Extended interaction oscillator based on staggered double gates

Abstract

In order to solve the application problem of a traditional extended interaction device in a high-frequency terahertz frequency band, the characteristic impedance and interaction efficiency of the resonant cavity need to be improved, and the most effective method for improving the impedance is to introduce a new working mode of the extended interaction resonant cavity. On the basis of an existing extended interaction oscillator, two groups of gratings are distributed in a staggered mode in the z direction to form a staggered double-gate structure, and meanwhile, a coupling input and output structure is moved to an electron beam injection end on the outer side of a resonant cavity in the y direction to form a double-gate structure. Therefore, a new working mode which is close to a 2pi mode is generated, a stronger interaction effect is generated, coupled energy is output to the rectangular waveguide through the coupling input and output structure, and the purpose of reducing and expanding the length of an interaction circuit of the interaction oscillator is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of vacuum electronic devices, and more particularly, relates to an extended interaction oscillator based on staggered double gates. Background Art

[0002] The extended interaction oscillator is an important vacuum electronic device with the characteristics of simple design, easy processing, high power, high efficiency and good stability. It has very wide applications in many fields such as radar and plasma diagnosis.

[0003] Traditional extended interaction oscillators such as the Chinese invention patent application published on October 3, 2023, with publication number CN116844929A, entitled "Dual-strip injection gap coupled slow-wave structure and extended interaction oscillator and method", such as Figure 1 As shown, it consists of two sets of gratings 2, electron beam channels 3, and a rectangular coupled cavity (resonant cavity) 1, symmetrically distributed about the central axis. The gratings 2 in each set are aligned with each other. This extended interaction oscillator generally operates in the 2π mode. The rectangular coupled cavity has a low characteristic impedance, resulting in low interaction efficiency, which can lead to an excessively long interaction circuit. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and propose an extended interaction oscillator based on an interleaved double-gate to improve the characteristic impedance of the entire resonant cavity, thereby improving the interaction efficiency and achieving the purpose of reducing the interaction circuit length of the extended interaction oscillator.

[0005] To achieve the above-mentioned object, the present invention provides an extended interaction oscillator based on staggered dual gratings, comprising a resonant cavity, an input electron beam channel and an output electron beam channel located at both ends of a central axis, two sets of gratings symmetrically distributed about the central axis, and a coupled input and output structure, characterized in that:

[0006] The two sets of gratings, symmetrically distributed about the central axis, are both rectangular and of identical size. The central axis is aligned with the z-direction, i.e., the direction of electron beam propagation. Each set of gratings is aligned along the z-direction and periodically placed, connected to the inner wall of the resonant cavity in the transverse direction, i.e., the x-direction, and spaced apart from the inner wall in the longitudinal direction, i.e., the y-direction. The two sets of gratings are staggered along the z-direction to form an interleaved double-grating structure, and are placed within the resonant cavity.

[0007] The input electron injection channel and the output electron injection channel are aligned with the gap between the two sets of gratings. The electron beam is injected from the input electron injection channel, enters the resonant cavity through the input segment electron injection channel, then enters the output electron injection channel through the gap between the two sets of gratings, and is output through the output electron injection channel.

[0008] The coupled input-output structure is located at the electron injection end outside the resonant cavity in the y direction and is used to connect the resonant cavity with the rectangular waveguide. The coupled energy is output to the rectangular waveguide through the coupled input-output structure.

[0009] The object of the invention is achieved like this:

[0010] To address the application issues of traditional extended interaction devices in the high-frequency terahertz band, it is necessary to improve the characteristic impedance and interaction efficiency of the resonant cavity. The most effective way to improve the impedance is to introduce a new operating mode of the extended interaction resonant cavity. The present invention, based on the staggered double-gate extended interaction oscillator, builds on the existing extended interaction oscillator by staggering two sets of gratings along the z direction to form a staggered double-gate structure. At the same time, the coupled input-output structure is moved to the electron injection end outside the resonant cavity in the y direction, thereby generating a new operating mode that is close to the 2π mode and produces a stronger interaction effect. The coupled energy is output to the rectangular waveguide through the coupled input-output structure, thereby achieving the purpose of reducing the interaction circuit length of the extended interaction oscillator. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a structural diagram of an existing extended interaction oscillator;

[0012] Figure 2 3D structural cross-sectional diagram of a specific embodiment of the extended interaction oscillator based on staggered double gates of the present invention;

[0013] Figure 3 yes Figure 2 A schematic cross-sectional view of the center point of the extended interaction oscillator based on the staggered double gates along the z direction is shown;

