Axial magnetic field analysis method of traveling wave tube composite period focusing system and analysis model construction method

Abstract

The invention relates to an axial magnetic field analysis method for a traveling wave tube composite period focusing system, the system comprises first pole shoes arranged along the axial direction, magnetic steel arranged between the first pole shoes, and a plurality of second pole shoes arranged between the first pole shoes, and a non-zero magnetic potential difference exists at a gap between a first pole shoe head and a second pole shoe head; the method comprises the following steps: determining direct magnetic circuit magnetic conductance and gap magnetic circuit magnetic conductance of each magnetic circuit between adjacent pole shoes; determining the magnetic resistance of each magnetic circuit in the composite period focusing system according to the direct magnetic circuit magnetic conductance and the gap magnetic circuit magnetic conductance of each magnetic circuit; determining a magnetic potential distribution function at the radial position r = r1 of the focusing system according to the magnetic resistance of each magnetic circuit, wherein r1 is the inner diameter of the first pole shoe and the inner diameter of the second pole shoe; determining radial magnetic potential distribution of the focusing system by taking a magnetic potential distribution function of the focusing system at a radial coordinate r = r1 as a boundary condition, wherein r is greater than 0 and less than r1; and calculating the axial magnetic field distribution of the composite period focusing system. According to the method, the calculation precision of the axial magnetic field is improved, and the simulation design process is simplified.

Description

Technical Field

[0001] The present invention relates to the field of traveling wave tube focusing system design, and more specifically, to an axial magnetic field analysis method of a traveling wave tube composite period focusing system, an axial magnetic field analysis model construction method, equipment, medium and product of the traveling wave tube composite period focusing system. Background Art

[0002] The focusing system is a key part of the electron optical system of microwave vacuum electron devices. Its function is to generate a magnetic field parallel to the electron beam axis in the linear electron injection tube to prevent the electron beam from diverging due to the space charge force. The main methods for generating the focusing magnetic field are permanent magnets and electromagnets. Among them, electromagnets are rarely used due to their large coil size and bulky power supply. At present, the mainstream focusing structure uses permanent magnets. In order to overcome the problem of large size and mass of permanent magnets that generate unidirectional magnetic fields, the method of periodic permanent magnet focusing system is often used to reduce the mass of the focusing system by 1 to 2 orders of magnitude. The design of the periodic permanent magnet focusing system is relatively complex, and its axial magnetic field distribution and magnetic flux density need to be strictly calculated.

[0003] When designing a focusing system, it usually takes 2 to 3 hours to calculate the focusing system once using three-dimensional electromagnetic simulation design software to obtain its magnetic field distribution. In order to obtain a good electron beam trajectory, the magnetic field needs to be adjusted continuously. If the three-dimensional focusing magnetic field is calculated every time the magnetic field is adjusted, the design and development efficiency of the focusing system will be greatly reduced. In order to save time and cost, it is generally necessary to first conduct a theoretical analysis of the axial magnetic field distribution of the focusing system to obtain the theoretical value, and then optimize the structure of the focusing system according to the theoretical value, and then replace the focusing system with the simulated magnetic field model set in the simulation design software to calculate the simulated magnetic field distribution. After the simulation results meet the requirements, the focusing system is designed according to the simulated magnetic field distribution, and the actual magnetic field distribution generated by the focusing system is calculated and back-substituted. At present, the main method for calculating the theoretical magnetic field distribution is the uniform magnetization method. Since this method makes a lot of idealized assumptions when establishing the model and ignores the influence of some parameters, the calculated axial magnetic field distribution has a large error with the simulation value and the actual value, which makes the uniform magnetization method have limited reference value in the design of the focusing system. In engineering practice, it relies more on numerical simulation calculation results, which affects the design and production efficiency and causes a large waste of time and computing power. Summary of the invention

[0004] In view of the above problems, one aspect of the present invention provides an axial magnetic field analysis method for a traveling wave tube composite period focusing system.

