Method for effectively increasing klystron bandwidth and multi-beam klystron high-frequency structure

Abstract

The invention discloses a method for effectively improving the bandwidth of a klystron and a multi-beam klystron high-frequency structure, and the method comprises the steps: designing a conventional high-power high-efficiency klystron high-frequency structure, and enabling the resonant frequencies of an input cavity and an output cavity of the conventional high-power high-efficiency klystron high-frequency structure to be signal working frequencies, the resonant frequency of all the middle resonant cavities is greater than the signal working frequency, so that input electron beams are focused; adjusting the resonant frequency of the first intermediate resonant cavity to the relative working frequency to defocus the electron beam; the relative working frequency is smaller than the signal working frequency; the resonant frequency of other intermediate resonant cavities is greater than the signal working frequency, so that the electron beam is focused; and adjusting and optimizing the position of the first middle resonant cavity to obtain the same efficiency as the high-frequency structure of the traditional high-power high-efficiency klystron, thereby improving the bandwidth of the klystron. The bandwidth of the klystron is expanded while the klystron is ensured to realize high power and high efficiency and the length is not increased.

Description

Technical Field

[0001] The invention relates to the technical field of vacuum electronic devices, and in particular to a method for effectively improving the bandwidth of a klystron and a high-frequency structure of a multi-injection klystron. Background Art

[0002] With the rapid development of applications such as communications, electronic countermeasures, and accelerators, higher power and higher efficiency requirements have been put forward for radiation sources. Compared with solid-state devices, the radiation source of vacuum electronic devices has the advantages of higher power and better stability. Therefore, vacuum electronic devices still play an irreplaceable role in high-frequency and high-power demand scenarios. Among this type of devices, the klystron, as an important device, has attracted much attention in microwave vacuum devices for its excellent performance in high power and high efficiency.

[0003] As the core component of the klystron, the high-frequency structure (output circuit) is used to realize the interaction between the electron beam and the high-frequency electric field, convert the energy of the grouped electron beam into microwave energy, and realize microwave amplification. The characteristics of the high-frequency structure have an important influence on the efficiency, bandwidth and other performance indicators of the klystron. The application of klystron in information transmission, such as various radar systems, electronic countermeasure systems, communications and television broadcasting, in these occasions, in addition to meeting the performance indicators of microwave electronic systems such as power, efficiency and gain, the klystron also has certain requirements for working bandwidth.

[0004] Therefore, in order to expand the bandwidth of klystrons, various output circuits have been developed over the years, including filter-loaded broadband output circuits, dual-gap coupled cavity broadband output circuits, etc. However, these high-frequency structures (output circuits) are relatively complex, and it is difficult to ensure that the bandwidth of the klystron is effectively improved while achieving high power and high efficiency. This makes the existing high-power and high-efficiency klystrons have a narrow bandwidth and limited development. The processing accuracy needs to be very high to ensure the accurate frequency of the resonant cavity of the high-frequency structure, which increases the cost and also reduces the success rate of manufacturing high-power and high-efficiency klystrons.

[0005] In view of this, this application is hereby filed. Summary of the invention

[0006] The technical problem to be solved by the present invention is that the high-frequency structure of the existing klystron is complex, and it is difficult to ensure that the bandwidth of the klystron is effectively improved while achieving high power and high efficiency, which makes the bandwidth of the existing high-power and high-efficiency klystron narrow, increases the cost and also reduces the success rate of tube manufacturing of the high-power and high-efficiency klystron. The purpose of the present invention is to provide a method for effectively improving the bandwidth of a klystron and a high-frequency structure of a multi-injection klystron, which expands its bandwidth while ensuring that the klystron achieves high power and high efficiency without increasing its length, reduces processing costs, improves the success rate of engineering tube manufacturing, and provides an important reference for the development of broadband, high-power and high-efficiency klystrons.

[0007] The present invention is achieved through the following technical solutions:

[0008] In a first aspect, the present invention provides a method for effectively improving the bandwidth of a klystron, the method comprising:

[0009] Design a high-frequency structure of a traditional high-power and high-efficiency klystron. The resonance frequencies of the input and output cavities of the high-frequency structure of the traditional high-power and high-efficiency klystron are the signal operating frequency, and the resonance frequencies of all the intermediate resonant cavities are greater than the signal operating frequency to focus the input electron beam.

[0010] The resonant frequency of the first intermediate resonant cavity is adjusted to the relative operating frequency to defocus the electron beam; the relative operating frequency is less than the signal operating frequency; and the resonant frequencies of other intermediate resonant cavities are kept greater than the signal operating frequency to focus the electron beam; and the position of the first intermediate resonant cavity is adjusted and optimized to obtain the same high efficiency as the high-frequency structure of a traditional high-power and high-efficiency klystron, thereby improving the bandwidth of the klystron.

