CN118016489A - Folded waveguide slow wave structure, design method thereof and vacuum electron tube - Google Patents
Folded waveguide slow wave structure, design method thereof and vacuum electron tube Download PDFInfo
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Abstract
The invention discloses a folded waveguide slow wave structure, a design method thereof and a vacuum electron tube, which comprises at least one folded waveguide unit which is sequentially connected, wherein the folded waveguide unit comprises two sections of quarter-arc bent waveguide sections and a straight waveguide section, the two sections of the straight waveguide section are respectively and smoothly connected with one section of quarter-arc bent waveguide section in a tangential manner, the head-tail quarter-arc bent waveguide sections of two adjacent folded waveguide units are spliced into a smooth half-arc bent waveguide section, and an electron beam channel vertically passes through the straight waveguide section and has an intersecting part with the quarter-arc bent waveguide section. The waveguide sections of the folded waveguide slow wave structure provided by the embodiment are smoothly connected in a tangential mode, so that the folded waveguide slow wave structure can be applied to a high-power scene, the diameter of an electron beam channel is effectively increased, the current is increased, the interaction efficiency and the output power of a device are kept from being reduced, the cut-off frequency of a fundamental mode is improved, the working bandwidth is expanded, and the risk of self-oscillation is reduced.
Description
Technical Field
The invention belongs to the technical field of vacuum electronic devices, and particularly relates to a folded waveguide slow wave structure, a design method thereof and a vacuum electronic tube.
Background
At present, the slow wave structure mainly studied in the terahertz section traveling wave tube has structures such as folding waveguides, rectangular staggered double grids, sine waveguides and the like. The terahertz wave has a short working wavelength, and the size of the high-frequency system becomes very small due to the influence of the size co-transition effect, so that the processing difficulty is high, the processing precision is low, and the reflection and the loss of the high-frequency system are high. The folded waveguide slow wave structure has the characteristics of wide bandwidth, low loss, high heat conduction and easy processing and assembly, and is widely applied to the slow wave structure of the traveling wave tube.
However, conventional folded waveguide slow wave structures are not suitable for high power operating scenarios, where higher currents and higher operating voltages are required for high power folded waveguide traveling wave tubes to provide sufficiently high power output. In order to improve the working current, the radius of the electron beam channel needs to be increased, but the coupling impedance of the folded waveguide slow wave structure can be rapidly reduced along with the increase of the electron beam channel, so that the injection interaction efficiency and the output power of the device are seriously affected, meanwhile, under the high-voltage working condition, the problem of bandwidth reduction can occur after the radius of the electron beam channel is increased, and the upper cut-off frequency can overlap with an electron beam voltage line, so that the self-oscillation risk is greatly increased.
Disclosure of Invention
The method aims to solve the problems of power and efficiency reduction, bandwidth reduction and increase of self-oscillation risks which can occur when the conventional folded waveguide slow wave structure is applied to a high-power scene. The invention provides a folded waveguide slow wave structure, a design method thereof and a vacuum electron tube, wherein the folded waveguide slow wave structure can effectively increase the diameter of an electron beam channel, increase current, keep the interaction efficiency, output power and bandwidth characteristics of a device not to be reduced, and avoid self-oscillation risks.
The invention is realized by the following technical scheme:
a folded waveguide slow wave structure comprising at least one folded waveguide unit connected in sequence;
The two ends of the straight waveguide section are respectively and smoothly communicated with one section of the quarter arc bending waveguide section in a tangent mode, the head-tail quarter arc bending waveguide sections of two adjacent folding waveguide units are spliced into smooth half arc bending waveguide sections, the two adjacent folding waveguide units are symmetrical about the central axial surfaces of the two folding waveguide units, and the central axial surfaces are planes perpendicular to the arrangement direction of the folding waveguide units;
an electron beam channel passes vertically through the straight waveguide section and has an intersection with the quarter-circular curved waveguide section.
