A PPM structure inverse analysis method and device based on equivalent current source model

Abstract

The present invention discloses a PPM structure inverse analysis method and device based on an equivalent current source model, the method comprising: obtaining electron beam parameters, calculating basic parameters of the PPM structure according to the electron beam parameters; initializing the PPM structure, initializing the structural parameters of the PPM structure according to the basic parameters of the PPM structure, and obtaining the PPM initial structure; determining the maximum magnetic field of the pole shoe material according to the pole shoe material according to the pole shoe of the PPM initial structure; according to the PPM initial structure and the maximum magnetic field of the pole shoe material, using a finite length PPM fast calculation method considering the influence of the pole shoe to inversely analyze the PPM initial structure, and obtaining a PPM final structure that meets the requirements. The present invention has very fast calculation, no need to use electromagnetic simulation software for forward design, no need for a large number of simulation calculations, thus saving a lot of time costs, and also reducing a lot of manual operations.

Description

Technical Field

[0001] The present invention relates to the technical field of periodic permanent magnet focusing system PPM, and in particular to a PPM structure inverse analysis method and device based on an equivalent current source model. Background Art

[0002] The advantages of PPM (periodic permanent magnet focusing system) are its small size and light weight. Its volume and mass are only 1 / 5 or even smaller than those of uniform permanent magnet system or spiral tube focusing system. In addition, PPM does not consume power. The PPM structure saves more power and can easily realize a packaged structure, so it has been widely used.

[0003] In the terahertz frequency band, due to the high frequency, the critical dimensions in the structure of the electron optical system are very small, and the electron transmission channel is narrow. The electron gun in the high-frequency device usually requires high current density and large area compression ratio. Therefore, in order to obtain an electron beam with small pulsation and good laminar flow, the design requirements for the magnetic focusing system are also more stringent. In addition, traditional PPM structure analysis and optimization are mostly directly modeled and optimized through simulation software such as CST, and the PPM structure that meets the index requirements is forward analyzed. However, there are many structural parameters and design indicators that need to be adjusted and optimized, and it takes a long time. Therefore, the analysis and simulation calculation of the PPM structure consumes a lot of time and energy, which brings great troubles to the simulation design of the electron optical system and seriously hinders the development of the electron optical system. Summary of the invention

[0004] The technical problem to be solved by the present invention is that the forward analysis process of the PPM structure of the prior art electronic optical system is too lengthy, thus wasting a lot of time and cost. The purpose of the present invention is to provide a PPM structure inverse analysis method and device based on an equivalent current source model to solve the problem that the forward analysis process of the PPM structure of the electronic optical system is too lengthy, thus wasting a lot of time and cost, which will effectively promote the development of the electronic optical system.

[0005] The present invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a PPM structure inverse analysis method based on an equivalent current source model, the method comprising:

[0007] Acquire electron beam parameters, and calculate basic parameters of a PPM structure that enables small electron beam fluctuation and good laminar flow according to the electron beam parameters;

[0008] Initializing the PPM structure, initializing the structural parameters of the PPM structure according to the basic parameters of the PPM structure to obtain the PPM initial structure;

[0009] According to the pole shoes of the initial structure of the PPM, the maximum magnetic field of the pole shoe material is determined by the pole shoe material;

[0010] According to the PPM initial structure and the maximum magnetic field of the pole shoe material, a finite length PPM fast calculation method considering the influence of the pole shoe is used to perform an inverse analysis on the PPM initial structure to obtain a PPM final structure that meets the requirements.

[0011] The present invention involves three objects, namely, a high-frequency structure, a PPM structure and an electron beam. The electron beam passes through the high-frequency structure. However, when the electron beam passes through the high-frequency structure, it often causes the electron beam to diverge. Therefore, a PPM structure is arranged outside the high-frequency structure to limit the fluctuation of the electron beam within a certain range.

[0012] The invention discloses a PPM structure inverse analysis method based on an equivalent current source model. It only takes a very short time (about 2 minutes) to write a program to calculate the final PPM structure that meets the design requirements. There is no need to use electromagnetic simulation software for forward design, and no longer requires a large amount of simulation calculations. Therefore, a large amount of time cost is saved, and a large amount of manual operations are also reduced, which greatly promotes the development of the design of electronic optical systems of electric vacuum devices.

[0013] Furthermore, the basic parameters of the PPM structure include a uniform magnetic field peak value B0, a range of a single cycle length of the PPM structure, and a number of cycles N.

[0014] Furthermore, the number of periods N is obtained by the length of the high-frequency structure.

