Slow wave structure of a traveling wave tube and traveling wave tube

Abstract

The application relates to a slow wave structure of a traveling wave tube. The slow wave structure comprises a waveguide, a rectangular grid and an electron beam channel. The waveguide comprises two periodically arranged waveguides; a coupling cavity is formed between the two periodically arranged waveguides, and the periods of the two periodically arranged waveguides are the same; the rectangular grid is arranged in the coupling cavity; the number of rectangular blocks in the rectangular grid corresponds to the number of periods of the periodically arranged waveguides; the electron beam channel is arranged between the waveguide and the rectangular grid; the advancing direction of electromagnetic waves in the waveguide, the arrangement direction of the rectangular blocks in the rectangular grid and the transmission direction of the electron beam in the electron beam channel satisfy a similarity condition. The method can improve the input direct current of the slow wave structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vacuum electron technology, in particular to a slow wave structure of a traveling wave tube and a traveling wave tube. BACKGROUND

[0002] Terahertz waves have a frequency range of 0.1-10 THz between the infrared and microwave bands. It is well known that electromagnetic waves in this frequency range have important research value and wide application prospects in high-speed space communication, ultra-high resolution weapon guidance, medical imaging, material terahertz spectral feature analysis, security inspection, material detection, etc. The traveling wave tube is a very important vacuum electron tube in the field of microwave technology. Due to its high power, wide frequency band, large dynamic range, low noise, high gain and other excellent characteristics, it is widely used in radar, communication, television, broadcasting, telemetry, electronic countermeasure and other electronic equipment.

[0003] At present, the main slow wave structures of the traveling wave tube in the terahertz wave band are the trapezoidal staggered double-grid slow wave structure, the rectangular staggered double-grid structure, etc. However, the axial coupling impedance of the existing trapezoidal staggered double-grid slow wave structure, rectangular staggered double-grid structure, etc. is low, which means that the beam-wave interaction efficiency is not high, which will lead to the problem of low input direct current of the slow wave structure. SUMMARY

[0004] Therefore, it is necessary to provide a slow wave structure of a traveling wave tube and a traveling wave tube capable of improving the input direct current.

[0005] In a first aspect, the present application provides a slow wave structure of a traveling wave tube, comprising a waveguide, a rectangular grid and an electron beam channel:

[0006] The waveguide comprises two periodically arranged waveguides; a coupling cavity is formed between each of the periodically arranged waveguides, and the periods of the periodically arranged waveguides are the same;

[0007] The rectangular grid is located in the coupling cavity; the number of rectangular blocks in the rectangular grid corresponds to the number of periods of the periodically arranged waveguides;

[0008] The electron beam channel is located between the waveguide and the rectangular grid;

[0009] The advancing direction of the electromagnetic wave in the waveguide, the arrangement direction of each rectangular block in the rectangular grid, and the transmission direction of the electron beam in the electron beam channel satisfy the similarity condition.

[0010] In one embodiment, the periodically arranged waveguide is a sinusoidal waveguide.

[0011] In one of the embodiments, the periodic waveguide includes a first periodic waveguide and a second periodic waveguide; the electron beam channel includes a first electron beam channel between the first periodic waveguide and the rectangular grid, and a second electron beam channel between the second periodic waveguide and the rectangular grid.

[0012] In one of the embodiments, the number of the rectangular grids is plural, wherein,

[0013] The number of the rectangular blocks in each of the rectangular grids is the same as the number of the periods of the periodic waveguide; the arrangement direction of the rectangular blocks in each of the rectangular grids is the same.

[0014] In one of the embodiments, the included angle between the rectangular blocks and the arrangement direction in different rectangular grids is the same.

[0015] In one of the embodiments, the included angle between the rectangular blocks and the arrangement direction is 20° to 40°.

[0016] In one of the embodiments, further comprising:

[0017] A third electron beam channel between the rectangular grids; the transmission direction of the electron beam in the third electron beam channel and the advancing direction of the electromagnetic wave in the waveguide satisfy the similarity condition.

[0018] In one of the embodiments, the electron beam channel is separated from the rectangular grid; the electron beam channel is separated from the waveguide.

[0019] In one of the embodiments, the cross-sectional shape of the electron beam channel is circular.

[0020] In a second aspect, the application provides a traveling wave tube, including the slow wave structure.

