CN115295377A - Permanent magnet focusing system of microwave device - Google Patents
Permanent magnet focusing system of microwave device Download PDFInfo
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- CN115295377A CN115295377A CN202211170587.1A CN202211170587A CN115295377A CN 115295377 A CN115295377 A CN 115295377A CN 202211170587 A CN202211170587 A CN 202211170587A CN 115295377 A CN115295377 A CN 115295377A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
- H01J23/02—Electrodes; Magnetic control means; Screens
- H01J23/08—Focusing arrangements, e.g. for concentrating stream of electrons, for preventing spreading of stream
- H01J23/087—Magnetic focusing arrangements
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Abstract
The invention discloses a permanent magnetic focusing system of a microwave device, belonging to the field of microwave vacuum electronics, and comprising a main magnetic circuit (1), an auxiliary magnetic circuit (2), an electron gun shielding shell (3) and a shell (4); the invention adopts a mixed permanent magnetic circuit structure of radial magnetization and axial magnetization, and the combined magnetic field distribution of a high uniform magnetic field region and a reverse magnetic field region with micro gradient is formed on the central axis, thereby overcoming the problems of low magnetic field intensity at the middle part of a permanent magnetic focusing system, uncontrollable distribution of the reverse magnetic field and the like; meanwhile, the volume and the weight of the whole system are greatly reduced, the manufacturing cost is reduced, and the miniaturization development of a vacuum electronic device is facilitated; the invention can be widely popularized and used in microwave devices and can also be popularized in other microwave vacuum electronic devices.
Description
Technical Field
The invention relates to the field of microwave vacuum electronics, in particular to a permanent magnet focusing system of a microwave device.
Background
The wireless power transmission technology has great significance and has wide application prospect in the fields of military affairs, communication industry, electric power, aerospace and the like.
The microwave device is used as a core device of a wireless power transmission system, is a special vacuum electronic device taking free electrons as a working medium, and is used for converting microwave energy into direct current electric energy.
The microwave device is operated in a high vacuum state and is subjected to an axial magnetic field. The magnetic field is an important factor influencing the injection-wave interaction, and the distribution and the size of the magnetic field directly influence the resonance condition of the high-frequency interaction region, the electron energy conversion efficiency of the energy conversion region and the focusing action of the collector. In view of the relativistic effects, higher requirements are put on the magnetic field design: the uniform magnetic field area needs to have a smaller gradient, the inverted field area adopts a decreasing magnetic field with cosine distribution, the peak value of the inverted magnetic field is about 0.1 time of the magnetic field value of the uniform area, and the magnetic field of the collection level area is gradually increased to zero from a negative value. Therefore, the design of the inverted field permanent magnet focusing system of the microwave device is very important.
Early microwave electronics typically utilized an energized coil to obtain the required magnetic field. Chinese patent publication No. CN 206685344U's utility model discloses an adopt solenoid as magnetic field generating device, the magnetic field size that the electromagnetic focusing system produced is controllable, and the homogeneity is better, but its shortcoming is also very obvious, and electromagnetic system must be equipped with power and cooling system, and the energy consumption is high, weight and bulky, is not conform to miniaturization, lightweight development trend, and is difficult to form controllable magnetic field that turns to. The invention patent application of Chinese patent publication No. CN101944469A discloses that the magnetic field generated by permanent magnets is used as a focusing magnetic field, the magnetizing directions of the permanent magnets in two areas are opposite, and the purpose of opposite directions of the magnetic fields in the two areas is realized by reversing pole shoes; the patent adopts an axial magnetizing scheme, when the length of the permanent magnet focusing system with the structure is longer, the magnetic field distribution along the axis is concave at the center, and in order to overcome the problem, the size of the permanent magnet at the middle position of the system is increased by a conventional method, namely the using amount of the permanent magnet is increased in the middle area, so that the whole weight is large, and the cost is high.
