Method and device for acquiring electromagnetic property of target wrapped by plasma around flow field

Abstract

The invention provides a method and a device for acquiring electromagnetic characteristics of a plasma surrounding flow field coating target. The method comprises the following steps: determining scattering center data of a target body based on a high-frequency electromagnetic modeling method; the scattering center data comprises coordinates and field intensity of a scattering center point; performing ray tracing on the plasma sheath generated by the target body, and determining the track of rays; determining an intersection point of the track of the ray and the target body; when the intersection point comprises a scattering center point, coupling two-way attenuation and phase shift generated by a ray where the intersection point is located on a propagation path to the scattering center point to obtain coupled field intensity of the scattering center after plasma electromagnetic characteristic modulation; and according to the coordinate of the scattering center point and the field intensity after coupling, determining electromagnetic characteristic data of the target body wrapped by the plasma around the flow field. According to the scheme, the electromagnetic characteristics of the target wrapped by the plasma around the flow field in any flight state can be accurately and rapidly obtained, and engineering application is achieved while the calculation efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of plasma flow fields, and in particular to a method and device for acquiring electromagnetic characteristics of a target covered by a plasma flow field. Background Art

[0002] When a target moves at high speed in the atmosphere, a plasma flow field will be generated around the target. Plasma is continuously generated on the windward side of the target and flows backward. The speed of movement is different from that of the target itself. In addition, due to the dispersion characteristics of the plasma itself and the non-uniform distribution around the target, the plasma flow field will produce amplitude, frequency and phase modulation effects on the radar waves incident therein, further causing radar imaging defocusing and Doppler measurement inaccuracy, affecting the radar's ability to detect, track and identify the target. Therefore, accurate acquisition of the electromagnetic characteristics of plasma-encapsulated targets is a prerequisite for understanding and mastering the mechanism and change law of plasma electromagnetic characteristics, and is also the basis for stable tracking and identification of high-speed moving aircraft. Modeling of the electromagnetic characteristics of plasma-encapsulated targets has clear application value.

[0003] The traditional method for calculating the electromagnetic scattering characteristics of a target covered by a plasma flow field is to first track the propagation path and field strength of the ray in the plasma sheath when calculating the coupling between the plasma flow field and the target body. When the ray intersects the surface of the target body, not only is the reflection direction calculated using Snell's law, but also the field strength after the ray interacts with the target is calculated by combining high-frequency asymptotic methods such as GO, PO, and EEC. After obtaining the reflection direction and field strength of the ray, continue to track its propagation path in the plasma sheath. For complex targets, the ray may intersect with the target body multiple times, so it is necessary to repeat the above steps to calculate the reflection direction and field strength of the ray. The calculation efficiency is low and cannot meet the needs of engineering applications. Therefore, there is an urgent need for a method and device for obtaining the electromagnetic characteristics of a target covered by a plasma flow field. Summary of the invention

[0004] The present invention provides a method and device for acquiring electromagnetic characteristics of a target covered by a plasma flow field, which can achieve accurate and rapid acquisition of the electromagnetic characteristics of the target covered by a plasma flow field under any flight state, improve the calculation efficiency and realize engineering application at the same time.

[0005] In a first aspect, the present invention provides a method for acquiring electromagnetic characteristics of a target covered by a plasma flow field, comprising:

[0006] Determine the scattering center data of the target body based on a high-frequency electromagnetic modeling method; wherein the scattering center data includes the coordinates and field strength of the scattering center point;

[0007] Performing ray tracing on the plasma sheath generated by the target body to determine the trajectory of the ray;

[0008] Determine the intersection point of the trajectory of the ray and the target body;

[0009] When the intersection point includes the scattering center point, the two-way attenuation and phase shift generated by the ray at the intersection point on the propagation path are superimposed on the scattering center point to obtain the coupled field strength of the scattering center after the electromagnetic properties of the plasma are modulated;

[0010] According to the coordinates of the scattering center point and the post-coupling field strength, the electromagnetic characteristic data of the plasma flow field covering the target body are determined.

