Mixed slow wave structure for regulating and suppressing backward wave oscillation based on transmission forbidden band

Abstract

The invention discloses a mixed slow wave structure for regulating and suppressing backward wave oscillation based on a transmission forbidden band, which comprises two unit structures: a working unit and a regulating unit, each of the two unit structures is composed of a rectangular coupling cavity, a circular electron beam channel and a grating gap, the y-direction length of the grating gap of the regulating unit is greater than that of the working unit, and the y-direction length of the circular electron beam channel is greater than that of the working unit. Therefore, compared with the working unit, the forbidden band between the mode 1 and the mode 2 of the regulation and control unit moves downwards, so that the backward wave competition frequency point of the working unit is regulated and controlled to the position close to the forbidden band in the regulation and control unit, and even if the backward wave competition frequency point of the working unit is located in the forbidden band of the regulation and control unit in the mixed slow wave structure, the backward wave competition frequency point is not limited. And the working frequency point of the working unit is located outside the forbidden band of the regulation and control unit and still has good transmission characteristics in the regulation and control unit, so that backward wave competition oscillation is suppressed, and signal transmission of the working frequency point is not influenced. The mixed slow wave structure has the characteristic of regulating and controlling a transmission forbidden band, and has important application value in the field of terahertz electric vacuum devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of vacuum electronic devices, and more specifically, relates to a hybrid slow-wave structure for suppressing backward wave oscillation based on transmission bandgap regulation, which is used in backward wave tubes and traveling wave tubes, and is particularly suitable for terahertz backward wave tubes working in high-order modes. Background Art

[0002] The slow-wave structure is the core of the traveling wave tube and the backward wave tube, which have very wide applications in many fields such as communications, spectral imaging, and plasma diagnosis. For the injection wave interaction circuit composed of a single slow-wave structure, the working voltage line not only intersects with the working mode at the working point, but also has intersections with other modes. When the intersection of other modes is located in the backward wave region, it is easy to generate a backward wave oscillation. The commonly used methods to solve the backward wave oscillation are to cut off the circuit or add an attenuator. Although these methods cut off the backward wave oscillation loop, they also cut off the loop of the working mode signal and cannot be applied to the backward wave tube. In order to suppress the backward wave competition oscillation mode without affecting the working mode, it is necessary to insert a circuit with a special control function into the working circuit, which only affects the oscillation loop of the backward wave competition frequency point.

[0003] In the Chinese invention with the authorization announcement number "CN112216579B" published on March 15, 2022, a high-order backward wave oscillation suppression structure for a strip-shaped traveling wave tube is disclosed. The structure includes a shell, rectangular grids staggered on the upper top surface and the lower bottom surface of the shell cavity, and a row of rectangular coupled waveguides of the same size and periodic arrangement are respectively arranged on the two side surfaces of the shell. The two rows of rectangular coupled waveguides are staggered by half a slow wave period along the axial direction and are also staggered in the longitudinal direction, so that one rectangular coupled waveguide corresponds to one rectangular cavity. The present invention realizes the suppression and absorption of high-order modes synchronously without affecting or destroying the working mode by loading staggered rectangular coupled waveguides on both sides of the slow-wave structure.

[0004] This invention patent is only applicable to strip-type traveling wave tubes, and the rectangular coupled waveguides are placed on both sides of the slow-wave structure in a staggered arrangement. The structural design is relatively complex and difficult to process and manufacture. Summary of the invention

[0005] The purpose of the present invention is to solve the problem of return wave competition oscillation in a single slow-wave structure, and propose a hybrid slow-wave structure based on transmission bandgap regulation to suppress return wave oscillation. A control unit slow-wave structure with a certain number of periods is inserted into a circuit composed of a working unit slow-wave structure, thereby increasing the signal transmission attenuation and destroying the excitation conditions for the return wave competition frequency in the working unit, cutting off its return wave oscillation loop without affecting the signal transmission of the working frequency, thereby achieving the purpose of stable operation of the hybrid slow-wave structure working mode.