[0011] Furthermore, the relative operating frequency is twice the signal operating frequency minus the frequency of the first intermediate resonant cavity in the high-frequency structure of the conventional high-power and high-efficiency klystron.

[0012] Furthermore, the design of the high-frequency structure of the conventional high-power and high-efficiency klystron also includes:

[0013] The point where the electron injection density of each drift tube is the largest is calculated, and the position of the middle resonant cavity is placed corresponding to the calculated point where the electron injection density of each drift tube is the largest.

[0014] Furthermore, the design of the high-frequency structure of the conventional high-power and high-efficiency klystron also includes:

[0015] The resonant frequency, position and input and output external quality factors of the intermediate resonant cavity are optimized and adjusted to obtain the klystron high-frequency structure with the highest efficiency.

[0016] Furthermore, the method enables the klystron to achieve a high power of 4.2MW and a high efficiency of 50.2%, and without increasing the length of the klystron, can increase its -1dB power bandwidth to 2.1 times that of a conventional high-power and high-efficiency klystron.

[0017] In a second aspect, the present invention provides a multi-injection klystron high-frequency structure, which is designed based on the above-mentioned method for effectively improving the bandwidth of the klystron;

[0018] The high-frequency structure of the multi-injection klystron comprises an input cavity with the same inner diameter, a plurality of intermediate resonant cavities and an output cavity, and also comprises a multi-injection drift section, wherein the multi-injection drift section runs through the input cavity, the intermediate resonant cavity and the output cavity; the intermediate resonant cavity comprises a first intermediate resonant cavity, a second intermediate resonant cavity, a third intermediate resonant cavity, a fourth intermediate resonant cavity and a fifth intermediate resonant cavity;

[0019] The resonant frequency of the first intermediate resonant cavity is twice the signal operating frequency minus the frequency of the first intermediate resonant cavity in the high-frequency structure of a traditional high-power and high-efficiency klystron; the resonant frequencies of the other intermediate resonant cavities are all greater than the signal operating frequency.

[0020] Furthermore, the resonant frequencies of the input cavity, the first intermediate resonant cavity, the second intermediate resonant cavity, the third intermediate resonant cavity, the fourth intermediate resonant cavity, the fifth intermediate resonant cavity and the output cavity are 2998 MHz, 2964 MHz, 3058 MHz, 3116 MHz, 3156 MHz, 3100 MHz and 2998 MHz respectively.

[0021] Furthermore, the input cavity and the output cavity are elliptical resonant cavities, and the first intermediate resonant cavity, the second intermediate resonant cavity, the third intermediate resonant cavity, the fourth intermediate resonant cavity and the fifth intermediate resonant cavity are circular resonant cavities.

[0022] Further, the inner diameter of the input cavity is 42 mm, the outer diameter of the short axis is 62.01 mm, and the outer diameter of the long axis is 68.21 mm;

[0023] The inner diameter of the first intermediate resonant cavity is 42 mm, and the outer diameter is 64.47 mm; the inner diameter of the second intermediate resonant cavity is 42 mm, and the outer diameter is 62.66 mm; the inner diameter of the third intermediate resonant cavity is 42 mm, and the outer diameter is 61.62 mm; the inner diameter of the fourth intermediate resonant cavity is 42 mm, and the outer diameter is 60.93 mm; the inner diameter of the fifth intermediate resonant cavity is 42 mm, and the outer diameter is 69.21 mm;

[0024] The inner diameter of the output cavity is 42 mm, the outer diameter of the short axis is 47.02 mm, and the outer diameter of the long axis is 61.13 mm.

[0025] Furthermore, the gap widths of the input cavity, the first intermediate resonant cavity, the second intermediate resonant cavity, the third intermediate resonant cavity, the fourth intermediate resonant cavity, and the fifth intermediate resonant cavity are all 16.5 mm; the gap width of the output cavity is 9.5 mm;