[0005] The composite periodic focusing system comprises a first pole shoe arranged along the axial direction of the focusing system, a magnetic steel between the first pole shoes, and a plurality of second pole shoes arranged between the first pole shoes, and a non-zero magnetic potential difference exists at the gap between the first pole shoe head and the second pole shoe head;

[0006] The analysis method comprises:

[0007] Determining the direct magnetic path permeability and the gap magnetic path permeability of each magnetic path between adjacent pole shoes;

[0008] Determine the magnetic resistance of each magnetic circuit in the composite periodic focusing system according to the direct magnetic circuit permeability and the gap magnetic circuit permeability of each magnetic circuit;

[0009] Determine the magnetic potential distribution function of the focusing system at a radial position r=r1 according to the magnetic resistance of each magnetic circuit, where r1 is the inner diameter of the first pole shoe and the second pole shoe;

[0010] Determine the radial magnetic potential distribution of the focusing system using the magnetic potential distribution function of the focusing system at a radial position r=r1 as a boundary condition, 0<r<r1; and

[0011] Calculate the axial magnetic field distribution of the compound periodic focusing system.

[0012] Preferably, the focusing system comprises a plurality of first pole shoes arranged along the axial direction of the focusing system, magnetic steels arranged between adjacent first pole shoes, and a plurality of second pole shoes.

[0013] Preferably, the magnetization directions of adjacent magnetic steels through the first pole shoe are opposite.

[0014] Preferably, the number of second pole shoes between the first pole shoes is the same, and the second pole shoes are arranged at equal intervals between the first pole shoes.

[0015] Another aspect of the present invention provides a method for constructing an axial magnetic field analysis model of a traveling wave tube composite periodic focusing system, wherein the composite periodic focusing system comprises a first pole shoe arranged along the axial direction of the focusing system and a magnetic steel between the first pole shoes, and a plurality of second pole shoes arranged between the first pole shoes, wherein the first pole shoe comprises a first pole shoe body and a first pole shoe head, and the second pole shoe comprises a second pole shoe body and a second pole shoe head, and the method comprises:

[0016] The structural parameters of the traveling wave tube composite periodic focusing system are set, including the number of second pole shoes N, the magnetic field period L, the axial length of the first pole shoe head L2, the axial length of the second pole shoe head L1, the gap length between the pole shoe heads d1, the pole shoe inner diameters of the first pole shoe and the second pole shoe r1, and a non-zero magnetic potential difference at the gap between the first pole shoe head and the second pole shoe head;

[0017] Determine the direct magnetic permeability P of each magnetic path between the pole shoes 1j and gap magnetic circuit permeability P 2j , j = 1, ..., N + 1, where N is the number of second pole pieces;

[0018] According to the direct magnetic path permeability P 1j and gap magnetic circuit permeability P2j Determine the magnetic resistance R of each magnetic circuit in the compound periodic focusing system j ;

[0019] According to the magnetic resistance R of each magnetic circuit j Determine the magnetic potential distribution function at the radial coordinate r=r1 of the compound periodic focusing system;

[0020] Calculating the radial magnetic potential distribution of the focusing system using the magnetic potential distribution function of the focusing system at position r=r1 as the boundary condition, 0<r<r1; and

[0021] Calculate the axial magnetic field distribution of the focusing system.

[0022] Preferably, the direct magnetic circuit permeability P 1j The calculation formula is:

[0023]

[0024] Where μ is the magnetic permeability of the pole shoe material, S is the cross-sectional area of ​​the magnetic circuit, and D j is the magnetic circuit length;

[0025] The gap magnetic circuit permeability P 2j The calculation formula is:

[0026]

[0027] Among them, r is the radial coordinate of the magnetic circuit, and d is the pole shoe gap length of the magnetic circuit.

[0028] Preferably, the magnetic group R j The calculation formula is:

[0029]

[0030] Among them, P0 is the leakage magnetic constant.

[0031] According to one aspect of the present invention, there is provided a computer device, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, it implements a method for analyzing the axial magnetic field of a focusing system, or an analysis model constructed using the method described above.