[0021] The slow wave structure of the traveling wave tube, by setting two periodic waveguides, setting a rectangular grid in the coupling cavity between the periodic waveguides, and setting an electron beam channel between the waveguide and the rectangular grid, and the advancing direction of the electromagnetic wave in the waveguide, the arrangement direction of the rectangular blocks in the rectangular grid, and the transmission direction of the electron beam in the electron beam channel satisfy the similarity condition, so that the electron beam transmitted in the electron beam channel acts on the longitudinal electric field formed by the electromagnetic wave transmitted in the periodic waveguide, which can improve the coupling impedance, and also can increase the input direct current of the slow wave structure. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description only represent some embodiments of the present application, and for those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0023] Figure 1 A slow wave structure of a traveling wave tube in an embodiment;

[0024] Figure 2 A schematic diagram of a forward direction of electromagnetic waves in an embodiment;

[0025] Figure 3 A left side view of a slow wave structure of a traveling wave tube in a specific embodiment;

[0026] Figure 4 A front view of a slow wave structure of a traveling wave tube in a specific embodiment;

[0027] Figure 5 A three-dimensional front view of a slow wave structure of a traveling wave tube in a specific embodiment;

[0028] Figure 6 A three-dimensional front view of a slow wave structure of a traveling wave tube in another specific embodiment;

[0029] Figure 7 A normalized phase velocity curve of a slow wave structure of a traveling wave tube in a specific embodiment.

[0030] BRIEF DESCRIPTION OF DRAWINGS DETAILED DESCRIPTION

[0031] In order to facilitate the understanding of the present application, the present application will be described in more detail below with reference to the relevant drawings. The drawings show embodiments of the present application. However, the present application can be implemented in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein only for the purpose of describing specific embodiments of the present application, and is not intended to limit the present application.

[0033] It will be understood that the terms "first", "second", etc. can be used herein to describe various elements, but the elements should not be limited by these terms. The terms are only used to distinguish one element from another. For example, a first periodic waveguide could be termed a second periodic waveguide, and similarly, a second periodic waveguide could be termed a first periodic waveguide, without departing from the scope of the present application. Both the first periodic waveguide and the second periodic waveguide are periodic waveguides, but they are not the same periodic waveguide.

[0034] Spatially relative terms, such as "beneath", "below", "lower", "under", "above", "upper" and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use and / or operation in addition to the orientations depicted in the figures. For example, if a device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device can also be oriented in the other direction, and the spatially relative terms used herein are intended to encompass such additional

[0035] It will be understood that the "connection" in the following embodiments, if the circuits, modules, units and the like connected between each other have the transmission of electrical signals or data, should be understood as "electrically connected", "communicatively connected" and the like.

[0036] As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. It will be further understood that the terms "comprises", "comprising", "includes" and / or "including", or the like, when used in this specification, specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

[0037] In some embodiments, as Figure 1As shown, the slow wave structure 100 of the traveling wave tube includes a waveguide 110, a rectangular grid 120, and an electron beam channel 130. The waveguide 110 includes two periodically arranged waveguides, a coupling cavity is formed between each of the periodically arranged waveguides, and the periods of the periodically arranged waveguides are the same. The rectangular grid 120 is located in the coupling cavity, and the number of rectangular blocks in the rectangular grid 120 corresponds to the number of periods of the periodically arranged waveguides. The electron beam channel 130 is located between the waveguide 110 and the rectangular grid. The direction of the electromagnetic wave in the waveguide 110, the arrangement direction of the rectangular blocks in the rectangular grid 120, and the transmission direction of the electron beam in the electron beam channel 130 satisfy the similarity condition.

[0038] The waveguide is a structure for directional guiding of electromagnetic waves. For example, a periodically arranged waveguide. The periodically arranged waveguide refers to a waveguide in which the wave shape periodically changes. For example, a sinusoidal waveguide, a flat-top sinusoidal waveguide, and a half-period rectangular staggered double-grid waveguide, etc. The positions of the two periodically arranged waveguides in the slow wave structure of the traveling wave tube are relative positions. For example, periodically arranged waveguide A is located on the upper side of the slow wave structure of the traveling wave tube, and periodically arranged waveguide B is located on the lower side of the slow wave structure of the traveling wave tube. For another example, periodically arranged waveguide A is located on the left side of the slow wave structure of the traveling wave tube, and periodically arranged waveguide B is located on the right side of the slow wave structure of the traveling wave tube. In addition, the two periodically arranged waveguides have the same undulation height and period. The undulation height refers to the amplitude, that is, the maximum height difference perpendicular to the direction of the electromagnetic wave, and the period corresponds to the frequency.

