CN111341631A - An Electromagnetic Wave Generator Using Secondary Electron Multiplication - Google Patents

Abstract

The invention discloses an electromagnetic wave generator utilizing secondary electron multiplication to divide a slow wave structure or a resonant cavity into two sections or three sections, and a secondary electron multiplication sheet is vertically inserted between the front section and the rear section. The secondary electron multiplication piece is provided with a plurality of micro-diameter micro-channels along the thickness direction, the inner wall of each micro-channel is coated with a secondary electron multiplication film, the height or the diameter of each micro-channel is far smaller than the thickness of the secondary electron multiplication piece, namely the length of each micro-channel, electrons can collide with the inner wall of each micro-channel for many times, tens of secondary electrons can be generated in each collision, electron beam current multiplication is realized through secondary electron multiplication, namely energy multiplication, but the density modulation generated by electron beams is not influenced, so that higher power and higher gain electromagnetic wave output can be obtained. Meanwhile, no focusing magnetic field needs to be added, and only a small amount of electrons can hit the secondary electron multiplying plate after dispersion, but the gain of the secondary electron multiplying plate is as high as tens of thousands of times, so that the electron beam current can be amplified sufficiently.

Description

An Electromagnetic Wave Generator Using Secondary Electron Multiplication

technical field

The invention belongs to the technical field of microwave devices, and relates to vacuum electronic devices such as klystrons, traveling wave tubes, and return wave tubes, and more specifically, to an electromagnetic wave generator utilizing secondary electron multiplication.

Background technique

Vacuum electronic devices include klystrons, traveling wave tubes, return wave tubes, etc., using hot cathodes to emit electron beams, and the electron beams are velocity modulated in a resonant cavity or slow-wave structure. The electrons catch up with the slower electrons to form a clustered electron cluster, and the clustered electron cluster transfers energy to the electromagnetic wave, thereby forming an amplified or oscillating electromagnetic wave output. When the electron beam is transmitted in a vacuum electronic device, a magnetic field is required for focusing, and a solenoid or a periodic permanent magnet magnetic field is generally used for focusing.

Vacuum electronic devices have the advantages of high output power, high operating frequency, radiation resistance and long life, so they are widely used in wireless communications, satellite communications, radio and television, aerospace, weather radar, global positioning system (GPS), deep space exploration, medical accelerators , missile guidance, security links, battlefield surveillance, and electronic countermeasures are extremely widely used, especially in various fighters, bombers, UAVs, ships, tanks and satellite systems. It is the heart of modern high-end electronic information equipment and has an irreplaceable role.

With the development of society and the advancement of science and technology, the application breadth and depth of vacuum electronic devices in various fields are also increasing. High requirements: Radar, electronic countermeasures systems require amplifiers with higher power, wider bandwidth, and higher gain; medical imaging and big data transmission require amplifiers with higher frequency, wider bandwidth, and smaller volume; in terahertz technology On the other hand, there is an urgent need for high-frequency, high-power amplifiers that can fill the "terahertz gap"; in satellite communications and deep space exploration, vacuum amplifiers with smaller size, higher power, and higher gain are needed; especially Elon Ma After SK proposed the Starlink concept, tens of thousands of small satellites will fly into space in the next few years, and there will be nearly 10,000 replacements every year. There is an urgent need for a communication system composed of nearly 100,000 amplifiers, which not only requires the volume of new spaceborne vacuum amplifiers Small size, light weight, high gain, simple structure and mass production. In a word, the development of new vacuum electronic devices with small volume, light weight, high gain, high power, wide frequency band, simple structure, and mass production has important scientific significance and urgent practical needs.

Existing vacuum electronic devices such as traveling wave tubes, klystrons, magnetrons, and gyrotrons, that is, high-power electromagnetic wave generators use hot cathodes, which require additional heating of the cathodes, emit low electron density, and require magnetic field focusing. Electromagnetic waves have low power.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the prior art, and to propose an electromagnetic wave generator utilizing secondary electron multiplication, which does not require magnetic field focusing and at the same time increases the power and gain of the output electromagnetic wave signal.

