A power adjustable multi-mode operation traveling wave tube

Abstract

The application discloses a multi-mode working traveling wave tube slow wave structure, which comprises an input end, a first output spiral line, a first output end, a second output spiral line and a second output end which are arranged along an axis in sequence, and the length and the pitch of the first output spiral line and the second output spiral line are such that an input power level greater than a first power is output from the first output end, an input power level less than a second power is output from the second output end, and the first output end output power is greater than the second output end output power. The traveling wave tube comprising the slow wave structure can realize high-power output for use as an interference signal and can also realize small-power communication data transmission with excellent linearity, effectively solving the urgent need of users for multi-mode working scene application of the traveling wave tube. That is, under the same working voltage, only one input signal is given, and two output signals of high-power and small-power high linearity can be realized, meeting the needs of different working scenes.

Description

Technical Field

[0001] This invention relates to the field of microwave vacuum electronics technology. More specifically, it relates to a power-tunable, multi-mode traveling wave tube. Background Technology

[0002] In the field of microwave electronics, the traveling wave tube (TWT), as an important vacuum electronic device, works by the interaction between an electron beam and electromagnetic waves through a high-frequency slow-wave structure. The phase velocity of the fundamental wave is synchronized with the electron velocity of the electron beam. After the microwave gains energy from the electron beam, the amplified fundamental wave signal is coupled out through the output system. Currently, the K-band is the mainstream band for microwave communication signals and is widely used in fields such as high-capacity, high-resolution, and low-distortion digital information transmission.

[0003] Current traveling wave tube products often fail to guarantee signal nonlinearity under high power output conditions, while they cannot meet the user's purpose of signal interference under low power conditions. Therefore, a traveling wave tube structure with adjustable power is needed to meet the application requirements of different operating modes. Summary of the Invention

[0004] According to one aspect of the present invention, a slow-wave structure for a multi-mode operating traveling-wave tube is provided, the slow-wave structure comprising at least...

[0005] The input terminal, the first output spiral, the first output terminal, the second output spiral, and the second output terminal are sequentially distributed along the axial direction.

[0006] The lengths and pitches of the first and second output spirals are such that an input level greater than the first power is output from the first output terminal, and an input level less than the second power is output from the second output terminal, with the output power of the first output terminal being greater than the output power of the second output terminal.

[0007] Preferably, the first power is 3mW and the second power is 0.5mW.

[0008] Preferably, the slow wave structure further includes a spiral at the input end and a cut-off point between the input spiral and the first output spiral.

[0009] Preferably, the length of the spiral at the input end is 0-50mm; the length of the spiral at the first output end is 30-100mm; and the length of the spiral at the second output end is 100-150mm.

[0010] Preferably, the first output spiral has a length of 30-70mm and a pitch p2, a length of 70-90mm and a pitch that gradually decreases from p2 to p3, and a length of 90-100mm and a pitch p3, wherein the pitch p3 satisfies 2 to 3 times half the wavelength of the transmitted signal.

[0011] Preferably, the input spiral has a pitch p1, the second output spiral has a pitch p4, the pitch p2 is 1-2 times larger than the pitch p1 to transmit half the signal wavelength, and the pitch p4 is 1-1.5 times larger than the pitch p1 to transmit half the signal wavelength.

[0012] Preferably, the inner diameter of the second output spiral gradually increases along the direction of electron beam travel in order to suppress oscillations.

[0013] According to another aspect of the present invention, a multi-mode operating traveling wave tube is provided, comprising the slow wave structure described above.

[0014] Preferably, the first output terminal adopts a waveguide window structure, and the second output port adopts a coaxial transmission structure.

[0015] The present invention further provides a method for operating a multi-mode traveling wave tube as described above, comprising inputting a transmission signal with a constant operating frequency and having a first power and a second power at the input terminal, wherein the first power is greater than the second power, an input level greater than the first power outputs power from a first output terminal, and an input level less than the second power outputs power from a second output terminal, wherein the output power of the first output terminal is greater than the output power of the second output terminal.