[0039] The coupling cavity is a cavity formed by the space between the two periodic waveguides and the sidewall of the slow wave structure. In one embodiment, the phase difference between the two periodic waveguides is zero. That is, the distance between the two periodic waveguides is the same in any cross section perpendicular to the direction of the electromagnetic wave. The rectangular grid is a full-metal structure formed by a plurality of parallel rectangular blocks with equal width and equal spacing arranged in a specific direction, which has the advantages of good heat dissipation, large power capacity, high coupling impedance, easy processing, etc., and can be applied to the terahertz frequency band. The number of rectangular grids is not unique, for example, it can be one or more. The arrangement direction of the rectangular blocks in the plurality of rectangular grids can be the same or different. In the case where the arrangement direction of the rectangular blocks in each rectangular grid is different, the included angle between each arrangement direction is less than a set angle, or the included angle between each arrangement direction is less than or equal to a set angle. Further, the spacing between adjacent rectangular blocks in each rectangular grid can be the same or different. In the case where the spacing between adjacent rectangular blocks in each rectangular grid is different, it is only necessary to ensure that the number of rectangular blocks in the rectangular grid corresponds to the number of periods of the periodic waveguide. The number of rectangular blocks in the rectangular grid corresponding to the number of periods of the periodic waveguide can mean that the number of the two is the same, or the number of rectangular blocks and the number of periods are in a multiple relationship. For example, when the number of rectangular grids is one, the number of rectangular blocks in the rectangular grid is the same as the number of periods of the periodic waveguide. For another example, when the number of rectangular grids is two, the number of rectangular blocks in the rectangular grid is twice the number of periods of the periodic waveguide, and the two rectangular grids are evenly distributed in the space between the two periodic waveguides.

[0040] The electron beam channel is a channel for transmitting the electron beam with a certain size, shape and current generated by the electron gun, and accelerating the electron beam to be faster than the phase velocity of the electromagnetic wave in the slow wave mode, so as to exchange energy with the electromagnetic wave. The electron beam can also be understood as an electron beam. The number of electron beam channels depends on the number of rectangular grids, which can be one, two or three, and the transmission direction of the electron beam is consistent with the extension direction of the electron beam channel. For example, when one rectangular grid is loaded in the coupling cavity formed by two waveguides, one electron beam channel can be arranged between one of the waveguides and the rectangular grid, that is, the distribution among the waveguide, the electron beam channel and the rectangular grid is waveguide-electron beam channel-rectangular grid-waveguide or waveguide-rectangular grid-electron beam channel-waveguide. For another example, when one rectangular grid is loaded in the coupling cavity formed by two waveguides, one electron beam channel can be arranged between the two waveguides and the rectangular grid, that is, the distribution among the waveguide, the electron beam channel and the rectangular grid is waveguide-electron beam channel-rectangular grid-electron beam channel-waveguide. For another example, when two rectangular grids are loaded in the coupling cavity between the two waveguides, the distribution among the waveguide, the electron beam channel and the rectangular grid can also be waveguide-electron beam channel-rectangular grid-electron beam channel-rectangular grid-electron beam channel-waveguide.

[0041] The relative positional relationship between the electron beam channel and the waveguide, and between the electron beam channel and the rectangular grating, can be intersecting, tangent, or disjoint. For example, the electron beam channel may intersect with the waveguide, intersect with the rectangular grating, be disjoint with the waveguide, be tangent to the waveguide, or be tangent to the rectangular grating. Any one or more of these conditions can constitute the relative positional relationship between the electron beam channel and the waveguide, and between the electron beam channel and the rectangular grating, in this embodiment.

[0042] The cross-sectional shape of an electron beam channel is not unique. For example, when there is only one electron beam channel, its cross-sectional shape can be circular, rectangular, or elliptical. Similarly, when there are two or more electron beam channels, the cross-sectional shape of each channel can be the same or different.