Disclosure of Invention
The present invention aims at providing a permanent magnetic focusing system for microwave devices to solve the above problems.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a permanent magnetic focusing system for microwave device is composed of main magnetic circuit, auxiliary magnetic circuit, shielding case of electron gun and casing,
the main magnetic circuit comprises at least two radial magnetizing magnetic rings arranged at intervals, the outer ring of each radial magnetizing magnetic ring is fixedly provided with a corresponding outer ring, and the inner ring of each radial magnetizing magnetic ring is fixedly provided with a corresponding inner ring; the inner ring is equivalent to a pole shoe and is arranged for improving the uniformity of a magnetic field, meanwhile, if the tile-shaped splicing does not have the inner ring, the flatness of the inner ring is difficult to ensure after the tile-shaped splicing, and the arrangement of the inner ring can also improve the matching degree of a magnetic system and an inner pipe.
The auxiliary magnetic circuit comprises at least three axial magnetizing magnetic rings, and the axial magnetizing magnetic rings are respectively fixed at two ends of the main magnetic circuit and between the two radial magnetizing magnetic rings; the inner ring of the axial magnetizing magnetic ring positioned between the two radial magnetizing magnetic rings is provided with a pole shoe, and the main magnetic circuit and the auxiliary magnetic circuit are coaxial;
the electron gun shielding shell is arranged on the inner rings of the radial magnetizing magnetic ring and the axial magnetizing magnetic ring which are positioned at the end heads, and the centers of the main magnetic circuit and the auxiliary magnetic circuit penetrate through the electron gun shielding shell;
the main magnetic circuit and the auxiliary magnetic circuit are both fixed with the inner side of the shell.
The permanent magnet focusing system adopts a mixed permanent magnet magnetic circuit structure with radial magnetization and axial magnetization, wherein a main magnetic circuit is used for generating a magnetic field meeting the requirement of magnetic field intensity; the auxiliary magnetic circuit is used for adjusting the uniformity of the uniform region, the magnetic field gradient and the distribution and size of the reverse field.
It should be noted that: regarding the number of the radial magnetizing magnetic rings, two radial magnetizing magnetic rings are generally adopted, and as an example, two radial magnetizing magnetic rings a and two radial magnetizing magnetic rings B are taken as an example, since a single radial magnetizing magnetic ring a cannot form the magnetic circuit, and the addition of the radial magnetizing magnetic ring C has no great significance to the magnetic circuit, since the required magnetic field radial magnetizing magnetic ring a and the radial magnetizing magnetic ring B can be formed; the number of the axial magnetizing magnetic rings is also the same reason, and three are preferably adopted.
When two radial magnetizing magnetic rings are adopted, the shapes of the radial magnetizing magnetic ring A and the radial magnetizing magnetic ring B are preferably different, and the main reasons are as follows: firstly, the uniform area of the magnetic field requires a small gradient change, and two magnetic rings with different shapes are arranged in the main magnetic circuit, so that the gradient change is easier to realize; secondly, the arrangement is easier to realize due to the requirement of the tail inverted magnetic field;
of course, even if two radial magnetizing magnetic rings with the same shape are adopted, the uniform area and the reverse magnetic field area can be optimized through the auxiliary magnetic field to achieve similar effects.
As a preferred technical scheme: the shielding shell of the electron gun is made of magnetic materials, such as soft magnetic alloy materials of Q235, DT4, DT8 and the like, can provide a magnetic shielding environment for the electron gun, can be used as a pole shoe of a magnetic circuit and a shielding shell of the electron gun, and greatly simplifies the design of the electron gun and the whole tube; the traditional design is that the magnetic system is designed independently, but the invention combines the shielding structure and the pole shoe into a whole, so that the shielding problem is not considered when designing the electron gun, and only the internal structure is designed to be matched with the electron gun.
As a preferable technical scheme: the radial magnetizing magnetic ring and the axial magnetizing magnetic ring are selected from rare earth cobalt or neodymium iron boron permanent magnet rings.
