Non-uniform periodic phase velocity jump velocity-modulated tube

Abstract

The application relates to the technical field of amplifiers, in particular to a non-uniform period phase velocity jump velocity klystron, which comprises an input waveguide, an output waveguide, a coupling cavity, an electron beam channel, a first gap group and a second gap group; the input waveguide and the output waveguide are respectively arranged at two ends of the coupling cavity; a plurality of first gaps are arranged in the first gap group, a plurality of second gaps are arranged in the second gap group, the first gaps and the second gaps are arranged on the lower surface of the coupling cavity in a staggered mode, the axial width of the first gaps and the second gaps is the same, the length of the first gaps and the second gaps is different, the distance between the first gaps and the second gaps presents a decreasing trend along the electron flow direction, and the electron beam channel passes through the first gaps and the second gaps, so that the klystron works in a traveling wave state to obtain a wider frequency band, the phase velocity resynchronization technology is applied, the non-uniform structure is adopted, the electron velocity is synchronized with the high-frequency signal velocity, relatively large power output is obtained, and the electron efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of amplifiers, in particular to a non-uniform periodic phase-speed jump klystron. Background Art

[0002] An extended interaction klystron is typically composed of several interaction gaps, beam channels, and coupling cavities, and is a short-circuited slow-wave device. There are three main types of extended interaction trapezoidal slow-wave structures: through-coupling slots, staggered coupling slots, and double-staggered coupling slots. These topologies have low assembly and processing requirements, offering greater design and implementation flexibility and making it easier to achieve engineering requirements such as light weight, compact structure, and ease of processing. The development of new, compact terahertz vacuum electron sources with engineering practicality plays a vital role in medical imaging, communications, high-energy particle accelerators, radar, and other applications.

[0003] Since the 1980s, numerous institutions at home and abroad, such as the U.S. Naval Research Laboratory and Canada's CPI, have conducted a series of studies on extended interaction devices. Building on research on extended interaction klystrons, the "Terahertz Extended Interaction Oscillator" project proposed a rectangular reentrant coupling cavity, investigated the dispersion characteristics of the slow-wave structure, used equivalent circuit methods to study the electromagnetic properties of the resonant cavity, and used kinematic theory, an electron disk model, and MATLAB software to study the device's beam-wave interaction. Simulations and experimental studies were also conducted.

[0004] The Institute of High Energy Physics has proposed a tunable four-cavity extended interaction klystron with an average output power of 400W and a 3dB bandwidth of nearly 200MHz.

[0005] The paper "Theoretical Study and Numerical Simulation of a W-Band Strip-Beam Spread Interaction Klystron Amplifier" proposes a structure with four three-gap uniform resonant cavities, which operates in the TM110 mode transversely and the 2π mode longitudinally. It outputs 5773 W of power at 94.47 GHz, has a gain of 37.6 dB, an electronic efficiency of 8.46%, and a 3dB bandwidth of 140 MHz.

[0006] Chinese patent publication number CN117747382A discloses an extended interaction klystron operating in a traveling standing wave mode, in which long and short gaps are uniformly periodically arranged with the same spacing. This makes it difficult to achieve relatively high efficiency within a limited length and achieve stable high-power output. Summary of the Invention

[0007] In view of the above problems, the present invention provides a non-uniform periodic phase velocity jump klystron.

[0008] The adopted technical solution is a non-uniform periodic phase velocity jump klystron, comprising an input waveguide, an output waveguide, a coupling cavity, an electron beam channel, a first gap group and a second gap group;

[0009] The input waveguide and the output waveguide are respectively arranged at two ends of the coupling cavity;

[0010] A plurality of first gaps are provided in the first gap group, a plurality of second gaps are provided in the second gap group, and the first gaps and the second gaps are alternately arranged on the lower surface of the coupling cavity, and the first gaps and the second gaps have the same axial width, but different lengths, and the distance between the first gaps and the second gaps decreases along the direction of electron flow;

[0011] The electron beam passes through the first gap and the second gap.

