CN108831815B - A Periodic Dielectric Filled Coaxial High-Power Microwave Device - Google Patents

Abstract

The invention discloses a periodic dielectric-filled coaxial high-power microwave device, comprising an outer cylinder, a cathode is arranged in the outer cylinder, a coaxial inner conductor arranged in the axis direction of the outer cylinder, the cathode and the coaxial inner conductor are arranged in the outer cylinder. Coaxial, a coaxial dielectric is filled between the outer cylinder and the coaxial inner conductor. The coaxial dielectric is two kinds of dielectrics that are periodically interleaved and filled with different dielectric coefficients. The coaxial dielectric has a ring structure formed by Coaxial dielectric cavity, the coaxial dielectric is divided into inner and outer coaxial dielectrics through the coaxial dielectric cavity, the inner coaxial dielectric and the outer coaxial dielectric are arranged in the same way, and the annular strong current electrons emitted by the cathode The beam is guided by a magnetic field and transported within a coaxial dielectric cavity. The invention adopts the device with the above structure, so that the microwave is totally reflected in the transmission medium, thereby enhancing the clustering of the electron beam and improving the beam conversion efficiency.

Description

A Periodic Dielectric Filled Coaxial High-Power Microwave Device

technical field

The invention belongs to the technical field of high-power microwave devices, and in particular relates to a periodic dielectric-filled coaxial high-power microwave device.

Background technique

High-power microwave (HPM) generally refers to electromagnetic waves with a peak power above 100 MW and an operating frequency in the range of 1 to 300 GHz. The research and development of high-power microwave technology and microwave devices has a history of more than 30 years. In recent years, with the continuous development of pulsed power technology and plasma physics, high-power microwave technology has developed rapidly, especially in high-power microwave sources. Great progress has been made in research and development. So far, its power level has been increased by several orders of magnitude compared with ordinary microwave sources, and it has been widely used in many scientific fields, thus making high-power microwaves a new technology, which uses modern strong relativistic electron beams. The huge power and energy storage capabilities of the technology are moving in the direction of shorter wavelengths and ultra-high power.

So far, the development of high-power microwaves has passed the stage of simple new concept exploration of single-power pursuit, and the research focus has shifted to more detailed technologies related to the practical application of high-power microwaves. Among them, improving the generation efficiency and single-pulse energy of high-power microwave source systems, system miniaturization, integrated design, and developing intelligent high-power microwave devices are the main research contents of high-power microwave source technology. A further practical aspect of high-power microwave devices is miniaturization.

Charged particles moving along the surface of a medium produce Cherenkov radiation when their speed exceeds the speed of light propagating in that medium. When a beam of electrons is transported in a partially filled dielectric waveguide, this radiation can be decomposed into various mode components in the waveguide. When the electron beam velocity is close to and greater than the phase velocity of one of the modes, the interaction of this mode with the electron beam is amplified, resulting in coherent stimulated radiation, which is the Cherenkov radiation device.

In the dielectric Cherenkov radiation oscillator, the slow-wave structure is not a waveguide with periodically changing metal walls, but a dielectric with a constant ε ₁ greater than the vacuum permittivity ε ₀ on the inner surface of the coaxial metal circular waveguide. the coaxial dielectric waveguide. Since the slow-wave structure is not periodic, its dispersion curve is more like that of a cylindrical waveguide. The effective dielectric constant ε _eff of the waveguide lies between ε ₀ and ε ₁ , and its value depends on the overall structural size of the system. As the thickness of the dielectric increases, the effective permittivity of the system increases towards ε ₁ , causing the output frequency to decrease. When a dielectric with a large dielectric constant is used instead of a dielectric with a small dielectric constant as the lining, the phase velocity of the structural mode can be slowed down more effectively, which will also cause the output frequency to decrease.

The single dielectric waveguide dispersion curve can notice that the group velocity of the radiated microwave is always positive at resonance. The device of this structure has no anti-wave medium Cherenkov device, only traveling wave medium Cherenkov device.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a high-power microwave device that enhances the clustering of high-current electron beams and improves beam conversion efficiency.

The present invention is mainly realized through the following technical solutions in order to achieve the above-mentioned purpose:

A periodic dielectric-filled coaxial high-power microwave device comprises an outer cylinder, a cathode is arranged in the outer cylinder, a coaxial inner conductor arranged in the axis direction of the outer cylinder, the cathode is coaxial with the coaxial inner conductor, and the It is characterized in that a coaxial dielectric is filled between the outer cylinder and the coaxial inner conductor, and the coaxial dielectric is two kinds of dielectrics that are periodically interlaced and filled with different dielectric coefficients, and the coaxial dielectric has a ring-shaped structure. Coaxial dielectric cavity, the coaxial dielectric is divided into inner and outer coaxial dielectrics through the coaxial dielectric cavity, the inner coaxial dielectric and the outer coaxial dielectric are arranged in the same way, and the annular high-current electron beam emitted by the cathode Guided by a magnetic field, the transmission takes place in a coaxial dielectric cavity.

