Slow wave structure of G-band dual-mode traveling wave tube

Abstract

The embodiment of the invention provides a slow wave structure of a G-band dual-mode traveling wave tube, which is characterized by comprising a cathode, a first slow wave structure, an attenuator and a second slow wave structure, the cathode is a section of cylindrical structure, is positioned at the starting section of the first slow wave structure and is connected with the first slow wave structure; the first slow wave structure comprises a microwave input channel, a first electron beam channel and a first folded waveguide structure; the attenuator comprises an attenuation waveguide, a wave absorbing material structure and a drift channel, and the attenuator is connected with the first slow wave structure and the second slow wave structure; the second slow wave structure comprises a second folded waveguide structure, a second electron beam channel and a microwave output channel; wherein microwaves propagate in the folded waveguide structure. According to the invention, the power of the G-band dual-mode traveling wave tube is effectively improved, and the requirements of various different occasions on high-power traveling wave tube devices are met.

Description

TECHNICAL FIELD

[0001] The present document relates to the technical field of vacuum electron devices, and in particular to a G-band dual-mode traveling wave tube slow wave structure. BACKGROUND

[0002] Terahertz waves are unique in the position of the wave spectrum, and are connected with microwave electronics in the low frequency band and intersect with infrared photonics in the high frequency band, making terahertz wave technology have important applications in terahertz communication, terahertz imaging, biomedical detection, security inspection, etc. Due to the development of terahertz vacuum electron devices towards miniaturization, high power and high frequency band, the folded waveguide slow wave structure has unique advantages and has become a hot research topic at present.

[0003] In high-frequency structures, the folded waveguide slow wave structure has the characteristics of all-metal structure, high reliability, high bandwidth, easy to manufacture, etc., and has an important position in the family of traveling wave tubes. The terahertz folded waveguide traveling wave tube can amplify electromagnetic waves because of the energy exchange between the electron beam and the electromagnetic wave in the high-frequency structure, i.e. the beam-wave interaction. The folded waveguide is the core device of the traveling wave tube, responsible for the energy exchange between the electron beam and the electromagnetic wave in the traveling wave tube. The electron beam is emitted from the position of the cathode to the slow wave structure region of the folded waveguide, and the electron beam and the electromagnetic wave are matched in phase velocity at the incident position, so that the phase velocity of the electron beam and the phase velocity of the electromagnetic wave are synchronized to exchange energy. Finally, the amplified electromagnetic wave signal is emitted from the output port of the folded waveguide slow wave structure to complete the energy exchange process. The design of the slow wave structure determines the strength of the output capacity of the traveling wave tube.

[0004] Dual-mode traveling wave tubes are widely used in satellite communication, radar systems (such as airborne fire control radars, phased array radars), electronic countermeasure equipment and space exploration, etc. due to their wide frequency band, high power and multi-mode compatibility.

[0005] The existing high-frequency circuit of the dual-mode traveling wave tube has the following technical problems: (1) The frequency band direction designed for the dual-mode traveling wave tube is mainly concentrated in the lower frequency band, and there is less research on high power. The output power level of the traveling wave tube needs to be improved, which greatly limits its application in ultra-wideband radar long-distance detection, high-resolution imaging radar, etc. (2) The current research on traveling wave tubes, especially in the G-band, cannot effectively improve the bandwidth of the dual-mode traveling wave tube, especially the compatibility of high power and wide bandwidth. This limits the radar target detection in electronic countermeasures and is not conducive to application in military and civilian fields.

[0006] The existing research results design a phase velocity gradient technology on the basis of the folded waveguide slow wave structure to improve the output power, but this result cannot directly improve the bandwidth of the traveling wave tube, and the power improvement effect cannot meet the demand of the dual-mode traveling wave tube with larger power pulse rise ratio. SUMMARY

[0007] One or more embodiments of the present specification provide a G-band dual-mode waveguide tube slow wave structure, comprising a cathode, a first slow wave structure, an attenuator and a second slow wave structure; the cathode is a cylindrical structure, located at the beginning of the first slow wave structure, connected to the first slow wave structure; the first slow wave structure comprises a microwave input channel, a first electron beam channel and a first folded waveguide structure; the attenuator comprises an attenuating waveguide, a wave-absorbing material structure and a drift channel, the attenuator is connected to the first slow wave structure and the second slow wave structure; the second slow wave structure comprises a second folded waveguide structure, a second electron beam channel and a microwave output channel; wherein the microwave propagates in the folded waveguide structure.

[0008] Further, the folded waveguide structure is connected by a single independent folded waveguide unit, and each folded waveguide unit is periodically arranged in a serpentine connection, wherein the folded waveguide unit comprises a straight waveguide structure and a curved waveguide structure.