In order to realize the above-mentioned purpose of the invention, the present invention utilizes the electromagnetic wave generator of secondary electron multiplication, including:

The cathode, which emits electrons to form an electron beam;

It is characterized in that it also includes:

One or two pieces of secondary electron multiplying sheet, there are multiple micro-channels with micrometer diameter along the thickness direction (electron transport direction), the inner wall of the micro-channel is coated with a secondary electron multiplying film (micro-channel inner wall film), the height of the micro-channel or The diameter is much smaller than the thickness of the secondary electron multiplier sheet, that is, the length of the microchannel. The electrons will collide on the inner wall of the microchannel for many times, and each collision will generate dozens of secondary electrons (the secondary electron emission coefficient is generally much higher than 3) ;

Two-segment or three-segment slow-wave structure (mainly for traveling wave tube, return wave tube) or resonant cavity (mainly for klystron, gyrotron), the secondary electron multiplier is vertically inserted into the two-segment slow-wave structure or Between the resonators, after the electrons are emitted from the cathode, they are first modulated by the first segment of the slow-wave structure or the resonator, resulting in initial velocity and density modulation, and then enter the secondary electron multiplier, where electrons multiply in the microchannels. The secondary collision produces tens of thousands of times of electron multiplication, that is, the increase of the number of electrons by tens of thousands of times, that is, the increase of tens of thousands of times of current, because when the electrons enter the secondary electron multiplier sheet, there is already density modulation, and there is still an increase in the current after the increase. Density modulation; the secondary electron multiplier is followed by a second slow wave structure or resonant cavity. At this time, the electron beam current with density modulation can excite electromagnetic waves to generate output; if the gain or output power does not meet the requirements, the second section can be used. The slow-wave structure or resonant cavity modulates the electron beam current again, and then the secondary electron multiplier and the third segment of the slow-wave structure or resonant cavity are connected as the output.

The object of the present invention is achieved in this way.

The invention utilizes a secondary electron multiplying electromagnetic wave generator to divide the slow wave structure or resonant cavity into two or three segments, and vertically inserts a secondary electron multiplying sheet between the front and rear segments. The secondary electron multiplier sheet has multiple micro-channels with micrometer diameter along the thickness direction (electron transport direction), and the inner wall of the micro-channel is coated with a secondary electron multiplier film (the inner wall film of the micro-channel), and the height or diameter of the micro-channel is much smaller than that of the secondary electron. The thickness of the multiplier sheet is the length of the microchannel. The electrons will collide on the inner wall of the microchannel for many times, and each collision will generate dozens of secondary electrons (the emission coefficient of secondary electrons is generally much higher than 3), which can generate several electrons. The tens of thousands of times of electron multiplication means that the number of electrons increases by tens of thousands of times, that is, the increase of current is tens of thousands of times. Since the electrons enter the secondary electron multiplier, there is already density modulation, and there is still density modulation after the current increases. The secondary electron multiplier is followed by a second slow-wave structure or resonant cavity. At this time, the electron beam current with density modulation can excite electromagnetic waves to generate output; if the gain or output power does not meet the requirements, the second slow-wave structure can be used. Or the resonant cavity modulates the electron beam current again, and then connects the secondary electron multiplier and the third slow-wave structure or the resonant cavity as the output. In the present invention, the slow-wave structure or resonant cavity and the secondary electron multiplier sheet are interleaved. The secondary electron multiplication realizes the multiplication of the electron beam current, that is, the energy multiplication, but does not affect the density modulation produced by the electron beam, so it can obtain the electromagnetic wave output with higher power and higher gain. At the same time, due to the insertion of the secondary electron multiplier, the vacuum electronic device does not need an external focusing magnetic field, because even if the electron beam is dispersed, this does not affect the change of the electron beam density, although only a small amount of electrons can be hit after the dispersion. to the secondary electron multiplier, but since the gain of the secondary electron multiplier is as high as tens of thousands of times, it is enough to amplify the electron beam current.

In addition, since there is no need for an external focusing magnetic field and the power and gain of the output electromagnetic wave are improved, the volume and quality of the electromagnetic wave generator can be greatly reduced. Compared with the existing electromagnetic wave generator, its volume is reduced to half of the original, the gain will be expanded to twice the original, and the structure is simpler, which can meet the needs of small satellites, phased array systems, etc. There is an urgent need for high-quality, high-gain, mass-producible new vacuum electronic devices.

Description of drawings

1 is a schematic structural diagram of a specific embodiment (folded waveguide slow-wave structure) of an electromagnetic wave generator utilizing secondary electron multiplication according to the present invention;

2 is a schematic structural diagram of another specific embodiment (resonant cavity) of an electromagnetic wave generator utilizing secondary electron multiplication according to the present invention;

3 is a schematic structural diagram of another specific embodiment (rectangular grating slow-wave structure) of an electromagnetic wave generator utilizing secondary electron multiplication according to the present invention;

4 is a schematic structural diagram of another specific embodiment (spiral slow wave structure) of an electromagnetic wave generator utilizing secondary electron multiplication according to the present invention.