The existing folded waveguide slow wave structure can improve output power to a certain extent, reduce the length of a slow wave line required by power saturation, and realize high-power miniaturization, however, in the structure, the coupling impedance of an electron beam and a high-order mode electromagnetic wave is very high, self-oscillation phenomenon is easy to generate, an output signal is a return wave signal with higher frequency than an input signal, namely, the output signal deviates from a frequency point of the input signal, and normal amplification function cannot be realized. The cross section sizes of the waveguide sections of the folded waveguide slow wave structure are the same, and the waveguide sections are sequentially and smoothly connected in a tangential mode, so that the lower cut-off frequency of a high-order mode electromagnetic wave mode can be improved while high-power miniaturization is realized, the interaction between the high-order mode and an electron beam is avoided, the self-oscillation phenomenon is effectively restrained, and the output performance of the traveling wave tube is ensured.
As a preferred embodiment, the cross section of the electron beam channel of the invention is circular, and the diameter of the electron beam channel is larger than the length of the straight waveguide section and smaller than the length of the straight waveguide section plus the length of the single period minus the length of the wide side of the waveguide;
or the cross section of the electron beam channel is rectangular, the length of the electron beam channel is smaller than the length of the long side of the waveguide, and meanwhile, the width of the electron beam channel is larger than the length of the straight waveguide section and smaller than the length of the straight waveguide section plus the length of the single period minus the length of the wide side of the waveguide.
As a preferred embodiment, the central angles of the outer circular arc and the inner circular arc of the smooth semicircular arc bending waveguide section are 180 degrees, the outer circular arc and the inner circular arc share the same center, the center is positioned on a central axis and at a position which is one half of the length of the straight waveguide section from the axis of the electron beam channel, and the central axis is positioned on the central axis.
As a preferred embodiment, the radius of the outer circular arc of the smooth semicircular arc bending waveguide section is half of the sum of the period length of the folded waveguide slow wave structure and the waveguide broadside; the radius of the inner circular arc of the smooth semicircular arc bent waveguide section is half of the difference of the period length of the folded waveguide slow wave structure minus the waveguide broadside.
As a preferred embodiment, the outer circular arc and the inner circular arc of the smooth semicircular arc bending waveguide section of the present invention each comprise two parts, wherein one part is located outside the electron beam channel and the other part is located inside the electron beam channel; and the outside central angle in the part outside the electron beam channel is larger than the inside central angle and smaller than 180 degrees.
As a preferred embodiment, the folded waveguide slow wave structure is provided with two cylindrical electron beam channels at the center, the sum of the diameters of the two cylindrical electron beam channels is smaller than the length of the long side of the waveguide, and meanwhile, the diameter of a single cylindrical electron beam channel is larger than the length of the straight waveguide section and smaller than the length of the straight waveguide section plus the length of a single period minus the length of the wide side of the waveguide.
As a preferred embodiment, the electron beam channel of the present invention is located at the center of the folded waveguide slow wave structure.
In a second aspect, the present invention provides a method for designing a folded waveguide slow wave structure, the method comprising:
Designing an initial folded waveguide slow wave structure according to the requirement, wherein the initial folded waveguide slow wave structure comprises at least one folded waveguide unit which is sequentially connected, and the folded waveguide unit is sequentially connected with the at least one folded waveguide unit; the two ends of the straight waveguide section are respectively and smoothly communicated with one section of the quarter arc bending waveguide section in a tangent mode, the head-tail quarter arc bending waveguide sections of two adjacent folding waveguide units are spliced into smooth half arc bending waveguide sections, the two adjacent folding waveguide units are symmetrical about the central axial surfaces of the two folding waveguide units, and the central axial surfaces are planes perpendicular to the arrangement direction of the folding waveguide units; an electron beam channel vertically passes through the straight waveguide section;
And shortening the length of the straight waveguide section by using three-dimensional electromagnetic simulation software to be smaller than the diameter of the electron beam channel, namely, the electron beam channel vertically passes through the straight waveguide section and has an intersection part with the quarter-arc bent waveguide section.
In a preferred embodiment, the diameter of the electron beam channel of the present invention is greater than the length of the straight waveguide section and less than the length of the straight waveguide section plus the period length of the folded waveguide slow wave structure minus the length of the waveguide broadside.
In a third aspect, the present invention provides a vacuum electron tube, which includes the folded waveguide slow wave structure of the present invention.
Compared with the prior art, the invention has the following advantages and beneficial effects:
The cross sections of the waveguide sections of the folded waveguide slow wave structure provided by the invention have the same size, are smoothly connected in a tangential mode, can improve the coupling impedance of a fundamental mode, improve the problems of gain reduction and bandwidth limitation caused by continuous reduction of the coupling impedance in the same-frequency band high-frequency region, and can also destroy interaction conditions of high-order mode electromagnetic waves and electron beams and effectively inhibit self-excitation oscillation.