[0009] Further, the electron beam channel is at the center of the folded waveguide structure, the first electron beam channel is circular, and the electron beam channel start end is connected to the cathode, and the beginning of the first folded waveguide structure is the microwave input channel.

[0010] Further, the microwave output channel is located at the end of the second slow wave structure, and the radius of the second electron beam channel changes with the number of folded waveguide periods.

[0011] Further, the drift channel connects the first slow wave structure and the second slow wave structure, the attenuating waveguide is located at the end of the first slow wave structure to connect the attenuation area, and the wave-absorbing material is located above the attenuating waveguide.

[0012] Further, the attenuator is divided into upper and lower parts, and the upper and lower parts are symmetric about the horizontal center, the upper half of the attenuator is connected to the second slow wave structure, and the lower half is connected to the first slow wave structure.

[0013] Further, the drift channel is located between the two slow wave structures, and the length of the drift channel is a multiple t of the half-period length of the two slow wave structures, wherein 5≤t≤7.

[0014] Further, the number of periods of the first slow wave structure is different from the number of periods of the second slow wave structure.

[0015] Further, the radius of the electron beam channel is less than half the height of the straight waveguide.

[0016] Further, the waveguide wall material of the folded waveguide structure is composed of oxygen-free copper, and the wave-absorbing material is beryllium oxide.

[0017] The two different working modes can be realized by changing the voltage and other parameters of the electron beam under the same structure, the output power, the bandwidth, the gain output of the traveling wave tube are improved by using the phase velocity gradient and the electron beam channel gradient technology, the power of the G-band dual-mode traveling wave tube is effectively improved, the demand of the high-power traveling wave tube device for various occasions is met, the traveling wave tube amplifier has the characteristics of high power, high gain and wide frequency band, has absolute advantages in realizing the THz vacuum electron device, and has important application prospects in THz radar, communication, detection and electronic warfare.

[0018] The above description is only a summary of the technical scheme of the present application, in order to more clearly understand the technical means of the present application, the content of the specification can be implemented, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described below. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical scheme in the one or more embodiments of the present application or the prior art, the drawings needed in the embodiment or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments described in the present specification, and those skilled in the art can also obtain other drawings according to these drawings without creating additional labor.

[0020] Figure 1 A schematic diagram of a G-band dual-mode traveling wave tube slow wave structure is provided for one or more embodiments of the present application.

[0021] Figure 2 A unit slow wave structure diagram of a G-band dual-mode traveling wave tube slow wave structure is provided for one or more embodiments of the present application.

[0022] Figure 3 A dispersion curve diagram of a G-band dual-mode traveling wave tube slow wave structure is provided for one or more embodiments of the present application.

[0023] Figure 4 An output power and spectrum diagram of a G-band dual-mode traveling wave tube slow wave structure under high power mode is provided for one or more embodiments of the present application.

[0024] Figure 5 A low power mode output power and gain and frequency relationship diagram of a G-band dual-mode traveling wave tube slow wave structure is provided for one or more embodiments of the present application.

[0025] Figure 6 A high power mode output power and gain and frequency relationship diagram of a G-band dual-mode traveling wave tube slow wave structure is provided for one or more embodiments of the present application.

[0026] Reference signs:

[0027] 1. cathode; 2. beginning of electron beam channel; 3. microwave input channel; 4. first electron beam channel;

[0028] 5. first straight waveguide structure; 6. first curved waveguide structure; 7. wave-absorbing material structure; 8. attenuator; 9. drift channel; 10. second curved waveguide structure; 11. second straight waveguide structure; 12. second electron beam channel; 13. microwave output channel; 14. end of electron beam channel. DETAILED DESCRIPTION

[0029] In order to make the technical scheme in one or more embodiments of the present specification better understood by the person skilled in the art, the technical scheme in one or more embodiments of the present specification will be clearly and completely described below in conjunction with the drawings in one or more embodiments of the present specification. Obviously, the described embodiments are only a part of the embodiments of the present specification, rather than all the embodiments. Based on one or more embodiments of the present specification, all other embodiments obtained by the person skilled in the art without creative labor should belong to the protection scope of the present document.

[0030] The embodiment of the present application provides a G-band dual-mode traveling wave tube slow wave structure, Figure 1 A schematic diagram of a G-band dual-mode traveling wave tube slow wave structure provided by one or more embodiments of the present specification is shown in Figure 1, which specifically comprises a cathode 1, a first slow wave structure, an attenuator and a second slow wave structure according to the G-band dual-mode traveling wave tube slow wave structure of the present application. Figure 1

[0031] The cathode 1 is a cylindrical structure, located at the beginning of the entire structure, the beginning of the first slow wave structure, and connected to the first slow wave structure. The cathode 1 is a PEC material, which is a cylindrical body with a radius of 0.06mm, used to generate an electron beam. The first slow wave structure includes a microwave input channel 3, a first electron beam channel 4 and a first folded waveguide structure; the attenuator includes an attenuator 8, a wave-absorbing material structure 7 and a drift channel 9, the attenuator is connected to the first slow wave structure and the second slow wave structure; the second slow wave structure includes a second folded waveguide structure, a second electron beam channel 12 and a microwave output channel 13; wherein the microwave propagates in the folded waveguide structure.

