiment, the electron beam channel of the application can adopt a strip-shaped channel. Compared with a circular channel, the strip-shaped channel has a larger electron beam cross-sectional area, can load a larger working current, increases the output power capacity of the device, and is convenient to process.

[0015] As a preferred embodiment, the electron beam channel of the application is a circular channel or an elliptical channel. The electron beam channel of the application is not limited to a strip-shaped channel, and can also adopt a circular channel or an elliptical channel.

[0016] As a preferred embodiment, the electron beam channel of the application is at least one. The electron beam channel of the application can be arranged as one, two or more.

[0017] As a preferred embodiment, the at least one electron beam channel of the present application is arranged uniformly along the waveguide transversely.

[0018] As a preferred embodiment, the straight waveguide section and the curved waveguide section of the present application have the same cross section.

[0019] In a second aspect, the present application provides a traveling wave tube, which comprises the meandering waveguide slow wave structure of the present application.

[0020] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0021] 1. The meandering waveguide slow wave structure of the present application prolongs the transmission path of electromagnetic waves in the slow wave structure by arranging the staggered grid structure on both sides of the electron beam channel of the straight waveguide section of the meandering waveguide, reduces the speed of the equal phase surface transmission, reduces the group velocity, and improves the coupling impedance in the slow wave system.

[0022] 2. The meandering waveguide slow wave structure of the present application adopts a strip-shaped electron beam channel, which has a larger electron beam cross-sectional area compared with the traditional circular electron beam channel, can load a larger working current, and increases the output power capacity of the device; and the strip-shaped electron beam channel structure is simple and easy to assemble, which is beneficial to the implementation of micro-processing technology.

[0023] 3. The meandering waveguide slow wave structure of the present application has higher coupling impedance, wider working frequency band, and easier processing. BRIEF DESCRIPTION OF DRAWINGS

[0024] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present application and constitute a part of the application, illustrate embodiments of the present application and do not limit the present application. In the drawings:

[0025] Figure 1 is a single period vacuum model of a traditional meandering waveguide slow wave structure;

[0026] Figure 2 is a single period metal model cross-sectional view of a traditional meandering waveguide slow wave structure;

[0027] Figure 3 is a single period metal model of a traditional meandering waveguide slow wave structure;

[0028] Figure 4 is a single period vacuum model of a ridge-loaded meandering waveguide slow wave structure.

[0029] Figure 5 is a single period metal model cross-sectional view of a ridge-loaded meandering waveguide slow wave structure;

[0030] Figure 6Single period metal model of the ridge-loaded meander waveguide slow wave structure;

[0031] Figure 7 Single period vacuum model of the single period interleaved grid distributed loaded meander waveguide slow wave structure according to an embodiment of the present invention.

[0032] Figure 8 Single period metal model cross section of the single period interleaved grid distributed loaded meander waveguide slow wave structure according to an embodiment of the present invention;

[0033] Figure 9 Single period metal model of the single period interleaved grid distributed loaded meander waveguide slow wave structure according to an embodiment of the present invention;

[0034] Figure 10 Multi period vacuum model of the single period interleaved grid distributed loaded meander waveguide slow wave structure according to an embodiment of the present invention;

[0035] Figure 11 Single period vacuum model of the three period interleaved grid distributed loaded meander waveguide slow wave structure according to an embodiment of the present invention;

[0036] Figure 12 Single period vacuum model of the single period interleaved grid distributed loaded meander waveguide slow wave structure according to an embodiment of the present invention (with 2 electron beam channels);

[0037] Figure 13 Dispersion characteristic curve of the slow wave structure.

[0038] Figure 14 Coupling impedance characteristic curve of the slow wave structure.