The folded waveguide slow wave structure provided by the invention can be well applied to high-power scenes, is applied to vacuum electronic devices such as traveling wave tubes and the like to realize the wave injection amplifying function, and provides technical support for the research of the high-power vacuum electronic devices.
Drawings
The accompanying drawings, which are included to provide a further understanding of embodiments of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:
fig. 1 is a diagram of a conventional folded waveguide slow wave structure model.
Fig. 2 is a schematic diagram of a folded waveguide slow wave structure according to an embodiment of the present invention.
Fig. 3 is a schematic diagram of a dimensional relationship of a folded waveguide slow wave structure according to an embodiment of the present invention.
Fig. 4 is a graph showing a phase shift-frequency dispersion curve of a folded waveguide slow-wave structure according to an embodiment of the present invention and the conventional folded waveguide slow-wave structure shown in fig. 1.
Fig. 5 is a graph showing a comparison of frequency-phase velocity dispersion curves of a folded waveguide slow-wave structure according to an embodiment of the present invention and a conventional folded waveguide slow-wave structure shown in fig. 1.
Fig. 6 is a graph showing the comparison of the coupling impedance of the fundamental mode of the folded waveguide slow wave structure according to the embodiment of the present invention and the conventional folded waveguide slow wave structure shown in fig. 1.
Fig. 7 is a graph showing gain and bandwidth performance comparison between a folded waveguide slow-wave structure according to an embodiment of the present invention and the conventional folded waveguide slow-wave structure shown in fig. 1.
Fig. 8 is a graph comparing output power of a folded waveguide slow wave structure according to an embodiment of the present invention with that of the conventional folded waveguide slow wave structure shown in fig. 1.
Reference numerals and corresponding part names:
10-folded waveguide unit.
Detailed Description
Hereinafter, the terms "comprises" or "comprising" as may be used in various embodiments of the present invention indicate the presence of inventive functions, operations or elements, and are not limiting of the addition of one or more functions, operations or elements. Furthermore, as used in various embodiments of the invention, the terms "comprises," "comprising," and their cognate terms are intended to refer to a particular feature, number, step, operation, element, component, or combination of the foregoing, and should not be interpreted as first excluding the existence of or increasing likelihood of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing.
In various embodiments of the invention, the expression "or" at least one of a or/and B "includes any or all combinations of the words listed simultaneously. For example, the expression "a or B" or "at least one of a or/and B" may include a, may include B or may include both a and B.
Expressions (such as "first", "second", etc.) used in the various embodiments of the invention may modify various constituent elements in the various embodiments, but the respective constituent elements may not be limited. For example, the above description does not limit the order and/or importance of the elements. The above description is only intended to distinguish one element from another element. For example, a first element and a second element may be referred to as different elements, although both may be implemented using the same device. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of various embodiments of the present invention.
It should be noted that: if it is described to "connect" one component element to another component element, a first component element may be directly connected to a second component element, and a third component element may be "connected" between the first and second component elements. Conversely, when one constituent element is "directly connected" to another constituent element, it is understood that there is no third constituent element between the first constituent element and the second constituent element.
The terminology used in the various embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the various embodiments of the invention. As used herein, the singular is intended to include the plural as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments of the invention belong. The terms (such as those defined in commonly used dictionaries) will be interpreted as having a meaning that is the same as the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein in connection with the various embodiments of the invention.
For the purpose of making apparent the objects, technical solutions and advantages of the present invention, the present invention will be further described in detail with reference to the following examples and the accompanying drawings, wherein the exemplary embodiments of the present invention and the descriptions thereof are for illustrating the present invention only and are not to be construed as limiting the present invention.