In the above technical solution, the two dielectrics are periodically staggered and filled along the axis direction of the outer cylinder.

In the above technical solution, the coaxial dielectric cavity is a vacuum cavity.

In the above technical solution, the outer coaxial dielectric between the coaxial dielectric cavity and the outer cylinder is an outer waveguide, the inner coaxial dielectric between the coaxial dielectric cavity and the coaxial inner conductor is an inner waveguide, and the outer waveguide and the inner waveguide are The two dielectrics are staggered in the same way.

In the above technical solution, one end of the coaxial dielectric cavity is provided with a metal plate vertically connected to the outer cylinder, and the metal plate is provided with an annular injection port for guiding the high-current electron beam into the coaxial dielectric cavity.

In the above technical solution, the diameter of the annular injection port is the same as that of the coaxial dielectric cavity.

In the above technical solution, the other end of the coaxial dielectric is the end of the conical structure. In the above technical solution, the ends of the outer coaxial dielectric and the inner coaxial dielectric form a horn structure, one end of the horn structure has the same size as the coaxial dielectric cavity, and the other end of the horn structure has an opening between the outer cylinder and the coaxial inner conductor. The distance between them is the same. In the above technical solution, the axial length of one of the dielectrics is L ₁ , and the wavelength of the microwave propagating in the medium by the device is λ ₁ , then:

where n ₁ is an odd number.

In the above technical solution, the axial length of another dielectric medium is L ₂ , and the wavelength of the microwave propagating in the medium by the device is λ ₂ , which satisfies:

where n ₂ is an odd number.

To sum up, due to the adoption of the above technical solutions, the present invention has the following beneficial effects:

The high-power microwave device of the present invention adopts a coaxial dielectric, and the coaxial dielectric is two kinds of dielectrics which are periodically and interlacedly filled between the inner wall of the outer cylinder and the coaxial inner conductor, and the dielectric coefficients of the two kinds of dielectrics are different. The device generates high-power microwaves, and the axial length of the coaxial dielectric is about an odd multiple of one-half the wavelength of the high-power microwaves. It is the cross-arrangement design of the respective two dielectrics of the outer coaxial dielectric and the inner coaxial dielectric, so that the microwave is totally reflected in the transmitted medium, thereby enhancing the clustering of the electron beam and improving the beam conversion efficiency.

Description of drawings

FIG. 1 is a schematic diagram of the overall structure of the periodic dielectric-filled coaxial high-power microwave device of the present invention. Among them: 1. Cathode, 2. Outer cylinder, 3. Metal circular waveguide, 4. A dielectric with a smaller dielectric constant in a coaxial dielectric waveguide, 5. A dielectric with a larger dielectric constant in a coaxial dielectric waveguide , 6, annular high-current electron beam, 7, metal coaxial inner conductor.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

As shown in Figure 1, a periodic dielectric-filled coaxial high-power microwave device includes an outer cylinder, a cathode and a coaxial inner conductor are arranged in the outer cylinder, and the coaxial inner conductor is in the axis direction of the outer cylinder and coaxial with the cathode. The cathode is generally made of graphite material, which relies on the electric field force between the cathode and anode to explode and emit a ring-shaped high-current electron beam. Under the guidance of a magnetic field, the annular high-current electron beam is axially transmitted in a vacuum chamber composed of a coaxial dielectric. The selection of voltage and beam intensity needs to comprehensively consider the structure of the device, and then optimize the design. The metal outer cylinder and the coaxial metal inner conductor are generally made of non-magnetic stainless steel or oxygen-free copper.

具体的轴向长度需要综合考虑器件整体结构尺寸，进而进行优化设计。另一种电介质的介电常数在两种电介质中相对较大，该电介质的轴向长度为L₂，器件产生微波在该介质内传播的波长为λ₂，则满足：

具体的轴向长度需要综合考虑器件整体结构尺寸，进而进行优化设计。式中n₁，n₂均为自然数。Two kinds of coaxial dielectrics with different dielectric constants are periodically filled between the inner wall of the outer cylinder and the coaxial inner conductor, and the coaxial dielectric is supported by the outer cylinder. The axial length of the dielectric is an odd multiple of one-half the wavelength of the device-generated microwaves propagating in the medium. The dielectric constant of one of the dielectrics is relatively small among the two dielectrics, the axial length of the dielectric is L ₁ , and the wavelength of the microwave propagating in the medium is λ ₁ , which satisfies:

The specific axial length needs to comprehensively consider the overall structure size of the device, and then optimize the design. The dielectric constant of the other dielectric is relatively large among the two dielectrics, the axial length of the dielectric is L ₂ , and the wavelength of the microwave propagating in the medium is λ ₂ , then:

The specific axial length needs to comprehensively consider the overall structure size of the device, and then optimize the design. In the formula, n ₁ and n ₂ are both natural numbers.

