Mode suppression device for a gyrotron

Abstract

This invention discloses a mode suppression device for a gyroscopic traveling-wave tube, relating to the fields of microwave, millimeter-wave, and terahertz wave vacuum device technology. (The invention is described in section TE.) 21 The attenuation of the backwave mode reaches -10dB while the TE 01 The operating mode remains unaffected, allowing for normal amplification, thus effectively improving the stability of the gyroscopic traveling wave tube. This invention provides a transverse structure, due to the TE... 0n The mode only has wall current in the angular direction, therefore the operating mode (TE) 01 The wavelet-injection interaction will not be affected and will proceed normally. For TE... mn (m≠0) type parasitic modes are coupled to the annular coupling slot waveguides, which are uniformly distributed longitudinally along the outer wall of the circular waveguide, and are absorbed by the continuously attenuating material closely attached to the outer wall of the annular resonant cavity. Therefore, this invention can achieve this without affecting the TE... 01 Effectively suppress TE in the working mode 21 The backward oscillation mode effectively improves the stability of the gyroscopic traveling wave tube.

Description

Technical Field

[0001] This invention relates to the field of microwave, millimeter-wave, and terahertz wave vacuum device technology, specifically a mode suppression device for selectively suppressing parasitic modes of cyclotron traveling wave tubes. Background Technology

[0002] The gyrotron traveling wave tube (TWT) is an important source of microwave, millimeter-wave, and terahertz signals. Due to its high efficiency, high power, wide bandwidth, and high gain, it has broad application prospects in military and civilian fields such as high-resolution radar, high-power communication systems, and electronic warfare systems, and is therefore highly valued both internationally and domestically. However, the backward oscillation in the nonlinear interaction section severely limits the stability of the gyrotron.

[0003] The nonlinear interaction section is one of the core components of a gyro Traveling Wave Tube (TWT), and its structure affects the TWT's bandwidth, efficiency, and other performance characteristics. Traditional gyro Traveling Wave Tubes typically employ a tapered waveguide with a radius matched to a gradually decreasing magnetic field as the nonlinear interaction device. This leads to magnetic field detuning, thereby increasing the oscillation threshold of parasitic modes and thus improving stability. However, the range of magnetic field detuning cannot be too large, otherwise it will reduce the interaction efficiency of the operating modes. Therefore, this method has limited effectiveness in improving the oscillation threshold, especially under high electron beam velocity ratios and currents. This limits the development of gyro Traveling Wave Tubes towards higher output power. Therefore, how to further improve the stability of gyro Traveling Wave Tubes is our research focus. Summary of the Invention

[0004] To overcome the stability issues encountered in the nonlinear interaction section of traditional gyrotransmitters, this invention proposes a mode suppression device. This device selectively suppresses parasitic modes through a mode suppression structure, thereby increasing the oscillation threshold of parasitic modes in the gyrotransmitter and improving its stability.

[0005] The technical solution adopted in this invention is as follows:

[0006] A mode suppression device for a gyroscopic traveling wave tube (GWT) includes: a smooth circular waveguide, multiple annular cavity structures, multiple metal pillars, and a continuous attenuation material. The multiple annular cavity structures are uniformly distributed along the axial direction of the smooth circular waveguide on its outer wall, and the cavities of the annular cavity structures are connected to the cavities of the smooth circular waveguide. Each annular cavity structure includes an inner ring and an outer ring; the inner ring is an annular coupled slot waveguide, and the outer ring is an annular resonant cavity. The radial width of the inner ring is smaller than that of the outer ring, and the cavity thickness of the inner ring is greater than that of the outer ring. The multiple metal pillars pass through the outer rings of all the annular cavity structures and are uniformly surrounding the smooth circular waveguide, with the axial direction of the metal pillars parallel to the axial direction of the smooth circular waveguide. The continuous attenuation material is tubular, enclosing all the annular cavity structures and in close contact with the outer ring edges of the annular cavity structures.