Example 1:
when the conventional folded waveguide (shown in fig. 1) is applied to a high-power scene, due to the requirement for high voltage and high current, the radius of an electron beam channel is increased, the upper cut-off frequency is shifted downwards, the bandwidth is reduced, the working frequency band is limited, the working voltage is increased, the slope of a voltage line is increased, and the voltage line intersects with a high-order mode electromagnetic field dispersion curve, so that the problem of self-oscillation is more easily caused. An increase in the radius of the electron beam channel also results in a decrease in coupling impedance and a decrease in interaction efficiency. In view of this problem, the present embodiment proposes a folded waveguide slow-wave structure, which includes at least one folded waveguide unit sequentially connected, where the folded waveguide unit includes two sections of quarter-arc curved waveguide sections and a straight waveguide section, the two sections of the straight waveguide section are respectively and smoothly connected with one section of quarter-arc curved waveguide section in a tangential manner, the front-to-back quarter-arc curved waveguide sections of two adjacent folded waveguide units are spliced into a smooth half-arc curved waveguide section, and the two adjacent folded waveguide units are symmetrical about the central axes of the two sections, and an electron beam channel vertically passes through the straight waveguide section and has an intersection portion with the quarter-arc curved waveguide section. The cross section sizes of the waveguide sections of the folded waveguide slow wave structure provided by the embodiment are the same, the waveguide sections are smoothly connected in a tangential mode, the coupling impedance of a fundamental mode can be improved, the total output power is improved, the slow wave line length required by power saturation is reduced, the high-power miniaturization is realized, the interaction condition of high-order mode electromagnetic waves and electron beam is also damaged, and the self-oscillation phenomenon can be effectively restrained.
As shown in fig. 2, the folded waveguide slow wave structure proposed in the present embodiment specifically includes at least one folded waveguide unit 10 connected in sequence.
The folded waveguide units 10 include two sections of quarter-arc curved waveguide sections and straight waveguide sections, the cross sections of the quarter-arc curved waveguide sections and the straight waveguide sections are the same, two ends of the straight waveguide section are respectively and smoothly communicated with one section of quarter-arc curved waveguide sections in a tangent mode, an electron beam channel vertically passes through the straight waveguide sections and has an intersecting part with the quarter-arc curved waveguide sections, the quarter-arc curved waveguide sections of two adjacent folded waveguide units 10 are spliced into a smooth half-arc curved waveguide section P, and the two adjacent folded waveguide units 10 are symmetrical about the central axial surfaces of the two sections, wherein the central axial surfaces are planes perpendicular to the arrangement direction of at least one folded waveguide unit 10. The sections of the folded waveguide slow wave structure provided by the embodiment are smoothly connected, so that the interaction condition of the high-order mode electromagnetic wave and the electron beam is destroyed while high-power miniaturization is realized, and the self-oscillation phenomenon can be effectively inhibited.
Further, as shown in fig. 2, in the folded waveguide slow wave structure of the present embodiment, the straight waveguide section of the former folded waveguide unit 10 is Z1, the straight waveguide section of the latter folded waveguide unit 10 is Z2, the cylindrical electron beam channel penetrating through the former folded waveguide unit is R, the outer arc of the smooth semicircular arc curved waveguide section P is P1, the inner arc is P2, the central angles of the inner arc and the outer arc are 180 °, the inner arc P2 and the outer arc P1 share the same center, the center is on the central axis X and is at a position away from the axis h/2 of the electron beam channel, and the central axis X is on the central axis surface.
Further, as shown in fig. 3, in this embodiment, the length of the straight waveguide segment is h, the width of the waveguide is b, the length of the waveguide is a (not shown in the figure), the single period length is p, the radius of the electron beam channel is r0, the length h of the straight waveguide segment is smaller than the diameter 2×r0 of the electron beam channel, and meanwhile, the diameter of the electron beam channel must be larger than the length of the straight waveguide segment plus the single period length minus the width of the waveguide, i.e., h <2×r0< h+p-b, based on this, the working mode is not changed, the electric field intensity in the electromagnetic wave transmission direction is enhanced, the coupling impedance of the fundamental mode is improved, the total output power is improved, the power saturation length is reduced, thereby achieving the purpose of high-power miniaturization, and meanwhile, the interaction condition of the electromagnetic wave and the electron beam of the high-order mode is destroyed, and the phenomenon of self-excited oscillation can be effectively inhibited. The folded waveguide slow wave structure shown in fig. 2 and 3 is preferably a cylindrical electron beam channel, so that the design difficulty can be reduced, and the focusing system can be designed conveniently. It should be noted that, in another alternative embodiment, a rectangular beam channel may be used, where the rectangular beam channel is used, the length of the rectangular beam channel must not be greater than the length of the long side of the waveguide, and the width of the rectangular beam channel must be greater than the length of the straight waveguide segment, and must not be greater than the length of the straight waveguide segment plus the length of the single period minus the length of the wide side of the rectangular waveguide. In further alternative embodiments, two or more beam channels may be used, where two beam channels are used, the sum of the two beam channel diameters must not be greater than the length of the long side of the waveguide, and a single beam channel diameter is greater than the length of the straight waveguide section, while less than the length of the straight waveguide section plus the length of the single period minus the length of the wide side of the waveguide. Preferably, the radius of the electron beam channel can be enlarged by a milling machine until the diameter of the electron beam channel is larger than the length of the straight waveguide section in the conventional fixed folding waveguide processing mode.