[0032] The folded waveguide structure is connected by a single independent folded waveguide unit, and each folded waveguide unit is periodically arranged in a serpentine connection, wherein the folded waveguide unit includes a straight waveguide structure and a curved waveguide structure, as shown in Figure 1 ​As shown, the first folded waveguide structure includes a first straight waveguide structure 5 and a first curved waveguide structure 6, and the second folded waveguide structure includes a second straight waveguide structure 11 and a second electron beam channel 12. The electron beam channel is at the center of the folded waveguide structure, the first electron beam channel 4 is circular, including an electron beam channel start end 2 connected to the cathode and the folded waveguide structure, and the first folded waveguide structure has a microwave input channel 3 at the beginning, which is the electromagnetic wave input port of the folded waveguide structure.

[0033] In this embodiment, the number of folded waveguide unit periods N = 37, and each period unit is as shown in FIG. 2. Figure 2 As shown, it includes an electron beam channel 41, a curved waveguide section 51, and a straight waveguide section 61; the straight waveguide section 61 has a waveguide wide side length a = 0.83 mm, a waveguide narrow side width b = 0.16 mm, and a straight waveguide height h = 0.26 mm, the curved waveguide section 51 has a half-period length p = 0.31 mm, and the electron beam channel 41 has an electron beam channel radius of 0.12 mm. The curved waveguide section 51 is an arc-shaped curved section structure, which adopts an asymmetric design with an outer circle center offset outward by 0.04 mm (dout) and an inner circle center offset inward by 0.03 mm (din) to optimize the electric field distribution and improve the coupling impedance.

[0034] The attenuator part is composed of an absorbing material structure 7, an attenuating waveguide 8, and a drift channel 9, the drift channel 9 connects the first slow wave structure and the second slow wave structure, the attenuating waveguide 8 is located at the end of the first slow wave structure to connect the attenuation area, and the absorbing material structure 7 is located above the attenuating waveguide. The attenuator is divided into upper and lower parts, which are symmetric about the horizontal center, the upper half of the attenuator connects the second slow wave structure, and the lower half connects the first slow wave structure. The absorbing material structure adopts a lossy metal of beryllium oxide, which can absorb electromagnetic waves when the electromagnetic waves pass through, reduce the size of the reflected signal and the spurious oscillation of the traveling wave tube, and design the attenuating waveguide 8 as an E-plane boundary wedge-shaped structure to increase the contact area between the electromagnetic wave and the absorbing material to increase the processing function of the attenuator on the electromagnetic wave signal. The distribution of the electron beam in the drift channel 9 during the movement is beneficial to the energy exchange between the electron beam and the electromagnetic wave signal in the second slow wave structure.

[0035] The drift channel 9 is located in the middle of the two slow wave structures, and the drift channel length is a multiple t of the half-period length of the two slow wave structures, where 5≤t≤7.

[0036] The second slow-wave structure includes a second curved waveguide structure 10, a second straight waveguide structure 11, a second electron beam channel 12, a microwave output channel 13, and an electron beam channel terminal 14. The microwave output channel 13 is located at the terminal of the second slow-wave structure. Unlike the first slow-wave structure, the second slow-wave structure uses a phase velocity gradient technique to further reduce the axial phase velocity of the electromagnetic wave signal and reduce the radius of the electron beam channel at the output end. Since the coupling impedance also increases, this method maintains the electron throughput rate while increasing the axial coupling impedance without changing the electron beam filling ratio of the first slow-wave structure. This further improves the energy exchange efficiency between the electron beam and the electromagnetic wave, thereby increasing the output power.

[0037] The radius of the second electron injection channel 12 changes with the number of folded waveguide periods. The half-period length of the second curved waveguide structure 10 is 0.295 mm, and the rectangular waveguide height of the second straight waveguide structure 11 is 0.29 mm. The radius of the electron injection channel is less than half the straight waveguide height. In this embodiment, the radius of the second electron injection channel 12 is 0.11 mm and 0.08 mm. The second electron injection channel is a gradual structure composed of two different parameter segments. The period number of the first slow-wave structure is different from the period number of the second slow-wave structure. The waveguide wall material of the folded waveguide structure is made of oxygen-free copper.

