Super-radiation microwave pulse sequence generator

Abstract

The invention discloses a super-radiation microwave pulse sequence generator, and belongs to the technical field of high-power microwaves. Cathode explosion emission generates a high-current relativistic electron beam; the front-end reflector is used for reflecting super-radiation microwave pulses and extracting microwave energy from the collector side; the slow wave structure adopts a multi-period non-uniform structure, and the gradually-changed ripple depth is optimally designed, so that efficient beam-wave interaction is ensured, and super-radiation microwave pulses with high conversion factors are generated; the tail end reflector is used for providing a seed signal for the next super-radiation microwave pulse; the collector is used for absorbing a high-current relativistic electron beam subjected to beam-wave interaction; the guiding magnet is used for guiding the high-current relativistic electron beam to be transmitted from the cathode to the collector. The reflection coefficient R1 of the front end reflector is close to 1, and the reflection coefficient R2 of the tail end reflector is far smaller than 1. The high-power microwave generator has the characteristics of high peak power and high conversion efficiency, the performance of a high-power microwave system can be improved, and the high-power microwave generator has a development prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of high-power microwaves and relates to a super-radiant microwave pulse sequence generator. Background Art

[0002] The target characteristics and electromagnetic environment of electronic systems are becoming increasingly complex. High-power microwave sources with wide spectrum characteristics can meet future application needs to a certain extent. In 2021, the United States issued an announcement on an agile waveform RF directed energy project, aiming to design agile high-power microwave pulses through theoretical analysis and modeling simulation of the interaction mechanism and process between high-power microwaves and targets, thereby reducing the demand for device power. Agile waveform high-power microwave pulses are different from traditional narrow-spectrum high-power microwave pulses. They usually have a wider spectrum range and the center frequency can be flexibly changed. High-power microwave generators with the ability to generate agile waveforms have become one of the development trends. The microwave pulses generated by devices based on the super-radiant mechanism have wide spectrum characteristics and can greatly improve the efficiency of beam-wave interaction. Therefore, super-radiant high-power microwave generators are expected to significantly reduce the volume and weight of high-power microwave sources and improve the performance of high-power microwave sources.

[0003] Since the 1990s, researchers have conducted a large number of theoretical and experimental studies on superradiant high-power microwave generators, and observed that different stimulated radiation mechanisms can achieve superradiance, such as bremsstrahlung, cyclotron radiation, Cherenkov radiation, Smith-Purcell effect, etc. Among them, the Cherenkov superradiance mechanism has become a mainstream research direction due to its high output power, and is mainly used to generate superradiant high-power microwave pulses with frequencies in the X-band and millimeter-wave bands. Some typical results of superradiant high-power microwave generators are given below. In 2006, superradiant high-power microwave outputs with X-band peak power of 1.2GW and conversion factor of 1.5 and Ka-band peak power of 1.2GW and conversion factor of 1.4 were obtained (SD Korovin, AA Eltchaninov, VV Rostov, et al, Generation of Cherenkov superradiance pulses with a peak power exceeding the power of driving short electron beam [J], Phys. Rev. E, 2006, 74 (1), 016501-1–016501-8). In 2013, an experiment was conducted to achieve an X-band peak power of 3 GW and a conversion factor of 1.8 for ultra-radiant high-power microwave output (NS Ginzburg, IV Zotova, Adrian W. Cross, et al, Generation, Amplification, and Nonlinear Self-Compression of Powerful Superradiance Pulses [J]. IEEE TRANSACTIONS ON PLASMA SCIENCE, 2013, 41 (4), 646-660.). Recently, researchers have been working on generating periodic sequences of ultrashort pulses.In 2018, Russian scientists constructed a feedback loop consisting of a relativistic backward-wave oscillator and a traveling-wave oscillator, one of which served as an active amplifier and the other as a nonlinear saturated absorber in the feedback circuit, obtaining an X-band ultrashort pulse sequence with a peak power of 0.8 to 1.3 GW and a conversion factor of 0.7 to 1.2 (NS Ginzburg, EBA Bubakirov, MN Vilkov, et al, Generation of a Periodic Sequence of High-Power Ultrashort Pulses in a Chain of Coupled Backward-Wave and Traveling-Wave Tubes Operating in the Regimes of Amplification and Nonlinear Kompfner Suppression[J]. Tech. Phys. 2018, 63, 1205-1211.).