Further, as shown in fig. 2 and 3, the radius r1 of the inner circular arc P2 is the period length P minus half the difference of the waveguide broadside length b, i.e., (P-b)/2, and the radius r2 of the outer circular arc P1 is the period length P plus half the sum of the waveguide broadside lengths b, i.e., (p+b)/2. The inner circular arc P2 and the outer circular arc P1 are divided into two parts, one part is positioned in the electron beam channel, the other part is positioned outside the electron beam channel and positioned outside the electron beam channel, and the central angle A2 of the outer side is larger than the central angle A1 of the inner side and smaller than 180 degrees (namely, the red part in fig. 2). The electron beam channel just comprises the whole straight waveguide section and the inner boundary of the quarter-arc bent waveguide section, but does not completely comprise the quarter-arc bent waveguide section, so that the coupling impedance of the slow wave structure is higher than that of the existing folded waveguide slow wave structure, and the working mode of electromagnetic waves in the slow wave structure is not changed.
According to the folded waveguide slow wave structure provided by the embodiment, the length of the straight waveguide section is shortened to be smaller than the diameter of the electron beam channel, and meanwhile, the inner side boundary of the quarter arc bending waveguide section is positioned in the electron beam channel, so that the flatness and the central interaction frequency point of a dispersion curve are kept unchanged, meanwhile, the intersection part of the quarter arc bending waveguide section and the straight waveguide section is consistent in the direction of the arc tangent line and the straight waveguide section, the straight waveguide section and the quarter arc bending waveguide section are smoothly connected, and the cross section sizes of the straight waveguide section and the quarter arc bending waveguide section are the same.
The embodiment also provides a vacuum electron tube which adopts the folding slow wave structure to carry out wave injection amplification. The vacuum electron tube can be any one of a traveling wave tube, a return wave tube, a klystron and a magnetron.
The embodiment also provides a design method of the folded waveguide slow wave structure, which specifically comprises the following steps:
Designing an initial folded waveguide slow wave structure according to the requirement, wherein the initial folded waveguide slow wave structure comprises at least one folded waveguide unit and an electron beam channel which are arranged along the axial direction, the folded waveguide unit consists of a quarter arc bent waveguide section, a straight waveguide section and a quarter arc bent waveguide section which are sequentially and smoothly connected, and two adjacent folded waveguide units are communicated through the respective quarter arc bent waveguide sections; the electron beam channel passes through the straight waveguide section.
The three-dimensional electromagnetic simulation software is utilized to shorten the length of the straight waveguide section so as to be smaller than the diameter of the electron beam channel, but the electron beam channel is required to be ensured not to intersect with the outer edge of the quarter circular arc bending waveguide section (namely, the diameter of the electron beam channel is not larger than the length of the straight waveguide section plus the single period length minus the broadside length of the waveguide), so that the working mode is ensured to be unchanged, the length of the straight waveguide section is shortened so as to improve the coupling impedance of the fundamental mode of the slow wave structure, and meanwhile, the single period length of the slow wave structure is shortened so as to reduce the electromagnetic wave phase velocity, and the phenomenon of reduced dispersion flatness is compensated, so that the working voltage is not required to be changed.
Example 2:
The embodiment utilizes three-dimensional electromagnetic simulation software and traveling wave tube beam-wave interaction simulation software to perform simulation test on the folded waveguide slow wave structure provided by the embodiment and the traditional folded slow wave structure shown in fig. 1, wherein in a Ka band, the size of the folded waveguide slow wave structure provided by the embodiment of the invention can be (unit: mm): a=5.2, b=1.5, p=2.5, h=0.7, r0=0.75, rb=0.375. rb is the electron beam radius. The traditional folded waveguide slow wave structure size can be (unit: mm): a=5.2, b=1.5, p=2.7, h=1.65, r0=0.75, rb=0.375.