[0026] The length of the input cavity is 23.51 mm, the lengths of the first intermediate resonant cavity, the second intermediate resonant cavity, the third intermediate resonant cavity, and the fourth intermediate resonant cavity are all 27.5 mm, the length of the fifth intermediate resonant cavity is 20.5 mm, and the length of the output cavity is 22.66 mm.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] The present invention discloses a method for effectively improving the bandwidth of a klystron tube and a high-frequency structure of a multi-injection klystron tube, which can effectively improve the -1dB power bandwidth of the klystron tube to 2.1 times of the original value while ensuring that the klystron tube achieves high power (4.2MW) and high efficiency (50.2%), and without increasing the tube length. The method of the present invention is simple and easy to operate, the bandwidth of the klystron tube is improved, the acceptable frequency deviation in processing becomes larger (reducing the processing accuracy requirement), saving costs, and improving the success rate of engineering tube manufacturing, providing an important reference for the development of high-power and high-efficiency klystron tubes. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0030] Figure 1 A flow chart of a method for effectively improving the bandwidth of a klystron according to the present invention;

[0031] Figure 2 This is a structural diagram of the input cavity of a high-frequency structure of a multi-injection klystron of the present invention;

[0032] Figure 3 This is a diagram showing the angular distribution of the electric field in the input cavity of a high-frequency structure of a multi-injection klystron according to the present invention;

[0033] Figure 4 This is a structural diagram of the output cavity of a high-frequency structure of a multi-injection klystron according to the present invention;

[0034] Figure 5 This is a diagram showing the angular distribution of the electric field in the output cavity of a high-frequency structure of a multi-beam klystron according to the present invention;

[0035] Figure 6 A three-dimensional structural diagram of a high-frequency structure of a multi-injection klystron according to the present invention;

[0036] Figure 7 It is a cross-sectional view of a high-frequency structure of a multi-injection klystron of the present invention;

[0037] Figure 8 A phase space diagram of a high frequency structure of a multi-injection klystron according to the present invention;

[0038] Fig. 9 This is an output power diagram of a high-frequency structure of a multi-injection klystron of the present invention;

[0039] Fig.10 This is an output spectrum diagram of a high-frequency structure of a multi-injection klystron according to the present invention;

[0040] Fig.11The figure is a comparison diagram of efficiency-frequency curves between the traditional method and the method of the present invention.

[0041] Reference numerals and corresponding component names:

[0042] 1-input cavity, 2-intermediate resonant cavity, 21-first intermediate resonant cavity, 22-second intermediate resonant cavity, 23-third intermediate resonant cavity, 24-fourth intermediate resonant cavity, 25-fifth intermediate resonant cavity, 3-output cavity, 4-drift section. DETAILED DESCRIPTION

[0043] Hereinafter, the term "include" or "may include" used in various embodiments of the present invention indicates the presence of the invented function, operation or element, and does not limit the addition of one or more functions, operations or elements. In addition, as used in various embodiments of the present invention, the terms "include", "have" and their cognates are intended only to indicate specific features, numbers, steps, operations, elements, components or combinations of the foregoing items, and should not be understood as first excluding the presence of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing items or the possibility of adding one or more features, numbers, steps, operations, elements, components or combinations of the foregoing items.

[0044] In various embodiments of the present invention, the expression "or" or "at least one of A or / and B" includes any combination or all combinations of the words listed at the same time. 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.

[0045] The expressions (such as "first", "second", etc.) used in various embodiments of the present invention may modify the various constituent elements in various embodiments, but may 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 only used for the purpose of distinguishing an element from other elements. For example, the first user device and the second user device indicate different user devices, although both are user devices. For example, without departing from the scope of various embodiments of the present invention, the first element may be referred to as the second element, and similarly, the second element may also be referred to as the first element.

[0046] It should be noted that if it is described that one component element is “connected” to another component element, the first component element may be directly connected to the second component element, and a third component element may be “connected” between the first component element and the second component element. Conversely, when one component element is “directly connected” to another component element, it can be understood that there is no third component element between the first component element and the second component element.

[0047] The terms used in various embodiments of the present invention are only used for the purpose of describing specific embodiments and are not intended to limit various embodiments of the present invention. As used herein, the singular form is intended to also include the plural form, unless the context clearly indicates otherwise. Unless otherwise limited, all terms used here (including technical terms and scientific terms) have the same meaning as the meaning generally understood by those of ordinary skill in the art to which the various embodiments of the present invention belong. The terms (such as the terms defined in the dictionary generally used) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having an idealized meaning or an overly formal meaning, unless clearly defined in various embodiments of the present invention.

[0048] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0049] Klystrons are widely used in military fields and civilian production and life due to their advantages such as high power, high efficiency, high gain and high stability. However, their disadvantages are that their bandwidth is relatively narrow, high processing precision is required, and engineering pipe manufacturing is difficult. The technical methods of increasing bandwidth in the existing technology are difficult to effectively improve the bandwidth of the klystron while ensuring that the klystron achieves high power and high efficiency without increasing its length.