[0032] According to one aspect of the present invention, there is provided a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements a method for analyzing the axial magnetic field of a focusing system, or an analysis model constructed using the method described above.

[0033] According to one aspect of the present invention, there is provided a computer program product, comprising a computer program, which, when executed by a processor, implements a method for analyzing the axial magnetic field of a focusing system, or an analysis model constructed using the method described above.

[0034] The beneficial effects of the present invention are as follows:

[0035] In view of the technical problems existing in the prior art, the present invention provides an axial magnetic field analysis method for a traveling wave tube composite periodic focusing system, an axial magnetic field analysis model construction method, equipment, medium and product for a traveling wave tube composite periodic focusing system. The theoretical analysis method of the axial magnetic field of the focusing system is optimized on the basis of an ideal uniform magnetization method, taking into account the complete parameters of the focusing system, and finding that there is a gradual change in magnetic potential caused by non-uniform magnetization at the junction of the second pole shoe head and the gap. When considering the magnetic potential at r=r1 of the focusing structure, by considering the non-zero magnetic potential difference at the gap between the first pole shoe head and the second pole shoe head in the overall magnetic circuit of the focusing structure and the direct magnetic circuit permeance and indirect magnetic circuit permeance at various locations, the magnetic field intensity H at the first pole shoe head and the second pole shoe head is obtained. j , thus the magnetic potential difference of the second pole shoe head section of the ideal uniform magnetization method r = r1 is corrected from 0 to H j D1. Based on this, the axial magnetic field distribution at 0<r<r1 can be re-derived to obtain more accurate theoretical data, which is closer to the actual situation, to meet the needs of magnetic field theoretical analysis and engineering practice design, improve the theoretical calculation accuracy of the axial magnetic field, improve the design efficiency of the focusing system and the harmonic analysis ability, and also provide theoretical guidance for the optimization of the axial magnetic field distribution of the focusing system, and provide inspiration for the optimization of high-order harmonics and low-order harmonics. The setting of the second pole shoe in the focusing system helps to reduce the inhomogeneity of the magnetic field, make the magnetic field distribution more uniform, optimize the motion trajectory of the charged particle beam in the magnetic field, and improve the focusing accuracy and efficiency.

[0036] The method for constructing an axial magnetic field analysis model of a traveling wave tube compound periodic focusing system of the present invention can significantly reduce the amount of calculation and calculation time of the simulation process while improving the theoretical calculation accuracy of the magnetic field, thereby optimizing the design process of the compound periodic focusing system and providing a design method that meets the design needs of engineering practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0038] Figure 1 A cross-sectional view showing a complete cycle of the focusing system provided by an embodiment of the present invention.

[0039] Figure 2 A schematic diagram showing half a cycle of a focusing system provided by an embodiment of the present invention.

[0040] Figure 3 A cross-sectional schematic diagram of half a period of the focusing system provided by an embodiment of the present invention is shown.

[0041] Figure 4 The corresponding diagrams of the cross-sectional structure of the focusing system and the magnetic potential distribution diagram provided by the embodiment of the present invention are shown.

[0042] Figure 5 A comparison diagram of the magnetic potential distribution at r=r1 of the comparative example, the embodiment and the reference example is shown.

[0043] Figure 6 A comparison diagram of the magnetic potential distribution at r=0 of the comparative example, the embodiment and the reference example is shown.

[0044] Figure 7 A comparison diagram of the axial magnetic field distribution of the comparative example and the reference example is shown.

[0045] Figure 8 A comparison diagram of axial magnetic field distribution of the embodiment and the reference example is shown. DETAILED DESCRIPTION

[0046] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0047] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or connected through an intermediate medium gap, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] In the present invention, unless otherwise clearly stipulated and limited, a first feature being “on” or “under” a second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through another feature between them.

