A radial electron beam staggered grid structure traveling wave amplifier

Abstract

The application discloses a radial electron beam staggered grid structure traveling wave amplifier, which comprises coaxial staggered grid leaves with different radii and made of metal at the lower side and the upper side of upper and lower metal ring shells, the lower side and the upper side of the grid leaves are staggered, and a cavity is formed between the lower side and the upper side of the grid leaves, thereby forming a slow wave structure. Electromagnetic waves are injected from the cavity between two adjacent grid leaves at the lower side of the upper metal ring shell or the upper side of the lower metal ring shell near a hot cathode through an input structure as a signal to be amplified, the electromagnetic waves are transmitted along the cavity in the coaxial staggered grid and interact with electron beams transmitted along the radial direction, thereby converting electron kinetic energy into electromagnetic wave energy, amplifying the input electromagnetic wave signal, and outputting the amplified electromagnetic waves from the lower metal ring shell or the upper metal ring shell through an output structure. The application has the characteristics of high interaction efficiency, high output power, high coupling impedance and simple structure.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of microwave devices, and more particularly relates to a radial electron beam staggered grid structure traveling wave amplifier. BACKGROUND

[0002] Vacuum electron devices refer to devices that convert electron kinetic energy or potential energy into electromagnetic wave energy by means of interaction between electrons and electromagnetic fields in a vacuum. According to different running modes and conversion modes of electron beams, conventional vacuum electron devices mainly include linear electron beam devices, cross-field devices, and gyro devices.

[0003] Klystrons, traveling wave tubes, and backward wave tubes belong to linear beam vacuum electron devices. They utilize electron beams emitted by electron guns to form electron clusters and lose energy in a decelerating field, so that electron kinetic energy is converted into electromagnetic wave energy, thereby forming amplified or oscillating electromagnetic wave output. Since the electron beam is linear, it is called a linear electron beam device. In this type of device, electron kinetic energy is converted into electromagnetic waves.

[0004] Magnetrons and cross-field amplifiers belong to cross-field devices. Electrons are emitted from a central cathode and rotate under the action of a magnetic field. The rotating electrons interact with high-frequency structures to generate electromagnetic waves. Since the device moves under the action of an electric field and a perpendicular magnetic field, it is called a cross-field device. They convert the potential energy of electrons into electromagnetic wave energy.

[0005] Gyro klystrons, gyro traveling wave tubes, and other devices utilize electron angular kinetic energy to convert into electromagnetic wave energy. Electrons spiral forward, so they are called gyro devices.

[0006] Linear electron beam devices are the most widely used devices. However, when the frequency is increased to the millimeter wave and terahertz wave band, linear electron beam devices also face the following main problems due to the "size co-passing" effect: 1) high electromagnetic loss, 2) low coupling impedance between electrons and high-frequency structures, 3) low slow-wave interaction efficiency, 4) structure shrinkage, high current density requirement, and inability to implement, and 5) the device structure is too small to be precisely machined, and even cannot be machined.

[0007] For example, Figure 1As shown, Chinese invention patent CN109148242B, authorized on April 14, 2020, discloses "An Electromagnetic Wave Oscillator," comprising a metal ring 1, a cathode, and an output structure 2. The metal ring 1 has concentric circular grooves 101 of different radii etched on one of its surfaces. A cathode placed at the edge or center of the metal ring 1 generates electron beams 4 pointing inwards or outwards. The electron beams 4 interact with the concentric circular grooves 101 to generate electromagnetic waves, which are then output through the output structure. Compared to linear electron beams, the cathodes have lower emission densities, resulting in less cathode loss and improved cathode lifespan and emission stability. The electron motion direction of the electron beams 4 is either the same as or opposite to the direction of the space charge force, eliminating the need for focusing. Simultaneously, the generated heat can be dissipated through the metal edge, providing a large heat dissipation area for rapid cooling. This ring-shaped electromagnetic wave oscillator is an oscillator, not an amplifier; it takes an input voltage signal and outputs electromagnetic wave oscillations, requiring no input signal and having only one external output port.