[0050] The present invention designs a simple and easy-to-operate method for effectively improving the bandwidth of a klystron and a high-frequency structure of a broadband, high-power, and high-efficiency multi-injection klystron working in the S band, which expands its -1dB power bandwidth to 81MHz (the bandwidth is increased to 2.1 times that of the S-band 4.2MW peak output power and 50.2% efficiency multi-injection klystron designed by the traditional method) while ensuring that the klystron achieves a large peak output power (4.2MW) and a high efficiency (50.2%) without increasing the length, thereby reducing the processing cost, improving the success rate of engineering tube manufacturing, and providing an important reference for the development of broadband, high-power, and high-efficiency klystrons.

[0051] The working principle of the present invention is as follows: the output circuit of the klystron is composed of an input cavity 1, a plurality of intermediate resonant cavities 2, a drift section, an output cavity 3 and the like. When the electron beam passes through the gap of the input cavity 1, speed modulation is generated under the action of the high-frequency electric field, that is, the electrons passing through the resonant gap in the positive half-cycle of the high-frequency cycle are accelerated, and the electrons passing through the resonant cavity gap in the negative half-cycle are decelerated. After the speed-modulated electron beam passes through a certain length of drift section, density modulation is generated, that is, the fast electrons gradually catch up with the slow electrons, so that the electron distribution in the electron beam is uneven and clustering occurs. The density-modulated electron beam contains the fundamental and harmonic components of the input high-frequency electric field. When it passes through the first intermediate resonant cavity gap, it will excite a high-frequency induced current in the resonant cavity and establish a higher high-frequency electric field than the input resonant cavity on the resonant cavity gap. The high-frequency electric field in turn generates a greater speed modulation on the electron beam, thereby generating a stronger density modulation in the second section of the drift tube. When the electron beam passes through multiple intermediate resonant cavities 2 and the drift section, the above-mentioned speed and density modulation process is repeated, and when it reaches the entrance of the output cavity 3, a highly clustered electron beam is formed. The clustered electron beam entering the output cavity 3 contains a high fundamental current component. When it passes through the gap of the output cavity 3, a high high-frequency electric field is established, which converts part of its kinetic energy into high-frequency energy, thereby amplifying the high-frequency signal. The high-frequency structure of the traditional high-power and high-efficiency klystron is designed so that the resonance frequencies of the input cavity 1 and the output cavity 3 are both based on the signal operating frequency, and the resonance frequency of the intermediate clustering cavity is greater than the signal operating frequency, so that the electron beam is in a "focused" state when passing through each intermediate clustering cavity gap, thereby forming a highly clustered electron beam in the gap of the output cavity 3. However, the method of the present invention makes the resonance frequency of the first intermediate resonant cavity (gain cavity) equal to 2 times the working frequency minus the frequency of the traditionally designed gain cavity, so that the electron beam that has undergone density modulation after passing through the input cavity 1 reaches the first intermediate resonant cavity (gain cavity) and the high-frequency electric field excited by the gap performs "special modulation" on the electron beam, so that the clustered electron beam coming out of the input cavity 1 presents a form of first "defocusing" and then "focusing", and the subsequent intermediate resonant cavity and output cavity 3 continue to "focus" the electron beam repeatedly in accordance with the traditional design method, thereby achieving a highly clustered electron beam with the same effect as the traditional high-frequency structure design method of high-power and high-efficiency klystron. Therefore, this improvement obtains a high-frequency structure of the highly clustered electron beam process, which not only guarantees the advantages of high power and high efficiency, but also effectively expands the bandwidth without increasing the tube length.

[0052] Example 1

[0053] like Figure 1 As shown, the present invention provides a method for effectively improving the bandwidth of a klystron, the method comprising:

[0054] S1, design a high-frequency structure of a traditional high-power and high-efficiency klystron. The resonance frequencies of the input cavity 1 and the output cavity 3 of the high-frequency structure of the traditional high-power and high-efficiency klystron are the signal operating frequency, and the resonance frequencies of all the intermediate resonant cavities 2 are greater than the signal operating frequency to focus the input electron beam; calculate the maximum clustering point of the electron injection density of each drift tube section, and place the position of the intermediate resonant cavity 2 corresponding to the calculated maximum clustering point of the electron injection density of each drift tube section.

[0055] The resonance frequency, position and input and output external quality factors of the intermediate resonance cavity 2 are further optimized and adjusted to obtain a klystron high-frequency structure with the highest efficiency.