[0015] Furthermore, the calculation expression of the uniform magnetic field peak value B0 is:

[0016] B0=δB 0b

[0017]

[0018]

[0019] In the formula, δ is the coefficient of the traveling wave tube. For a traveling wave tube operating in low-power continuous wave mode, δ is 1.4 to 1.6; for a traveling wave tube operating in medium or high power or pulse mode, δ is 1.6 to 1.8; B 0b is the ideal magnetic field value; B b is the Brillouin magnetic field; I is the current of the electron beam emitted from the electron gun area, V is the voltage of the electron beam emitted from the electron gun area, r b is the electron beam radius;

[0020] The calculation expression of the range of the single cycle length of the PPM structure is:

[0021]

[0022] Where L is the length of a single cycle of the PPM structure.

[0023] Furthermore, the structural parameters of the PPM structure include lateral parameters, axial parameters and residual magnetism; the lateral parameters include the inner radius r of the pole shoe head f1 , Pole shoe outer radius r f2 , pole shoe height r3, magnetic ring inner radius r m1 and the outer radius r of the magnetic ring m2 The axial parameters include the magnetic ring thickness T, the pole shoe thickness t p , pole shoe gap g;

[0024] The inner radius r of the pole shoe head f1 is determined by the high-frequency structure; the outer radius r of the pole shoe head f2 , pole shoe height r3, magnetic ring inner radius r m1 and the outer radius r of the magnetic ring m2 The inner radius r of the pole shoe head f1 To determine; the magnetic ring thickness T, the pole shoe thickness t p are determined according to the period L; the pole shoe gap g is equal to the pole shoe gap value when the intermediate magnetic field peak value B-peak reaches the maximum value; the residual magnetic field B r It is a preset given.

[0025] Furthermore, the specific steps of the finite length PPM fast calculation method considering the influence of the pole shoe for inverse analysis of the PPM initial structure are:

[0026] Step A, calculate the maximum magnetic field of the PPM structure, and compare the maximum magnetic field of the PPM structure with the maximum magnetic field of the pole shoe material: if the maximum magnetic field of the PPM structure is less than or equal to a preset coefficient multiplied by the maximum magnetic field of the pole shoe material, execute step B; if the maximum magnetic field of the PPM structure is greater than the preset coefficient multiplied by the maximum magnetic field of the pole shoe material, correct it by reducing the maximum magnetic field of the PPM structure; wherein the preset coefficient is 0.6 to 0.8, for example, it can be 0.7.

[0027] Step B, calculate the equivalent magnetic ring inner diameter r' through an iterative algorithm m1 , so that the intermediate magnetic field peaks obtained by the infinite length PPM fast calculation method considering the influence of the pole shoe and the finite length PPM fast calculation method without considering the influence of the pole shoe are equal; and the equivalent magnetic ring inner diameter r′ m1 Substituting it into the finite length PPM fast calculation method without considering the influence of the pole shoe, the finite length PPM fast calculation method considering the influence of the pole shoe is obtained, that is, the finite length PPM equivalent current source model considering the influence of the pole shoe;

[0028] Step C, using the finite length PPM equivalent current source model considering the influence of the pole shoe to calculate the peak values ​​of the magnetic field P1, P2, ..., P of the current PPM structure i ,…,P N ;

[0029] Step D, calculate the difference ΔP i =P i -D i , D i is the expected magnetic field peak value; P i The peak values ​​of the magnetic fields of the current PPM structure are calculated; the difference is judged against the preset allowable error value: if the maximum absolute value of the difference is less than or equal to the preset allowable error value, the current PPM structure is output as the final PPM structure; if the maximum absolute value of the difference is greater than the preset allowable error value, the difference is compared with the zero value, and corresponding corrections are made, and the calculation is returned to step A for recalculation.

[0030] Furthermore, the calculation expression of the maximum magnetic field of the PPM initial structure is:

[0031]

[0032] P t =P1+P2+P3

[0033] F t =B d ·A

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042] In the formula, B max is the maximum magnetic field of the initial structure of PPM; F t is the total magnetic flux that the magnetic block can generate; P1 is the first magnetic flux path; P2 is the second magnetic flux path; P3 is the third magnetic flux path; P t is the magnetic flux path and; rf1 is the inner diameter of the pole shoe head; r f2 B is the outer diameter of the pole shoe head; d is the ordinate of the intersection of the loading line and the demagnetization curve; μ is the magnetic permeability; A is the cross-sectional area of ​​the magnetic ring; k is the slope of the demagnetization curve; f2(2nr f1 / L) is the first intermediate variable function; f3(2nr3 / L) is the second intermediate variable function; I0 is the zero-order modified Bessel function of the first kind; I1 is the order first-kind modified Bessel function; K0 is the zero-order modified Bessel function of the second kind; K1 is the order second-kind modified Bessel function.

[0043] Furthermore, if the maximum value of the absolute value of the difference is greater than the preset allowable error value, the difference is compared with the zero value and a corresponding correction is performed; specifically including:

[0044] If the difference ΔP i >0, the corresponding magnetic field peak is reduced, thereby reducing the magnetic field; specifically, by increasing g to reduce the magnetic field peak, the pole shoe gap g is corrected: [g i ] n+1 =1.1·[g i ] n ;

[0045] If the difference ΔP i <0, the corresponding magnetic field peak value is increased, thereby increasing the magnetic field; specifically, by increasing Br, the magnetic field peak value is increased [B ri ] n+1 =1.1·[B ri ] n .