The simulation test results in the performance such as the dispersion characteristic, the fundamental mode coupling impedance, the gain, the bandwidth, the output power, the device length required by the power saturation of the folded waveguide slow wave structure shown in fig. 4 to 8.
Fig. 4 is a phase shift-frequency dispersion curve comparison diagram of a folded waveguide slow-wave structure according to an embodiment of the present invention and a conventional folded waveguide slow-wave structure, fig. 4 (a) is a conventional folded waveguide slow-wave structure, and fig. 4 (b) is a folded waveguide slow-wave structure according to an embodiment of the present invention. The upper cutoff frequency of the traditional folded waveguide fundamental mode is lower, the cold bandwidth is about 29-39 GHz, the upper cutoff frequency of the folded waveguide fundamental mode provided by the embodiment of the invention is higher, the cold bandwidth is about 30-44 GHz, and the bandwidth of 4GHz is expanded.
As can be seen from fig. 4, in the conventional folded waveguide, the phase of the intersection point of the voltage line and the higher-order mode is 5.9rad, the corresponding self-oscillation frequency is 41.48GHz, which is relatively consistent with the oscillation frequency simulated by CST, while the voltage line in the embodiment of the present invention avoids the dispersion curve of the higher-order mode electromagnetic field, has no intersection point, and does not satisfy the synchronization condition of the higher-order mode electromagnetic wave, so that the folded waveguide slow wave structure provided by the embodiment of the present invention can effectively reduce the risk of self-oscillation.
In addition, as can be seen from the steepness of the dispersion curve, the dispersion curve of the folded waveguide structure provided by the embodiment of the invention is flatter, the synchronization effect is better, and the working bandwidth is wider.
Fig. 6 is a diagram showing a comparison of coupling impedance between a folded waveguide slow-wave structure and a conventional folded waveguide slow-wave structure according to an embodiment of the present invention, where the diagram can be seen: the folding waveguide slow wave structure provided by the embodiment of the invention has coupling impedance higher than that of the traditional folding waveguide slow wave structure under the same frequency in the whole working frequency band, namely the folding waveguide slow wave structure provided by the embodiment of the invention can more effectively support the injection-wave interaction, thereby being beneficial to improving the output power of the traveling wave tube.
Fig. 7 is a graph showing gain and bandwidth performance comparison between a folded waveguide slow-wave structure according to an embodiment of the present invention and a conventional folded waveguide slow-wave structure. As can be seen from the figure: the gain of the folded waveguide slow wave structure in the whole frequency range is obviously higher than that of the traditional folded waveguide slow wave structure, and is more than 30dB, and the interaction of the traditional folded waveguide high-frequency region is weak, so that the gain is extremely low. In addition, from the in-band gain fluctuation, the gain fluctuation of the folded waveguide slow wave structure provided by the embodiment of the invention is far lower than that of the existing folded waveguide slow wave structure, only 9dB is achieved by the traditional structure, and from the bandwidth, the bandwidth of the folded waveguide slow wave structure provided by the embodiment of the invention is relatively wider.
Fig. 8 is a graph comparing output power of the folded waveguide slow-wave structure provided by the embodiment of the invention with that of the traditional folded waveguide slow-wave structure, and as can be seen from the graph, the output power of the folded waveguide slow-wave structure provided by the embodiment of the invention is above 21.6kW, and the output power of each frequency point is greater than that of the traditional folded waveguide. The folded waveguide slow wave structure provided by the embodiment of the invention has higher output power and better electromagnetic performance.