[0012] Optionally, the first gaps in the first gap group are all equal in length, and the second gaps in the second gap group are all equal in length.

[0013] Optionally, the axial widths of the first gap and the second gap range from p / 3 to p / 2, where p is the output cavity period length corresponding to the traveling wave cavity.

[0014] Optional, p satisfies, p=Nv e / f, where N is the mode coefficient, v e is the electron velocity, and f is the central operating frequency of the klystron.

[0015] Optionally, the diameter of the electron beam channel is larger than the gap width between the first gap and the second gap, and smaller than the output cavity period length corresponding to the traveling wave cavity.

[0016] Optionally, the number of the first gaps is set to 21, and the number of the second gaps is set to 22.

[0017] Optionally, it is applied to the traveling wave cavity working mode, using the fundamental mode TM11 mode of the traveling wave mode, and transmitting through a rectangular waveguide using the formula f=c / 2gx, where f is the electromagnetic wave frequency, c is the speed of light in vacuum, and gx is the x-direction dimension of the gap. The center frequency range is determined, and the center frequency and bandwidth are obtained by the combined electromagnetic simulation analysis method, and the result is f0;

[0018] Through the electron motion equation, we can get the electron motion equation when passing through the gap:

[0019]

[0020] Where d is the gap width of the first gap and the second gap, the distance of the drift section is set to l, the period length p = d + l, and the phase is φ i, integrating the above equations, we can get the electron velocity and displacement equations:

[0021]

[0022] At the same time, the gap voltage ratio and gap crossing angle Simplify the above two formulas, The velocity and phase equations of the electron are:

[0023] u i+1 =u i -ε i u i (cosφ i+1 -cosφ i );

[0024] θ di =(1+ε i cosφ i )(φ i+1 -φ i )-ε i (sinφ i+1 -sinφ i );

[0025] When the electron passes through the drift section, the velocity and phase of the electron can be obtained as follows:

[0026] u i+1 =u i ;

[0027]

[0028] Combining the above formula, the speed and phase of the electron are:

[0029]

[0030] The electron velocity equation is the solution of Kepler's equation, Jn is the Legendre function, ξ i is the phase quantity determined by the phase Kepler equation, z is the axial coordinate, t is the time, e is the electron charge, m is the electron mass, V is the gap voltage, d i is the z-direction width of the i-th gap, Φ is the electron phase, δ is the initial electron phase, ω is the angular velocity, and then through the conservation of energy, the theoretical conversion efficiency of electrons is expressed as:

[0031]

[0032] The beneficial effects of the present invention are:

[0033] 1. A non-uniform periodic phase velocity jump klystron is proposed. It operates in a traveling wave state to obtain a wider frequency band. Phase velocity resynchronization technology is applied and a non-uniform structure is adopted to synchronize the electron velocity with the high-frequency signal speed, thereby obtaining a relatively large power output and improving the electronic efficiency.

[0034] 2. Using staggered first and second gaps, the distance between the gaps gradually decreases along the direction of electron flow, that is, the distance of the drift segment is reduced so that the electron speed is synchronized with the speed of the high-frequency signal;

[0035] 3. It adopts the traveling wave working mode to achieve relatively high efficiency within a limited length and realize stable high-power output. In terms of working parameters, it can operate in the W band and output kW-level power under the conditions of 17600V and 1A;

[0036] 4. Compared with the traditional extended interaction klystron, under a certain working length, due to the phase velocity resynchronization of the non-uniform period, the output power and efficiency of the klystron are greatly improved, so that the entire non-uniform period phase velocity jump klystron achieves a relatively high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The overall schematic diagram of a non-uniform periodic phase velocity jump klystron is shown;

[0038] Figure 2 A front view of a non-uniform periodic phase velocity jump klystron;

[0039] Figure 3 A diagram showing the output signal of the uniform period extended interaction klystron in working mode;

[0040] Figure 4 The output spectrum of the uniform period extended interaction klystron is shown;

[0041] Figure 5 A diagram showing the output signal of a non-uniform periodic phase-speed jump klystron operating mode;

[0042] Figure 6 The output spectrum of a non-uniform periodic phase-speed jump klystron is shown.