As a preferred technical scheme: the radial magnetizing magnetic ring is an integral magnetic ring or is formed by splicing a plurality of tile-shaped magnets.
As a preferred technical scheme: the axial magnetizing magnetic ring is an integral magnetic ring or is formed by splicing a plurality of tile-shaped magnets.
As a preferred technical scheme: the outer ring, the inner ring and the pole shoe are made of magnetic materials.
As a further preferable technical scheme: the magnetic conductive material is selected from Q235, DT4 and DT8 soft magnetic alloy materials.
As a preferred technical scheme: the shell is made of non-magnetic conducting materials.
As a further preferred technical scheme: the non-magnetic conductive material is selected from 2A12 and 304 stainless steel.
Compared with the prior art, for example, in the Chinese patent application CN101944469A, the magnetic field intensity of the middle area is improved by increasing the using amount of the middle permanent magnet, and the whole pipe is provided with the magnetic ring which is axially magnetized, so that the using amount of the permanent magnet is obviously larger; in the invention, the magnetic rings are not required to be assembled on the whole pipe, the auxiliary magnetic circuit is arranged in the main magnetic circuit to adjust the uniformity of the uniform region of the magnetic field, the magnetic field gradient of the uniform region and the inverted magnetic field, and the design concept is better than that of CN101944469A in terms of volume, weight and cost.
Compared with the prior art, the invention has the advantages that: the invention adopts a mixed permanent magnetic circuit structure of radial magnetization and axial magnetization, and the combined magnetic field distribution of a high uniform magnetic field region and a reverse magnetic field region with micro gradient is formed on the central axis, thereby overcoming the problems of low magnetic field intensity at the middle part of a permanent magnetic focusing system, uncontrollable distribution of the reverse magnetic field and the like; meanwhile, the volume and the weight of the whole system are greatly reduced, the manufacturing cost is reduced, and the miniaturization development of a vacuum electronic device is facilitated; the invention can be widely popularized and used in microwave devices and can also be popularized in other microwave vacuum electronic devices.
Drawings
FIG. 1 is a schematic structural diagram of a permanent magnet focusing system according to embodiment 1 of the present invention;
FIG. 2 is a schematic diagram of the main magnetic circuit of comparative example 1;
FIG. 3 is a graph showing the results of the magnetic field distribution in example 1 of the present invention;
FIG. 4 is a graph showing the results of the magnetic field distribution of comparative example 1 of the present invention.
In the figure: 1. a main magnetic circuit; 1-1, radial magnetizing magnetic rings A;1-2, radial magnetizing magnetic rings B;1-3, an outer ring A;1-4, an outer ring B;1-5 inner circles; 2 an auxiliary magnetic circuit; 2-1, axially magnetizing a magnetic ring A;2-2, axially magnetizing a magnetic ring B;2-3, axially magnetizing a magnetic ring C;2-4, pole shoes; 3. an electron gun shield case; 4. a housing.
Detailed Description
The invention will be further explained with reference to the drawings.