[0049] In the description of this embodiment, the terms "upper", "lower", "left", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0050] In view of the defects of the prior art, an axial magnetic field analysis method for a traveling wave tube composite periodic focusing system is provided. The composite periodic focusing system comprises a first pole shoe arranged along the axial direction of the focusing system and a magnetic steel between the first pole shoes, and a plurality of second pole shoes arranged between the first pole shoes. A non-zero magnetic potential difference exists at the gap between the first pole shoe head and the second pole shoe head. The analysis method comprises:

[0051] Determining the direct magnetic path permeability and the gap magnetic path permeability of each magnetic path between adjacent pole shoes;

[0052] Determine the magnetic resistance of each magnetic circuit in the composite periodic focusing system according to the direct magnetic circuit permeability and the gap magnetic circuit permeability of each magnetic circuit;

[0053] Determine the magnetic potential distribution function of the focusing system at a radial position r=r1 according to the magnetic resistance of each magnetic circuit, where r1 is the inner diameter of the first pole shoe and the second pole shoe;

[0054] Determine the radial magnetic potential distribution of the focusing system using the magnetic potential distribution function of the focusing system at a radial position r=r1 as a boundary condition, 0<r<r1; and

[0055] Calculate the axial magnetic field distribution of the compound periodic focusing system.

[0056] An embodiment of the present invention provides a focusing system, combined with Figure 1-4 As shown, the focusing system includes a magnetic group, which includes a magnetic steel 10 and a first pole shoe 20 arranged and fixed along the axial direction of the focusing system, and a plurality of second pole shoes 30 arranged on the inner side of the magnetic steel 10, and the magnetic steel 10 and the first pole shoe 20 are coaxially arranged.

[0057] The second pole shoe 30 is annular and disposed between two adjacent first pole shoes 20 . In this embodiment, three second pole shoes 30 are disposed between two adjacent first pole shoes 20 , and the distance between each pole shoe 20 , 30 and the adjacent pole shoe is equal.

[0058] In a specific embodiment, the outer peripheral surface of the second pole shoe 30 is fixed to the inner wall of the magnetic steel 10 , and the second pole shoe 30 is coaxially arranged with the magnetic steel 10 and the first pole shoe 20 .

[0059] The first pole shoe 20 includes a first pole shoe head 201 located in the magnetic focusing cavity, and a first pole shoe body 202 that is fixedly attached to the end surface of the magnetic steel 10 .

[0060] The second pole shoe 30 includes a second pole shoe head 301 located in the magnetic focusing cavity, and a second pole shoe body 302 located between the inner wall surface of the magnetic steel 10 and the second pole shoe head 301 .

[0061] In this embodiment, the inner end surface of the first pole shoe 20 and the inner end surface of the second pole shoe 30 in the magnetic focusing cavity are 1 / 40 mm apart from the axis of the magnetic focusing system (i.e. Figure 2 The distances between the two axes are equal.

[0062] In one embodiment, the focusing system includes a plurality of magnetic groups arranged along the axial direction of the focusing system, and the magnetic steels 10 and the first pole shoes 20 are arranged alternately.

[0063] In a specific embodiment, Figure 1 As shown, the magnetizing directions of the magnetic steels 10 in two adjacent magnetic groups are opposite.

[0064] The axial magnetic field of the focusing system relies on the Lorentz force to provide a restoring force to the electron beam therein, that is, when the electron beam moves along the axis of the focusing system, the velocity direction is consistent with the magnetic field direction, and the electrons are not subjected to force. When the electrons diffuse outward, their radial velocity component and the axial magnetic field generate a Lorentz force, which deflects the radial velocity of the electrons and stops them from moving outward, optimizing the motion trajectory of the charged particle beam in the magnetic field and improving the focusing accuracy and efficiency. In this process, the size of the magnetic field directly affects the restoring force on the electron beam. If it is too large or too small, the electron beam may not be transmitted stably. Therefore, when designing the focusing system, it is necessary to finely control the distribution of the magnetic field to ensure the stable transmission of the electron beam.