[0043] The accompanying drawings are:

[0044] 1 is the input waveguide, 2 is the output waveguide, 3 is the coupling cavity, 4 is the electron beam channel, 5 is the first gap, and 6 is the second gap. DETAILED DESCRIPTION

[0045] Following make the specific concrete example explanation the embodiment of the present application, the person skilled in the art can be easily understood from the disclosure of the present application other advantages and efficacy of the present application. The present application can also be implemented or applied by another different specific embodiment, the details in the present application can be based on different views and applications, in the spirit of the present application is not deviated from various modifications or changes. It should be noted that, in the following examples and the features in the embodiment can be combined with each other without conflict.

[0046] Need to explain, the following examples provided in the figure only in a schematic way illustrates the basic idea of the present application, so the figure shows only the components related to the present application and not according to the actual implementation of the number of components, shape and size of drawing, the actual implementation of each component type, quantity and proportion can be a kind of arbitrary change, and its component layout type may be more complex.

[0047] As shown in Figure 1 And Figure 2 A non-uniform period phase speed jump klystron, comprising input waveguide 1, output waveguide 2, coupling cavity 3, electron beam channel 4, first gap group and second gap group;

[0048] The input waveguide 1 and output waveguide 2 are respectively arranged at both ends of the coupling cavity 3;

[0049] The first gap group is provided with a plurality of first gaps 5, and the second gap group is provided with a plurality of second gaps 6, and the first gaps 5 and the second gaps 6 are arranged on the lower surface of the coupling cavity 3 in an alternating manner, and the axial width of the first gaps 5 and the second gaps 6 is the same, the length of the first gaps 5 and the second gaps 6 is different, and the distance between the first gaps 5 and the second gaps 6 decreases along the direction of electron flow;

[0050] The electron beam channel 4 passes through the first gaps 5 and the second gaps 6.

[0051] The purpose of such design is to propose a non-uniform period phase velocity jump klystron, which works in a traveling wave state to obtain a wider frequency band, applies phase velocity resynchronization technology, adopts a non-uniform structure, synchronizes the electron velocity and the high-frequency signal velocity, obtains a relatively large power output, and improves the electron efficiency; the first gap and the second gap are arranged in a staggered manner, the distance between the gaps gradually decreases along the electron flow direction, that is, the distance of the drift section is reduced to synchronize the electron velocity and the high-frequency signal velocity; the working mode is a traveling wave, a relatively high efficiency is achieved in a limited length, and stable high-power output is realized. In terms of working parameters, kW-level power can be output under the condition of 17600V and 1A in the W wave band; compared with the traditional extended interaction klystron, the output power and efficiency of the klystron are greatly improved due to the non-uniform period phase velocity resynchronization in a certain working length, so that the entire non-uniform period phase velocity jump klystron achieves a relatively high efficiency.

[0052] It should be noted that, for the convenience of description, in the embodiment, the first gap 5 is described as a long gap and the second gap 6 is described as a short gap according to the lengths of the first gap 5 and the second gap 6.

[0053] Meanwhile, the "decreasing trend along the electron flow direction" in the embodiment does not mean a uniform decrease, but a general decreasing trend, that is, in the entire trend, the local period may rise due to the influence of the depth of the electron beam modulation, in order to obtain better electron efficiency, but the rising amount does not exceed the initial value.

[0054] Meanwhile, in the specific scenario, the input waveguide and the output waveguide are standard BJ-900 type rectangular waveguides, and the cross-sectional size is 2.54*1.27mmx-z direction. The electron beam channel diameter is 0.62mm, the diameter of the electron beam is 0.36mm, the three-dimensional size of the long gap of the traveling wave input cavity is 1.73*2.92*0.21mmx-y-z direction, the three-dimensional size of the short gap is 1.73*1.8*0.21mmx-y-z direction, and the three-dimensional size of the coupling cavity is 1.73*0.5*16.97mmx-y-z direction.