Example 1
A permanent magnetic focusing system of microwave device is shown in figure 1, and comprises a main magnetic circuit 1, an auxiliary magnetic circuit 2, an electron gun shielding case 3 and a shell 4, wherein,
in the embodiment, the main magnetic circuit 1 comprises two radial magnetizing magnetic rings which are different in shape and are arranged at intervals, wherein the radial magnetizing magnetic rings are respectively a radial magnetizing magnetic ring A1-1 and a radial magnetizing magnetic ring B1-2, the radial magnetizing magnetic ring A1-1 and the radial magnetizing magnetic ring B1-2 have opposite magnetic poles, the outer ring of the radial magnetizing magnetic ring A1-1 is fixedly provided with a corresponding outer ring A1-3, the outer ring of the radial magnetizing magnetic ring B1-2 is fixedly provided with a corresponding outer ring B1-4, and the inner ring of the radial magnetizing magnetic ring B1-2 is provided with an inner ring 1-5;
the auxiliary magnetic circuit 2 comprises three axial magnetizing magnetic rings, namely an axial magnetizing magnetic ring A2-1, an axial magnetizing magnetic ring B2-2 and an axial magnetizing magnetic ring C2-3, the axial magnetizing magnetic ring A2-1 is bonded at the left end of a radial magnetizing magnetic ring A1-1 of the main magnetic circuit through glue, and the axial magnetizing magnetic ring C2-3 is bonded at the right end of a radial magnetizing magnetic ring B1-2 of the main magnetic circuit through glue, and the design is mainly used for adjusting the magnetic field gradient and the magnetic field distribution and the size of a reverse field in a uniform area; the axial magnetizing magnetic ring B2-2 is bonded with the shell 4 by glue and fixed in the middle of the main magnetic circuit 1 and is used for adjusting the uniformity of the uniform area; an inner ring of the axial magnetizing magnetic ring B2-2 is provided with a pole shoe 2-4, and the main magnetic circuit 1 and the auxiliary magnetic circuit 2 are coaxial;
the electron gun shielding shell 3 is arranged in the inner rings of the axial magnetizing magnetic ring A2-1 and the radial magnetizing magnetic ring A1-1, and the centers of the main magnetic circuit 1 and the auxiliary magnetic circuit 2 penetrate through the electron gun shielding shell 3;
the main magnetic circuit 1 and the auxiliary magnetic circuit 2 are coaxially fixed on the shell 4, the center of the main magnetic circuit and the auxiliary magnetic circuit passes through the electron gun shielding shell 3, the electron gun shielding shell is made of a magnetic conductive material, a magnetic shielding environment is provided for an electron gun, and the design of the electron gun is simplified; the existing electron gun design comprises an inner structure design and an outer shielding design of the electron gun, the influence of a magnetic field on the inside of the electron gun is considered, the shielding structure is directly used as a part of a magnetic circuit in the embodiment, the shielding structure is used as a pole shoe, the uniformity of the magnetic field is improved, the assembly process of a magnetic ring is simplified, and the design of the electron gun is simplified;
the permanent magnet ring is made of 2: a type 17 samarium cobalt permanent magnet material, with the results shown in figure 3. The magnetic field in the uniform area is distributed in a small gradient, the length of the uniform area is about 57mm, and the value of the magnetic field in the uniform area is about B Z =0.22T, the distribution of the magnetic field of the inverted field meets the decreasing requirement of cosine distribution, and the peak value size B of the magnetic field of the inverted field Z reverse =0.025T。
Comparative example 1
The comparative example shows a permanent magnetic focusing system using the main magnetic circuit of example 1 without the auxiliary magnetic circuit in fig. 2, and the same permanent magnetic material as that of example 1 was used to obtain the results shown in fig. 4. The magnetic field in the uniform area is distributed in a concave manner, and the average value of the magnetic field in the uniform area is about B Z =0.2T, magnitude of magnetic field peak in inverted field B Z reverse =0.165T。
Because of the relativistic effect, requirements are placed on the magnetic field distribution. The magnetic field in the uniform area has a small gradient, the inverted magnetic field area conforms to the decreasing magnetic field with cosine distribution, and the inverted peak value of the magnetic field is 10 percent of the magnetic field in the uniform area;
when the auxiliary magnetic field is not available, the central magnetic field is distributed as shown in fig. 4, the magnetic field in the uniform area is in concave-down distribution, the uniformity is poor and does not accord with gradient distribution, and the inverted peak value of the magnetic field also does not meet the requirement; after the auxiliary magnetic field is added, the distribution of the central magnetic field is shown in figure 3, and the distribution of the magnetic field is obviously improved. The magnetic field in the uniform area is distributed in a small gradient mode, the distribution of the magnetic field of the reverse field meets the decreasing requirement of cosine distribution, and the peak value of the magnetic field of the reverse field is about 10 percent of that of the magnetic field in the uniform area.