[0011] Optionally, determining the scattering center data of the target body based on the high-frequency electromagnetic modeling method includes:

[0012] According to the three-dimensional geometric model of the target body and the preset radar observation condition parameters, the scattering field data of the target body is calculated based on the bouncing ray method;

[0013] Generating a three-dimensional ISAR image of the target body using a ray integral imaging method according to the scattering field data;

[0014] An iterative peak search algorithm is used to extract three-dimensional scattering center data of the target body under the preset radar observation condition parameters from the three-dimensional ISAR image; wherein the three-dimensional scattering center data includes the coordinates and field intensity of the scattering center point.

[0015] Optionally, performing ray tracing on the plasma sheath generated by the target body to determine the trajectory of the ray includes:

[0016] The three-dimensional geometric model of the target body and the plasma sheath are segmented to obtain a plurality of grids;

[0017] The Haselgrove equation in the plasma is used to solve the trajectory of the ray; the trajectory includes the coordinates of the first grid that the trajectory passes through.

[0018] Optionally, determining the intersection point of the trajectory of the ray and the target body includes:

[0019] Determine a first grid parameter of the first grid and a second grid parameter of a second grid through which the target body passes;

[0020] Determine whether the first grid parameter is the same as the second grid parameter;

[0021] If the judgment result is yes, the trajectory of the ray is intersected with the target body, and the intersection point is determined in the first grid corresponding to the first grid parameter.

[0022] Optionally, when the intersection point includes the scattering center point, the two-way attenuation and phase shift generated by the ray at the intersection point on the propagation path are superimposed on the scattering center point to obtain the coupled field strength of the scattering center after the electromagnetic properties of the plasma are modulated, including:

[0023] The three-dimensional geometric model of the target body and the plasma sheath are segmented to obtain a plurality of grids;

[0024] Determine the target grid where the intersection point is located;

[0025] Determine whether there are coordinates in the target grid that are the same as the coordinates of the scattering center point;

[0026] If the judgment result is yes, it is determined that the intersection point includes the scattering center point, and a two-way attenuation constant and a phase shift constant are calculated according to the acquired electromagnetic wave frequency, plasma collision frequency, plasma resonance frequency and magnetic permeability in vacuum;

[0027] The post-coupling field intensity of the scattering center point included in the intersection point is obtained according to the two-way attenuation constant and the phase shift constant.

[0028] Optionally, the two-way attenuation constant is calculated by the following formula:

[0029]

[0030] The phase shift constant is calculated by the following formula:

[0031]

[0032] Wherein, α is the two-way attenuation constant; β is the phase shift constant; ω is the electromagnetic wave frequency; ν is the plasma collision frequency; ω p is the plasma resonance frequency; μ0 is the magnetic permeability in vacuum; ε0 is the dielectric constant in vacuum;

[0033] The post-coupling field strength is calculated by the following formula:

[0034] E=E0e -αz-jβz

[0035] Wherein, E is the field strength after coupling; E0 is the field strength at the scattering center point, Z is the transmission distance, and j is an imaginary unit.

[0036] Optionally, determining electromagnetic characteristic data of a plasma flow field enveloping the target body according to the coordinates of the scattering center point and the post-coupling field strength includes:

[0037] Using the coordinates of the scattering center point and the post-coupling field strength, coupled scattering center data is obtained;

[0038] The coupled scattering center data is input into a geometric diffraction theory model, and the electromagnetic characteristic data of the plasma flow field covering the target body is output.

[0039] In a second aspect, the present invention provides a device for acquiring electromagnetic characteristics of a target covered by a plasma flow field, comprising:

[0040] A computing module, used to determine the scattering center data of the target body based on a high-frequency electromagnetic modeling method; wherein the scattering center data includes the coordinates and field strength of the scattering center point;

[0041] A trajectory determination module, used for ray tracing of the plasma sheath generated by the target body to determine the trajectory of the ray;

[0042] A coupling module is used to determine the intersection point of the trajectory of the ray and the target body; and when the intersection point contains the scattering center point, the two-way attenuation and phase shift generated by the ray at the intersection point on the propagation path are superimposed on the scattering center point to obtain the coupled field strength of the scattering center after the electromagnetic characteristics of the plasma are modulated;

[0043] The operation module is also used to determine the electromagnetic characteristic data of the plasma flow field covering the target body according to the coordinates of the scattering center point and the post-coupling field strength.

[0044] In a third aspect, an embodiment of the present invention further provides a computing device, comprising a memory and a target processor, wherein the memory stores a computer program, and when the target processor executes the computer program, the method described in any first aspect of this specification is implemented.