[0014] Figure 4 yes Figure 2 Schematic diagram of the eigenvalue simulated z-direction electric field lines of the extended interaction oscillator based on staggered double gates;

[0015] Figure 5 This is a comparison chart of the interaction efficiency of three different working modes;

[0016] Figure 6 yes Figure 2 The S parameters of the extended interaction oscillator input and output structure based on staggered dual gates are shown;

[0017] Figure 7 is a graph of the output signal changing with time;

[0018] Figure 8 It is the FFT spectrum of the input and output signals;

[0019] Figure 9 It is the phase space diagram after the output signal stabilizes. DETAILED DESCRIPTION

[0020] The following describes the specific embodiments of the present invention 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 detailed descriptions of known functions and designs may dilute the main content of the present invention, such descriptions will be omitted here.

[0021] Figure 2 、 3 They are respectively a schematic diagram of a three-dimensional cross-sectional structure of a specific embodiment of the extended interaction oscillator based on the staggered double gate of the present invention and a schematic diagram of a cross-sectional view of the center point in the x direction along the z direction.

[0022] In this embodiment, if Figure 2 、 3 As shown, the extended interaction oscillator based on the staggered double grating of the present invention includes a resonant cavity 1, an input electron injection channel 201 and an output electron injection channel 202 located at both ends of the central axis, two groups of gratings symmetrically distributed about the central axis, namely an upper grating 301 and a lower grating 302, and a coupled input and output structure 4.

[0023] The two groups of gratings 301 and 302 symmetrically distributed about the central axis are both rectangular with the same size. The central axis is consistent with the z direction, i.e., the direction of electron beam transmission. Each group of gratings 301 and 302 is aligned along the z direction and placed periodically. They are connected to the inner wall of the resonant cavity 1 in the transverse direction, i.e., the x direction, and are separated from the inner wall of the resonant cavity in the longitudinal direction, i.e., the y direction. The two groups of gratings 301 and 302 are staggered along the z direction to form a staggered double-grating structure and are placed in the resonant cavity 1.

[0024] The input electron injection channel 201 and the output electron injection channel 202 are aligned with the gap between the two sets of gratings. The electron beam is injected from the input electron injection channel 201, enters the resonant cavity 1 through the input electron injection channel 201, then enters the output electron injection channel 202 through the gap between the two sets of gratings, and is output through the output electron injection channel 202.

[0025] The coupling input-output structure 4 is located at the electron injection end outside the resonant cavity in the y direction, and is used to connect the resonant cavity 1 with the rectangular waveguide. The coupled energy is output to the rectangular waveguide through the coupling input-output structure.

[0026] To solve the problem of excessively long grating periods in the resonant cavity of a conventional extended interaction oscillator, the present invention provides an extended interaction resonant cavity structure based on staggered double gratings. Two sets of gratings 301 and 302 are staggered along the z-direction to form a staggered double grating structure. At the same time, the coupled input-output structure 4 is moved to the electron injection end outside the resonant cavity in the y-direction, thereby generating a new operating mode close to the 2π mode, thereby reducing the interaction circuit length of the extended interaction oscillator.

[0027] In this embodiment, the resonant cavity 1 is made of oxygen-free copper material, such as Figure 2 As shown, the gratings 301 and 302 in the resonant cavity are also oxygen-free copper. The upper grating 301 is close to the coupling input-output structure 4 and contains 11 periods. The lower grating 302 is far away from the coupling input-output structure 4 and contains 12 periods. The staggered period is half a period, that is, each upper grating is directly opposite the middle of the gap between the two lower gratings. At this time, a new working mode is generated, which is the 23π / 12 mode.

[0028] The length of one period in the z direction is p, the z and y directions of the grating are g and h respectively, and the height of the electron beam channel in the y direction is t, wherein the length of the input electron beam channel 201 is A1, the length of the output electron beam channel 202 is A2, the lengths of the BJ1400 standard rectangular waveguide 5 connected to the resonant cavity 1 in the z and y directions are sz and sy respectively, the height of the resonant cavity 1 in the y direction is cuy, and the lengths of the coupled input and output structure 4 in the z and y directions are oz and oy respectively.

[0029] For the x direction, Figure 1 As shown, the length of the BJ1400 standard rectangular waveguide external to the resonant cavity 1 in the x direction is sx, the length of each grating in the x direction is w, the length of the electron beam channel in the x direction is ex, and the length of the coupling input-output structure 4 in the x direction is ox.

[0030] In this embodiment, the resonant cavity is made of oxygen-free copper with a conductivity of σ = 2.2 × 107 S / m. The specific structural parameters and dimensions are (unit: mm): t = 0.3, ex = 1.2, p = 0.83, h = 1.6, g = 0.25, A1 = 9.96, A2 = 3.32, cuy = 16.2, w = 1.6, sx = 2.54, sy = 6, sz = 1.27, ox = 1.6, oy = 0.1, oz = 1.8.