[0016] The power-adjustable multi-mode traveling wave tube of the present invention can achieve both high-power output for interference signals and low-power, high-linearity communication data transmission, effectively solving the urgent needs of users for multiple operating modes of traveling wave tubes. That is, under the same operating voltage, only one input signal is required to achieve two output signals: high-power and low-power with high linearity, meeting the needs of different operating scenarios. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of a multimode traveling wave tube according to an embodiment of the present invention is shown.

[0019] Figure 2 A schematic cross-sectional view of a helical slow-wave structure according to an embodiment of the present invention is shown.

[0020] Figure 3 A schematic diagram of the high-frequency spiral slow-wave structure according to an embodiment of the present invention is shown.

[0021] Figure 4 The simulation curve of the phase shift at the second output port of the example slow-wave structure of the present invention is shown.

[0022] Figure 5 The diagram illustrates the axial distribution of output power within the operating bandwidth of an example slow-wave structure of the present invention under high-level input.

[0023] Figure 6 The axial distribution of electronic efficiency within the operating bandwidth of the example slow-wave structure of the present invention under high-level input is shown.

[0024] Figure 7 The axial distribution of the high-level mid-frequency output power of the example slow-wave structure of the present invention is shown.

[0025] Figure 8 The axial distribution of output power within the operating bandwidth of the example slow-wave structure of the present invention under low-level input is shown.

[0026] Figure 9 The axial distribution of electronic efficiency within the operating bandwidth of the example slow-wave structure of the present invention under low-level input is shown.

[0027] Figure 10 The axial distribution of the low-level mid-frequency output power of the example slow-wave structure of the present invention is shown. Detailed Implementation

[0028] To make the present invention, its technical solutions, and advantages clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0029] The purpose of this invention is to provide a traveling wave tube (TWT) that is flexibly suitable for space applications, maintaining high overall efficiency under different operating levels. This invention designs a high-efficiency, single-input, dual-output, multi-mode TWT. Utilizing the characteristics of helical slow-wave interaction technology, under high input levels, the first output port performs high-power electronic interference applications in the communication frequency band (Ku band), while the second output channel's interaction is suppressed, resulting in no power output. Under low input levels, the excitation signal at the first output port is small and quickly attenuates, while the second output channel, due to long-distance coupling, outputs low-power microwave signals for communication data transmission applications with good frequency domain bandwidth characteristics. In both operating modes, under the same operating voltage and current, the interaction efficiency (electronic efficiency) of signal amplification exceeds 25%. Calculations show an electron recovery efficiency of 80% achieved through multi-stage step-down collectors, with a flux ratio T≈98% and an overall tube efficiency exceeding 60%.

[0030]

[0031] Figure 1 This diagram illustrates a multi-mode traveling wave tube according to an embodiment of the present invention. Figure 2 This is a cross-sectional view of a high-frequency spiral slow-wave structure. Figure 3This is a schematic diagram of the axial direction of the high-frequency helical slow-wave structure according to an embodiment of the present invention. As shown in the figure, the power-adjustable multi-mode traveling wave tube of the present invention includes an electron gun 4, an input structure 5, a helical slow-wave structure 6, a high-power output terminal 7, a low-power output terminal 8, and a multi-stage step-down collector 9. In a preferred embodiment, the high-power output terminal adopts a high-power waveguide output structure, and the low-power output terminal adopts a high-linearity power coaxial output structure. The helical slow-wave structure 6 includes a tube shell 2 under vacuum and multiple helical segments 3 fixed inside the tube shell by a clamping rod 1. According to the power-adjustable multi-mode traveling wave tube of the present invention, the electron gun generates an electron beam through focusing. A periodic magnetic focusing system is added along the axial direction of the high-frequency slow-wave structure to generate beam-wave interaction, thereby realizing the millimeter-wave microwave signal output power amplification function. High-power output is achieved from the first output port using the waveguide structure, and the remaining electron beam continues to generate beam-wave interaction in the high-frequency slow-wave structure, and high-linearity signal transmission is achieved at the second output port using the coaxial structure.