The coaxial dielectric has a ring-shaped coaxial dielectric cavity extending along the axis of the outer cylinder, so that the coaxial dielectric cavity is the coaxial dielectric cavity and divides the coaxial dielectric into two parts. One part is the outer coaxial dielectric (ie the outer waveguide) between the outer diameter of the coaxial dielectric cavity and the outer cylinder, and the other part is the inner coaxial dielectric (ie the inner waveguide) between the inner diameter of the coaxial dielectric cavity and the coaxial metal inner conductor ). The two dielectrics of the outer waveguide and the inner waveguide are staggered in the same manner, the positions of the two dielectrics in the inner and outer waveguides correspond one-to-one, and the axial lengths of the inner waveguide and the outer waveguide are the same.

One end of the coaxial dielectric cavity is the starting end, and the starting end is a metal cylinder with the same diameter, and a metal plate (ie, a metal circular waveguide) vertically connected to the outer cylinder is provided, which is usually made of non-magnetic stainless steel or oxygen-free copper material. Its function is to collect high-energy electrons generated by the explosion of the cathode, which are not constrained by the magnetic field, so as to prevent the high-energy electrons from bombarding the dielectric and causing damage to the performance of the dielectric. The metal plate is supported by a coaxial inner conductor, and the coaxial inner conductor is connected to the outer cylinder through a support rod, forming an equipotential with the outer cylinder. The metal plate is provided with an annular injection port for guiding the high-current electron beam into the coaxial dielectric cavity, and the diameter of the annular injection port is the same as the diameter of the coaxial dielectric cavity.

The other end of the coaxial dielectric cavity is the end, the end is a cone structure, the diameter of the cone structure increases along the axis direction of the outer cylinder, a horn structure is formed between the outer coaxial dielectric and the end of the inner coaxial dielectric, and the diameter of the horn structure It increases along the axis of the outer cylinder, that is, the end of the coaxial dielectric cavity is a horn structure. Specifically, the opening at one end of the horn structure is the same size as the coaxial dielectric cavity, and the opening at the other end of the horn structure is the same size as the distance between the outer cylinder and the coaxial inner conductor, that is, the coaxial dielectric cavity is connected to the coaxial metal through the cone distribution. The inner diameter of the circular waveguide is the same.

Example 1

The cathode in the device is made of graphite material, which relies on the electric field force between the cathode and anode to explode and emit a ring-shaped high-current electron beam. The inner diameter of the graphite cathode is 1.5 cm and the outer diameter is 1.6 cm. Under the guidance of the magnetic field, the annular high-current electron beam enters the coaxial dielectric cavity through the annular injection port for transmission. The guiding magnetic field strength of the electron beam is 0.8T, the voltage is 400kV, and the current is 2kA. The inner diameter of the metal outer cylinder is 2.6cm, the inner wall of the metal outer cylinder and the coaxial inner conductor are periodically filled with two kinds of dielectrics with different dielectric constants, and the structural parameters of the coaxial dielectric filled on the inner wall of the metal outer cylinder and the outer wall of the coaxial inner conductor are as follows: The arrangement is exactly the same. One of the dielectrics has a dielectric constant of 2.5, and the microwave with a wavelength of 3.3 cm in vacuum propagates half of the wavelength in this medium; the other dielectric has a dielectric constant of 9 and a wavelength of 3.3 cm in a vacuum. One-half of the microwave propagation wavelength in this medium is 0.55cm. In this example, the structural parameters of the device are comprehensively considered. The axial length of one of the dielectrics is optimized and designed to be 3.25cm, and the axial length of the other dielectric is 3.25cm. The length is 1.72cm.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included in the protection of the present invention. within the range.

Claims (6)

1. A periodic dielectric filling coaxial high-power microwave device comprises an outer cylinder, wherein a cathode and a coaxial inner conductor arranged in the axial direction of the outer cylinder are arranged in the outer cylinder, and the cathode is coaxial with the coaxial inner conductor;

wherein one dielectric has an axial length of L₁The wavelength of the microwave generated by the device and propagated in the medium is lambda₁Then, the following conditions are satisfied:

wherein n is₁Is odd;

another dielectric medium having an axial length L₂The wavelength of the microwave generated by the device and propagated in the medium is lambda₂Then, the following conditions are satisfied:

wherein n is₂Is an odd number.

2. A periodic dielectric filled coaxial high power microwave device according to claim 1, characterized in that the two dielectrics are periodically and alternately filled in the direction of the device axis.

3. A periodic dielectric filled coaxial high power microwave device according to claim 1 characterized in that the coaxial dielectric cavity is a vacuum cavity.

4. The microwave device according to claim 1, wherein the coaxial dielectric cavity is provided with a metal plate vertically connected to the outer cylinder near one end of the cathode, and the metal plate is provided with a ring-shaped injection port for guiding the high current electron beam into the coaxial dielectric cavity.

5. A periodic dielectric filled coaxial high power microwave device according to claim 4, characterized in that the aperture size of the annular injection port is the same size as the coaxial dielectric cavity.

6. A periodic dielectric filled coaxial high power microwave device according to claim 1, characterized in that the other end of the coaxial dielectric is the end of a conical structure.

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