[0039] Reference signs and corresponding names of parts:

[0040] 1 - bend waveguide section, 2 - straight waveguide section, 3 - electron beam channel, 4 - metal ridge structure, 5 - interleaved grid structure. DETAILED DESCRIPTION

[0041] Hereinafter, the term "include" or "may include" used in various embodiments of the present invention indicates the existence of the invented function, operation, or element, and does not limit one or more functions, operations, or elements to be added. Also, as used in various embodiments of the present invention, the terms "include", "have", and their conjugates merely indicate the presence of specific features, numbers, steps, operations, elements, components, or combinations thereof, and should not be construed as excluding the presence or addition of one or more other features, numbers, steps, operations, elements, components, or combinations thereof in advance.

[0042] In various embodiments of the present application, the expression "or" or "at least one of A or / and B" includes any and all combinations of the listed terms. For example, the expression "A or B" or "at least one of A or / and B" can include A, can include B, or can include both A and B.

[0043] The expressions used in various embodiments of the present application, such as "first", "second", and the like, can modify various constituent elements in various embodiments, but can not limit the corresponding constituent elements. For example, the above expressions do not limit the order and / or importance of the elements. The above expressions are used only for the purpose of distinguishing one element from another. For example, the first user device and the second user device indicate different user devices, although both are user devices. For example, a first element can be called a second element, and likewise, a second element can be called a first element, without departing from the scope of various embodiments of the present application.

[0044] It should be noted that if a description connects one constituent element to another constituent element, the first constituent element can be directly connected to the second constituent element, and a third constituent element can be "connected" between the first constituent element and the second constituent element. Conversely, when one constituent element is "directly connected" to another constituent element, it can be understood that there is no third constituent element between the first constituent element and the second constituent element.

[0045] The terms used in various embodiments of the present application are used only for the purpose of describing particular embodiments and are not intended to limit various embodiments of the present application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms used herein, including technical terms and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments of the present application belong. The terms such as those defined in a generally used dictionary will be interpreted to have the same meaning as the contextual meaning in the relevant technical field and will not be interpreted to have idealized or overly formal meanings, unless clearly defined in various embodiments of the present application.

[0046] In order to make the purposes, technical solutions, and advantages of the present application more clear, further detailed descriptions of the present application will be made below in conjunction with embodiments and drawings, the illustrative embodiments of the present application and the descriptions thereof are used only to explain the present application and do not limit the present application.

[0047] Embodiment 1:

[0048] As Figures 1-3As shown, the traditional tortuous waveguide slow wave structure consists of three parts: a bent waveguide section 1, a straight waveguide section 2, and an electron beam channel 3. The bent waveguide section 1 and the straight waveguide section 2 have identical cross-sections. By connecting the bent waveguide section 1 and the straight waveguide section 2 end-to-end, and opening an electron beam channel 3 along the central axis of symmetry of the straight waveguide section 2, the traditional tortuous waveguide slow wave structure can be obtained.

[0049] However, with increasing operating frequencies, the size of traditional tortuous waveguide slow-wave structures shrinks due to size coherence effects, limiting the electron beam cross-sectional area and current capacity. Therefore, to improve the coupling impedance of tortuous waveguides, a ridge-loaded tortuous waveguide slow-wave structure has been proposed, specifically as follows: Figures 4-6 As shown, based on the traditional tortuous waveguide structure, the tortuous waveguide is made possible by adding a metal ridge structure 4 to the straight waveguide segment 2 (a total of 8 ridge structures are loaded in a single cycle), which increases the coupling impedance while increasing the size of the slow wave structure.

[0050] Although the ridge-loaded tortuous waveguide slow-wave structure can improve the coupling impedance to some extent, it will increase the dispersion. At the same time, as the operating frequency rises to the W-band and terahertz band, the effect of ridge loading on improving the coupling impedance is poor, and it also brings great difficulties to the manufacturing process.