[0004] At present, the output power of a single super-radiant microwave of the X-band super-radiant high-power microwave generator is at the level of 1 to 3 GW, and the peak power of a microwave pulse train is at the level of 0.8 to 1.3 GW. Therefore, it is necessary to explore higher-power super-radiant microwave pulse train generators to meet the urgent application needs in complex electromagnetic environments. Summary of the invention

[0005] (I) Purpose of the invention

[0006] The purpose of the present invention is to develop a super-radiant microwave pulse train generator to achieve ultra-high power, ultra-high repetition rate, wide spectrum high-power microwave pulse train output, thereby improving the performance of the high-power microwave system.

[0007] (II) Technical solution

[0008] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows:

[0009] A superradiant microwave pulse train generator, the main components of the device include an explosive emission cathode, a front reflector, a multi-period non-uniform slow wave structure, an end reflector, an electron beam collector, and a guide magnet; each component is a coaxial rotating body structure;

[0010] The cathode explosion emits a strong relativistic electron beam, and the electron beam and the electromagnetic field interact with each other in the slow-wave structure, converting the electrical pulse into a microwave pulse.

[0011] The front reflector is used to reflect the superradiant microwave pulses to extract microwave energy from the collecting pole side;

[0012] The slow-wave structure adopts a multi-period non-uniform structure to ensure efficient beam-wave interaction, generating super-radiant broadband microwave pulses; to improve the conversion factor, a sufficiently long beam-wave interaction region is required to generate super-radiant microwave pulses with a high conversion factor. The number N of slow-wave structures ranges from 30 < N < 70. Appropriately increasing the number N of slow-wave structures is beneficial to enhancing the peak power of super-radiant pulses; the conversion factor is the ratio of the peak power of super-radiant microwave pulses to the electron beam power.

[0013] The end reflector reflects a small part of the microwave power back to the slow-wave structure to provide a seed signal for the next super-radiant microwave pulse.

[0014] The electron beam collector is used to absorb the high-current relativistic electron beam after beam-wave interaction.

[0015] The guiding magnet surrounds the periphery of the generator to guide the high-current relativistic electron beam to stably transmit from the cathode to the collector.

[0016] The multi-period non-uniform slow-wave structure and the front reflector and end reflector form a beam + microwave feedback loop, thereby generating a sequence of super-radiant microwave pulses.

[0017] Furthermore, by adopting a gradually changing ripple depth l of the slow-wave structure to match the high-current relativistic electron beam, the power and conversion factor of super-radiant microwave pulses are improved, and the ripple depth l varies within the range of 0.02λ and 0.2λ.

[0018] Furthermore, to increase the power capacity of the device, the average radius r of the slow-wave structure ripple is appropriately increased, and r is within the range of 0.5λ and 1.5λ, where λ is the wavelength of the microwave.

[0019] Furthermore, the ripple period d of the slow-wave structure is within the range of λ / 4 to λ / 2.

[0020] Furthermore, the front reflector and end reflector can adopt various structural forms, and it is necessary to ensure that the reflection coefficient |R1| of the front reflector is approximately 1, and the reflection coefficient |R2| of the end reflector is much less than 1.