[0045] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when executed in a computer, enables the computer to execute the method described in any first aspect of this specification.

[0046] In a fifth aspect, an embodiment of the present invention further provides a computer program product, comprising computer instructions, which, when executed by a processor, implement the steps of the method described in any first aspect of this specification.

[0047] The present invention provides a method and device for acquiring electromagnetic characteristics of a target covered by a plasma flow field. The method adopts a high-frequency electromagnetic modeling method to calculate the scattering center data of the target body; then the ray trajectory is calculated according to the ray tracing method in non-uniform plasma, and the intersection position of the ray and the target body is found; secondly, it is determined whether the position contains a scattering center point. If the position contains a scattering midpoint, the two-way attenuation and phase shift generated by the ray on the propagation path are superimposed on the scattering center as a new scattering center at the position; finally, the electromagnetic scattering characteristic data of the target covered by the plasma flow field is synthesized according to the geometric diffraction theory model. In this way, even if the ray may intersect with the target body multiple times, there is no need to repeatedly calculate the reflection direction and field strength of the ray, which solves the problem of low calculation efficiency and inability to perform engineering applications based on the electromagnetic scattering characteristics of the target covered by the plasma flow field, and realizes accurate and rapid acquisition of the electromagnetic characteristics of the target covered by the plasma flow field. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 It is a flow chart of a method for acquiring electromagnetic characteristics of a target covered by a plasma flow field provided by one embodiment of the present invention;

[0050] Figure 2 is a schematic diagram of the path of the electromagnetic rays of the target body provided by an embodiment of the present invention;

[0051] Figure 3 is a hardware architecture diagram of a computing device provided by an embodiment of the present invention;

[0052] Figure 4 It is a schematic structural diagram of a device for acquiring electromagnetic characteristics of a target covered by a plasma flow field provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0054] The inventive concept of this application is described in detail below.

[0055] like Figure 1 As shown, an embodiment of the present invention provides a method for acquiring electromagnetic characteristics of a target covered by a plasma flow field, the method comprising:

[0056] Step 100, determining the scattering center data of the target body based on a high-frequency electromagnetic modeling method; wherein the scattering center data includes the coordinates and field strength of the scattering center point;

[0057] Step 102, ray tracing is performed on the plasma sheath generated by the target body to determine the trajectory of the ray;

[0058] Step 104, determining the intersection point between the trajectory of the ray and the target body;

[0059] Step 106, when the intersection point includes a scattering center point, the two-way attenuation and phase shift generated by the ray at the intersection point on the propagation path are superimposed on the scattering center point to obtain the coupled field strength of the scattering center after the electromagnetic properties of the plasma are modulated;

[0060] Step 108, determining the electromagnetic characteristic data of the plasma flow field covering the target body according to the coordinates of the scattering center point and the field strength after coupling.

[0061] In the present invention, the scattering center data of the target body is calculated by adopting a high-frequency electromagnetic modeling method; then the ray trajectory is calculated according to the ray tracing method in non-uniform plasma, and the intersection position of the ray and the target body is found; secondly, it is determined whether the position contains a scattering center point. If the position contains a scattering midpoint, the two-way attenuation and phase shift generated by the ray on the propagation path are superimposed on the scattering center as a new scattering center at the position; finally, the electromagnetic scattering characteristic data of the target covered by the plasma flow field is synthesized according to the geometric diffraction theory model. In this way, even if the ray may intersect with the target body multiple times, there is no need to repeatedly calculate the reflection direction and field strength of the ray, which solves the problem of low calculation efficiency and inability to perform engineering applications based on the electromagnetic scattering characteristics of the target covered by the plasma flow field, and realizes accurate and rapid acquisition of the electromagnetic characteristics of the target covered by the plasma flow field.

[0062] For step 100, determining the scattering center data of the target body based on a high-frequency electromagnetic modeling method includes:

[0063] According to the three-dimensional geometric model of the target body and the preset radar observation condition parameters, the scattering field data of the target body is calculated based on the bouncing ray method;

[0064] According to the scattered field data, the 3D ISAR image of the target body is generated by using the ray integral imaging method.

[0065] The iterative peak search algorithm is used to extract the three-dimensional scattering center data of the target body under the preset radar observation condition parameters from the three-dimensional ISAR image; wherein the three-dimensional scattering center data includes the coordinates and field intensity of the scattering center point.