[0031] Using 3D electromagnetic simulation software, Figure 1 The structure and dimensions shown in FIG are used to simulate and calculate the extended interaction oscillator based on the staggered double-gate of the present invention to obtain high-frequency characteristic parameters.

[0032] Figure 3 is a schematic diagram of the eigenvalue simulated z-direction electric field lines, as shown in Figure 3 As shown, the electric field lines cross the zero point 23 times, so the working mode is 23π / 12 mode.

[0033] The electric field strength of the 23 / 12π, 2π, and 11π / 6 modes was imported into Matlab to calculate the equivalent impedance of different modes. The equivalent impedance is a parameter used to evaluate whether the resonant cavity can effectively interact with the electron beam. The calculation formula is as follows:

[0034]

[0035] ω0=2πf0

[0036]

[0037] E z is the longitudinal electric field, β e is the propagation constant of the electron beam, f0 is the resonant frequency of the resonant cavity, W s is the energy of the resonant cavity. The effective impedance (M) of the resonant cavity (EISRC) was calculated using MATLAB. 2 R / Q).

[0038] like Figure 4 As shown in the figure, it can be seen that when the operating voltage varies between 19kV and 20kV, the 23 / 12π mode has the strongest effective impedance, that is, the modulation effect on the electron beam is the strongest, so the resonant cavity in this mode has the highest modulation efficiency.

[0039] Using the time domain solver, the background material is set to oxygen-free copper (σ=2.8×10 7 S / m), for the center frequency of 96.5GHz, S 11 is -16.56dB, and the group delay τ is 29.65 nanoseconds. Figure 5 As shown, in the frequency range of 96.4-96.54GHz, S 11 Below -10dB.

[0040] Figure 6 The maximum output power of the extended interacting staggered resonant cavity is demonstrated. Figure 6 As shown in the figure, the electron beam begins to cluster at 20 ns, the output signal tends to be stable at 100 ns, and no oscillation occurs within 100 ns.

[0041] Figure 7 The spectrum of the input and output signals of the extended interactive interleaved resonant cavity is shown, as Figure 7 As shown in Figure 1, the output signal spectrum is relatively pure, without any signs of oscillation. When the input frequency is 96.5 GHz and the input power is 5 mW, the saturated output power is 655.22 W, corresponding to a gain of 61.87 dB.

[0042] Figure 8 This is the electron phase space diagram during the beam-wave interaction process, which can clearly reflect the modulation effect of the electromagnetic field on the electron beam.

[0043] Although the above describes the illustrative specific embodiments of the present invention to facilitate understanding of the present invention by those skilled in the art, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concepts of the present invention are protected.

Claims

1. An extended interaction oscillator based on staggered dual-gates, comprising a resonant cavity, an input electron beam channel and an output electron beam channel located at both ends of a central axis, two sets of gratings symmetrically distributed about the central axis, and a coupled input and output structure, characterized in that: The two sets of gratings, symmetrically distributed about the central axis, are both rectangular and of identical size. The central axis is aligned with the z-direction, i.e., the direction of electron beam propagation. Each set of gratings is aligned along the z-direction and periodically placed, connected to the inner wall of the resonant cavity in the transverse direction, i.e., the x-direction, and spaced apart from the inner wall in the longitudinal direction, i.e., the y-direction. The two sets of gratings are staggered along the z-direction to form an interleaved double-grating structure, and are placed within the resonant cavity. The input electron injection channel and the output electron injection channel are aligned with the gap between the two sets of gratings. The electron beam is injected from the input electron injection channel, enters the resonant cavity through the input segment electron injection channel, then enters the output electron injection channel through the gap between the two sets of gratings, and is output through the output electron injection channel. The coupled input-output structure is located at the electron injection end outside the resonant cavity in the y direction and is used to connect the resonant cavity with the rectangular waveguide. The coupled energy is output to the rectangular waveguide through the coupled input-output structure.

2. The extended interaction oscillator based on staggered dual gates according to claim 1, characterized in that: The two sides close to the coupling input and output structure are upper gratings, which include 11 periods, and the side away from the coupling input and output structure is lower gratings, which include 12 periods. The staggered periods are half a period, that is, each upper grating is directly opposite the middle of the gap between the two lower gratings.

3. The extended interaction oscillator based on staggered dual gates according to claim 1, characterized in that: The resonant cavity and the grating in the resonant cavity are both made of oxygen-free copper.

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