[0032] The high-frequency slow-wave structure includes at least two spiral segments along its axis, providing an input terminal 5, a first output port 7, and a second output port 8. As a preferred embodiment of the invention, a spiral slow-wave structure comprising three spiral segments is provided: an input spiral structure 10, a first output spiral structure 12, and a second output spiral structure 14, with a preferred length ratio of 1:1.5-4.5:1-2. In a preferred embodiment, the input spiral has a length of 0-50 mm and a pitch p1; the first output spiral has a length of 30-70 mm and a pitch p2, a length of 70-90 mm with the pitch gradually decreasing from p2 to p3, and a length of 90-100 mm with a pitch p3; the second output spiral has a length of 100-150 mm and a pitch p4, with the inner diameter of the spiral gradually increasing from r1 to r2. The pitch p2 is 1-2 times larger than the pitch p1 by half the working signal wavelength, and the pitch p4 is 1-1.5 times larger than the pitch p1 by half the wavelength. By adjusting the pitches p1, p2, p3, and p4, as well as r1 and r2, it can be determined that when the input level of the input port is low (below 0.5mW), power is output from the second output port 8, and when the input level is high (greater than 3mW), high power is output from the second output port 7.

[0033] The spiral slow-wave interaction input terminal 5 can perform high-low input level conversion. The main function of the input spiral structure is to improve the small-signal gain of the traveling wave tube. There is a spiral cut-off 11 and attenuation material added between the input spiral structure 10 and the first output spiral structure 12, which can meet the transmission matching requirements between the input spiral structure 10 and the first output spiral 12. The first output spiral structure exchanges energy between high and low level signals and the electron beam passing through the center by changing the pitch and the tight winding method. During the structural optimization process, the tight winding size at the tail of the spiral must meet 2 to 3 times the half wavelength of the transmission signal, so that the high-frequency signal attenuates more when the low level is less than 1mW, thus suppressing the interaction due to mismatch, while achieving complete matching when the high level is greater than 5mW, resulting in high-power output at the output terminal 7. The first output spiral structure 12 and the second output spiral structure 14 have attenuation material added for the second spiral output structure, ensuring good transmission matching for the second output spiral 14. In the second-stage output spiral structure, when the high-level signal is greater than 5mW, the electron beam undergoes sufficient energy exchange at the first-stage output spiral 12, resulting in electron beam aggregation. Therefore, after the disabled electron beam passes through the second-stage output spiral 14, the interaction energy exchange is suppressed, resulting in almost no power output from the second output port 8. When the low-level signal propagation is less than 1mW, the interaction energy exchange between the electron beam and the first-stage output spiral 12 is suppressed, and a large number of electrons aggregate at the second-stage output spiral 14. Therefore, sufficient interaction energy exchange can occur, enabling a certain level of amplified signal output at the output port 8 for signal data transmission.

[0034] A high-power waveguide window structure is externally connected at the first output port 7. This structure can maximize the power output by reducing transmission loss of the high-power output signal at port 7 under high-level input conditions, thereby enabling high-power space electronic warfare applications. A coaxial transmission device is externally connected at the second output port 8. This structure can further ensure the phase-frequency characteristics at port 8 under low-level input conditions, transmitting low-power, high-linearity signals for communication signal data transmission. After energy exchange with the microwave signal in the high-frequency helical interaction structure 6, the electron beam is fully recovered in the multi-stage step-down collector 9 to improve the overall system efficiency.

[0035] In operation, the electron gun provides an electron beam that can exchange energy with the microwave signal. The electron beam interacts with the input microwave signal through a high-frequency slow-wave system, and after being modulated by an interaction signal, the microwave signal receives energy from the electron beam and is amplified at the high-power output port to achieve a high-power signal output used as an interference signal. After exchanging energy with the microwave signal, the remaining energy is further modulated by the high-frequency slow-wave system and output at the low-power linearity output port to obtain a small signal with excellent linearity and a phase shift of less than 45° for communication data transmission.

[0036] Figure 4-10 The output characteristics of the slow-wave structure example of this invention, simulated using MTSS software (provided by the University of Electronic Science and Technology of China), are presented. In this example, the input helix length is approximately 33 mm; the first output helix length is approximately 66 mm, with the pitch gradually decreasing along the electron beam propagation direction; the second output helix length is approximately 50 mm, with the inner diameter of the helix gradually increasing along the electron beam propagation direction. At the 8 high-frequency points at the output end, with an output power of 54 W, the maximum simulated nonlinear phase shift from a -20 dB input power back to saturation is 41.5 degrees, exhibiting good linearity.