Detailed ways

The specific embodiments of the present invention are described below with reference to 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 the detailed description of known functions and designs may dilute the main content of the present invention, these descriptions will be omitted here.

FIG. 1 is a schematic structural diagram of a specific embodiment (folded waveguide slow wave structure) of an electromagnetic wave generator utilizing secondary electron multiplication according to the present invention.

In this embodiment, as shown in FIG. 1 , the present invention utilizes a secondary electron multiplying electromagnetic wave generator, including: a cathode 1 , a two-stage slow-wave structure 2 and a secondary electron multiplying sheet 3 . In this embodiment, the slow-wave structure is a folded waveguide slow-wave structure, and the cathode 1 is a hot cathode.

The secondary electron multiplying sheet 3 has a plurality of micro-channels with micrometer diameters along the thickness direction (electron transport direction), the inner wall of the micro-channel is coated with a secondary electron multiplying film (the inner wall film of the micro-channel), and the height or diameter of the micro-channel is much smaller than that of the secondary electron multiplying film. The thickness of the electron multiplier sheet is the length of the microchannel. The electrons will collide on the inner wall of the microchannel for many times, and each collision will generate several secondary electrons (the secondary electron emission coefficient, generally δ>3); the secondary electron multiplier sheet 3 Vertically inserted into the two-segment folded waveguide slow-wave structure 2 connected back and forth.

The cathode 1 emits electrons to form an electron beam. After the electrons are emitted from the cathode 1, they are first modulated by the first segment of the folded waveguide slow-wave structure 2, resulting in initial velocity and density modulation, and then enter the secondary electron multiplier 3, where the electrons collide multiple times in the microchannel, The electron multiplication of tens of thousands of times is generated, forming an electron beam current 4 with an amplification of tens of thousands of times with density modulation. The secondary electron multiplier 3 is followed by a second segment of the folded waveguide slow-wave structure 2. At this time, the amplification of the specific density modulation is tens of thousands of times. The electron beam current 4 times is able to excite and generate electromagnetic wave output that is amplified by tens of thousands of times.

In this embodiment, the radius of the secondary electron multiplier sheet 3 is 1 mm and the thickness is 1 mm, the cathode 1 emits an initial electron beam, the first segment of the folded waveguide slow-wave structure 2 is modulated, passes through the secondary electron multiplier sheet 3, and then uses a second The segment-folded waveguide slow-wave structure 2 generates 2-8 GHz electromagnetic waves.

FIG. 2 is a schematic structural diagram of another specific embodiment (resonant cavity) of an electromagnetic wave generator utilizing secondary electron multiplication according to the present invention.

In this embodiment, as shown in FIG. 2 , the electromagnetic wave generator using secondary electron multiplication is similar in structure to that shown in FIG. 1 , except that three-segment resonant cavities 501 , 502 , and 503 are used, and two secondary electron multiplying sheets 301 , 503 are used. 302. The secondary electron multipliers 301, 302 are vertically inserted between the two resonant cavities 501, 502, 503 connected back and forth, that is, the secondary electron multiplier 301 is vertically inserted between the two resonators 501, 502 connected back and forth, and the two The sub-electron multiplier 302 is vertically inserted between the two resonant cavities 502 and 503 connected back and forth.

The secondary electron multiplier sheets 301 and 302 are elliptical sheets with a long axis of 5.5 mm, a short axis of 1.2 mm, and a thickness of 2 mm. The cathode 1 generates an initial electron bunch, which is modulated by the first resonant cavity 501 and passed through the first sheet The secondary electron multiplier 301 is multiplied, then modulated by the second resonant cavity 502 , and multiplied by the second secondary electron multiplier 302 again, and finally an electromagnetic wave output of 32-40 GHz is generated in the third resonant cavity 503 .

FIG. 3 is a schematic structural diagram of another specific embodiment of the electromagnetic wave generator utilizing secondary electron multiplication (rectangular grating slow-wave structure) according to the present invention.