[0046] Furthermore, the method further comprises: optimizing the PPM final structure by increasing or decreasing the magnetic field, by fine-tuning the inner and outer radius r of the magnetic ring. m1 ,r m2 And the outer diameter of the pole shoe r f2 Perform stabbing to increase or decrease the magnetic field; m1 Decrease, r m2 Increase, r f2 Reducing r can increase the magnetic field; m1 Increase, r m2 Decrease, r f2 Increasing can reduce the magnetic field.

[0047] In a second aspect, the present invention further provides a PPM structure inverse analysis device based on an equivalent current source model, the device supports the PPM structure inverse analysis method based on an equivalent current source model, and the device comprises:

[0048] An acquisition unit, used for acquiring electron beam parameters;

[0049] A basic parameter calculation unit of the PPM structure, used for calculating the basic parameters of the PPM structure according to the electron injection parameters;

[0050] A PPM initial structure initialization unit, used to initialize the PPM structure, and initialize the structural parameters of the PPM structure according to the basic parameters of the PPM structure to obtain the PPM initial structure;

[0051] A maximum magnetic field determination unit for a pole shoe material, used to determine the maximum magnetic field of the pole shoe material from the pole shoe material according to the pole shoe of the initial structure of the PPM;

[0052] An inverse analysis calculation unit, configured to perform an inverse analysis on the PPM initial structure according to the PPM initial structure and the maximum magnetic field of the pole shoe material by using a finite length PPM fast calculation method considering the influence of the pole shoe, so as to obtain a PPM final structure that meets the requirements;

[0053] An output unit is used to output the final structure of the PPM.

[0054] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0055] 1. The present invention determines the PPM structure by combining the joint adjustment of the electron optical system, while the existing PPM structure is designed and then joint adjusted with the electron beam.

[0056] 2. The present invention obtains an equivalent inner diameter r' of the equivalent magnetic ring through an iterative algorithm m1 The existing fast calculation method of finite length PPM without considering the influence of pole shoes is introduced, thus establishing a fast calculation method model of finite length PPM considering the influence of pole shoes.

[0057] 3. The calculation of the present invention is very fast and takes only a few minutes. Traditional PPM design takes several days or even weeks or months, which is too long because the simulation calculation is particularly time-consuming. The present invention only needs a very short time (about 2 minutes) to write a program to calculate the final PPM structure that meets the design requirements. There is no need to use electromagnetic simulation software for forward design, and no longer requires a large amount of simulation calculations. Therefore, a large amount of time cost is saved, and a large amount of manual operation is also reduced, which greatly promotes the development of the design of electronic optical systems of electric vacuum devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0059] Figure 1 The present invention is a flow chart of a PPM structure inverse analysis method based on an equivalent current source model.

[0060] Figure 2 It is a schematic diagram of the initial structure of the PPM of the present invention.

[0061] Figure 3 This is a graph showing the change of the intermediate magnetic field peak value B-peak calculated by the present invention with respect to the pole shoe gap g.

[0062] Figure 4 It is the BH curve diagram of the pole shoe material of the present invention.

[0063] Figure 5 The maximum magnetic field B calculated by the present invention is max Graph showing the variation of pole shoe height r3.

[0064] Figure 6 Schematic diagram of the finite-length PPM equivalent current source model without considering the influence of the pole shoe.

[0065] Figure 7 This is a schematic diagram of the structure of an infinite length PPM equivalent current source model considering the influence of pole shoes of the present invention, which is equivalent to a finite length PPM equivalent current source model considering the influence of pole shoes.

[0066] Figure 8 This is the axial magnetic field distribution diagram of the PPM structure obtained by inverse analysis of the present invention.

[0067] Fig. 9 The intermediate magnetic field peak value B-peak calculated by the present invention is related to the inner diameter r of the magnetic ring. m1 's change graph.

[0068] Fig.10 The intermediate magnetic field peak value B-peak calculated by the present invention is related to the outer diameter r of the magnetic ring. m2 's change graph.

[0069] Fig.11 The intermediate magnetic field peak value B-peak calculated by the present invention is related to the outer diameter r of the pole shoe head f2 's change graph.

[0070] Fig.12 This is a schematic diagram of the structure of a PPM structure inverse analysis device based on an equivalent current source model according to Example 3 of the present invention.