[0043] Furthermore, the propagation direction of the electromagnetic wave in the waveguide, the arrangement direction of the rectangular blocks in the rectangular grating, and the propagation direction of the electron beam in the electron beam channel satisfy similarity conditions. Here, the propagation direction of the electromagnetic wave in the waveguide refers to the direction of wave propagation, such as... Figure 2 As shown. Satisfying the similarity condition means that the angle between any two lines containing the propagation direction of the electromagnetic wave in the waveguide, the arrangement direction of the rectangular blocks in the rectangular grating, and the propagation direction of the electron beam in the electron beam channel must be within an allowable range. The allowable range can be a closed range including the upper and lower limits, and all values ​​between the upper and lower limits; it can be a half-open range including one of the upper and lower limits, and all values ​​between the upper and lower limits; or it can be a fully open range including only all values ​​between the upper and lower limits. No limitation is made here. The lower limit can be zero, and the upper limit can be a set angle greater than zero, such as 0.5° or 1°.

[0044] Specifically, in the slow-wave structure of the traveling wave tube, two periodic waveguides with the same period are set up, and a coupling cavity can be formed between the two periodic waveguides. A rectangular grating is set in the coupling cavity, and the number of rectangular blocks in the rectangular grating corresponds to the number of periods of the periodic waveguides. An electron beam channel is set between the waveguides and the rectangular grating to transmit the electron beam emitted by the electron gun. The transmission direction of the electron beam in the electron beam channel, the propagation direction of the electromagnetic wave in the waveguide, and the arrangement direction of the rectangular blocks in the rectangular grating are all set, and the included angles between the straight lines containing these three directions are within an allowable range.

[0045] In the embodiment, two periodic waveguides are arranged, a rectangular grid is arranged in the coupling cavity between the periodic waveguides, and an electron beam channel is arranged between the waveguides and the rectangular grid, and the advancing direction of the electromagnetic wave in the waveguide, the arrangement direction of the rectangular blocks in the rectangular grid, and the transmission direction of the electron beam in the electron beam channel satisfy the similar condition, so that the electron beam transmitted in the electron beam channel acts on the longitudinal electric field formed by the electromagnetic wave transmitted in the periodic waveguide, and the coupling impedance can be improved, and at the same time, the structure can also increase the input direct current of the slow wave structure.

[0046] In one of the embodiments, the periodic waveguide is a sinusoidal waveguide.

[0047] The sinusoidal waveguide refers to a waveguide with a sinusoidal function form, and is formed by periodically rising and falling along the direction perpendicular to the electromagnetic wave transmission direction with the axis of the conventional rectangular waveguide as the center line. In one of the embodiments, the phase difference between the two sinusoidal waveguides can be zero or within a set range. The set range can be less than or equal to a set phase difference. The set phase difference can be 0.1π, 0.5π or π, which is not limited herein.

[0048] In the embodiment, the sinusoidal waveguide with the advantage of reducing transmission loss is used as the periodic waveguide in the slow wave structure, which can reduce the loss of the electron beam transmitted in the electron beam channel, so that the slow wave structure formed can be suitable for high-power terahertz traveling wave devices.

[0049] In one of the embodiments, the periodic waveguide includes a first periodic waveguide and a second periodic waveguide. The electron beam channel includes a first electron beam channel between the first periodic waveguide and the rectangular grid, and a second electron beam channel between the second periodic waveguide and the rectangular grid.

[0050] The first periodic waveguide and the second periodic waveguide are two waveguides arranged correspondingly, and the first electron beam channel and the second electron beam channel are respectively located in the gap between the rectangular grid and the two waveguides. In one of the embodiments, the transmission directions of the electron beams in the first electron beam channel and the second electron beam channel can be the same or opposite.

[0051] The positions of the first electron beam channel and the second electron beam channel in the slow wave structure can be completely corresponding or different. The completely corresponding means that the positions of the first electron beam channel between the first periodic waveguide and the rectangular grid and the second electron beam channel between the second periodic waveguide and the rectangular grid are completely the same. For example, the first electron beam channel is located at the edge side of the gap between the first periodic waveguide and the rectangular grid, and the second electron beam channel is also located at the edge side of the gap between the second periodic waveguide and the rectangular grid.