[0056] The above provides reference values ​​for the design of the high-frequency structure of a high-power and high-efficiency klystron using the new method of the present invention, that is, it can be known that the highest efficiency that can be achieved, assuming that at this time the frequency of the first intermediate resonant cavity (gain cavity) relative to the operating frequency is the resonant frequency of the first intermediate resonant cavity minus the signal operating frequency.

[0057] S2, adjust the resonant frequency of the first intermediate resonant cavity to the relative operating frequency to defocus the electron beam; the relative operating frequency is less than the signal operating frequency, specifically the relative operating frequency is twice the signal operating frequency minus the frequency of the first intermediate resonant cavity in the high-frequency structure of the traditional high-power and high-efficiency klystron; and keep other parameters of the high-frequency structure of the traditional high-power and high-efficiency klystron unchanged, that is, the resonant frequency of other intermediate resonant cavities is still greater than the signal operating frequency to focus the electron beam; and slightly adjust and optimize the position of the first intermediate resonant cavity to obtain the same high efficiency as the high-frequency structure of the traditional high-power and high-efficiency klystron, at which time the bandwidth of the klystron is greatly improved. At this time, the high-frequency structure of the high-power and high-efficiency klystron obtained is the high-frequency structure whose bandwidth is effectively broadened under the method of the present invention.

[0058] By utilizing the above method of the present invention, an improved broadband, high-power, high-efficiency multi-injection klystron high-frequency structure operating in the S band is obtained, which ensures that the klystron achieves a large peak output power (4.2MW) and a high efficiency (50.2%) without increasing the length, while extending its -1dB power bandwidth to 81MHz (the -1dB power bandwidth is increased to 2.1 times that of the S-band 4.2MW peak output power and 50.2% efficiency multi-injection klystron designed by the traditional method).

[0059] In the specific implementation, take the S-band 4-injection 7-cavity klystron as an example, as follows:

[0060] S1: Design a traditional high-power and high-efficiency S-band 4-beam 7-cavity klystron high-frequency structure, with an operating frequency of 2998MHz, a voltage of 68KV, a current of 31A for each of the 4 beams, a conductivity of 1.75μP for each beam, a drift tube radius of 4mm, an electron beam radius of 2.4mm, and an input power of 45W. The resonant frequencies of the input cavity 1 and the output cavity 3 are the operating frequency 2998 MHz. The frequency of the intermediate resonant cavity 2 is greater than the signal operating frequency 2998 MHz, which allows the electron beam to be "focused". Therefore, the resonant frequencies of the seven cavities (from left to right, the input cavity 1, the first intermediate resonant cavity 21, the second intermediate resonant cavity 22, the third intermediate resonant cavity 23, the fourth intermediate resonant cavity 24, the fifth intermediate resonant cavity 25, and the output cavity 3) are 2998 MHz, 3036 MHz, 3058 MHz, 3116 MHz, 3156 MHz, 3100 MHz, and 2998 MHz, respectively. The length of the first drift tube section (i.e., the distance between the center of the input cavity 1 and the center of the first intermediate resonant cavity 21) is calculated to be 60 mm, the second section (i.e., the distance between the center of the first intermediate resonant cavity 21 and the center of the second intermediate resonant cavity 22) is 53 mm, and the third section (i.e., the distance between the center of the second intermediate resonant cavity 22 and the center of the third intermediate resonant cavity 23) is 60 mm. The fourth section (i.e., the distance between the center of the third intermediate resonant cavity 23 and the center of the fourth intermediate resonant cavity 24) is 84mm, the fourth section (i.e., the distance between the center of the third intermediate resonant cavity 23 and the center of the fourth intermediate resonant cavity 24) is 60mm, the fifth section (i.e., the distance between the center of the fourth intermediate resonant cavity 24 and the center of the fifth intermediate resonant cavity 25) is 48mm, and the sixth section (i.e., the distance between the center of the fifth intermediate resonant cavity 25 and the center of the output cavity 3) is 24mm, that is, the center positions of the input cavity 1, each intermediate resonant cavity 2 and the output cavity 3 are placed at 0mm, 60mm, 113mm, 197mm, 257mm, 305mm, and 329mm respectively, and the input and output external quality factors are 43 and 21 respectively. At this time, the high-frequency structure design of the klystron with the highest efficiency under the S-band 4-injection conductance coefficient of 1.75μP is obtained, and the efficiency is 50.2%, the peak output power is 4.2MW, the gain is about 50dB, and the -1dB saturated power bandwidth is 38MHz (-1dB relative bandwidth is 1%). According to the empirical formula of the efficiency limit of the klystron, limit efficiency (%) = 78-16*conductance (μP), the maximum efficiency that can be achieved by the klystron with an S-band conductivity of 1.75μP is about 50%, so it can be known that the efficiency of the klystron has reached the empirical limit.