[0021] (III) Effective benefits

[0022] The beneficial effects of the present invention are: the super-radiant microwave pulse sequence generator can generate broadband high-power microwave pulses with ultra-high power, ultra-high repetition frequency, and ultra-short pulses, which can better act on various targets with frequency selection characteristics, thereby enhancing the power of high-power microwave sources and providing a new technical route for compact and highly reliable high-power microwave sources. Description of the drawings

[0023] Figure 1 Schematic diagram of the principle of the circumferentially symmetric super-radiant microwave pulse sequence generator of the present invention;

[0024] Figure 2 Example diagram of a superradiant microwave pulse train generator;

[0025] Figure 3 The power of superradiant microwave pulse trains;

[0026] Figure 4 The spectrum of a superradiant microwave pulse train;

[0027] Figure 1 In the figure: 1-explosive emission cathode; 2-front-end emitter; 3-high-current relativistic electron beam; 4-multi-period non-uniform slow-wave structure; 5-guiding magnet; 6-end reflector; 7-electron beam collector. DETAILED DESCRIPTION

[0028] The superradiant microwave pulse train generator of the present invention is described in detail below in conjunction with the accompanying drawings and embodiments.

[0029] Determine the state of the front-stage pulse power driving source, and design the structural parameters of the super-radiant microwave pulse train generator according to technical indicators such as peak power and operating frequency. Figure 1 As shown in the figure, the main components of the device include explosive emission cathode, front reflector, multi-period non-uniform slow-wave structure, end reflector, electron beam collector and guide magnet, all of which are coaxial rotating body structures. The cathode explosive emission generates a strong relativistic electron beam, and the electron beam and electromagnetic field interact with each other in the slow-wave structure to convert the electrical pulse into a microwave pulse; the front reflector is used to reflect the super-radiant microwave pulse to extract microwave energy from the collector side; the slow-wave structure adopts a multi-period non-uniform structure to ensure efficient beam-wave interaction and generate super-radiant wide-spectrum microwave pulses; the end reflector reflects a small part of the microwave power back to the slow-wave structure to provide a seed signal for the next super-radiant microwave pulse; the collector is used to absorb the strong relativistic electron beam that has undergone beam-wave interaction; the guide magnet surrounds the periphery of the device to guide the strong relativistic electron beam to be stably transmitted from the cathode to the collector. Among them, the multi-period non-uniform slow-wave structure and the two reflectors are the core components of the pulse sequence generator, forming a "beam + microwave" feedback loop, thereby generating a super-radiant microwave pulse sequence.

[0030] Based on a Cherenkov-type high-power generator, a superradiant microwave pulse train generator is designed through theoretical analysis and PIC simulation. The multi-period non-uniform slow-wave structure is optimized with emphasis on improving the conversion factor (defined as the ratio of the peak power of the superradiant microwave pulse to the electron beam power), while considering the volume and weight of the high-power microwave device. A sufficiently long beam-wave interaction region is required to generate superradiant microwave pulses with a high conversion factor. The number of slow-wave structures N ranges from 30 < N < 70. Appropriately increasing the number N of slow-wave structures is beneficial to enhancing the peak power of the superradiant pulse. By using a gradually varying slow-wave structure ripple depth l, the non-uniform slow-wave structure can better match the modulated intense relativistic electron beam, improving the power and conversion factor of the superradiant microwave pulse. The ripple depth l varies within the range of 0.02λ and 0.2λ. To increase the power capacity of the device and avoid RF breakdown, the average radius r of the slow-wave structure ripple needs to be appropriately increased, which can be within the range of 0.5λ and 1.5λ. Additionally, the ripple period d ranges from λ / 4 to λ / 2, where λ is the wavelength of the microwave.

[0031] The design of the reflectors at both ends of the radiation microwave pulse train generator is carried out. The front and end reflectors can adopt various structural forms. It is necessary to ensure that the reflection coefficient |R1| of the front reflector is approximately 1, and at the same time, the reflection coefficient |R2| of the end reflector is much less than 1, so as to generate a high-repetition-rate superradiant microwave pulse train more efficiently. In addition, the generated superradiant microwave pulse train is extracted from the collector side, which is beneficial to realizing a simple and practical superradiant microwave pulse train generator.