[0052] The different positions of the first electron beam channel and the second electron beam channel in the slow wave structure refer to, for example, that the first electron beam channel is located at the edge side of the gap between the first periodic waveguide and the rectangular grid, and the second electron beam channel is located at the center of the gap between the second periodic waveguide and the rectangular grid.

[0053] The cross-sectional shapes of the first electron beam channel and the second electron beam channel can be the same or different. For example, the cross-sectional shape of the first electron beam channel is circular, and the cross-sectional shape of the second electron beam channel is rectangular. For another example, the first electron beam channel and the second electron beam channel are both circular.

[0054] Specifically, the relative positions in the slow wave structure of the traveling wave tube correspond to the arrangement of the first periodic waveguide and the second periodic waveguide, a coupling cavity is formed between the first periodic waveguide and the second periodic waveguide, and the periods of the first periodic waveguide and the second periodic waveguide are the same. The rectangular grid is located in the coupling cavity formed by the first periodic waveguide and the second periodic waveguide, and the number of rectangular blocks in each rectangular grid corresponds to the number of periods of the first periodic waveguide. The first electron beam channel is located between the first periodic waveguide and the rectangular grid, and the second electron beam channel is located between the second periodic waveguide and the rectangular grid. The angle between the straight lines where the advancing direction of the electromagnetic wave in the first periodic waveguide and the second periodic waveguide, the arrangement direction of the rectangular blocks in the rectangular grid, and the transmission direction of the electron beam in the first electron beam channel and the second electron beam channel are zero or within an allowable range.

[0055] In the present embodiment, by arranging the electron beam channels between the first periodic waveguide and the rectangular grid, and between the second periodic waveguide and the rectangular grid, the input direct current of the slow wave structure can be increased, so that the output power of the slow wave structure of the traveling wave tube is increased.

[0056] In one of the embodiments, the angle between the rectangular block and the arrangement direction is 20° to 40°, for example, 20°, 25°, 30°, 35°, or 40°.

[0057] When the angle between the rectangular block and the arrangement direction is outside the range of 20° to 40°, for example, the angle between the rectangular block and the arrangement direction is 15°, the longitudinal magnetic field in the slow wave structure will be weakened, which will result in that the phase velocity of the electromagnetic wave cannot be effectively reduced, and thus the effective energy conversion between the electron beam and the field cannot be guaranteed. In the present embodiment, by setting the angle between the rectangular block and the arrangement direction within the range of 20° to 40°, the longitudinal magnetic field in the electron beam channel can be enhanced, so that the phase velocity of the electromagnetic wave is reduced, and thus the effective energy conversion between the electron beam and the field can be guaranteed. In one of the embodiments, the number of the rectangular grids is multiple, and the number of the rectangular blocks in each rectangular grid is the same as the number of the periods of the periodic waveguide. The arrangement direction of the rectangular blocks in each rectangular grid satisfies the similar condition with the advancing direction of the electromagnetic wave in the waveguide.

[0058] The number of the rectangular grids is at least two or more. For example, the number of the rectangular grids is two or three.

[0059] The similar condition is that the angle between the arrangement direction of the rectangular blocks in each row of the rectangular grids and the straight line on which the electromagnetic wave in the waveguide and the propagation direction of the wave lie is within the allowable range.

[0060] Specifically, two periodic waveguides are arranged at the relative positions in the slow wave structure of the traveling wave tube, and a coupling cavity is formed between the two periodic waveguides. The two rectangular grids are evenly distributed in the coupling cavity and form three highly equivalent gaps with the two periodic waveguides. The channel on the gap is the electron beam channel, and the number of the rectangular blocks in each rectangular grid is the same as the number of the periods of the periodic waveguide. The angle between the arrangement direction of the rectangular blocks in the rectangular grid and the straight line on which the electromagnetic wave in the waveguide and the propagation direction of the wave lie is within the allowable range.

[0061] In the embodiment, by arranging the number of the rectangular blocks in each rectangular grid to be the same as the number of the periods of the periodic waveguide, it can be ensured that each period has the same number of electron beam channels and has a consistent coupling impedance, so that the electron beam can be effectively converted when transmitting, thereby improving the input direct current of the slow wave structure.

[0062] In one of the embodiments, the angles between the rectangular blocks and the arrangement direction in different rectangular grids are the same.