[0071] Fig.13 This is a schematic diagram of the structure of a PPM structure inverse analysis device based on an equivalent current source model according to Example 4 of the present invention. DETAILED DESCRIPTION

[0072] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0073] Example 1

[0074] like Figure 1 As shown, the present invention provides a PPM structure inverse analysis method based on an equivalent current source model, the method comprising:

[0075] Acquire electron injection parameters, and calculate basic parameters of the PPM structure according to the electron injection parameters;

[0076] Initializing the PPM structure, initializing the structural parameters of the PPM structure according to the basic parameters of the PPM structure to obtain the PPM initial structure;

[0077] According to the pole shoes of the initial structure of the PPM, the maximum magnetic field of the pole shoe material is determined by the pole shoe material;

[0078] According to the PPM initial structure and the maximum magnetic field of the pole shoe material, a finite length PPM fast calculation method considering the influence of the pole shoe is used to perform an inverse analysis on the PPM initial structure to obtain a PPM final structure that meets the requirements.

[0079] The present invention involves three objects, namely, a high-frequency structure, a PPM structure and an electron beam. The electron beam passes through the high-frequency structure. However, when the electron beam passes through the high-frequency structure, it often causes the electron beam to diverge. Therefore, a PPM structure is arranged outside the high-frequency structure to limit the fluctuation of the electron beam within a certain range.

[0080] The specific implementation is as follows:

[0081] Step 1, obtaining electron beam parameters, and calculating basic parameters of the PPM structure according to the electron beam parameters; the basic parameters of the PPM structure include the uniform magnetic field peak value B0, the range of the single cycle length of the PPM structure, and the number of cycles N. Specifically including:

[0082] Obtain the electron beam parameters emitted from the sub-gun area. The electron beam parameters include: the voltage V of the electron beam emitted from the electron gun area, the current I of the electron beam, and the radius r of the electron beam b ;

[0083] According to the electron beam parameters, the Brillouin magnetic field B is calculated. b , the calculation formula is:

[0084]

[0085] According to the Brillouin magnetic field B b , the uniform magnetic field peak value B0 and the range of PPM structure period L that the electron beam can stably transmit are calculated, and the number of periods N is converted from the high-frequency structure length;

[0086]

[0087] B0=δB 0b

[0088] In the formula, δ is the coefficient of the traveling wave tube. For a traveling wave tube operating in low-power continuous wave mode, δ is 1.4 to 1.6; for a traveling wave tube operating in medium or high power or pulse mode, δ is 1.6 to 1.8; B 0b is the ideal magnetic field value; B b is the Brillouin magnetic field; I is the current of the electron beam emitted from the electron gun area, V is the voltage of the electron beam emitted from the electron gun area, r b is the electron beam radius;

[0089] The calculation expression of the range of the single cycle length of the PPM structure is:

[0090]

[0091] Where L is the length of a single cycle of the PPM structure.

[0092] Take the length of a single cycle of the PPM structure L as a typical value within the range, such as Then, the transition zone magnetic field is set to 60% of the uniform magnetic field peak value, and the initial magnetic field distribution can be obtained. The electron beam parameters are substituted into it for joint adjustment to determine the electron beam fluctuation. If This indicates that the fluctuation is small. Otherwise, adjust the transition magnetic field size, period L, and the relative position of the electron beam and the magnetic field until the electron beam fluctuation is small. Until (R max is the maximum radius of the electron beam in the entire action area, that is, the maximum radius of the electron beam during joint modulation; R min is the minimum radius of the electron beam in the entire action area, that is, the minimum radius of the electron beam during joint modulation). At this point, the determined magnetic field distribution can be obtained, that is, the expected magnitudes of the various magnetic field peaks D1, D2, ..., D i , …, D N and period L.

[0093] Step 2, initializing the PPM structure, initializing the structural parameters of the PPM structure according to the basic parameters of the PPM structure to obtain the PPM initial structure; specifically including:

[0094] The initial structure of PPM is as follows Figure 2 As shown, the inner diameter of the pole shoe head is r f1 Determined by the high-frequency structure, the period L is determined, and the outer diameter r of the pole shoe head is given f2 The inner radius of the magnetic ring is r m1 The same is 1.25r f1 , the pole shoe height r3 and the outer diameter of the magnetic ring r m2 Both are 6.5rf1 , magnetic ring thickness Pole shoe thickness The pole shoe gap g = g0, the residual magnetism Br = 1.05T, so far, the initial structure of PPM is determined;

[0095] Among them, the equivalent current source model of the finite length PPM magnetic field fast calculation is used to scan the pole shoe gap g, and the change curve of the intermediate magnetic field peak B-peak with respect to g is calculated, and g0 is the pole shoe gap value when B-peak reaches the maximum value. Figure 3 As shown, Figure 3 The horizontal axis g is the pole shoe gap (unit: mm), the vertical axis B-peak is the peak value of the intermediate magnetic field of the PPM structure (unit: T), and g0 in the figure is the initial value of the pole shoe gap.

[0096] Step 3: According to the pole shoe of the initial structure of PPM, the maximum magnetic field B of the pole shoe material is determined by the BH curve of the pole shoe material. p-max ;like Figure 4 As shown, Figure 4 In the figure, the horizontal axis H is the external magnetic field intensity of the pole shoe material (unit A / m), and the vertical axis B is the magnetic flux density of the pole shoe material (unit T).