[0065] When calculating the axial magnetic field of the focusing system, the uniform magnetization method will establish an idealized model and make idealized assumptions, specifically: (1) It is assumed that the magnetic steel 10 and the first pole shoe body 202 have no effect on the harmonic distribution of the axial magnetic field; (2) It is assumed that the second pole shoe 30 and the first pole shoe 20 have the same thickness and the structure is infinitely extended in the axial direction of the focusing system; (3) It is assumed that the magnetic steel 10, the first pole shoe 20 and the second pole shoe 30 are linear materials, and the magnetic permeability of the first pole shoe 20 and the second pole shoe 30 is infinite, that is, the magnetic potential does not change at the first pole shoe 20 and the second pole shoe 30. Since this method introduces a large number of idealized assumptions and ignores the influence of some parameters on the axial magnetic field distribution, there is a large error, and the obtained theoretical value provides limited reference value for the design of the focusing magnetic field.

[0066] Another embodiment of the present invention provides a method for constructing an analytical model of an axial magnetic field of a traveling wave tube composite periodic focusing system, specifically comprising the following steps:

[0067] S1, such as Figure 3As shown, the structural parameters of the focusing system are set, for example, the number of second pole shoes is N, the length of one cycle of the magnetic field is L, the axial length of the first pole shoe head 201 is L2, the axial length of the second pole shoe head 301 is L1, the gap length between the pole shoe heads is d1, the distance between the inner surface of the pole shoe heads of the first pole shoe 20 and the second pole shoe 30 close to the central axis and the central axis of the focusing system (i.e., the inner diameter of the pole shoe) is r1, the magnetic potential difference at the gap between the first pole shoe head 201 and the second pole shoe head 301 is F0, the length of the magnetic steel 10 along the axial direction is d2, the axial length of the first pole shoe body 202 is d3, the distance between the side surface of the first pole shoe head 201 and the second pole shoe head 301 away from the central axis and the central axis (i.e., the outer diameter of the pole shoe head) is r2, the inner diameter of the magnetic steel 10 and the outer diameter of the second pole shoe body 302 are r3, the outer diameter of the first pole shoe body 202 (i.e., the outer diameter of the first pole shoe) is r4, and the outer diameter of the magnetic steel 10 is r5. ;

[0068] S2, calculate the direct magnetic permeability P of each pole shoe to its adjacent pole shoe 1j and gap magnetic circuit permeability P 2j , j = 1, ..., N + 1, where N is the number of second pole pieces;

[0069] S3, according to the obtained direct magnetic circuit permeability P 1j and gap magnetic circuit permeability P 2j Calculate the magnetic resistance R of each part of the focusing system j ;

[0070] S4, according to the obtained magnetic resistance R j Obtain the magnetic potential distribution function of the focusing system at r = r1, where r is the radial distance of the magnetic circuit from the central axis, also called the radial coordinate;

[0071] S5, using the magnetic potential distribution function of the focusing system at r=r1 as a boundary condition to obtain the magnetic potential distribution in the region 0<r<r1, and then obtain the axial magnetic field distribution in this range.

[0072] In this embodiment, r represents the radial coordinate, and r=0 is the central axis of the focusing system. The magnetic potential distribution function is the magnetic potential distribution at r=r1 (i.e., the inner surface of the pole shoe head of the first pole shoe 20 and the second pole shoe 30), which can be used as the boundary condition of the magnetic field at the axis to obtain the axial magnetic field distribution.

[0073] like Figure 3 and Figure 4 As shown, it is a schematic diagram of the structure and magnetic circuit of a schematic half-period structure of a compound periodic focusing system and a magnetic potential distribution diagram of a periodic structure, and three second pole shoes 30 are arranged between the first pole shoes 20, j=1, 2, 3, 4.

[0074] In a specific embodiment, the direct magnetic path permeability P in step S21j The calculation formula is:

[0075]

[0076] Where μ is the magnetic permeability of the pole shoe material, S is the cross-sectional area of ​​the magnetic circuit, and D j is the magnetic path length.

[0077] For this embodiment, three second pole shoes 30 are arranged between two first pole shoes 20, and the distance d1 between a first pole shoe 20 and an adjacent second pole shoe 30 is equal to the distance between two adjacent second pole shoes 30. The direct magnetic path permeance P of each part of the focusing system in half a cycle is calculated respectively. 1j , calculated as follows:

[0078]

[0079]

[0080]

[0081]

[0082] In a specific embodiment, the gap magnetic circuit permeability P in step S2 2j The calculation formula is:

[0083]

[0084] Among them, r is the radius of the cross-sectional area of ​​the magnetic circuit, and d is the required gap length of the magnetic circuit between the two pole shoes.