[0055] Meanwhile, it should be noted that the traveling wave cavity in the embodiment is a set composed of the long gap, the short gap and the coupling cavity, and the output cavity is used in combination with the traveling wave cavity, which usually includes a standing wave cavity gap, an output coupling port, an output cavity upper coupling cavity and an output cavity lower coupling cavity. The two can be referred to the Chinese patent with the publication number CN117747382A in the specific application scenario.

[0056] Meanwhile, in the embodiment, Figure 1As shown, the traveling wave cavity adopts a unilateral trapezoidal structure, with the axial direction being the z direction, the input waveguide and the output waveguide facing each other in the y direction, and the direction perpendicular to the yz plane being the x direction. The upper coupling cavity of the traveling wave cavity is directly connected to the standard rectangular waveguide through a standard twist waveguide to form an input end, and the upper coupling cavity of the traveling wave cavity is connected to the standard rectangular waveguide through a coupling port to form an output end.

[0057] Furthermore, in this embodiment, the region where the non-uniform periodic phase velocity jump klystron structure is located is a vacuum region, the region not declared is a background region, and the material of the non-uniform periodic phase velocity jump klystron is a metal conductor.

[0058] In this embodiment, the lengths of the first gaps 5 in the first gap group are all equal, and the lengths of the second gaps 6 in the second gap group are all equal. At the same time, the axial widths of the first gaps 5 and the second gaps 6 range from p / 3 to p / 2, where p is the output cavity period length corresponding to the traveling wave cavity, and p satisfies, p=Nv e / f, where N is the mode coefficient, v e is the electron velocity, f represents the central operating frequency of the klystron, and the diameter of the electron beam channel 4 is larger than the gap width between the first gap 5 and the second gap 6, and smaller than the output cavity period length corresponding to the traveling wave cavity.

[0059] At the same time, the non-uniform periodic phase velocity jump klystron structure provided in this embodiment is applied to the traveling wave cavity working mode, using the fundamental mode TM11 mode of the traveling wave mode. The central frequency range is determined by the formula f=c / 2gx (where f is the electromagnetic wave frequency, c is the speed of light in vacuum, and gx is the x-direction dimension of the gap) transmitted through a rectangular waveguide. The central frequency and bandwidth are obtained by combining electromagnetic simulation analysis methods, and the result is f0.

[0060] Through the electron motion equation, we can get the electron motion equation when passing through the gap:

[0061]

[0062] Where d is the gap width of the first gap 5 and the second gap 6, the distance of the drift section is set to l, the period length p = d + l, and the phase is φ i , integrating the above equations, we can get the electron velocity and displacement equations:

[0063]

[0064] At the same time, the gap voltage ratio and gap crossing angle Simplify the above two formulas, The velocity and phase equations of the electron are:

[0065] u i+1 =ui -ε i u i (cosφ i+1 -cosφ i );

[0066] θ di =(1+ε i cosφ i )(φ i+1 -φ i )-ε i (sinφ i+1 -sinφ i );

[0067] When the electron passes through the drift section, the velocity and phase of the electron can be obtained as follows:

[0068] u i+1 =u i ;

[0069]

[0070] Combining the above formula, the speed and phase of the electron are:

[0071]

[0072] The electron velocity equation is the solution of Kepler's equation, Jn is the Legendre function, ξ i is the phase quantity determined by the phase Kepler equation, z is the axial coordinate, t is the time, e is the electron charge, m is the electron mass, V is the gap voltage, d i is the z-direction width of the i-th gap, Φ is the electron phase, δ is the initial electron phase, ω is the angular velocity, and then through the conservation of energy, the theoretical conversion efficiency of electrons is expressed as:

[0073]

[0074] Based on the above calculation method, and for comparison with the Chinese patent publication number CN117747382A, a uniform period-extended interaction klystron (UPEI) provided in that patent was used as a control group for simulation tests. In this case, a uniform structure was used between the long and short gaps. The theoretical value of the proposed UPEI klystron model was calculated, resulting in a theoretical electronic efficiency of 33.76%.