[0063] Specifically, two periodic waveguides are arranged at the relative positions in the slow wave structure of the traveling wave tube, and a coupling cavity is formed between the two periodic waveguides. The two rectangular grids are evenly distributed in the coupling cavity and form three highly equivalent gaps with the two periodic waveguides. The channel on the gap is the electron beam channel. The number of the rectangular blocks in each rectangular grid is the same as the number of the periods of the periodic waveguide, and the angle between the rectangular blocks and the arrangement direction in each rectangular grid is the same. The angle between the arrangement direction of the rectangular blocks in the rectangular grid and the straight line on which the electromagnetic wave in the waveguide and the propagation direction of the wave lie is zero or within the allowable range.

[0064] In the embodiment, by arranging the angles between the rectangular blocks and the arrangement direction in different rectangular grids to be the same, the longitudinal electric field in the slow wave structure can be enhanced, the input direct current of the slow wave structure can be improved, the output power of the slow wave structure can be increased, and the gain can be increased.

[0065] In one of the embodiments, the slow wave structure of the traveling wave tube further comprises:

[0066] A third electron beam channel is located between the rectangular grids. The transmission direction of the electron beam in the third electron beam channel and the propagation direction of the electromagnetic wave in the waveguide satisfy the similar condition.

[0067] The relative position relationship between the third electron beam channel and each rectangular grid can be intersecting, tangential or separated.

[0068] In the embodiment, the number of electron beam channels is increased by arranging the third electron beam channel between two adjacent rectangular grids, so that each electron beam interacts with the high-frequency field in the drift space, thereby increasing the high-frequency amplification factor of the slow wave structure, improving the input direct current and the output power, and increasing the gain.

[0069] In one of the embodiments, the electron beam channel is separated from the rectangular grid. The electron beam channel is separated from the waveguide.

[0070] The separation means that there is no contact between the two. For example, if there is no contact point or contact surface between the electron beam channel and the rectangular grid, it means that the electron beam channel is separated from the rectangular grid. For another example, if there is no contact point or contact surface between the electron beam channel and the waveguide, it means that the electron beam channel is separated from the waveguide. When the distance between the rectangular grid and the waveguide or the distance between the rectangular grids cannot meet the condition that the electron beam channel is separated from the rectangular grid or the waveguide, a part of the rectangular block in the rectangular grid is removed, so that the electron beam channel is separated from the rectangular grid and the waveguide.

[0071] Specifically, the relative position relationship between the electron beam channel and the waveguide is set to be separated, and the relative position relationship between the electron beam channel and the rectangular grid is set to be separated.

[0072] In the embodiment, the electron beam channel is arranged to be separated from the rectangular grid and the waveguide, so that the electron beam can pass through the slow wave structure smoothly and fully interact with the electromagnetic wave when the electron beam is transmitted in the channel without contacting the hardware structure of the waveguide or the rectangular grid.

[0073] In one of the embodiments, the cross-sectional shape of the electron beam channel is circular.

[0074] Specifically, two periodic waveguides with the same period are arranged in the slow wave structure of the traveling wave tube, and a coupling cavity is formed between the two periodic waveguides. A rectangular grid is arranged in the coupling cavity, and the number of rectangular blocks in the rectangular grid corresponds to the number of periods of the periodic waveguide. An electron beam channel with a circular cross-sectional shape is arranged between the waveguide and the rectangular grid to transmit the electron beam emitted by the electron gun, and the transmission direction of the electron beam in the electron beam channel, the advancing direction of the electromagnetic wave in the waveguide and the arrangement direction of the rectangular blocks in the rectangular grid are arranged within the allowable range of the included angle between the straight lines where the three directions are located.

[0075] In the embodiment, the cross-sectional shape of the electron beam channel is set to be circular, which can reduce the loss of the electron beam, thereby improving the gain rate of the slow wave structure of the traveling wave tube.