[0097] Step 4, according to the PPM initial structure and the maximum magnetic field of the pole shoe material, a finite length PPM fast calculation method considering the influence of the pole shoe is used to perform an inverse analysis on the PPM initial structure to obtain a PPM final structure that meets the requirements. Specifically, it includes:

[0098] Step A, calculate the maximum magnetic field B of the PPM structure using the following formula max ,like Figure 5 As shown, Figure 5 In the figure, the horizontal axis r3 is the pole shoe height (in mm), and the vertical axis B max is the maximum magnetic field that can be generated in the PPM structure (unit T); and the maximum magnetic field of the PPM structure is compared with the maximum magnetic field of the pole shoe material: if the maximum magnetic field of the PPM structure is less than or equal to the preset coefficient multiplied by the maximum magnetic field of the pole shoe material (i.e., B max ≤0.7B p-max ), then execute step B2; if the maximum magnetic field of the PPM structure is greater than the preset coefficient multiplied by the maximum magnetic field of the pole shoe material (i.e., B max >0.7B p-max ), then execute step B1;

[0099] The preset coefficient is 0.6 to 0.8, and is 0.7 in this embodiment.

[0100] The calculation expression of the maximum magnetic field of the PPM initial structure is:

[0101]

[0102] P t =P1+P2+P3

[0103] F t =B d ·A

[0104]

[0105]

[0106]

[0107]

[0108]

[0109]

[0110]

[0111]

[0112] In the formula, B max is the maximum magnetic field of the initial structure of PPM; F t is the total magnetic flux that the magnetic block can generate; P1 is the first magnetic flux path; P2 is the second magnetic flux path; P3 is the third magnetic flux path; P t is the magnetic flux path and; r f1 is the inner diameter of the pole shoe head; r f2 B is the outer diameter of the pole shoe head; d is the ordinate of the intersection of the loading line and the demagnetization curve; μ is the magnetic permeability; A is the cross-sectional area of ​​the magnetic ring; k is the slope of the demagnetization curve; f2(2nr f1 / L) is the first intermediate variable function; f3(2nr3 / L) is the second intermediate variable function; I0 is the zero-order modified Bessel function of the first kind; I1 is the order first-kind modified Bessel function; K0 is the zero-order modified Bessel function of the second kind; K1 is the order second-kind modified Bessel function.

[0113] Step B1, making correction by reducing the maximum magnetic field of the PPM structure; max Too large, the pole shoe height r3 and B max There is a one-to-one correspondence, and as r3 increases, B max Monotonically decreasing, so by increasing the pole shoe height r3 to make B max Decrease, [r3] n+1 =[r3] n +0.5 until B is satisfied max ≤0.7Bp-max until.

[0114] Step B2, calculate the equivalent magnetic ring inner diameter r' through an iterative algorithm m1 , so that the intermediate magnetic field peaks obtained by the infinite length PPM fast calculation method considering the influence of the pole shoe and the finite length PPM fast calculation method without considering the influence of the pole shoe are equal; and the equivalent magnetic ring inner diameter r′ m1 Substituting it into the finite length PPM fast calculation method without considering the influence of the pole shoe, the finite length PPM fast calculation method considering the influence of the pole shoe is obtained, that is, the finite length PPM equivalent current source model considering the influence of the pole shoe;

[0115] in, Figure 6 This is a schematic diagram of the finite length PPM equivalent current source model without considering the influence of the pole shoe. Figure 6 Medium B r is the remanent magnetism of the magnetic ring, and I′ is the equivalent current density. Figure 7 This is a schematic diagram of the structure of an infinite length PPM equivalent current source model considering the influence of pole shoes of the present invention, which is equivalent to a finite length PPM equivalent current source model considering the influence of pole shoes.

[0116] Step C, using the finite length PPM equivalent current source model considering the influence of the pole shoe to calculate the peak values ​​of the magnetic field P1, P2, ..., P of the current PPM structure i ,…,P N ;

[0117] Step D, calculate the difference ΔP i =P i -D i , D i is the expected magnetic field peak value; P i The peak values ​​of the magnetic fields of the current PPM structure are calculated; the difference is judged against the preset allowable error value: if the maximum absolute value of the difference is less than or equal to the preset allowable error value (i.e. max|ΔP i |≤tolerable_error, tolerabl_error is the preset tolerable error value), the current PPM structure is output as the final PPM structure; otherwise, that is, if the maximum absolute value of the difference is greater than the preset tolerable error value, the difference is compared with the zero value, and corresponding corrections are made, and the calculation is returned to step A for recalculation.