[0075] And when the electron beam voltage is 17.6kV, the electron beam current is 1A, the magnetic field for electron beam focusing is 0.4T, and the input signal is 0.5W, the output power is 1152W, as shown in Figure 3 As shown, the electronic efficiency is 6.54% at this time and the frequency is 94.14 GHz, as shown in Figure 4Because there is ohmic loss in the device in the simulation, the ohmic loss part is about 25%, so the electronic efficiency plus the ohmic loss can be well combined with the electronic efficiency obtained by theoretical calculation.

[0076] The non-uniform periodic phase velocity jump klystron structure provided in this embodiment was used as an experimental group for simulation testing. In this embodiment, a non-uniform periodic structure was arranged between the long gap and the short gap. The theoretical value of the proposed non-uniform periodic phase velocity jump klystron model was calculated, and the theoretical electronic efficiency value was 40.97%, indicating a certain improvement in electronic efficiency.

[0077] And when the electron beam voltage is 17.6kV, the electron beam current is 1A, the magnetic field for electron beam focusing is 0.4T, and the input signal is 0.5W, the output power is 3234W, as shown in Figure 5 As shown, the electronic efficiency is 9.23% at this time and the frequency is 94.15 GHz. Figure 6 Because the device has ohmic losses in the simulation, which are approximately 30%, the electronic efficiency plus the ohmic losses can be well combined with the theoretically calculated electronic efficiency. Based on the simulation results, it can be seen that under the same test environment, the electronic efficiency of the experimental group is significantly improved compared to the control group.

[0078] The distance between the long and short gaps is non-uniform. When a microwave signal is injected into the input waveguide, an alternating high-frequency voltage is generated in the gap of the high-frequency structure, causing electrons to accelerate and decelerate. However, the drift phase is almost devoid of an electric field, so the electrons maintain their original motion. Electrons of different speeds catch up, forming an electron cluster. When the electron speed synchronizes with the high-frequency signal, the electrons inject energy into the cavity, and after releasing the energy, the electrons slow down. To align the electron speed with the high-frequency signal, phase velocity resynchronization technology is used to reduce the distance between the gaps to form a non-uniform structure, synchronizing the two speeds.

[0079] Since there are many gaps, long gaps and short gaps are grouped and calculated. The distances between long gaps and short gaps in the same group are equal, but the distances between different groups are not equal, and the gaps tend to decrease along the direction of electron flow.

[0080] Theoretical calculations of the model show that, under a certain gap ratio, the theoretical electronic efficiency is 66.68%. This shows that the electronic efficiency of the extended interaction klystron with a non-uniform period is significantly improved.

[0081] In a specific example, Figure 2 As shown, the number of the first gaps 5 is set to 21, and the number of the second gaps 6 is set to 22.

[0082] The second gap 6 is located on both sides of the first gap 5, and along the direction of electron flow, the gaps between the second gap 6 and the first gap 5, and the gaps between the first gap 5 and the second gap 6 are 0.19mm, ... mm, 0.19mm, 0.19mm, 0.17mm, 0.17mm, 0.17mm, 0.17mm, 0.16mm, 0.16mm, 0.16mm, 0.16mm, 0.19mm, 0.19mm, 0.19mm, 0.15mm, 0.15mm, 0.15mm, 0.15mm, a total of 42 gap data show an overall decreasing trend, among which there is a regional rebound in the middle and rear parts, which is determined by the depth of electron beam modulation. The rebound of local period length is to obtain better electron efficiency, and a very simple uniform reduction structure cannot be adopted. This is the gap length obtained by the optimization algorithm.

[0083] In addition, although it seems that the period length in the middle and rear parts has a regional rebound, compared with the uniform periodic structure, the absolute axial position of the rebound part has not further decreased, and thus the overall trend is reduced. This group of non-uniform periodic arrangements can obtain better electron conversion efficiency.