The folded waveguide slow wave structure provided by the embodiment of the invention can be suitable for a high-power working scene of a traveling wave tube, expands the reduced working bandwidth caused by the increase of an electron beam channel, and changes the dispersion characteristic to ensure that a voltage line avoids a high-order mode electromagnetic wave dispersion curve and the high-order mode electromagnetic wave does not meet interaction conditions, thereby reducing the risk of self-oscillation, improving the field distribution in the traditional folded waveguide slow wave structure, improving the coupling impedance, improving the total output power and having better electromagnetic performance.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (10)
1. The folded waveguide slow wave structure is characterized by comprising at least one folded waveguide unit which is connected in sequence;
The two ends of the straight waveguide section are respectively and smoothly communicated with one section of the quarter arc bending waveguide section in a tangent mode, the head-tail quarter arc bending waveguide sections of two adjacent folding waveguide units are spliced into smooth half arc bending waveguide sections, the two adjacent folding waveguide units are symmetrical about the central axial surfaces of the two folding waveguide units, and the central axial surfaces are planes perpendicular to the arrangement direction of the folding waveguide units;
an electron beam channel passes vertically through the straight waveguide section and has an intersection with the quarter-circular curved waveguide section.
2. The folded waveguide slow wave structure of claim 1 wherein the electron beam channel is circular in cross section, the diameter of the electron beam channel being greater than the length of the straight waveguide section and less than the length of the straight waveguide section plus the length of the single period minus the length of the waveguide broadside;
or the cross section of the electron beam channel is rectangular, the length of the electron beam channel is smaller than the length of the long side of the waveguide, and meanwhile, the width of the electron beam channel is larger than the length of the straight waveguide section and smaller than the length of the straight waveguide section plus the length of the single period minus the length of the wide side of the waveguide.
3. The folded waveguide slow wave structure according to claim 1, wherein central angles of an outer circular arc and an inner circular arc of the smooth semicircular curved waveguide section are 180 degrees, the outer circular arc and the inner circular arc share the same center, the center is located on a central axis and at a position which is one half of the length of the straight waveguide section from the electron beam channel axis, and the central axis is located on the central axis.
4. The folded waveguide slow wave structure of claim 1, wherein the outer circular arc radius of the smooth semi-circular arc curved waveguide section is half of the folded waveguide slow wave structure period length plus the waveguide broadside; the radius of the inner circular arc of the smooth semicircular arc bent waveguide section is half of the difference of the period length of the folded waveguide slow wave structure minus the waveguide broadside.
5. The folded waveguide slow wave structure of claim 1, wherein the outer circular arc and the inner circular arc of the smooth semi-arc curved waveguide section each comprise two parts, wherein one part is located outside the electron beam channel and the other part is located inside the electron beam channel; and the outside central angle in the part outside the electron beam channel is larger than the inside central angle and smaller than 180 degrees.
6. The folded waveguide slow wave structure of claim 1, wherein the folded waveguide slow wave structure is centrally provided with two cylindrical electron beam channels, the sum of the diameters of the two cylindrical electron beam channels being smaller than the length of the long side of the waveguide, while the diameter of a single cylindrical electron beam channel is larger than the length of the straight waveguide section and smaller than the length of the straight waveguide section plus the length of the single period minus the length of the wide side of the waveguide.
7. The folded waveguide slow wave structure, the design method thereof and the vacuum electron tube according to claim 1, wherein the electron beam channel is positioned at the center of the folded waveguide slow wave structure.
8. A method for designing a folded waveguide slow wave structure, the method comprising:
Designing an initial folded waveguide slow wave structure according to the requirement, wherein the initial folded waveguide slow wave structure comprises at least one folded waveguide unit which is sequentially connected, and the folded waveguide unit is sequentially connected with the at least one folded waveguide unit; the two ends of the straight waveguide section are respectively and smoothly communicated with one section of the quarter arc bending waveguide section in a tangent mode, the head-tail quarter arc bending waveguide sections of two adjacent folding waveguide units are spliced into smooth half arc bending waveguide sections, the two adjacent folding waveguide units are symmetrical about the central axial surfaces of the two folding waveguide units, and the central axial surfaces are planes perpendicular to the arrangement direction of the folding waveguide units; an electron beam channel vertically passes through the straight waveguide section;
And shortening the length of the straight waveguide section by using three-dimensional electromagnetic simulation software to be smaller than the diameter of the electron beam channel, namely, the electron beam channel vertically passes through the straight waveguide section and has an intersection part with the quarter-arc bent waveguide section.
9. The method of designing according to claim 8, wherein the diameter of the electron beam channel is greater than the length of the straight waveguide section and less than the length of the straight waveguide section plus the period length of the folded waveguide slow wave structure minus the length of the waveguide broadside.
10. A vacuum valve comprising a folded waveguide slow wave structure according to any one of claims 1-7.
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