[0118] Specifically, if the maximum value of the absolute value of the difference is greater than the preset allowable error value, the difference is compared with the zero value and a corresponding correction is performed; specifically including:

[0119] If the difference ΔP i>0, the corresponding magnetic field peak needs to be reduced. The calculated intermediate magnetic field peak value as a function of the pole shoe gap g shows that after the highest point, as g increases, the magnetic field peak value will decrease. The magnetic field peak value can be reduced by increasing g, and g can be corrected: [g i ] n+1 =1.1·[g i ] n ;

[0120] If the difference ΔP i <0, the corresponding magnetic field peak needs to be increased. There is a one-to-one correspondence between Br and the magnitude of the magnetic field, so increasing Br can increase the magnetic field peak [B ri ] n+1 =1.1·[B ri ] n .

[0121] The fast calculation method of the finite length PPM considering the influence of the pole shoe in the implementation step 4 described in the present invention is to calculate the equivalent magnetic ring inner diameter r' through an iterative algorithm. m1 , so that the intermediate magnetic field peaks obtained by the fast calculation method of infinite length PPM considering the influence of pole shoes and finite length PPM without considering the influence of pole shoes are equal, and the fast calculation method of equivalent current source model of finite length PPM considering the influence of pole shoes can be obtained. Then the calculation of PPM can be carried out with the inner diameter of the magnetic ring as r′ m1 The finite length PPM equivalent current source model without considering the influence of the pole shoe is used for calculation.

[0122] In order to demonstrate the effectiveness of the above method, a calculation example is now used to verify that the electron beam parameters selected are voltage V = 17 kV, current I = 38 mA, and electron beam radius r b =0.04mm, using the PPM structure inverse analysis method based on the equivalent current source model of the present invention, the axial magnetic field distribution of the PPM final structure is obtained as follows Figure 8 As shown, the maximum error does not exceed 3%. Figure 8 The horizontal axis is the axial distance (unit: mm), and the vertical axis is the axial magnetic field intensity in PPM (unit: T).

[0123] Fig. 9 The intermediate magnetic field peak value B-peak calculated by the present invention is related to the inner diameter r of the magnetic ring. m1 The change graph of Fig. 9 The horizontal coordinate r m1 is the inner diameter of the magnetic ring (unit: mm), and the ordinate B-peak is the peak value of the magnetic field in the middle of the PPM structure (unit: T).

[0124] Fig.10 The intermediate magnetic field peak value B-peak calculated by the present invention is related to the outer diameter r of the magnetic ring. m2 The change graph of Fig.10 The horizontal coordinate r m2 is the outer diameter of the magnetic ring (unit: mm), and the ordinate B-peak is the peak value of the magnetic field in the middle of the PPM structure (unit: T).

[0125] Fig.11 The intermediate magnetic field peak value B-peak calculated by the present invention is related to the outer diameter r of the pole shoe head f2 The change graph of Fig.11 The horizontal coordinate r f2 is the outer diameter of the pole shoe head (unit: mm), and the ordinate B-peak is the peak value of the magnetic field in the middle of the PPM structure (unit: T).

[0126] The present invention provides a PPM structure inverse analysis method based on an equivalent current source model. First, the PPM structure is determined by combining the joint adjustment of the electron optical system. The existing PPM structure is designed and then joint adjusted with the electron beam. Second, the present invention obtains an equivalent equivalent magnetic ring inner diameter r' through an iterative algorithm. m1 The existing fast calculation method of finite-length PPM without considering the influence of pole shoes is introduced, so as to establish a model of fast calculation method of finite-length PPM considering the influence of pole shoes. Third, the calculation of the present invention is very fast and takes only a few minutes. The traditional PPM design takes several days or even weeks or months, which is too long because the simulation calculation is particularly time-consuming. The program of the present invention only takes a very short time (about 2 minutes) to calculate the final structure of PPM that meets the design requirements. There is no need for forward design through electromagnetic simulation software, and no longer requires a large amount of simulation calculations. Therefore, a large amount of time cost is saved, and a large amount of manual operation is also reduced, which greatly promotes the development of the design of electronic optical systems of electric vacuum devices.

[0127] Example 2

[0128] like Figures 1 to 11 As shown, the difference between this embodiment and embodiment 1 is that the method further includes: optimizing the PPM final structure by increasing or decreasing the magnetic field, by fine-tuning the inner and outer radii r of the magnetic ring m1 ,r m2 And the outer diameter of the pole shoe r f2 Perform stabbing to increase or decrease the magnetic field; m1 Decrease, r m2 Increase, r f2 Reducing r can increase the magnetic field; m1 Increase, r m2 Decrease, r f2 Increasing can reduce the magnetic field.