[0076] The slow wave structure of the traveling wave tube is described in detail below. Figures 3 to 7

[0077] In one specific embodiment, two sinusoidal waveguides are arranged at opposite positions of the slow wave structure, the wide side length of the two sinusoidal waveguides is a = 1.77 mm, the narrow side length of the sinusoidal waveguide is b = 3.1 mm, the height of the periodic undulation is h = 0.55 mm, and the periodic length of the periodic undulation is p = 1.02 mm. Two rectangular grids are located in the coupling cavities in the middle of the two sinusoidal waveguides, the centers of the two rectangular grids are vertically arranged, and the number of rectangular blocks in each of the two rectangular grids is the same as the number of periods of the sinusoidal waveguide, that is, one pair of rectangular grids with vertically arranged centers is arranged in each waveguide period, and the two rows of rectangular grids are evenly distributed in the space between the two waveguides to form three gaps with the same height as the waveguides. The circular channel on the gap is the electron beam channel. The angle between each rectangular block and the arrangement direction of the rectangular blocks in the two rectangular grids is θ = 30°, and the vertical height with the arrangement direction is m = 0.775 mm, the thickness of each rectangular block is n = 0.2 mm, and the vertical distance between the two rectangular grids is t = 0.15 mm. The first electron beam channel is located between one of the sinusoidal waveguides and the rectangular grid adjacent to the sinusoidal waveguide, the second electron beam channel is located between the other sinusoidal waveguide and the rectangular grid adjacent to the sinusoidal waveguide, and the third electron beam channel is located between the two rectangular grids. The first electron beam channel, the second electron beam channel, and the third electron beam channel are spaced apart from the adjacent sinusoidal waveguide or rectangular grid, and the cross-sectional shape of the first electron beam channel, the second electron beam channel, and the third electron beam channel is a circle with a radius of R = 0.4 mm. In the frequency band of 84 GHz-110 GHz, the normalized phase velocity curve of the slow wave structure of the traveling wave tube is shown in FIG. 8, and the results show that the slow wave structure of the traveling wave tube has a wide working bandwidth, and the working bandwidth is 90 GHz-105 GHz. Figure 7

[0078] In some embodiments, the present application also provides a traveling wave tube, which comprises the slow wave structure described above.

[0079] The traveling wave tube comprises an electron gun, a slow wave system, a magnetic focusing system, an input / output waveguide, and a collector. For specific limitations of the slow wave structure, see the above description, which is not repeated here.

[0080] ​​The main function of the electron gun is to generate an electron beam with a certain size, shape and current, and accelerate the electron beam so that it is slightly faster than the phase velocity of the electromagnetic wave in the slow wave mode, so as to exchange energy with the electromagnetic wave and realize amplification. The main task of the slow wave system is to slow down the phase velocity of the electromagnetic wave, so that it is basically the same as the movement speed of the electron, so that the electron and the electromagnetic wave exchange energy fully, and the microwave signal is amplified. The magnetic focusing system can be used to constrain the electron beam, so that it is not "captured" by the slow wave structure and dissipates the energy of the electron beam. The electron beam must be able to pass through the slow wave structure smoothly and interact with the electromagnetic wave to realize amplification. The input and output waveguide is the entrance and exit of the signal amplified by the traveling wave tube. The collector is used to collect the electron beam after exchanging energy with the electromagnetic wave.

[0081] In a vacuum electron device, the effective interaction of the electron beam with the electron traveling wave requires that the phase velocity of the electromagnetic wave be synchronized with the speed of the electron flow. As is known, the speed of the electron is smaller than the speed of light in a vacuum, and the phase velocity of the electromagnetic wave propagating in a general uniform waveguide transmission line is comparable to the speed of light, which requires an electromagnetic system that can reduce the phase velocity of the electromagnetic wave to a certain extent. Such a system is called a slow wave system.

[0082] The essence of dispersion is the variation of the propagation speed of light in a medium with frequency, and the variation of the propagation speed of the electromagnetic wave with frequency in the slow wave circuit is generally represented by the dispersion characteristics of the slow wave circuit, which can be described by the relationship between the phase velocity and the speed of light. It is an important characteristic of the slow wave structure, mainly depending on the shape and size of the slow wave system. In order to enable the electromagnetic field in the slow wave structure to effectively interact with the electron in a wide frequency range, it is required that the slow wave structure has as weak dispersion as possible, in other words, it is desired that the variation of the phase velocity is small enough in as wide a frequency range as possible, i.e. the dispersion curve is as flat as possible.