[0037] Figures 5 to 7 An example of the slow-wave structure of the present invention operating at a high level of 45mW is given. The operating bandwidth at low, medium and high frequencies is 2GHz, the output power is 99mW, the first output port has 7 points, which is greater than 110W, and the electronic efficiency is greater than 32%. Figure 7 The axial distribution of output power at the mid-frequency point under high-level conditions of 5-50mW is given. It can be seen that under high-level conditions, at 150mm, at the second output port 8, the output power is almost zero. Therefore, as long as the high level is greater than 5mW, it can be effectively suppressed at the second output port 8.

[0038] Figures 8 to 10 An example of the slow-wave structure of the present invention operating at a low level of 0.3mW is given. The operating bandwidth at low, medium and high frequencies is 2GHz. The output power at the second output port 8 at 150mm is greater than 54W, and the electronic efficiency is greater than 25%. Figure 10 The axial distribution of output power at the mid-frequency point under low-level conditions of 0.0025mW-0.5mW is given. It can be seen that under low-level conditions, the output power at the first output port 7 of 99mm is effectively suppressed.

[0039] According to the power-adjustable multi-mode traveling wave tube slow-wave structure of the present invention, in the high-level input operating mode, the electron beam interacts with the input microwave signal through a high-frequency slow-wave system, resulting in an electron beam-electromagnetic wave interaction. After modulation by an interaction signal, the microwave signal receives energy from the electron beam and is amplified at the high-power output port 7, achieving a high-power signal output used as an interference signal. After exchanging microwave signal energy, the remaining energy continues to be modulated by the high-frequency slow-wave system and suppressed at the output port 8. In the low-level operating mode, the electron beam does not meet the excitation condition with the input microwave signal through the first output high-frequency slow-wave system, and the output power is suppressed at the output port 7. The electron beam continues to pass through a distance and undergoes modulation, interacting in the second output spiral slow-wave structure to achieve signal amplification at the output port 8, resulting in a linear microwave signal with a phase shift of less than 45°, which is excellent for communication data transmission.

[0040] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A multi-mode operating traveling wave tube slow wave structure, characterized in that, The slow-wave structure includes at least the following: The input terminal, the first output spiral, the first output terminal, the second output spiral, and the second output terminal are sequentially distributed along the axial direction. The lengths and pitches of the first and second output spirals are such that input levels greater than the first power are output from the first output terminal, and input levels less than the second power are output from the second output terminal, with the output power at the first output terminal being greater than the output power at the second output terminal. The slow-wave structure further includes a spiral at the input end, and a cut-off between the input spiral and the first output spiral. in The input spiral length is 0-50mm; the first output spiral length is 30-100mm, and the second output spiral length is 100-150mm. The first output spiral has a length of 30-70mm and a pitch of p2. The pitch gradually decreases from p2 to p3 for a length of 70-90mm. The pitch p3 for a length of 90-100mm satisfies 2 to 3 times half the wavelength of the transmitted signal. The input spiral has a pitch p1, and the second output spiral has a pitch p4. The pitch p2 is 1-2 times larger than the pitch p1, which is half the wavelength of the transmitted signal, and the pitch p4 is 1-1.5 times larger than the pitch p1, which is half the wavelength of the transmitted signal.

2. The multi-mode operating traveling wave tube slow wave structure according to claim 1, characterized in that, The first power is 3mW, and the second power is 0.5mW.

3. The multi-mode operating traveling wave tube slow wave structure according to claim 1, characterized in that, The inner diameter of the second-stage output spiral gradually increases along the direction of electron beam travel in order to suppress oscillations.

4. A power-adjustable multi-mode traveling wave tube, characterized in that, Includes the slow-wave structure according to claim 1.

5. The multi-mode traveling wave tube according to claim 4, characterized in that, The first output terminal adopts a waveguide window structure, and the second output terminal adopts a coaxial transmission structure.

6. The operating method of the multi-mode traveling wave tube according to claim 5, characterized in that, The input operating frequency remains constant, and the transmission signals have a first power and a second power respectively. The first power is greater than the second power. The input level that is greater than the first power outputs power from the first output terminal, and the input level that is less than the second power outputs power from the second output terminal. The output power of the first output terminal is greater than the output power of the second output terminal.

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