[0007] The inner radius of the standard smooth metallic circular waveguide is determined by the injection-wave synchronization condition; the size and number of periods of the annular cavity structure are determined by the required operating mode and the suppressed oscillation mode; the size and position of the circular pillar are determined by the required suppressed oscillation mode; the thickness of the continuous attenuation material can be adjusted according to the required attenuation amount.

[0008] Furthermore, the smooth circular waveguide and the annular cavity structure are both made of metal.

[0009] Furthermore, the continuously decaying material is a decaying ceramic.

[0010] The positive effects of this invention are:

[0011] In the TE of the present invention 21 The attenuation in the backwave mode reaches -10dB while the TE... 01 The operating mode remains unaffected and amplification is maintained, thus effectively improving the stability of the gyroscopic traveling wave tube.

[0012] This invention is a transverse structure, due to TE 0n The mode only has wall current in the angular direction, therefore the operating mode (TE) 01 The wavelet-injection interaction will not be affected and will proceed normally. For TE... mn (m≠0) type parasitic modes are coupled to the annular coupling slot waveguides, which are uniformly distributed longitudinally along the outer wall of the circular waveguide, and are absorbed by the continuously attenuating material closely attached to the outer wall of the annular resonant cavity. Therefore, this invention can achieve this without affecting the TE... 01 Effectively suppress TE in the working mode 21 The backward oscillation mode effectively improves the stability of the gyroscopic traveling wave tube. Attached Figure Description

[0013] Figure 1 This is a structural diagram of a mode suppression device applied to a gyroscopic traveling wave tube according to the present invention.

[0014] Smooth circular waveguide (main waveguide) (1), continuous attenuation material (2), metal pillar (3), annular coupled slot waveguide (4), annular resonant cavity (5);

[0015] Figure 2 This is a cross-sectional view of the present invention.

[0016] Figure 3 This is a side view of the present invention.

[0017] Figure 4 The dispersion curve of the injection-wave interaction in the G-band.

[0018] Figure 5 The mode suppression device obtained from CST high-frequency simulation software affects the returned wave mode (TE). 21 The attenuation parameter (S) 21 The relationship between parameters and operating frequency.

[0019] Figure 6 The mode suppression device obtained from CST high-frequency simulation software has a different operating mode (TE). 01 The attenuation parameter (S) 21 The relationship between parameters and operating frequency. Detailed Implementation

[0020] The working principle of this invention is as follows:

[0021] One end of the circular waveguide is connected to the linear interaction section of the gyrotron traveling wave tube (TWT), and the other end is connected to the TWT's output system. The gyrotron electron beam, modulated by the linear interaction section, enters the nonlinear interaction section, where it directly exchanges energy with the electromagnetic wave in a high-frequency electromagnetic field. The operating mode and oscillation mode can be modulated and suppressed through the slot coupling of the longitudinally distributed circular ring-coupled slot waveguide. The attenuation characteristics of the continuously attenuating material on the outer wall of the circular resonant cavity suppress TE (transient electron beam). 21 The backward oscillation of the mode achieves stable amplification of the gyroscopic traveling wave tube.

[0022] The invention will be further illustrated below with a design example and accompanying drawings of a nonlinear interaction device for a gyro traveling-wave tube with a G-band mode suppression structure:

[0023] Technical requirements for the high-frequency interaction device of a gyro traveling-wave tube with a G-band distributed radiation coupling loss device structure:

[0024] Main waveguide operating mode: TE 01 mold;

[0025] Operating frequency band: G band (210–220 GHz), operating voltage 50 kV, operating current 3 A.

[0026] Appendix Figure 1 A structural diagram of a mode suppression device for a gyroscopic traveling wave tube, as presented in this example, is attached. Figure 2 This is a cross-sectional view of the mode suppression device, and a side view of the mode suppression device. The invention includes a smooth circular waveguide (main waveguide) (1), a continuous attenuation material (2), a metal pillar (3), a ring-shaped coupled slot waveguide (4), and a ring-shaped resonant cavity (5).