[0085] For this embodiment, the gap magnetic circuit permeance of each part of the focusing system within half a cycle is calculated respectively, and the calculation is as follows:

[0086]

[0087]

[0088]

[0089]

[0090] In a specific embodiment, the magnetic resistance R in step S4 j The calculation formula is:

[0091]

[0092] Among them, P0 is the leakage magnetic constant.

[0093] For this embodiment, the leakage magnetic constant P0=P2+P3, and the magnetic resistance corresponding to each part of the focusing system in half a cycle is calculated as follows:

[0094]

[0095]

[0096]

[0097]

[0098] In a specific embodiment, the calculation of the distribution function of the magnetic potential at r=r1 is similar to Kirchhoff's law of circuits, and the magnetic steel 10 is regarded as a battery, the gap between the pole shoes is regarded as a resistor, and the pole shoes are regarded as wires. According to the first magnetic circuit equation:

[0099]

[0100] where φ j Represents the magnetic flux in each part of the magnetic circuit. And

[0101] The second equation of magnetic circuit:

[0102]

[0103] Among them, H j is the magnetic field strength of each part of the focusing system. Let the magnetic potential difference of each part of the magnetic circuit be F0 = H j D j , from which we can conclude that the magnetic potential distribution function is F = Φ j R j , substituting the data of each part, we can get the magnetic potential distribution at r = r1 in a complete cycle as follows Figure 4 As shown in the figure, the ordinate is the magnetic potential and the abscissa is the axial position. The four steeper places (a, b, m, n) in the half cycle correspond to the structural gaps, the three flatter places (e, f, g) correspond to the second pole shoe 30, the flat place where the maximum and minimum values ​​are located is the first pole shoe 20, and the slope of the broken line is the magnetic field intensity at that place.

[0104] The method for constructing an axial magnetic field analysis model of a traveling wave tube composite period focusing system of the present invention can conveniently change the structural parameters of the focusing system, such as the number of second pole shoes, the structural parameters of the pole shoes, etc., during the design process of the focusing system with a composite period, so as to quickly obtain the analysis results of the axial magnetic field. While improving the theoretical calculation accuracy of the magnetic field, it can significantly reduce the amount of calculation in the simulation process, reduce the calculation time, optimize the design process of the composite period focusing system, and provide a design method that meets the design needs of engineering practice.

[0105] The advantages of the theoretical analysis method of the axial magnetic field of the focusing system provided by the embodiment of the present invention are described with reference to examples:

[0106] The structural parameters are set to the length of one cycle of the magnetic field L = 20mm, the inner diameter of the pole shoe r1 = 1mm, the outer diameter of the pole shoe head r2 = 1.8mm, the inner diameter of the magnet r3 = 2mm, the outer diameter of the first pole shoe r4 = 12mm, the outer diameter of the magnet r5 = 15mm, the axial length of the magnet d2 = 8mm, the axial length of the first pole shoe body d3 = 2mm, the axial length of the second pole shoe head L1 = 1.2mm, and the axial length of the first pole shoe head L2 = 1.3mm.

[0107] Reference example

[0108] A four-period compound periodic focusing structure model (also called numerical simulation) was established using the three-dimensional electromagnetic software CST, and the magnetic potential at r=r1 and the axial magnetic field flux density distribution at r=0 were calculated.

[0109] Comparative Example

[0110] The uniform magnetization method (also called ideal model) is used to analyze the magnetic potential at r=r1 and the axial magnetic field flux density distribution at r=0 of the focusing system.

[0111] Example

[0112] The theoretical model (also called the modified model) of the axial magnetic field of the focusing system provided in the embodiment of the present invention is used to analyze the magnetic potential at r=r1 of the focusing system and the distribution of the axial magnetic field flux density at r=0.