[0008] like Figure 2 As shown, Chinese invention patent CN102903587B, authorized on July 15, 2015, discloses "A Radial Logarithmic Helical Microstrip Slow Waveline," a quasi-periodic structure along the radial direction. It operates using a planar fan-shaped electron beam and includes a fan-shaped metal shield 1, a fan-shaped dielectric substrate 5, and an angular radial logarithmic helical metal strip 4. The angular radial logarithmic helical metal strip 4 is composed of a portion of an arc cut at an angle θ from a single radial logarithmic helical microstrip line, and metal strips that alternately connect adjacent ends of the cut arcs. Traveling wave tubes using this invention's radial logarithmic helical microstrip slow waveline have a significantly lower operating voltage than conventional low-voltage helical traveling wave tubes, offering a greater advantage over coupled-cavity traveling wave tubes. Compared to radial logarithmic helical slow wavelines, angular radial logarithmic helical slow wavelines have a wider operating voltage tuning range. With the same electron beam current, this translates to a wider DC input power tuning range and greater output power, making it suitable for applications with higher power requirements. A traveling wave tube using this radial logarithmic spiral microstrip slow-wave line is used as an amplifier. However, since its slow-wave structure uses a microstrip line, electromagnetic wave energy is transmitted along the microstrip, and the input and output power is still relatively low.

[0009] The National University of Defense Technology has proposed several disk-shaped relativistic klystron amplifiers, but this structure is a klystron structure and a parallel wave amplifier. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of existing linear vacuum electronic devices, which suffer from low efficiency, high loss, and difficult processing due to the "size co-transfer" effect when the frequency increases to the millimeter wave and terahertz band, thus failing to meet the application requirements of advanced equipment. This invention provides a radial electron beam interlaced grid structure traveling wave amplifier to improve interaction efficiency and output power, while reducing electromagnetic loss and process implementation.

[0011] To achieve the above-mentioned objective, the present invention provides a radial electron beam interleaved grid structure traveling wave amplifier, characterized in that it comprises:

[0012] The upper and lower metal ring shells have coaxial grating blades of different radii made of metal on the lower side of the upper metal ring shell and the upper side of the lower metal ring shell. A cavity is formed between the lower and upper grating blades. The lower grating blades of the upper metal ring shell and the upper grating blades of the lower metal ring shell are interleaved to form a slow wave structure. This slow wave structure is a coaxial interleaved grating.

[0013] The cathode is placed at the edge of the outermost grid blade of the upper and lower metal ring shells or at the center of the upper and lower metal ring shells. Electrons are emitted using the thermionic cathode to form an electron beam, which is formed in the cavity between the lower and upper grid blades and emitted radially toward the center of the circle or toward the outer edge.

[0014] Near the hot cathode, an electromagnetic wave is injected through the input structure from the cavity between two adjacent grid blades on the lower side of the upper metal ring shell or the upper side of the lower metal ring shell. This electromagnetic wave serves as the signal to be amplified. It propagates interlaced along the cavity in the coaxial interlaced grid, interacting with the radially propagating electron beam to convert electron kinetic energy into electromagnetic wave energy, thus amplifying the input electromagnetic wave signal. In the cavity between two adjacent grid blades on the upper side of the lower metal ring shell or the lower side of the upper metal ring shell, which is furthest from the hot cathode, the amplified electromagnetic wave is output from the lower or upper metal ring shell through the output structure. The radially propagating electron beam still has some energy and will continue to propagate to the collector electrode.

[0015] The objective of this invention is achieved as follows.

[0016] This invention relates to a radial electron beam staggered grid traveling-wave amplifier. The lower and upper metal ring shells have coaxial grid blades of different radii made of metal on the lower and upper grid sides. These grid blades are staggered, forming a cavity between them, creating a slow-wave structure. The electron beam can be emitted from the center of the ring outwards or from the outer edge inwards. Compared to linear electron beam cathodes, this results in lower emission densities, less cathode loss, and improved cathode lifespan and emission stability. Near the hot cathode, an electromagnetic wave is injected through the input structure from the cavity between two adjacent grid blades on the lower side of the upper metal ring shell or the upper side of the lower metal ring shell. This electromagnetic wave serves as the signal to be amplified. It propagates along the cavity in the coaxial staggered grid, interacting with the radially propagating electron beam, converting electron kinetic energy into electromagnetic wave energy, and amplifying the input electromagnetic wave signal. The amplified electromagnetic wave is then output from the lower or upper metal ring shell through the output structure in the cavity between two adjacent grid blades on the upper side of the lower metal ring shell or the lower side of the upper metal ring shell, which is furthest from the hot cathode. Compared to linear electron beam devices, the radial electron beam staggered grid traveling wave amplifier of this invention has the following advantages: 1) high interaction efficiency and high output power; 2) large radial electron beam cross-sectional area and low emission and transmission current density; 3) high coupling impedance of radial staggered double grid slow wave structure; 4) simple radial staggered double grid structure, which can achieve high-precision processing and helps to reduce electromagnetic loss and process implementation; 5) all-metal structure with higher power capacity; 6) planar structure, which can be integrated on a circuit board. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of an electromagnetic wave oscillator in the prior art;