[0066] Specifically, in the high-frequency region, target scattering is not contributed by the entire target surface, but is localized and can be fully characterized by multiple isolated scattering centers. The geometric theory of diffraction (GTD) model is a commonly used scattering center model that can accurately describe the electromagnetic characteristics of the target. It is widely used in the fields of RCS reconstruction and frequency extrapolation, radar target scattering mechanism diagnosis and identification. The three-dimensional GTD model expression is:

[0067]

[0068] Among them, E s is the target scattered echo, N is the number of scattering centers, k is the wave number, θ, are the elevation angle and azimuth angle respectively, (A i ,a i ,x i ,y i ,z i ) represent the scattering intensity, frequency dependence parameter and three-dimensional position parameter of the i-th scattering center respectively.

[0069] It should be noted that the three-dimensional geometric model is obtained by performing three-dimensional geometric modeling on the target entity.

[0070] In step 100, the scattering field data of the target body is calculated by using the bouncing ray method (SBR technology) by giving the target geometric surface element model and the preset radar observation condition parameters. Based on the target scattering field data, the ray integral imaging method is further used to quickly generate a three-dimensional ISAR image of the target body. The ray integral imaging method directly generates a three-dimensional ISAR image I (x, y, z) by performing integral imaging calculation on each ray path and then summing them in the image domain. The calculation formula is:

[0071]

[0072] Where, the subscript i is the serial number of the ray path; * is the convolution operation; δ(·,·,·) is the three-dimensional Dirac function; k0 is the central wave number; z, x, y are the radial and two orthogonal lateral distances respectively; z' i is the total distance delay of each ray path; the lateral position x' i ,y' i is the average of the lateral positions of the first and last ejection points; α i is the complex amplitude value of the far-field scattering contribution of each ray; where h(x,y,z) is the ray spread function:

[0073] h(x,y,z)=k0sinc(Δk·z)sinc(k0Δφ·x)sinc(k0Δθ·y) (3)

[0074] Where Δk, Δφ, and Δθ are the wave number width, angular width of the azimuth angle, and angular width of the elevation angle, respectively;

[0075] After obtaining the three-dimensional ISAR image of the target body, the iterative peak search algorithm - CLEAN is used to further extract the three-dimensional scattering center of the target body at different viewing angles (including coordinates (i.e. three-dimensional position parameters) and field intensity in the body coordinate system). Specifically, for each pitch angle θ and azimuth angle φ, the peak point in the residual ISAR image is iteratively searched to extract the amplitude and position parameters of the corresponding scattering center under a single viewing angle, and then the point spread response of the scattering center is removed from the ISAR image. In the nth iteration, assuming A n 、z' n 、x' n ,y' n are the amplitude, radial and two lateral position parameters of the corresponding scattering center, then the residual ISAR image is:

[0076] R n+1 =R n -A n h(xx' n ,yy' n ,zz' n ) (4)

[0077] The iterative process ends when the peak value of the residual ISAR image is lower than the preset threshold. At this time, the coordinate transformation matrix is ​​used to transform the position (x' n ,y' n ,z' n ) is converted to the position (x) in the target coordinate system n ,y n ,z n ), and finally we can get the coordinates (x n ,y n ,z n ) and field strength A n The scattering center data.

[0078] With respect to step 102, ray tracing is performed on the propagation path of the electromagnetic wave in the plasma sheath generated by the target body to determine the trajectory of the ray, including:

[0079] The three-dimensional geometric model of the target body and the plasma sheath are divided to obtain a number of grids;

[0080] The Haselgrove equation in the plasma is used to solve the trajectory of the ray; the trajectory includes the coordinates of the first grid that the trajectory passes through.

[0081] In the present invention, the propagation of electromagnetic waves in plasma satisfies the following equation:

[0082]

[0083] Where p' is the integral path of the ray; ω is the frequency of the electromagnetic wave; X = 1-n 2 (n is the refractive index of the medium); c is the speed of light in a vacuum; r, θ and are the coordinate values ​​of the spherical coordinate system respectively; are the three components of the wave vector in the spherical coordinate system;

[0084] Formula (5) is solved using the Runge-Kutta method to obtain the coordinate values ​​and wave vectors of the spherical coordinate system for each step of each ray. At the same time, the coordinates of each first grid that the ray trajectory passes through can also be obtained, thereby realizing ray path tracking in non-uniform plasma.