[0051] Based on this, this embodiment proposes a tortuous waveguide slow-wave structure with staggered grating loading, specifically as follows: Figures 7-10 As shown, the tortuous waveguide slow-wave structure proposed in this embodiment is based on the traditional tortuous waveguide slow-wave structure, with staggered grid structures 5 placed on both sides of the electron beam channel 3 of the straight waveguide segment 2. This embodiment extends the propagation path of electromagnetic waves in the slow-wave structure by rationally distributing the staggered grids, reducing the phase velocity and group velocity of electromagnetic waves in the slow-wave structure, and concentrating more energy near the electron beam channel region. This effectively enhances the longitudinal electric field distribution within the electron beam channel region, improving the operating bandwidth and coupling impedance.

[0052] As an optional implementation, the staggered grid structures 5 are symmetrically arranged on adjacent straight waveguide segments 2.

[0053] It should be noted that, Figures 7-10 Only a single-period staggered grating structure is shown (i.e., only one set of staggered metal gratings is provided, the set of staggered metal gratings includes two metal gratings which are respectively staggered on both sides of a single straight waveguide segment, thus forming a single-period staggered grating structure). This is for illustrative purposes only and does not limit the period of the staggered grating structure. In other alternative embodiments, a two-period or multi-period staggered grating structure can also be provided (i.e., at least two sets of staggered metal gratings are provided along a single straight waveguide segment, thus forming a two-period or multi-period staggered grating structure). For example, it can be set as follows: Figure 11The three-period staggered grating structure shown is (i.e., three sets of staggered metal gratings are arranged along a single waveguide segment).

[0054] in addition, Figures 7-11 The staggered grid structure 5 shown is rectangular, which is an illustrative example and does not limit the shape of the grid structure. In other alternative embodiments, it can also be set as a semi-circle, polygon, etc.

[0055] In the tortuous waveguide slow-wave structure proposed in this embodiment, the electron beam channel 3 is preferably a strip-shaped electron beam channel. Compared with a circular electron beam channel, the strip-shaped electron beam channel has a larger electron beam cross-sectional area, which can carry a larger operating current and increase the output power capacity of the device. In addition, the strip-shaped electron beam channel has a simple structure, is easy to assemble, and is easy to process. It should be noted that... Figures 7-9 The illustrated strip-shaped electron beam channel is merely illustrative and not intended to limit the scope of the invention. In other alternative embodiments, the electron beam channel may also be a circular channel or an elliptical channel, etc. It should be noted that... Figures 7-11 Only one electron beam channel structure is shown for illustrative purposes and is not intended to limit the number of electron beam channels. In other alternative embodiments, two or more electron beam channels may be provided, and all two or more electron beam channels may be arranged on the central axis of symmetry of the straight waveguide segment 2 and uniformly distributed laterally along the waveguide structure. For example, a structure can be configured as follows: Figure 12 The two electron beam channels are shown.

[0056] This embodiment also proposes a traveling wave tube, which includes the above-mentioned tortuous waveguide slow wave structure with staggered dual-grid separate loading.

[0057] Example 2:

[0058] This embodiment compares the performance of the staggered-gate split-loaded tortuous waveguide slow wave structure proposed in the above embodiment with the traditional tortuous waveguide slow wave structure and the ridge-loaded tortuous waveguide slow wave structure by simulating the high-frequency electromagnetic characteristics.

[0059] In the traditional tortuous waveguide slow wave structure model, the single-cycle length P1 is 1.2 mm, the straight waveguide segment length h1 is 0.4 mm, the waveguide grating thickness w is 0.3 mm, and the electron beam channel height Tx is 0.2 mm.

[0060] The single-cycle length of the ridge-loaded tortuous waveguide slow-wave structure model is 1.2 mm, the straight waveguide segment length h2 is 0.4 mm, the waveguide grating thickness w is 0.3 mm, the electron beam channel Tx is 0.2 mm, the single grating width n of the loaded ridge structure is 0.1 mm, and the single grating thickness m of the loaded ridge structure is 0.1 mm.

[0061] The single-cycle length P2 of the tortuous waveguide slow wave structure model with staggered gratings separately loaded in Embodiment 1 above is 1.2 mm, the straight waveguide segment length h2 is 0.4 mm, the single grating width of the loaded staggered grating structure is 0.1 mm, and the single grating thickness of the loaded staggered grating structure is 0.1 mm.