[0129] Example 3

[0130] like Fig.12As shown, the difference between this embodiment and embodiment 1 is that this embodiment provides a PPM structure inverse analysis device based on an equivalent current source model, the device supports a PPM structure inverse analysis method based on an equivalent current source model described in embodiment 1, and the device includes:

[0131] An acquisition unit, used for acquiring electron beam parameters;

[0132] A basic parameter calculation unit of the PPM structure, used for calculating the basic parameters of the PPM structure according to the electron injection parameters;

[0133] A PPM initial structure initialization unit, used to initialize the PPM structure, and initialize the structural parameters of the PPM structure according to the basic parameters of the PPM structure to obtain the PPM initial structure;

[0134] A maximum magnetic field determination unit for a pole shoe material, used to determine the maximum magnetic field of the pole shoe material from the pole shoe material according to the pole shoe of the initial structure of the PPM;

[0135] An inverse analysis calculation unit, configured to perform an inverse analysis on the PPM initial structure according to the PPM initial structure and the maximum magnetic field of the pole shoe material by using a finite length PPM fast calculation method considering the influence of the pole shoe, so as to obtain a PPM final structure that meets the requirements;

[0136] An output unit is used to output the final structure of the PPM.

[0137] The execution process of each unit can be performed according to the process steps of the PPM structure inverse analysis method based on the equivalent current source model described in Example 1, and will not be described in detail in this embodiment.

[0138] Example 4

[0139] like Fig.13 As shown, the difference between this embodiment and embodiment 2 is that this embodiment provides a PPM structure inverse analysis device based on an equivalent current source model, the device supports a PPM structure inverse analysis method based on an equivalent current source model described in embodiment 2, and the device includes:

[0140] An acquisition unit, used for acquiring electron beam parameters;

[0141] A basic parameter calculation unit of the PPM structure, used for calculating the basic parameters of the PPM structure according to the electron injection parameters;

[0142] A PPM initial structure initialization unit, used to initialize the PPM structure, and initialize the structural parameters of the PPM structure according to the basic parameters of the PPM structure to obtain the PPM initial structure;

[0143] A maximum magnetic field determination unit for a pole shoe material, used to determine the maximum magnetic field of the pole shoe material from the pole shoe material according to the pole shoe of the initial structure of the PPM;

[0144] An inverse analysis calculation unit, configured to perform an inverse analysis on the PPM initial structure according to the PPM initial structure and the maximum magnetic field of the pole shoe material by using a finite length PPM fast calculation method considering the influence of the pole shoe, so as to obtain a PPM final structure that meets the requirements;

[0145] The optimization unit is used to adjust and optimize the PPM final structure by increasing or decreasing the magnetic field to obtain the adjusted PPM final structure; specifically, by fine-tuning the inner and outer radius r of the magnetic ring m1 ,r m2 And the outer diameter of the pole shoe r f2 Perform stabbing to increase or decrease the magnetic field; m1 Decrease, r m2 Increase, r f2 Reducing r can increase the magnetic field; m1 Increase, r m2 Decrease, r f2 Increasing can reduce the magnetic field;

[0146] The output unit is used to output the adjusted PPM final structure.

[0147] The execution process of each unit can be performed according to the process steps of the PPM structure inverse analysis method based on the equivalent current source model described in Example 2, and will not be described in detail in this embodiment.

[0148] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0149] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0150] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0151] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0152] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A PPM structure inverse analysis method based on an equivalent current source model, characterized in that: The method includes: Acquire electron injection parameters, and calculate basic parameters of the PPM structure according to the electron injection parameters; Initializing the PPM structure, initializing the structural parameters of the PPM structure according to the basic parameters of the PPM structure to obtain the PPM initial structure; According to the pole shoes of the initial structure of the PPM, the maximum magnetic field of the pole shoe material is determined by the pole shoe material; According to the PPM initial structure and the maximum magnetic field of the pole shoe material, a finite length PPM fast calculation method considering the influence of the pole shoe is used to perform an inverse analysis on the PPM initial structure to obtain a PPM final structure that meets the requirements; The specific steps of the finite length PPM fast calculation method considering the influence of the pole shoe to perform inverse analysis on the PPM initial structure are: Step A, calculating the maximum magnetic field of the PPM structure, and comparing the maximum magnetic field of the PPM structure with the maximum magnetic field of the pole shoe material: if the maximum magnetic field of the PPM structure is less than or equal to a preset coefficient multiplied by the maximum magnetic field of the pole shoe material, executing step B; if the maximum magnetic field of the PPM structure is greater than the preset coefficient multiplied by the maximum magnetic field of the pole shoe material, correcting by reducing the maximum magnetic field of the PPM structure; Step B, calculating the equivalent inner diameter of the magnetic ring by an iterative algorithm, and substituting the equivalent inner diameter of the magnetic ring into a finite length PPM fast calculation method that does not consider the influence of the pole shoe, to obtain a finite length PPM equivalent current source model that considers the influence of the pole shoe; Step C, using the finite length PPM equivalent current source model considering the influence of the pole shoe to calculate the peak values ​​of the magnetic field P1, P2, ..., P of the current PPM structure i ,…,P N ; Step D, calculate the difference ΔP i =P i -D i , D i is the expected magnetic field peak value, P i The peak values ​​of the magnetic fields of the current PPM structure are calculated; the difference is judged against the preset allowable error value: if the maximum absolute value of the difference is less than or equal to the preset allowable error value, the current PPM structure is output as the final PPM structure; if the maximum absolute value of the difference is greater than the preset allowable error value, a corresponding correction is made and the calculation is returned to step A for recalculation.