[0085] In step 104, determining the intersection point between the trajectory of the ray and the target body includes:

[0086] Determine a first grid parameter of the first grid and a second grid parameter of a second grid through which the target body passes;

[0087] Determine whether the first grid parameter is the same as the second grid parameter;

[0088] If the judgment result is yes, the trajectory of the ray is intersected with the target body, and the intersection point is determined in the first grid corresponding to the first grid parameter.

[0089] Specifically, the grid parameter of the target body is set to -1, that is, the second grid parameter is -1. During the ray path tracing process, when the first grid parameter of the first grid where the ray is located is -1, it is determined that the ray intersects with the target body. Figure 2 The ray path schematic diagram shown includes four ray trajectories, among which ray 4 does not intersect with the target body, and the first grid parameters of the first grid passed by ray 4 are not -1; ray 1, ray 2, and ray 3 all intersect with the target body.

[0090] For step 106, when the intersection point includes a scattering center point, the two-way attenuation and phase shift generated by the ray at the intersection point on the propagation path are superimposed on the scattering center point to obtain the coupled field strength of the scattering center after the electromagnetic properties of the plasma are modulated, including:

[0091] The three-dimensional geometric model of the target body and the plasma sheath are divided to obtain a number of grids;

[0092] Determine the target grid where the intersection point is located;

[0093] Determine whether there are coordinates in the target grid that are the same as the coordinates of the scattering center point;

[0094] If the judgment result is yes, it is determined that the intersection point includes the scattering center point, and the two-way attenuation constant and the phase shift constant are calculated based on the acquired electromagnetic wave frequency, plasma collision frequency, plasma resonance frequency and magnetic permeability in vacuum;

[0095] According to the two-way attenuation constant and the phase shift constant, the coupled field intensity of the scattering center point contained in the intersection point is obtained.

[0096] Specifically, to determine whether the intersection point includes the scattering center point, the following method can also be used: determine whether the distance between the coordinates of any scattering center point and the coordinates of the intersection point is less than the width of the grid, and if the judgment result is yes, determine that the intersection point includes the scattering center point. It should be noted that the width of the grid is determined according to the frequency of the electromagnetic wave, and the widths of the subdivided grids of different accuracies are also different.

[0097] Continuing from the previous example, Figure 2 As shown, the intersection point of ray 1, ray 3 and the target body includes the scattering center point (i.e. Figure 2 ), ray 2 is the ray that propagates to the surface grid of the target body, but there is no scattering center point at the location of the grid.

[0098] In the present invention, by converting the interaction between electromagnetic waves, plasma flow fields and target bodies into the interaction between electromagnetic waves, plasma flow fields and target scattering center models, the calculation of the reflection direction and field intensity after the rays intersect the target is omitted, thereby significantly improving the calculation efficiency.

[0099] In a preferred embodiment, the two-way attenuation constant is calculated by the following formula:

[0100]

[0101] The phase shift constant is calculated using the following formula:

[0102]

[0103] Among them, α is the two-way attenuation constant; β is the phase shift constant; ω is the electromagnetic wave frequency; ν is the plasma collision frequency; ω p is the plasma resonance frequency; μ0 is the magnetic permeability in vacuum (4π×10 -7 H / m); ε0 is the dielectric constant of a vacuum; and ω, ν, ω p Can be collected.

[0104] The field strength after coupling is calculated by the following formula:

[0105] E=E0e -αz-jβz (8)

[0106] Among them, E is the field strength after coupling; E0 is the field strength at the scattering center point, Z is the transmission distance, and j is the imaginary unit.

[0107] In the present invention, only the two-way attenuation and phase shift generated by the ray at the intersection point including the scattering center point on the propagation path (i.e., the ray trajectory) are considered, and the two-way attenuation and phase shift are superimposed on the scattering midpoint as the new scattering center point at that position, thereby realizing the updating of the field intensity of the scattering center point, thereby eliminating the need to repeatedly calculate the reflection direction and field intensity of the ray that may intersect with the target body multiple times, thereby improving the calculation efficiency.