[0062] The three tortuous waveguide slow wave structure models were constructed using vacuum as the material, and the model metal was high-conductivity oxygen-free copper with a surface roughness of 1 μm.

[0063] Simulations yielded dispersion characteristic curves for three slow-wave structures, such as... Figure 13 As shown in the figure, within the frequency range of 93GHz-130GHz, the phase velocity of the electromagnetic wave in the slow-wave structure proposed in this embodiment of the invention does not change significantly with frequency, ensuring that the slow-wave structure proposed in this embodiment of the invention has a wide operating bandwidth. Compared with the traditional tortuous waveguide slow-wave structure, the slow-wave structure proposed in this embodiment of the invention has lower phase velocity and group velocity, i.e., lower operating voltage, making it easier to implement, extending the device's lifespan, and improving safety; compared with the relatively narrow bandwidth of the ridged tortuous waveguide slow-wave structure, the slow-wave structure proposed in this embodiment of the invention has a significantly wider bandwidth.

[0064] Simulations yielded coupling impedance characteristic curves for three slow-wave structures, as follows: Figure 14 As shown in the figure, compared with the traditional tortuous waveguide slow wave structure and the tortuous waveguide slow wave structure with spine, the slow wave structure proposed in this embodiment of the invention has a higher coupling impedance. It is foreseeable that the tortuous waveguide slow wave structure with staggered dual-grid loading can be used in traveling wave tubes to perform injection-wave interaction more efficiently, thereby achieving greater power output and higher electronic efficiency.

[0065] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A tortuous waveguide slow-wave structure with staggered grid loading, comprising a curved waveguide section and a straight waveguide section; the curved waveguide section and the straight waveguide section are connected end-to-end to form a single-period structure of the slow-wave structure, and an electron beam channel is provided on the central axis of symmetry of the straight waveguide section, characterized in that, Each of the straight waveguide segments has an interleaved grating structure on both sides of the electron beam channel to extend the transmission path of electromagnetic waves in the slow-wave structure and reduce the phase velocity and group velocity of electromagnetic waves in the slow-wave structure; the interleaved grating structure includes at least two metal gratings and at least two metal gratings are interleaved on both sides of a single straight waveguide segment along the extension direction of the electron beam channel; the width of the metal grating is 0.1 mm and the thickness of the metal grating is 0.1 mm.

2. The tortuous waveguide slow-wave structure with staggered gratings and distributed loading according to claim 1, characterized in that, The staggered gate structure is a single-period staggered gate structure.

3. The tortuous waveguide slow-wave structure with staggered grating loading according to claim 1, characterized in that, The staggered gate structure is a two-period or multi-period staggered gate structure.

4. The tortuous waveguide slow-wave structure with staggered gratings and distributed loading according to claim 1, characterized in that, The staggered grid structure can be rectangular, semi-circular, or polygonal.

5. A tortuous waveguide slow-wave structure with staggered grating loading according to any one of claims 1-4, characterized in that, The electron beam channel is a strip channel.

6. A tortuous waveguide slow-wave structure with staggered grating loading according to any one of claims 1-4, characterized in that, The electron beam channel is either a circular channel or an elliptical channel.

7. A tortuous waveguide slow-wave structure with staggered grating loading according to any one of claims 1-4, characterized in that, The electron beam channel is at least one.

8. The tortuous waveguide slow-wave structure with staggered grating loading according to claim 7, characterized in that, At least one of the electron beam channels is uniformly arranged along the transverse direction of the waveguide.

9. A tortuous waveguide slow-wave structure with staggered grating loading according to any one of claims 1-4, characterized in that, The straight waveguide section and the curved waveguide section have the same cross-section.

10. A traveling wave tube, characterized in that, The traveling wave tube includes the tortuous waveguide slow wave structure as described in any one of claims 1-9.

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