[0018] Figure 2 This is a schematic diagram of a radial logarithmic spiral microstrip slow wave line in the prior art;

[0019] Figure 3 This is a schematic diagram of a specific embodiment of the radial electron beam interlaced grid traveling wave amplifier of the present invention;

[0020] Figure 4 This is a schematic diagram of another specific embodiment of the radial electron beam interleaved grid traveling wave amplifier of the present invention;

[0021] Figure 5 This is a time-domain signal diagram of the input and output signals of the radial electron beam interleaved grid structure traveling wave amplifier of the present invention, where (a) is the input signal and (b) is the output signal. Detailed Implementation

[0022] The specific embodiments of the present invention will now be described with reference to the accompanying drawings to enable those skilled in the art to better understand the invention. It should be particularly noted that in the following description, detailed descriptions of known functions and designs that might obscure the main content of the invention will be omitted here.

[0023] Example 1

[0024] Figure 3 This is a schematic diagram of a specific embodiment of the radial electron beam interleaved grid traveling wave amplifier of the present invention.

[0025] In this embodiment, as Figure 3 As shown, the radial electron beam interleaved grid traveling wave amplifier of the present invention includes upper and lower metal ring shells 1 and 2 and a cathode 3.

[0026] The lower side of the upper metal ring shell 1 and the upper side of the lower metal ring shell 2 both have coaxial grid blades 101 and 201 of different radii made of metal. A cavity is formed between the lower and upper grid blades 101 and 201. The lower grid blade 101 of the upper metal ring shell 1 and the upper grid blade 201 of the lower metal ring shell 2 are interleaved to form a slow wave structure, namely a coaxial interleaved grid slow wave structure. This slow wave structure is a coaxial interleaved grid.

[0027] The cathode 3 is placed at the edge of the outermost grid blades of the upper and lower metal ring shells 1 and 2. It emits electrons using a thermionic cathode to form an electron beam 4, which is formed in the cavity between the lower grid blade 101 and the upper grid blade 201 and emitted radially toward the center of the circle.

[0028] Near the hot cathode 3, an electromagnetic wave 6 is injected through the input structure from the cavity between two adjacent grid blades 201 on the upper side of the lower metal ring shell 2 as a signal to be amplified. This electromagnetic wave propagates interlaced along the cavity in the coaxial interlaced grid and interacts with the radially propagating electron beam 4, converting the electron kinetic energy into electromagnetic wave energy and amplifying the input electromagnetic wave signal. In the cavity between two adjacent grid blades 101 on the lower side of the upper metal ring shell 1, which is furthest from the hot cathode 3, the amplified electromagnetic wave 6 is output from the upper metal ring shell 1 through the output structure. The radially propagating electron beam still has some energy and will continue to propagate to the collector electrode 5.

[0029] In this embodiment, Figure 3 The diagram provided is a cross-sectional view of a radial electron beam interleaved grid traveling-wave amplifier. (See diagram for example.) Figure 3As shown, this radial electron beam staggered grid traveling-wave amplifier is symmetrical along the central axis z. Electron beam 4 is incident from the outside in. Electromagnetic waves are input from between the outermost grid blades and interact with the electron beams, generating an amplified signal, which is then output at the point closest to the central grid blade. The radii of the grid blades from the outside to the inside are 80mm, 75mm, 70mm, 65mm, 60mm, 55mm, 50mm, 45mm, and 40mm, respectively. The 35mm grid blade is 2mm thick, the electron beam height is 1.5mm, and the overall amplifier height is 25mm. This structure can operate in the Ku-band.

[0030] Example 2

[0031] Figure 4 This is a schematic diagram of another specific embodiment of the radial electron beam interleaved grid traveling wave amplifier of the present invention.

[0032] In this embodiment, as Figure 4 As shown, the radial electron beam staggered grid structure traveling wave amplifier of the present invention and Figure 3 The structures shown are similar, except that the cathode 3 is placed at the center of the upper and lower metal ring shells 1 and 2, and the electron beam 4 is emitted outward along the radial direction into a cavity formed between the lower grid blade 101 and the upper grid blade 201.