[0113] Comparing the calculation results of the reference example, comparative example and embodiment, the magnetic potential at r=r1 is shown in the attached figure. Figure 5 As shown, the magnetic potential at r = 0 is as shown in the attached Figure 6 As shown, the calculation result of the uniform magnetization method and the simulation result of the reference example are well matched near the center of the pole shoe or the center of the gap, but there is a certain distortion at the junction of the pole shoe and the gap. The embodiment of the present invention takes into account the uneven magnetization of the second pole shoe head 301 near the edge during the calculation process, so the calculation result and the simulation structure of the reference example have a reduced proportional error compared to the pole shoe and the gap.

[0114] The axial magnetic field distribution diagram obtained by proportional analysis is shown in Figure 7 As shown, the axial magnetic field distribution diagram obtained by analysis of the embodiment is as follows Figure 8 As shown, compared Figure 7 and Figure 8It can be seen that the calculation errors of the embodiment at each peak value of the magnetic field are relatively small. At the same time, both the peak value and the fluctuation amplitude at the small periodic fluctuation of the magnetic field are better than those of the control example. The theoretical analysis method of the axial magnetic field of the focusing system provided by the embodiment of the present invention is not only more operational in multi-parameter analysis, but also greatly improves the accuracy of magnetic field calculation.

[0115] Reference Figure 7 and Figure 8 It can be seen that the calculation error of the comparative example mainly occurs at the peak of the magnetic field, which is also the key area affecting the focusing stability of the electron beam. Compared with the comparative example, the error at the peak of the embodiment of the present invention is reduced from 8.08% to 3.91%, and the average error of the complete cycle is reduced from 1.30% to 1.04%, which is of great significance to the design of the composite periodic magnetic field structure and the optimization of high-order harmonics, as well as the subsequent calculation of the stability of the electron beam.

[0116] One embodiment of the present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the theoretical analysis method of the axial magnetic field of the focusing system when executing the program.

[0117] One embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the theoretical analysis method of the axial magnetic field of the focusing system described above.

[0118] One embodiment of the present invention provides a computer program product, including a computer program, which, when executed by a processor, implements the theoretical analysis method of the axial magnetic field of the focusing system.

[0119] The theoretical analysis method of the axial magnetic field of the focusing system provided in the embodiment of the present invention is optimized on the basis of the ideal uniform magnetization method, taking into account the complete parameters of the focusing system, and finding that there is a gradual change in magnetic potential caused by non-uniform magnetization at the junction of the second pole shoe head and the gap. When calculating the magnetic potential at r=r1 of the focusing structure, the magnetic field intensity H at the first pole shoe head and the second pole shoe head is obtained by calculating the overall magnetic circuit of the focusing structure and the magnetic permeance at various locations. j , thus the magnetic potential difference of the second pole shoe head 301 section of the magnetic potential distribution at r = r1 in the ideal uniform magnetization method is corrected from 0 to H jD1. Based on this, the axial magnetic field distribution at 0<r<r1 can be re-derived to obtain more accurate theoretical data, which is closer to the actual situation, to meet the needs of magnetic field theoretical analysis and engineering practice design, improve the theoretical calculation accuracy of the axial magnetic field, improve the design efficiency of the focusing system and the harmonic analysis ability, and also provide theoretical guidance for the optimization of the axial magnetic field distribution of the focusing system, and provide inspiration for the optimization of high-order harmonics and low-order harmonics. The setting of the second pole shoe in the focusing system helps to reduce the inhomogeneity of the magnetic field, make the magnetic field distribution more uniform, optimize the motion trajectory of the charged particle beam in the magnetic field, and improve the focusing accuracy and efficiency.