[0038] Reference Figure 1 The slow wave structure and parameters shown in the figure can realize two different power output modes. In the high power pulse mode, the working voltage is set to 23kV, the electron beam current is 70mA, the input power is 30mW, and the matching frequency band is 204-215GHz. Figure 3 The dispersion curve characteristics of the folded waveguide shown in the figure show the coupling between the electron beam and the electromagnetic wave at different voltages. When the voltage is higher, the operating frequency band is also lower. On the contrary, when the voltage is lower, the operating frequency band of the folded waveguide is also higher. The low voltage continuous wave mode voltage is set to 22.2kV. Under the premise that the conductivity coefficient remains unchanged, the current is reduced to 66mA.

[0039] The set parameters are simulated in the particle simulation of CST. The output power and spectrum of the high power mode at 210GHz are obtained when the input power is 30mW and the focusing magnetic field is set to 0.85T. Figure 4 As shown, the peak power reaches 155W and the gain is 37.1dB.

[0040] Figure 5 for Figure 1 The output power and gain vs. frequency curves in the low-power mode of the structure show a maximum output power of 100W and a 3dB bandwidth greater than 11GHz. Figure 6 for Figure 1The corresponding curve chart of output power and gain of the structure in high power mode and frequency, the maximum output power is 190W, and the bandwidth is 11GHz.

[0041] The present application has the following advantages:

[0042] By changing the voltage and other parameters of the electron beam in the same structure, two different working modes can be realized, the output power and bandwidth of the traveling wave tube are improved by using the phase velocity gradient and electron beam channel gradient technology, the gain output is improved, the power of the G-band dual-mode traveling wave tube is effectively improved, the demand of high-power traveling wave tube devices for various occasions is met, the traveling wave tube amplifier has the characteristics of high power, high gain and wide band, has an absolute advantage in realizing THz vacuum electronic devices, and has important application prospects in THz radar, communication, detection and electronic warfare.

[0043] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A G-band dual-mode traveling wave tube slow-wave structure, characterized in that: The invention comprises a cathode, a first slow-wave structure, an attenuator, and a second slow-wave structure; the cathode is a cylindrical structure located at the beginning of the first slow-wave structure and connected to the first slow-wave structure; the first slow-wave structure comprises a microwave input channel, a first electron beam channel, and a first folded waveguide structure; the attenuator comprises an attenuation waveguide, an absorbing material structure, and a drift channel, and the attenuator connects the first slow-wave structure and the second slow-wave structure; the second slow-wave structure comprises a second folded waveguide structure, a second electron beam channel, and a microwave output channel; The microwaves propagate in a folded waveguide structure.

2. The G-band dual-mode traveling wave tube slow-wave structure according to claim 1, characterized in that: The folded waveguide structure is obtained by connecting single independent folded waveguide units, and each folded waveguide unit is periodically arranged in a serpentine connection, wherein the folded waveguide unit includes a straight waveguide structure and a curved waveguide structure.

3. The G-band dual-mode traveling wave tube slow-wave structure according to claim 1, characterized in that: The electron injection channel is at the center of the folded waveguide structure. The first electron injection channel is circular and includes an electron injection channel starting end. The electron injection channel starting end is connected to the cathode. The beginning section of the first folded waveguide structure is a microwave input channel.

4. The G-band dual-mode traveling wave tube slow-wave structure according to claim 3, characterized in that: The microwave output channel is located at the end of the second slow-wave structure, and the radius of the second electron beam channel changes with the change of the number of folded waveguide cycles.

5. The G-band dual-mode traveling wave tube slow-wave structure according to claim 1, characterized in that: The drift channel connects the first slow-wave structure and the second slow-wave structure. The attenuation waveguide is located at the end of the first slow-wave structure and connected to the attenuation zone. The absorbing material is located above the attenuation waveguide.

6. The G-band dual-mode traveling wave tube slow-wave structure according to claim 5, characterized in that: The attenuator is divided into two parts, the upper and lower parts are symmetrical about the horizontal center, the upper half of the attenuator is connected to the second slow-wave structure, and the lower half is connected to the first slow-wave structure.

7. The G-band dual-mode traveling wave tube slow-wave structure according to claim 1, characterized in that: The drift channel is located between the two slow-wave structures, and the length of the drift channel is a multiple t of the half-period length of the two slow-wave structures, where 5≤t≤7.

8. The G-band dual-mode traveling wave tube slow-wave structure according to claim 1, characterized in that: The period number of the first slow-wave structure is different from the period number of the second slow-wave structure.

9. The G-band dual-mode traveling wave tube slow-wave structure according to claim 2, characterized in that: The radius of the electron injection channel is less than half the height of the straight waveguide.

10. The G-band dual-mode traveling wave tube slow-wave structure according to claim 1, characterized in that: The waveguide wall material of the folded waveguide structure is made of oxygen-free copper, and the absorbing material is beryllium oxide.

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