The foregoing is a more detailed description of the present invention that is presented in conjunction with specific embodiments, and the practice of the invention is not to be considered limited to those descriptions. It will be apparent to those skilled in the art that various modifications and substitutions can be made without departing from the spirit of the invention, and all such modifications and alterations should be considered to fall within the scope of the invention.
Claims (9)
1. A microwave device permanent magnetism focusing system which characterized in that: comprises a main magnetic circuit (1), an auxiliary magnetic circuit (2), an electron gun shielding case (3) and a shell (4),
the main magnetic circuit (1) comprises at least two radial magnetizing magnetic rings arranged at intervals, the outer ring of each radial magnetizing magnetic ring is fixedly provided with a corresponding outer ring, and the inner ring of each radial magnetizing magnetic ring is fixedly provided with a corresponding inner ring;
the auxiliary magnetic circuit (2) comprises at least three axial magnetizing magnetic rings which are respectively fixed at two ends of the main magnetic circuit (1) and between the two radial magnetizing magnetic rings; an inner ring of the axial magnetizing magnetic ring positioned between the two radial magnetizing magnetic rings is provided with a pole shoe, and the main magnetic circuit (1) and the auxiliary magnetic circuit (2) are coaxial;
the electron gun shielding shell (3) is arranged at the inner rings of the radial magnetizing magnetic ring and the axial magnetizing magnetic ring at the end, and the centers of the main magnetic circuit (1) and the auxiliary magnetic circuit (2) penetrate through the electron gun shielding shell (3);
the main magnetic circuit (1) and the auxiliary magnetic circuit (2) are fixed with the inner side of the shell (4).
2. The microwave device permanent magnet focusing system of claim 1, characterized in that: the electron gun shielding shell (3) is made of magnetic conductive materials.
3. The microwave device permanent magnet focusing system of claim 1, characterized in that: the radial magnetizing magnetic ring and the axial magnetizing magnetic ring are selected from rare earth cobalt or neodymium iron boron permanent magnet rings.
4. The microwave device permanent magnet focusing system of claim 1, characterized in that: the radial magnetizing magnetic ring is an integral magnetic ring or is formed by splicing a plurality of tile-shaped magnets.
5. The microwave device permanent magnet focusing system of claim 1, characterized in that: the axial magnetizing magnetic ring is an integral magnetic ring or is formed by splicing a plurality of tile-shaped magnets.
6. The microwave device permanent magnet focusing system of claim 1, wherein: the outer ring, the inner ring and the pole shoe are made of magnetic materials.
7. The microwave device permanent magnet focusing system of claim 6, wherein: the magnetic conductive material is selected from Q235, DT4 and DT8 soft magnetic alloy materials.
8. The microwave device permanent magnet focusing system of claim 1, characterized in that: the shell is made of non-magnetic conducting materials.
9. The microwave device permanent magnet focusing system of claim 1, characterized in that: the non-magnetic conductive material is selected from 2A12 and 304 stainless steel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211170587.1A CN115295377B (en) | 2022-09-26 | 2022-09-26 | Permanent magnet focusing system of microwave device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211170587.1A CN115295377B (en) | 2022-09-26 | 2022-09-26 | Permanent magnet focusing system of microwave device |
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| CN115295377A true CN115295377A (en) | 2022-11-04 |
| CN115295377B CN115295377B (en) | 2023-01-13 |
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| CN110459378A (en) * | 2019-09-11 | 2019-11-15 | 西南应用磁学研究所 | A kind of permanent magnetic device generating space uniform magnetic field |
| CN112214847A (en) * | 2020-09-18 | 2021-01-12 | 电子科技大学 | Design method of periodic permanent magnet focusing system of traveling wave tube |
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2022
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| Title |
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