[0006] To achieve the above-mentioned purpose, the present invention provides a hybrid slow-wave structure for suppressing backward oscillation based on transmission bandgap regulation, comprising:

[0007] A working unit circuit consisting of working units with a certain number of cycles;

[0008] It is characterized by further comprising:

[0009] A control unit circuit composed of control units with a certain number of cycles is inserted into the working unit circuit;

[0010] The working unit and the control unit each include a rectangular coupling cavity, a circular electron injection channel and a grating gap, the grating gap is connected to the rectangular coupling cavity and has the same x-direction depth as the rectangular coupling cavity, and the circular electron injection channel passes through the x-direction center of the grating gap;

[0011] The y-direction length of the grating gap of the regulating unit is longer than the y-direction length of the grating gap of the working unit.

[0012] The object of the present invention is achieved in this way.

[0013] The hybrid slow-wave structure for suppressing back-wave oscillation based on transmission bandgap regulation of the present invention comprises two unit structures: a working unit and a regulating unit. Both unit structures are composed of a rectangular coupling cavity, a circular electron beam channel and a grating gap. The grating gap of the regulating unit has a y-direction length greater than that of the working unit, so that the bandgap between mode 1 and mode 2 of the regulating unit is shifted downward compared to the working unit, resulting in the back-wave competition frequency point of the working unit being regulated to a position close to the bandgap in the regulating unit. Even if the back-wave competition frequency point of the working unit is located in the bandgap of the regulating unit in the hybrid slow-wave structure, and the working frequency point of the working unit is located outside the bandgap of the regulating unit, it still has good transmission characteristics in the regulating unit, thereby suppressing the back-wave competition oscillation and not affecting the signal transmission of the working frequency point. The hybrid slow-wave structure has the characteristic of regulating the transmission bandgap and has important application value in the field of terahertz electric vacuum devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of a single slow-wave structure circuit;

[0015] Figure 2 It is a structural schematic diagram of a specific implementation of the hybrid slow-wave structure for suppressing backward wave oscillation based on transmission bandgap regulation of the present invention;

[0016] Figure 3 yes Figure 1 Schematic diagram of the vacuum structure of the working unit and the regulating unit, wherein (a) is the working unit and (b) is the regulating unit;

[0017] Figure 4is a dispersion diagram of the working unit and the regulating unit structure in the present invention;

[0018] Figure 5 It is a phase-speed synchronous voltage diagram of the working unit and the regulating unit structure in the present invention;

[0019] Figure 6 It is a transmission loss comparison diagram of the hybrid slow-wave circuit and the single slow-wave circuit in the present invention;

[0020] Figure 7 It is a comparison diagram of the working spectra of the mixed slow-wave circuit and the single slow-wave circuit in the present invention. DETAILED DESCRIPTION

[0021] The specific implementation of the present invention is described below in conjunction with the accompanying drawings so that those skilled in the art can better understand the present invention. It should be noted that in the following description, when the detailed description of known functions and designs may dilute the main content of the present invention, these descriptions will be omitted here.

[0022] In this embodiment, if Figure 1 As shown, the single slow-wave structure is composed of only the working unit circuit 4a.

[0023] Figure 2 It is a structural schematic diagram of a specific implementation of the hybrid slow-wave structure for suppressing backward wave oscillation based on transmission bandgap regulation of the present invention.

[0024] In this embodiment, if Figure 2 As shown, the present invention is based on a hybrid slow wave structure for suppressing back wave oscillation by transmission bandgap regulation, a working unit circuit 4a composed of working units with a certain number of cycles and a control unit circuit 4b composed of control units with a certain number of cycles, and the control unit circuit 4b is inserted into the working unit circuit 4a. In this embodiment, compared with Figure 1 As shown in the single slow-wave structure, the present invention inserts the control unit circuit 4b into the working unit circuit 4a from the middle position based on the hybrid slow-wave structure of transmission bandgap regulation to suppress the return wave oscillation. The working unit circuit 4a includes 8 periods of working units on the left and 8 periods of working units on the right, and the control unit circuit 4b includes 4 periods of control units.

[0025] In this embodiment, if Figure 3 As shown, the working unit and the regulating unit each include a rectangular coupling cavity 1, a circular electron injection channel 2 and a grating gap 3a, 3b. The grating gaps 3a, 3b are connected to the rectangular coupling cavity 1 and have the same x-direction depth as the rectangular coupling cavity 1. The circular electron injection channel 2 passes through the x-direction center of the grating gaps 3a, 3b.