[0120] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A method for analyzing the axial magnetic field of a traveling wave tube composite periodic focusing system, characterized in that: The composite periodic focusing system comprises a first pole shoe arranged along the axial direction of the focusing system, a magnetic steel between the first pole shoes, and a plurality of second pole shoes arranged between the first pole shoes, and a non-zero magnetic potential difference exists at the gap between the first pole shoe head and the second pole shoe head; The analysis method comprises: Determining the direct magnetic path permeability and the gap magnetic path permeability of each magnetic path between adjacent pole shoes; Determine the magnetic resistance of each magnetic circuit in the composite periodic focusing system according to the direct magnetic circuit permeability and the gap magnetic circuit permeability of each magnetic circuit; Determine the magnetic potential distribution function of the focusing system at a radial position r=r1 according to the magnetic resistance of each magnetic circuit, where r1 is the inner diameter of the first pole shoe and the second pole shoe; Determine the radial magnetic potential distribution of the focusing system using the magnetic potential distribution function of the focusing system at a radial position r=r1 as a boundary condition, 0<r<r1; and Calculate the axial magnetic field distribution of the compound periodic focusing system.

2. The axial magnetic field analysis method according to claim 1, characterized in that: The focusing system includes a plurality of first pole shoes arranged along the axial direction of the focusing system, magnetic steels arranged between adjacent first pole shoes, and a plurality of second pole shoes.

3. The axial magnetic field analysis method according to claim 1, characterized in that: The magnetization directions of the adjacent magnetic steels through the first pole shoe are opposite.

4. The axial magnetic field analysis method according to claim 2, characterized in that: The number of the second pole shoes between the first pole shoes is the same, and the second pole shoes are arranged at equal intervals between the first pole shoes.

5. A method for constructing an axial magnetic field analysis model for a traveling wave tube composite periodic focusing system, characterized in that: The composite periodic focusing system comprises a first pole shoe arranged along the axial direction of the focusing system and a magnetic steel between the first pole shoes, and a plurality of second pole shoes arranged between the first pole shoes, wherein the first pole shoe comprises a first pole shoe body and a first pole shoe head, and the second pole shoe comprises a second pole shoe body and a second pole shoe head, and the method comprises: The structural parameters of the traveling wave tube composite periodic focusing system are set, including the number of second pole shoes N, the magnetic field period L, the axial length of the first pole shoe head L2, the axial length of the second pole shoe head L1, the gap length between the pole shoe heads d1, the pole shoe inner diameters of the first pole shoe and the second pole shoe r1, and a non-zero magnetic potential difference at the gap between the first pole shoe head and the second pole shoe head; Determine the direct magnetic permeability P of each magnetic path between the pole shoes 1j and gap magnetic circuit permeability P 2j , j = 1, ..., N + 1, where N is the number of second pole pieces; According to the direct magnetic path permeability P 1j and gap magnetic circuit permeability P 2j Determine the magnetic resistance R of each magnetic circuit in the compound periodic focusing system j ; According to the magnetic resistance R of each magnetic circuit j Determine the magnetic potential distribution function at the radial coordinate r=r1 of the compound periodic focusing system; Calculating the radial magnetic potential distribution of the focusing system using the magnetic potential distribution function of the focusing system at position r=r1 as the boundary condition, 0<r<r1; and Calculate the axial magnetic field distribution of the focusing system.

6. The method for constructing an axial magnetic field analysis model according to claim 5, characterized in that: The direct magnetic path permeance P 1j The calculation formula is: Where μ is the magnetic permeability of the pole shoe material, S is the cross-sectional area of ​​the magnetic circuit, and D j is the magnetic circuit length; The gap magnetic circuit permeability P 2j The calculation formula is: Among them, r is the radial coordinate of the magnetic circuit, and d is the pole shoe gap length of the magnetic circuit.

7. The method for constructing an axial magnetic field analysis model according to claim 5, characterized in that: The magnetic group R j The calculation formula is: Among them, P0 is the leakage magnetic constant.

8. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the method according to any one of claims 1 to 4 is implemented, or an analysis model constructed using the method according to any one of claims 5 to 7 is implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, it implements the method according to any one of claims 1 to 4, or uses the analysis model constructed according to any one of claims 5 to 7.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the method described in any one of claims 1 to 4 is implemented, or the analysis model constructed using the method described in any one of claims 5 to 7 is implemented.

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