[0083] In the present embodiment, the above-mentioned traveling wave tube, since the slow wave structure therein is provided with two periodic waveguides, a rectangular grid is arranged in the coupling cavity between the periodic waveguides, and an electron beam channel is arranged between the waveguide and the rectangular grid, and the forward direction of the electromagnetic wave in the waveguide, the arrangement direction of the rectangular blocks in the rectangular grid, and the transmission direction of the electron beam in the electron beam channel satisfy the similarity condition, so that the longitudinal electric field formed by the electromagnetic wave transmitted in the periodic waveguide acts on the electron beam transmitted in the electron beam channel, the coupling impedance can be improved, and the input direct current of the slow wave structure of the traveling wave tube is improved.

[0084] It can be understood that the slow wave structure of the above-mentioned traveling wave tube can also adopt other forms, and is not limited to the forms mentioned in the above-mentioned embodiment, as long as it can achieve the function of improving the input direct current.

[0085] In the description of the specification, the description of the terms "some embodiments", "other embodiments", "ideal embodiments", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are contained in at least one embodiment or example of the present application. In the description, the illustrative description of the above terms does not necessarily refer to the same embodiment or example.

[0086] The technical features of the above-described embodiments can be combined arbitrarily, and for the sake of brevity, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not contradict each other, they should be considered within the scope of the present application.

[0087] The above-described embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of protection of the patent of the present application should be subject to the appended claims.

Claims

1. A slow-wave structure for a traveling wave tube, characterized in that, Includes waveguides, rectangular gratings, and electron beam channels: The waveguide includes two periodic waveguides arranged accordingly; a coupling cavity is formed between each periodic waveguide, and the period of each periodic waveguide is the same; The rectangular grating is located in the coupling cavity; the number of rectangular blocks in the rectangular grating corresponds to the number of periods of the periodic waveguide; The electron beam channel is located between the waveguide and the rectangular grating; The propagation direction of the electromagnetic wave in the waveguide, the arrangement direction of each rectangular block in the rectangular grid, and the transmission direction of the electron beam in the electron beam channel satisfy similarity conditions; satisfying the similarity conditions for the three directions means that the included angle between any two of the straight lines containing the three directions is within the allowable range. The periodic waveguide includes a first periodic waveguide and a second periodic waveguide; the electron beam channel includes a first electron beam channel between the first periodic waveguide and the rectangular grating, and a second electron beam channel between the second periodic waveguide and the rectangular grating; The number of rectangular grids is multiple, and the number of rectangular blocks in each rectangular grid is the same as the number of periods of the periodic waveguide; the rectangular blocks in each rectangular grid are arranged in the same direction; the angle between the rectangular blocks in different rectangular grids and the arrangement direction is the same; the angle between the rectangular blocks and the arrangement direction is 20° to 40°. The electron beam channel also includes a third electron beam channel located between each of the rectangular grids; the transmission direction of the electron beam in the third electron beam channel satisfies the similarity condition with the propagation direction of the electromagnetic wave in the waveguide.

2. The slow-wave structure according to claim 1, characterized in that, The periodic waveguide is a sinusoidal waveguide.

3. The slow-wave structure according to claim 1, characterized in that, The periodic waveguide is a semi-periodic rectangular staggered double-grating waveguide.

4. The slow-wave structure according to claim 1, characterized in that, The phase difference between the first periodic waveguide and the second periodic waveguide is zero.

5. The slow-wave structure according to claim 1, characterized in that, The allowed range refers to: greater than or equal to zero and less than or equal to 0.5°, or greater than or equal to zero and less than or equal to 1°.

6. The slow-wave structure according to claim 1, characterized in that, The first electron beam channel is located on the edge side of the gap between the first periodic waveguide and the rectangular grating, and the second electron beam channel is located on the edge side of the gap between the second periodic waveguide and the rectangular grating.

7. The slow-wave structure according to claim 1, characterized in that, The first electron beam channel is located at the edge of the gap between the first periodic waveguide and the rectangular grating, and the second electron beam channel is located at the center of the gap between the second periodic waveguide and the rectangular grating.

8. The slow-wave structure according to any one of claims 1 to 7, characterized in that, The electron beam channel is separate from the rectangular grid; the electron beam channel is separate from the waveguide.

9. The slow-wave structure according to any one of claims 1 to 7, characterized in that, The cross-sectional shape of the electron injection channel is circular.

10. A traveling wave tube, characterized in that, Includes the slow-wave structure as described in any one of claims 1 to 9.

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