[0026] In this embodiment, if Figure 3As shown, the grating gaps 3a, 3b between the circular electron injection channel 2 and the rectangular coupling cavity 1 are in an arc shape, and the y-direction bottom surfaces of the grating gaps 3a, 3b are semicircular.

[0027] The y-direction length of the grating gap 3a of the control unit is longer than the y-direction length of the grating gap 3b of the working unit. Figure 4 As shown, the bandgap between mode 1, i.e., mode 1-b, and mode 2, i.e., mode 2-b of the control unit is shifted downward compared to the working unit, resulting in the return wave competition frequency point of the working unit being controlled to a position close to the bandgap in the control unit. Even if the return wave competition frequency point of the working unit is located in the bandgap of the control unit in the hybrid slow-wave structure, and the working frequency point of the working unit is located outside the bandgap of the control unit, it still has good transmission characteristics in the control unit, thereby suppressing the return wave competition oscillation and not affecting the signal transmission of the working frequency point.

[0028] In addition, if Figure 2 As shown, the hybrid slow-wave structure for suppressing backward oscillation based on transmission bandgap regulation of the present invention is connected to the standard waveguide 6 through a coupling structure 5, so that the input and output of the hybrid slow-wave structure are transitioned from the coupling structure to the standard waveguide. 7 is a metal shell.

[0029] Figure 5 is the phase speed synchronous voltage curve of the two unit structures in the present invention. Figure 5 As shown, since the return wave competition frequency of the working unit is located near the forbidden band of the control mode, the phase speed synchronization voltage difference between the working unit and the control unit is large, while the working frequency is very small. This destroys the excitation condition of the return wave competition frequency of the working unit in the control unit, but has little effect on the working frequency.

[0030] Figure 6 It is the transmission loss curve of the mixed slow-wave circuit and the single slow-wave circuit in the present invention. Figure 6 As shown, the transmission loss of the return wave competition frequency of the working unit is significantly improved in the hybrid slow-wave circuit, thereby attenuating and absorbing the return wave competition signal, while the transmission loss of the working frequency in the two circuits does not change significantly.

[0031] Figure 7 is the working spectrum of the mixed slow-wave circuit and the single slow-wave circuit in the present invention. Figure 7 As shown, the working spectrum of the single slow-wave structure circuit has both the return wave competition frequency and the working frequency, and competition oscillation occurs, while the working spectrum of the hybrid slow-wave circuit is pure and works stably at the working frequency, indicating that the control unit has a suppressive effect on the return wave competition frequency.

[0032] In summary, the hybrid slow-wave structure based on transmission bandgap regulation to suppress backward wave oscillation can regulate the transmission bandgap of a single slow-wave structure, thereby increasing the transmission loss of its backward wave competition frequency point and destroying the excitation conditions, thereby suppressing the backward wave competition oscillation and making the working mode work stably. The hybrid slow-wave structure has the characteristic of regulating the transmission bandgap and has important application value in the field of terahertz electric vacuum devices.

[0033] Although the above describes the illustrative specific embodiments of the present invention to facilitate those skilled in the art to understand the present invention, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

Claims

1. A hybrid slow-wave structure for suppressing backward wave oscillation based on transmission bandgap regulation, comprising: A working unit circuit consisting of working units with a certain number of cycles; It is characterized by further comprising: A control unit circuit composed of control units with a certain number of cycles is inserted into the working unit circuit; The working unit and the control unit each include a rectangular coupling cavity, a circular electron injection channel and a grating gap, the grating gap is connected to the rectangular coupling cavity and has the same x-direction depth as the rectangular coupling cavity, and the circular electron injection channel passes through the x-direction center of the grating gap; The y-direction length of the grating gap of the regulating unit is longer than the y-direction length of the grating gap of the working unit.

2. The hybrid slow-wave structure for suppressing backward oscillation based on transmission bandgap regulation according to claim 1, characterized in that: The regulating unit circuit is inserted into the working unit circuit from a middle position.

3. The hybrid slow-wave structure for suppressing backward oscillation based on transmission bandgap regulation according to claim 1, characterized in that: The grating gap between the circular electron injection channel and the rectangular coupling cavity is in an arc shape, and the bottom surface of the grating gap in the y direction is semicircular.

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