[0033] Near the hot cathode 3, an electromagnetic wave is injected through the input structure from the cavity between two adjacent grid blades 101 on the lower side of the upper metal ring shell 1 as a signal to be amplified. This electromagnetic wave propagates interlaced along the cavity in the coaxial interlaced grid and interacts with the radially propagating electron beam 4, converting the electron kinetic energy into electromagnetic wave energy and amplifying the input electromagnetic wave signal. In the cavity between two adjacent grid blades 201 on the upper side of the lower metal ring shell 2, which is furthest from the hot cathode 3, the amplified electromagnetic wave is output from the lower metal ring shell 2 through the output structure. The radially propagating electron beam still has some energy and will continue to propagate to the collector 5.

[0034] In this embodiment, Figure 4 The diagram provided is a cross-sectional view of a radial electron beam interleaved grid traveling wave amplifier. (See diagram for example.) Figure 4 As shown, the traveling wave tube amplifier is symmetrical along the central axis z. The electron beam 4 is generated by the cathode 3 and emitted from the inside out. The electromagnetic wave is input from between the innermost grating blades and interacts with the electron beam to generate an amplified signal, which is then output at the outermost grating blade. Electrons hit the collector 5 and are absorbed. In this embodiment, the outermost grating blade has a radius of 40 mm, the innermost grating blade has a radius of 15 mm, the grating blade is trapezoidal with a thickness of about 0.6 mm, and the electron beam height is 0.5 mm. This structure is a Ka-band amplifier.

[0035] In practical applications, depending on the design, the coaxial staggered grating slow-wave structure can be made of metals or alloys such as oxygen-free copper, stainless steel, and tungsten. The coaxial staggered grating blades can be rectangular, trapezoidal, triangular, or rectangular with rounded apexes. The input / output structure can use concentric circular slits, or rectangular or circular holes for output. The radius of the staggered grating blades increases linearly or exponentially from the inside out.

[0036] Figure 5 This is a time-domain signal diagram of the input and output signals of the radial electron beam interleaved grid traveling wave amplifier of the present invention, where (a) is the input signal, i.e., the input electromagnetic wave, and (b) is the output signal, i.e., the amplified electromagnetic wave. Figure 5 It can be seen that the input signal was amplified by 1.25 times.

[0037] Although the illustrative specific embodiments of the present invention have been described above to enable those skilled in the art to understand the invention, it should be understood that the invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of the present invention are protected.

Claims

1. A radial electron beam interleaved grid traveling-wave amplifier, characterized in that, include: The upper and lower metal ring shells have coaxial grating blades of different radii made of metal on the lower side of the upper metal ring shell and the upper side of the lower metal ring shell. A cavity is formed between the lower and upper grating blades. The lower grating blades of the upper metal ring shell and the upper grating blades of the lower metal ring shell are interleaved to form a slow wave structure. This slow wave structure is a coaxial interleaved grating. The cathode is placed at the edge of the outermost grid blade of the upper and lower metal ring shells or at the center of the upper and lower metal ring shells. Electrons are emitted using the thermionic cathode to form an electron beam, which is formed in the cavity between the lower and upper grid blades and emitted radially toward the center of the circle or toward the outer edge. Near the hot cathode, an electromagnetic wave is injected through the input structure from the cavity between two adjacent grid blades on the lower side of the upper metal ring shell or the upper side of the lower metal ring shell. This electromagnetic wave serves as the signal to be amplified. It propagates interlaced along the cavity in the coaxial interlaced grid, interacting with the radially propagating electron beam to convert electron kinetic energy into electromagnetic wave energy, thus amplifying the input electromagnetic wave signal. In the cavity between two adjacent grid blades on the upper side of the lower metal ring shell or the lower side of the upper metal ring shell, which is furthest from the hot cathode, the amplified electromagnetic wave is output from the lower or upper metal ring shell through the output structure. The radially propagating electron beam still has some energy and will continue to propagate to the collector electrode.

2. The radial electron beam staggered grid traveling wave amplifier according to claim 1, characterized in that, The grid blades are rectangular, trapezoidal, triangular, or rectangular with rounded apex.

3. The radial electron beam staggered grid traveling wave amplifier according to claim 1, characterized in that, The input / output structure uses concentric circular cracks, rectangular holes, or circular holes for output, and the radius of the grid blades increases linearly or exponentially from the inside to the outside.

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