[0061] S2: The resonance frequency of the first intermediate resonant cavity (gain cavity) is lowered to a value relative to the operating frequency, i.e., 2964 MHz, to make the electron beam "defocused", and the frequencies of the other cavities remain unchanged (the same as in the traditional high-frequency structure), namely, 2998 MHz for the input cavity, 3058 MHz for the second intermediate resonant cavity, 3116 MHz for the third intermediate resonant cavity, 3156 MHz for the fourth intermediate resonant cavity, 3100 MHz for the fifth intermediate resonant cavity, and 2998 MHz for the output cavity). The first intermediate resonant cavity (gain cavity) is slightly moved to the right to a position of 70 mm relative to the center of the input cavity 1, and the positions of the other intermediate resonant cavities, the input cavity, and the output cavity remain unchanged as in the traditional high-frequency structure), as shown in the diagram Figure 6 As shown, the efficiency is 50.2%, which is as high as the traditional method. At this time, the peak output power is 4.2MW (as shown in the figure Fig. 9 As shown in the figure), the gain is about 50dB, and the -1dB saturated power bandwidth is widened to 81MHz (-1dB relative bandwidth is about 3%), and the bandwidth is greatly increased to 2.1 times that of the traditional high-frequency structure. Fig.11 At this time, the obtained S-band 4-injection 7-cavity high-power high-efficiency klystron high-frequency structure (as shown in the schematic diagram) Figure 7 ) is a high-frequency structure whose bandwidth is effectively broadened under the current invention method.

[0062] The present invention lowers the frequency of the first intermediate resonant cavity (gain cavity) in the high-frequency structure of a conventional high-power and high-efficiency S-band 4-injection 7-cavity klystron to the frequency of the first intermediate resonant cavity in the high-frequency structure of a klystron designed by a conventional method, which is twice the signal operating frequency minus the frequency of the first intermediate resonant cavity in the high-frequency structure of a conventional high-power and high-efficiency klystron, so that the electron beam is "defocused" in the gain cavity gap, thereby effectively increasing the bandwidth of the klystron to 2.1 times of the original value while maintaining the advantages of the klystron such as high power and high efficiency and without increasing the tube length.

[0063] Example 2

[0064] like Figure 6 and Figure 7 As shown, the difference between this embodiment and embodiment 1 is that this embodiment provides a multi-injection klystron high-frequency structure, which is designed based on a method for effectively improving the bandwidth of a klystron in embodiment 1 to obtain an S-band 4-injection 7-cavity high-power and high-efficiency klystron high-frequency structure;

[0065] The high-frequency structure of the multi-injection klystron comprises an input cavity 1 with the same inner diameter, a plurality of intermediate resonant cavities and an output cavity 3, and also comprises a multi-injection drift section, wherein the multi-injection drift section runs through the input cavity 1, the intermediate resonant cavity and the output cavity 3; the intermediate resonant cavity comprises a first intermediate resonant cavity 21, a second intermediate resonant cavity 22, a third intermediate resonant cavity 23, a fourth intermediate resonant cavity 24 and a fifth intermediate resonant cavity 25;

[0066] The resonant frequency of the first intermediate resonant cavity 21 is twice the signal operating frequency minus the frequency of the first intermediate resonant cavity in the high-frequency structure of a traditional high-power and high-efficiency klystron; the resonant frequencies of the other intermediate resonant cavities are all greater than the signal operating frequency.

[0067] In this embodiment, the input cavity 1 and the output cavity 3 use double rectangular waveguide input and output, and the shape is a re-entrant elliptical resonant cavity, as shown in the schematic diagram. Figure 2 , as shown in 4, the electric field uniformity in the four injections is very good (above 90%), and the angular distribution of the electric field in the input and output resonant cavities is shown in the schematic diagram Figure 3 , as shown in Figure 5. Each intermediate resonant cavity 2 is a circular resonant cavity.

[0068] The center positions of the seven cavities from left to right (input cavity 1, first intermediate resonant cavity 21, second intermediate resonant cavity 22, third intermediate resonant cavity 23, fourth intermediate resonant cavity 24, fifth intermediate resonant cavity 25 and output cavity 3) are placed at 0 mm, 60 mm, 113 mm, 197 mm, 257 mm, 305 mm, and 329 mm respectively, as shown in the figure. Figure 6 shown.