[0108] In step 108, the electromagnetic characteristic data of the plasma flow field covering the target body is determined according to the coordinates of the scattering center point, the coupling field strength and the scattering center data, including:

[0109] The coupled scattering center data is obtained by using the coordinates of the scattering center point and the coupled field strength;

[0110] The coupled scattering center data is input into the geometric diffraction theory model, and the electromagnetic characteristic data of the plasma flow field covering the target body is output.

[0111] Specifically, by updating the field intensity data of the scattering center point included in the intersection point in the scattering center data obtained in step 100 to the field intensity after coupling, the coupled scattering center data of the scattering center point after the plasma electromagnetic characteristics are modulated is obtained, and the coupled scattering center data is input into the above formula (1), the electromagnetic characteristic data of the plasma flow field covering the target body can be output, thereby realizing the coupling of the scattering center model and the electromagnetic characteristics of the plasma sheath, and finally solving the problem of low calculation efficiency and inability to carry out engineering application based on the electromagnetic scattering characteristics of the plasma flow field covering the target, and realizing accurate and rapid acquisition of the electromagnetic characteristics of the plasma flow field covering the target.

[0112] like Figure 3 , Figure 4 As shown, an embodiment of the present invention provides an electromagnetic property acquisition device for a target covered by a plasma flow field. The device embodiment can be implemented by software, or by hardware or a combination of software and hardware. From the hardware level, Figure 3 As shown, a hardware architecture diagram of a computing device where an electromagnetic characteristic acquisition device for a plasma flow field covering a target provided by an embodiment of the present invention is located is shown. Figure 3In addition to the processor, memory, network interface, and non-volatile memory shown in the figure, the computing device in which the device is located in the embodiment may also generally include other hardware, such as a forwarding chip responsible for processing messages, etc. Taking software implementation as an example, Figure 4 As shown, as a device in a logical sense, the CPU of the computing device in which it is located reads the corresponding computer program in the non-volatile memory into the memory and runs it. This embodiment provides a device for obtaining electromagnetic characteristics of a target covered by a plasma flow field, and the device includes:

[0113] The operation module 400 is used to determine the scattering center data of the target body based on the high-frequency electromagnetic modeling method; wherein the scattering center data includes the coordinates and field strength of the scattering center point;

[0114] A trajectory determination module 402 is used to perform ray tracing on the plasma sheath generated by the target body to determine the trajectory of the ray;

[0115] The coupling module 404 is used to determine the intersection point between the trajectory of the ray and the target body; and when the intersection point contains the scattering center point, the two-way attenuation and phase shift generated by the ray at the intersection point on the propagation path are superimposed on the scattering center point to obtain the coupled field strength of the scattering center after the electromagnetic characteristics of the plasma are modulated;

[0116] The operation module 400 is also used to determine the electromagnetic characteristic data of the plasma flow field covering the target body according to the coordinates of the scattering center point and the field strength after coupling.

[0117] In some specific implementations, the operation module 400 may be used to execute the above steps 100 and 108 , the trajectory determination module 402 may be used to execute the above step 102 , and the coupling module 404 may be used to execute the above steps 104 and 106 .

[0118] In one embodiment of the present invention, the operation module 400 is further configured to perform the following operations:

[0119] According to the three-dimensional geometric model of the target body and the preset radar observation condition parameters, the target body scattering field data is calculated based on the bouncing ray method;

[0120] According to the scattered field data, the 3D ISAR image of the target body is generated by using the ray integral imaging method.

[0121] The iterative peak search algorithm is used to extract the three-dimensional scattering center data of the target body under the preset radar observation condition parameters from the three-dimensional ISAR image; wherein the three-dimensional scattering center data includes the coordinates and field intensity of the scattering center point.

[0122] In one embodiment of the present invention, the trajectory determination module 402 is further configured to perform the following operations:

[0123] The three-dimensional geometric model of the target body and the plasma sheath are divided to obtain a number of grids;

[0124] The Haselgrove equation in the plasma is used to solve the trajectory of the ray; the trajectory includes the coordinates of the first grid that the trajectory passes through.