2. The PPM structure inverse analysis method based on the equivalent current source model according to claim 1, characterized in that: The basic parameters of the PPM structure include the peak value of the uniform magnetic field, the range of the length of a single cycle of the PPM structure, and the number of cycles.

3. The PPM structure inverse analysis method based on the equivalent current source model according to claim 2 is characterized in that: The number of periods N is obtained by the length of the high-frequency structure; The calculation expression of the uniform magnetic field peak value is: B0=δB 0b Where, B0 is the peak value of the uniform magnetic field; δ is the coefficient of the traveling wave tube; B 0b is the ideal magnetic field value; B b is the Brillouin magnetic field; I is the current of the electron beam emitted from the electron gun area, V is the voltage of the electron beam emitted from the electron gun area, r b is the electron beam radius; The calculation expression of the range of the single cycle length of the PPM structure is: Where L is the length of a single cycle of the PPM structure.

4. The PPM structure inverse analysis method based on the equivalent current source model according to claim 2 is characterized in that: The structural parameters of the PPM structure include lateral parameters, axial parameters and residual magnetism; the lateral parameters include the inner radius of the pole shoe head, the outer radius of the pole shoe head, the pole shoe height, the inner radius of the magnetic ring and the outer radius of the magnetic ring; the axial parameters include the thickness of the magnetic ring, the thickness of the pole shoe and the gap of the pole shoe; The inner radius of the pole shoe head is determined by the high-frequency structure; the outer radius of the pole shoe head, the pole shoe height, the inner radius of the magnetic ring and the outer radius of the magnetic ring are all determined by the inner radius of the pole shoe head; the thickness of the magnetic ring and the thickness of the pole shoe are both determined according to the period; the pole shoe gap is equal to the pole shoe gap value when the intermediate magnetic field peak B-peak reaches the maximum value; the residual magnetism is preset.

5. The PPM structure inverse analysis method based on the equivalent current source model according to claim 1, characterized in that: The equivalent magnetic ring inner diameter is the magnetic ring inner diameter that makes the intermediate magnetic field peak values ​​obtained by the infinite length PPM fast calculation method considering the influence of the pole shoe and the finite length PPM fast calculation method not considering the influence of the pole shoe equal.

6. The PPM structure inverse analysis method based on the equivalent current source model according to claim 1, characterized in that: The calculation expression of the maximum magnetic field of the PPM initial structure is: In the formula, B max is the maximum magnetic field of the initial structure of PPM; F t is the total magnetic flux that the magnetic block can generate; P1 is the first magnetic flux path; P2 is the second magnetic flux path; P t is the magnetic flux path and r f1 is the inner diameter of the pole shoe head; r f2 is the outer diameter of the pole shoe head.

7. The PPM structure inverse analysis method based on the equivalent current source model according to claim 1, characterized in that: If the maximum absolute value of the difference is greater than the preset allowable error value, a corresponding correction is performed; specifically including: If the difference ΔP i >0, the corresponding magnetic field peak is reduced, thereby reducing the magnetic field; specifically, by increasing g to reduce the magnetic field peak, the pole shoe gap g is corrected: [g i ] n+1 =1.1·[g i ] n ; If the difference ΔP i <0, the corresponding magnetic field peak value is increased, thereby increasing the magnetic field; specifically, by increasing Br, the magnetic field peak value is increased [B ri ] n+1 =1.1·[B ri ] n .

8. The PPM structure inverse analysis method based on the equivalent current source model according to claim 1, characterized in that: The method further includes: optimizing the final structure of the PPM by adjusting the magnetic field to increase or decrease the magnetic field.

9. A PPM structure inverse analysis device based on an equivalent current source model, characterized in that: The device supports a PPM structure inverse analysis method based on an equivalent current source model as described in any one of claims 1 to 8, and the device comprises: An acquisition unit, used for acquiring electron beam parameters; A basic parameter calculation unit of the PPM structure, used for calculating the basic parameters of the PPM structure according to the electron injection parameters; A PPM initial structure initialization unit, used to initialize the PPM structure, and initialize the structural parameters of the PPM structure according to the basic parameters of the PPM structure to obtain the PPM initial structure; A maximum magnetic field determination unit for a pole shoe material, used to determine the maximum magnetic field of the pole shoe material from the pole shoe material according to the pole shoe of the initial structure of the PPM; An inverse analysis calculation unit, configured to perform an inverse analysis on the PPM initial structure according to the PPM initial structure and the maximum magnetic field of the pole shoe material by using a finite length PPM fast calculation method considering the influence of the pole shoe, so as to obtain a PPM final structure that meets the requirements; An output unit is used to output the final structure of the PPM.

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