In this embodiment, as shown in FIG. 3 , the electromagnetic wave generator using the secondary electron multiplication is similar to the structure shown in FIG. 2 , except that three-segment rectangular grating slow-wave structures 601 , 602 , and 603 are used, and two secondary electron multiplication pieces are used. The sheets 301 and 302 are rectangular sheets with a length and width of 5*2 mm and a thickness of 0.5 mm. The cathode 1 generates an initial electron bunch, which is modulated by the first segment of the rectangular grating slow-wave structure 601 and passed through the first secondary electron multiplier sheet 301 Multiplying, then modulated by the second rectangular grating slow-wave structure 602, and multiplying again by the second secondary electron multiplier 302, and finally generating an electromagnetic wave output of 10-20 GHz in the third rectangular grating slow-wave structure 603.

4 is a schematic structural diagram of another specific embodiment (spiral slow wave structure) of an electromagnetic wave generator utilizing secondary electron multiplication according to the present invention.

In this embodiment, as shown in FIG. 4 , the electromagnetic wave generator using secondary electron multiplication is similar to the structure shown in FIG. 2 , except that four-segment helical slow-wave structures 701 , 702 , 703 , and 704 are used, and three secondary The electron multiplier sheets 301, 302, and 303 are circular sheets with a radius of 1 mm and a thickness of 0.6 mm. The cathode 1 generates an initial electron bunch, which is modulated by the first segment of the helical slow-wave structure 701, and passes through the first sheet of secondary electrons. The multiplication plate 301 is multiplied, then modulated by the second spiral slow wave structure 702, and multiplied by the second secondary electron multiplier plate 302 again, and then modulated by the third spiral slow wave structure 703, and again through the third The secondary electron multiplying sheet 303 is multiplied, and finally an electromagnetic wave output of 65-75 GHz is generated in the fourth segment of the helical slow-wave structure 704 . That is to say, the present invention can be further expanded on the basis of two stages and three stages.

The above are four examples. In the actual application process, depending on the design, the materials of the secondary electron multiplier and the slow-wave structure can be made of oxygen-free copper, stainless steel, tungsten, molybdenum and other metal materials, alloy materials or gallium nitride, gallium arsenide , diamond and other semiconductor materials. Depending on the design and application, the slow-wave structure or resonant cavity can be a helix, a folded waveguide, a rectangular double grid, a rectangular single grid, a single resonant cavity, multiple resonant cavities, a rectangular cavity, an elliptical cavity, etc. applicability. The secondary electron multiplier sheet can be cylindrical, rectangular, tall oval, annular, and the like.

Although the illustrative specific embodiments of the present invention have been described above to facilitate the 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 utilizing the inventive concept are included in the protection list.

Claims (2)

1. An electromagnetic wave generator utilizing secondary electron multiplication, comprising:

a cathode for emitting electrons to form an electron beam;

it is characterized by also comprising:

one or two secondary electron multiplying sheets, wherein a plurality of micro-channels with the diameter of micrometers are arranged along the thickness direction (electron transmission direction), the inner walls of the micro-channels are coated with secondary electron multiplying films (micro-channel inner wall films), the height or the diameter of each micro-channel is far smaller than the thickness of the secondary electron multiplying sheet, namely the length of the micro-channel, electrons can collide for many times on the inner walls of the micro-channels, and tens of secondary electrons (the secondary electron emission coefficient is generally far higher than 3) can be generated by each collision;

the electron beam is emitted from a cathode and modulated by the first slow wave structure or resonant cavity to generate primary speed and density modulation, and then enters the secondary electron multiplying piece, the electrons collide for many times in a microchannel to generate electron multiplication of tens of thousands of times, namely the number of tens of thousands of times of electrons is increased, namely the current is increased by tens of thousands of times, when the electrons enter the secondary electron multiplying piece, the density modulation is already performed, and the density modulation still exists after the current is increased; the secondary electron multiplying piece is connected with a second section of slow wave structure or resonant cavity, and the electron beam current with density modulation can excite the electromagnetic wave to generate output; if the gain or the output power does not meet the requirement, or the current of the electron beam can be modulated again by utilizing the second-section slow-wave structure or the resonant cavity, and then the secondary electron multiplying piece and the third-section slow-wave structure or the resonant cavity are connected as output.

2. The generator of claim 1, wherein the secondary electron multiplying plate and the slow wave structure are made of oxygen-free copper, stainless steel, tungsten, molybdenum, alloy material, or gallium nitride, gallium arsenide, diamond, or other semiconductor material; the slow wave structure or the resonant cavity can be a spiral line, a folded waveguide, a rectangular double gate, a rectangular single gate, a single resonant cavity, a multi-resonant cavity, a rectangular cavity, an elliptical cavity and the like according to different designs and applications, and the secondary electron multiplier piece can be cylindrical, rectangular, high elliptical, annular and the like.

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