[0084] This invention provides a non-uniform periodic phase-velocity jump klystron. It employs phase-velocity resynchronization technology in the W band. By leveraging the design mechanism or mode tuning of the slow-wave geometry, the electron beam, which decelerates and releases energy into the circuit, regains phase-velocity synchronization with the slow-wave structure, improving beam-wave interaction efficiency. This provides a feasible method for improving the efficiency of millimeter-wave amplifier sources.

[0085] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A non-uniform periodic phase velocity jump klystron, characterized in that: It comprises an input waveguide (1), an output waveguide (2), a coupling cavity (3), an electron beam channel (4), a first gap group and a second gap group; The input waveguide (1) and the output waveguide (2) are respectively arranged at two ends of the coupling cavity (3); A plurality of first gaps (5) are provided in the first gap group, a plurality of second gaps (6) are provided in the second gap group, and the first gaps (5) and the second gaps (6) are arranged in a staggered manner on the lower surface of the coupling cavity (3), and the axial widths of the first gaps (5) and the second gaps (6) are the same, the lengths of the first gaps (5) and the second gaps (6) are different, and the distance between the first gaps (5) and the second gaps (6) tends to decrease along the direction of electron flow; The electron beam channel (4) passes through the first gap (5) and the second gap (6); Applied to the traveling wave cavity working mode, the fundamental mode TM11 mode of the traveling wave mode is adopted, and the transmission formula f=c / 2gx is transmitted through the rectangular waveguide, where f is the electromagnetic wave frequency, c is the speed of light in vacuum, and gx is the x-direction dimension of the gap. The center frequency range is determined, and the center frequency and bandwidth are obtained by the combined electromagnetic simulation analysis method, and the result is f0; Through the electron motion equation, we can get the electron motion equation when passing through the gap: Where d is the gap width of the first gap (5) and the second gap (6), the distance of the drift section is set to l, the period length p = d + l, and the phase is φ i , integrating the above equations, we can get the electron velocity and displacement equations: At the same time, the gap voltage ratio and gap crossing angle Simplify the above two formulas, The velocity and phase equations of the electron are: u i+1 =u i -ε i u i (cosφ i+1 -cosφ i ); i di =(1+e) i cosφ i )(φ i+1 -f i )-e i (sinφ i+1 -sinφ i ); When the electron passes through the drift section, the velocity and phase of the electron can be obtained as follows: in i+1 =in i ; Combining the above formula, the speed and phase of the electron are: The electron velocity equation is the solution of Kepler's equation, Jn is the Legendre function, ξ i is the phase quantity determined by the phase Kepler equation, z is the axial coordinate, t is the time, e is the electron charge, m is the electron mass, V is the gap voltage, d i is the z-direction width of the i-th gap, Φ is the electron phase, δ is the initial electron phase, ω is the angular velocity, and then through the conservation of energy, the theoretical conversion efficiency of electrons is expressed as:

2. The non-uniform periodic phase velocity jump klystron according to claim 1, characterized in that: The first gaps (5) in the first gap group are all of equal length, and the second gaps (6) in the second gap group are all of equal length.

3. The non-uniform periodic phase velocity jump klystron according to claim 1, characterized in that: The axial widths of the first gap (5) and the second gap (6) range from p / 3 to p / 2, where p is the output cavity period length corresponding to the traveling wave cavity.

4. The non-uniform periodic phase velocity jump klystron according to claim 3, characterized in that: The p satisfies, p=Nv e / f, where N is the mode coefficient, v e is the electron velocity, and f is the central operating frequency of the klystron.

5. The non-uniform periodic phase velocity jump klystron according to claim 4, characterized in that: The diameter of the electron beam channel (4) is larger than the gap width between the first gap (5) and the second gap (6), and smaller than the output cavity period length corresponding to the traveling wave cavity.

6. The non-uniform periodic phase velocity jump klystron according to claim 1, characterized in that: The number of the first gaps (5) is set to 21, and the number of the second gaps (6) is set to 22.

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