[0032] Example 1

[0033] The effects of the embodiment of a superradiant microwave pulse train generator of the present invention are as Figure 2 , Figure 3 and Figure 4 shown. Figure 2 The structure of the designed superradiant microwave pulse train generator is given. The front reflector is composed of a cathode baffle and a drift section, and its reflectivity |R1| = 96.4%; the slow-wave structure adopts a 56-period non-uniform slow-wave structure. The average radius r of the slow-wave structure ripple is 39 mm, the ripple period d is 12.7 mm, and the ripple depth l gradually increases from 1 mm to 4 mm; the end reflector is composed of 4-period slow-wave structures with a gradually decreasing ripple depth, and its reflectivity |R2| = 5.2%. Figure 3 and Figure 4The power and spectrum of the superradiant microwave pulse sequence are given respectively. Under the conditions of diode voltage of 530kV and current of 21.9kA, the designed superradiant high-power microwave generator outputs microwave center frequency of about 9.6GHz, the first superradiant microwave peak power is 16.6GW, and the conversion factor is 143%. The second peak power is 11GW, and the peak power of subsequent superradiant pulses is also maintained above 10GW, the spectrum width is about 1GHz, and the pulse sequence repetition frequency is about 126MHz.

[0034] The beneficial effect brought by the present invention is that the super-radiant microwave pulse sequence generator can generate ultra-high power, ultra-high repetition rate, wide-spectrum high-power microwaves, with a peak power of more than 10 GW, a repetition rate of more than 100 MHz, and a microwave spectrum width of 1 GHz. The super-radiant microwave pulse sequence can well match the frequency selection characteristics of multiple types of targets, thereby improving the performance of the high-power microwave system.

[0035] The above contents are further detailed descriptions of the present invention in combination with specific implementation methods, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A superradiant microwave pulse train generator, characterized in that: It includes an explosive emission cathode, a front reflector, a multi-period non-uniform slow-wave structure, a terminal reflector, an electron beam collector, and a guiding magnet; all component parts are coaxial rotating body structures; The cathode explosively emits to generate a high-current relativistic electron beam. The electron beam and the electromagnetic field perform beam-wave interaction in the slow-wave structure, converting the electrical pulse into a microwave pulse; The front reflector is used to reflect the super-radiant microwave pulse to extract microwave energy from the collector side; The slow-wave structure adopts a multi-period non-uniform structure to ensure efficient beam-wave interaction and generate a super-radiant broadband microwave pulse; To increase the conversion factor, a sufficiently long beam-wave interaction region is required to generate a super-radiant microwave pulse with a high conversion factor. The number of slow-wave structures N ranges from 30 < N < 70. Appropriately increasing the number N of slow-wave structures is beneficial to increasing the peak power of the super-radiant pulse; The conversion factor is the ratio of the peak power of the super-radiant microwave pulse to the electron beam power; The terminal reflector reflects a small part of the microwave power back to the slow-wave structure to provide a seed signal for the next super-radiant microwave pulse; The electron beam collector is used to absorb the high-current relativistic electron beam that has undergone beam-wave interaction; The guiding magnet surrounds the periphery of the generator and is used to guide the high-current relativistic electron beam to stably transmit from the cathode to the collector; The multi-period non-uniform slow-wave structure, the front reflector, and the terminal reflector form a beam + microwave feedback loop, thereby generating a sequence of super-radiant microwave pulses.

2. The superradiant microwave pulse train generator according to claim 1, characterized in that: Adopt a gradually changing corrugation depth l of the slow-wave structure to match the high-current relativistic electron beam, improve the power and conversion factor of the super-radiant microwave pulse. The corrugation depth l varies within the range of 0.02λ and 0.2λ.

3. The superradiant microwave pulse train generator according to claim 2, characterized in that: To increase the power capacity of the device, appropriately increase the average radius r of the slow-wave structure corrugation. r ranges from 0.5λ to 1.5λ, where λ is the wavelength of the microwave.

4. The superradiant microwave pulse train generator according to claim 3, characterized in that: The corrugation period d of the slow-wave structure ranges from λ / 4 to λ / 2.

5. The superradiant microwave pulse train generator according to claim 2, characterized in that: The front reflector and the terminal reflector can adopt various structural forms, and it is necessary to ensure that the reflection coefficient |R1| of the front reflector is approximately 1, and the reflection coefficient |R2| of the terminal reflector is much less than 1.

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