[0027] in:

[0028] Smooth circular waveguide (main waveguide) (1): radius 0.9 mm, length 12 mm;

[0029] Continuous attenuation material (2): inner radius 2.45 mm, outer radius 2.65 mm;

[0030] Metal pillar (3): radius 0.2 mm, length 5.54 mm, its center is 1.72 mm away from the center of the main waveguide;

[0031] In order to effectively implement TE 21 The parasitic modes are coupled from the main waveguide, and a total of 6 coupling structures were selected, including:

[0032] Six annular coupled slot waveguides (4): inner radius 0.9 mm, outer radius 1.3 mm, thickness 0.2 mm;

[0033] Six annular resonant cavities (5): inner radius 1.3 mm, outer radius 2.45 mm, thickness 0.14 mm.

[0034] Appendix Figure 4 This is a schematic diagram of the cold dispersion curve of the injection-wave interaction in the G-band. This diagram shows that the cyclotron traveling-wave tube operates at the fundamental TE... 01 The mode is simultaneously affected by the fundamental frequency TE. 11 and TE 21 The influence of the backward oscillation generated by the mode, where TE in the nonlinear segment 21 The mode has the greatest impact. Point A is the position where the electron beam dispersion curve and the high-frequency electromagnetic field reach their optimal synchronization condition during matching, from which TE can be obtained. 01 The operating frequency of the mode is 210–220 GHz; point B is TE. 21 The mode return wave oscillation start frequency is 182.3 GHz; point C is TE. 11 The mode backwave oscillation frequency is 166.4 GHz.

[0035] Appendix Figure 5 The mode suppression device obtained from CST high-frequency simulation software affects the returned wave mode (TE). 21 The attenuation parameter (S) 21 The graph shows the relationship between parameters and operating frequency. This structure achieves attenuation exceeding 10dB at 182-183GHz, effectively suppressing TE. 21 The backward oscillation mode improves the stability of the gyroscopic traveling wave tube.

[0036] Appendix Figure 6 The mode suppression device obtained from CST high-frequency simulation software has a different operating mode (TE). 01 The attenuation parameter (S) 21 A graph showing the relationship between parameters and operating frequency. This structure is relevant to the operating frequency. 01 The influence of the mode is very small, within the operating frequency range of S 21All are greater than -0.05dB and S 11 All values ​​are less than -15dB. This indicates that the mode suppression device will not interfere with the normal amplification of the operating mode.

[0037] The above description is merely a specific implementation of the present invention applied to a G-band cyclotron traveling wave tube. The present invention is also applicable to other frequency bands operating in TE mode. 0n The required mode for suppressing parasitic behavior is TE. mn A gyroscopic traveling wave tube with m≠0.

Claims

1. A mode suppression device for a gyrotron traveling wave tube, the device comprising: Smooth circular waveguide, multiple circular ring cavity structures, multiple metal columns, continuous attenuation material; The multiple circular ring cavity structures are uniformly distributed along the axial direction of the smooth circular waveguide on the outer wall of the smooth circular waveguide, and the cavities of the circular ring cavity structures are in communication with the cavity of the smooth circular waveguide; the circular ring cavity structure comprises an inner ring and an outer ring, the inner ring is a circular ring coupling gap waveguide, and the outer ring is a circular ring resonant cavity; the radial width of the inner ring is smaller than that of the outer ring, and the cavity thickness of the inner ring is greater than that of the outer ring; the multiple metal columns pass through the outer rings of all the circular ring cavity structures and are uniformly arranged around the smooth circular waveguide, and the axial direction of the metal columns is parallel to the axial direction of the smooth circular waveguide; the continuous attenuation material is tubular, and all the circular ring cavity structures are covered therein and are in close contact with the outer ring edges of the circular ring cavity structures; The inner radius of the smooth circular waveguide is determined by the injection-wave synchronization condition; the size and the number of periods of the circular ring cavity structure are determined by the required working mode and the suppressed oscillation mode; the size and the position of the metal column are determined by the required suppressed oscillation mode; the thickness of the continuous attenuation material can be adjusted according to the required attenuation amount; The smooth circular waveguide and the circular ring cavity structure are both made of metal.

2. A mode suppression device for a gyrotron traveling wave tube as defined in claim 1, wherein The continuous attenuation material is attenuation ceramic.

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