[0069] The resonant frequencies of the 7 cavities from left to right (input cavity 1, first intermediate resonant cavity 21, second intermediate resonant cavity 22, third intermediate resonant cavity 23, fourth intermediate resonant cavity 24, fifth intermediate resonant cavity 25 and output cavity 3) are 2998 MHz, 2964 MHz, 3058 MHz, 3116 MHz, 3156 MHz, 3100 MHz and 2998 MHz respectively.

[0070] The dimensions of the 7 cavities are shown in the figure Figure 6 As shown, the inner diameter Ri of the input cavity 1 is 42mm, the outer diameter short axis Ro1 is 62.01mm, and the outer diameter long axis is 68.21mm; the inner diameter Ri of the first intermediate resonant cavity 21 is 42mm, and the outer diameter Ro2 is 64.47mm; the inner diameter Ri of the second intermediate resonant cavity 22 is 42mm, and the outer diameter Ro3 is 62.66mm; the inner diameter Ri of the third intermediate resonant cavity 23 is 42mm, and the outer diameter Ro4 is 61.62mm; the inner diameter Ri of the fourth intermediate resonant cavity 24 is 42mm, and the outer diameter Ro5 is 60.93mm; the inner diameter Ri of the fifth intermediate resonant cavity 25 is 42mm, and the outer diameter Ro6 is 69.21mm; the inner diameter Ri of the output cavity 3 is 42mm, the outer diameter short axis Ro7 is 47.02mm, and the outer diameter long axis is 61.13mm. The long axes of the input cavity 1 and the output cavity 3 are shown in the figure. Figure 2 , as shown in 4, are 68.21mm and 61.13mm respectively; the short axis of the input cavity 1 and the output cavity 3 is as shown in the diagram Figure 6 As shown, they are Ro1 and Ro7.

[0071] The gap widths G1 of the input cavity 1, the first intermediate resonant cavity 21, the second intermediate resonant cavity 22, the third intermediate resonant cavity 23, the fourth intermediate resonant cavity 24, and the fifth intermediate resonant cavity 25 are all 16.5 mm; the gap width G2 of the output cavity 3 is 9.5 mm;

[0072] The length L1 of the input cavity 1 is 23.51 mm, the lengths L2 of the first intermediate resonant cavity 21, the second intermediate resonant cavity 22, the third intermediate resonant cavity 23, and the fourth intermediate resonant cavity 24 are all 27.5 mm, the length L3 of the fifth intermediate resonant cavity 25 is 20.5 mm, and the length L4 of the output cavity 3 is 22.66 mm.

[0073] The invention discloses a multi-injection klystron high-frequency structure, with a final efficiency of 50.2%, an output power of 4.2MW, a gain of about 50dB, and a -1dB saturated power bandwidth widened to 81MHz (-1dB relative bandwidth is about 3%). Its phase space diagram is shown in FIG. Figure 8 As shown, the output power diagram is as follows Fig. 9 As shown, the output spectrum is as follows Fig.10 As shown in the figure, the bandwidth comparison of the klystron before and after the improvement is as follows Fig.11 shown.

[0074] The present invention ensures that the klystron achieves high peak output power (4.2MW) and high efficiency (50.2%) without increasing the length, while expanding its -1dB power bandwidth to 81MHz (the bandwidth is increased to 2.1 times that of the S-band 4.2MW peak output power 50.2% efficiency 4-beam 7-cavity klystron designed by the traditional method). Its advantages are that it reaches the empirical efficiency limit (50%) under high conductance (1.75μP) and has a wide bandwidth (-1dB relative bandwidth is about 3%). At present, there is no klystron with a peak output power exceeding 4.2MW, an efficiency of 50.2%, and a -1-dB relative bandwidth of 3% under the same conductance in the S-band.

[0075] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method 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 in the scope of protection of the present invention.

Claims

1. A method for effectively improving the bandwidth of a klystron, characterized in that: The method includes: Design a conventional high-power high-efficiency klystron high-frequency structure, wherein the resonance frequencies of the input cavity and the output cavity of the conventional high-power high-efficiency klystron high-frequency structure are the signal operating frequency, and the resonance frequencies of all the intermediate resonant cavities are greater than the signal operating frequency to focus the input electron beam; The resonant frequency of the first intermediate resonant cavity is adjusted to the relative operating frequency to defocus the electron beam; the relative operating frequency is less than the signal operating frequency; and the resonant frequencies of other intermediate resonant cavities are kept greater than the signal operating frequency to focus the electron beam; and the position of the first intermediate resonant cavity is adjusted and optimized to obtain the same high efficiency as the conventional high-power and high-efficiency klystron high-frequency structure, thereby improving the klystron bandwidth.

2. A method for effectively improving the bandwidth of a klystron according to claim 1, characterized in that: The relative operating frequency is twice the signal operating frequency minus the frequency of the first intermediate resonant cavity in the high-frequency structure of a conventional high-power and high-efficiency klystron.

3. The method for effectively improving the bandwidth of a klystron according to claim 1, characterized in that: Design of high-frequency structure of traditional high-power and high-efficiency klystron, including: The point where the electron injection density of each drift tube is the largest is calculated, and the position of the middle resonant cavity is placed correspondingly to the calculated point where the electron injection density of each drift tube is the largest.

4. A method for effectively improving the bandwidth of a klystron according to claim 3, characterized in that: Design of high-frequency structure of traditional high-power and high-efficiency klystron, including: The resonant frequency, position and input and output external quality factors of the intermediate resonant cavity are optimized and adjusted to obtain the klystron high-frequency structure with the highest efficiency.

5. The method for effectively improving the bandwidth of a klystron according to claim 1, characterized in that: This method enables the klystron to achieve a high power of 4.2MW and a high efficiency of 50.2%, and without increasing the length of the klystron, it can increase its -1dB power bandwidth to 2.1 times that of a traditional high-power and high-efficiency klystron.

6. A multi-injection klystron high frequency structure, characterized in that: The multi-injection klystron high frequency structure is designed based on a method for effectively improving the bandwidth of a klystron as claimed in any one of claims 1 to 5; The high-frequency structure of the multi-injection klystron comprises an input cavity with the same inner diameter, a plurality of intermediate resonant cavities and an output cavity, and also comprises a multi-injection drift section, wherein the multi-injection drift section runs through the input cavity, the intermediate resonant cavity and the output cavity; the intermediate resonant cavity comprises a first intermediate resonant cavity, a second intermediate resonant cavity, a third intermediate resonant cavity, a fourth intermediate resonant cavity and a fifth intermediate resonant cavity; The resonant frequency of the first intermediate resonant cavity is twice the signal operating frequency minus the frequency of the first intermediate resonant cavity in the high-frequency structure of a traditional high-power and high-efficiency klystron; the resonant frequencies of the other intermediate resonant cavities are all greater than the signal operating frequency.

7. A multi-beam klystron high frequency structure according to claim 6, characterized in that: The resonant frequencies of the input cavity, the first intermediate resonant cavity, the second intermediate resonant cavity, the third intermediate resonant cavity, the fourth intermediate resonant cavity, the fifth intermediate resonant cavity and the output cavity are 2998 MHz, 2964 MHz, 3058 MHz, 3116 MHz, 3156 MHz, 3100 MHz and 2998 MHz respectively.

8. The high frequency structure of a multi-beam klystron according to claim 6, characterized in that: The input cavity and the output cavity are elliptical resonant cavities, and the first intermediate resonant cavity, the second intermediate resonant cavity, the third intermediate resonant cavity, the fourth intermediate resonant cavity and the fifth intermediate resonant cavity are circular resonant cavities.

9. A multi-beam klystron high frequency structure according to claim 8, characterized in that: The inner diameter of the input cavity is 42 mm, the outer diameter of the short axis is 62.01 mm, and the outer diameter of the long axis is 68.21 mm; The inner diameter of the first intermediate resonant cavity is 42 mm and the outer diameter is 64.47 mm; the inner diameter of the second intermediate resonant cavity is 42 mm and the outer diameter is 62.66 mm; the inner diameter of the third intermediate resonant cavity is 42 mm and the outer diameter is 61.62 mm; the inner diameter of the fourth intermediate resonant cavity is 42 mm and the outer diameter is 60.93 mm; the inner diameter of the fifth intermediate resonant cavity is 42 mm and the outer diameter is 69.21 mm; The inner diameter of the output cavity is 42 mm, the outer diameter of the short axis is 47.02 mm, and the outer diameter of the long axis is 61.13 mm.

10. The multi-beam klystron high frequency structure according to claim 6, characterized in that: The gap widths of the input cavity, the first intermediate resonant cavity, the second intermediate resonant cavity, the third intermediate resonant cavity, the fourth intermediate resonant cavity, and the fifth intermediate resonant cavity are all 16.5 mm; the gap width of the output cavity is 9.5 mm; The length of the input cavity is 23.51 mm, the lengths of the first intermediate resonant cavity, the second intermediate resonant cavity, the third intermediate resonant cavity, and the fourth intermediate resonant cavity are all 27.5 mm, the length of the fifth intermediate resonant cavity is 20.5 mm, and the length of the output cavity is 22.66 mm.

Images