[0125] In one embodiment of the present invention, the coupling module 404 is further configured to perform the following operations:

[0126] The three-dimensional geometric model of the target body and the plasma sheath are divided to obtain a number of grids;

[0127] Determine a first grid parameter of the first grid and a second grid parameter of a second grid through which the target body passes;

[0128] Determine whether the first grid parameter is the same as the second grid parameter;

[0129] If the judgment result is yes, the trajectory of the ray is intersected with the target body, and the intersection point is determined in the first grid corresponding to the first grid parameter;

[0130] Determine the target grid where the intersection point is located;

[0131] Determine whether there are coordinates in the target grid that are the same as the coordinates of the scattering center point;

[0132] If the judgment result is yes, it is determined that the intersection point includes the scattering center point, and the two-way attenuation constant and the phase shift constant are calculated based on the acquired electromagnetic wave frequency, plasma collision frequency, plasma resonance frequency and magnetic permeability in vacuum;

[0133] The two-way attenuation constant is calculated using the following formula:

[0134]

[0135] The phase shift constant is calculated using the following formula:

[0136]

[0137] Among them, α is the two-way attenuation constant; β is the phase shift constant; ω is the electromagnetic wave frequency; ν is the plasma collision frequency; ω p is the plasma resonance frequency; μ0 is the magnetic permeability in vacuum; ε0 is the dielectric constant in vacuum;

[0138] According to the two-way attenuation constant and the phase shift constant, the coupled field intensity of the scattering center point contained in the intersection point is obtained; the coupled field intensity is calculated by the following formula:

[0139] E=E0e-αz-jβz

[0140] Among them, E is the field strength after coupling; E0 is the field strength at the scattering center point, Z is the transmission distance, and j is the imaginary unit.

[0141] In one embodiment of the present invention, the operation module 400 is further configured to perform the following operations:

[0142] The coupled scattering center data is obtained by using the coordinates of the scattering center point and the coupled field strength;

[0143] The coupled scattering center data is input into the geometric diffraction theory model, and the electromagnetic characteristic data of the plasma flow field covering the target body is output.

[0144] It is to be understood that the structure illustrated in the embodiment of the present invention does not constitute a specific limitation on the electromagnetic characteristics acquisition device for a target covered by a plasma flow field. In other embodiments of the present invention, the electromagnetic characteristics acquisition device for a target covered by a plasma flow field may include more or fewer components than shown in the figure, or combine some components, or split some components, or arrange the components differently. The components shown in the figure may be implemented in hardware, software, or a combination of software and hardware.

[0145] The information interaction, execution process and other contents between the modules in the above-mentioned device are based on the same concept as the embodiment of the method of the present invention. For the specific contents, please refer to the description in the embodiment of the method of the present invention, and no further description is given here.

[0146] An embodiment of the present invention further provides a computing device, including a memory and a target processor, wherein a computer program is stored in the memory, and when the target processor executes the computer program, a method for acquiring electromagnetic characteristics of a target covered by a plasma flow field in any embodiment of the present invention is implemented.

[0147] An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the processor executes a method for acquiring electromagnetic characteristics of a target covered by a plasma flow field in any embodiment of the present invention.

[0148] An embodiment of the present application also provides a computer program product, which includes a computer program. A processor of a computer device reads the computer program from a computer-readable storage medium, and the processor executes the computer program, so that the computer device executes a method for acquiring electromagnetic characteristics of a target covered by a plasma flow field as described in any of the above embodiments.

[0149] Specifically, a system or device equipped with a storage medium can be provided, on which software program code that implements the functions of any of the above-mentioned embodiments is stored, and a computer (or CPU or MPU) of the system or device can be enabled to read and execute the program code stored in the storage medium.

[0150] In this case, the program code itself read from the storage medium can realize the function of any one of the above-mentioned embodiments, and thus the program code and the storage medium storing the program code constitute a part of the present invention.

[0151] The storage medium embodiments for providing the program code include a floppy disk, a hard disk, a magneto-optical disk, an optical disk (such as CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD+RW), a magnetic tape, a non-volatile memory card, and a ROM. Alternatively, the program code can be downloaded from a server computer by a communication network.

[0152] In addition, it should be clear that the functions of any of the above embodiments can be implemented not only by executing the program code read by the computer, but also by enabling the operating system on the computer to complete part or all of the actual operations based on the instructions of the program code.

[0153] In addition, it can be understood that the program code read from the storage medium is written to a memory provided in an expansion board inserted into the computer or to a memory provided in an expansion module connected to the computer, and then based on the instructions of the program code, a CPU installed on the expansion board or expansion module is enabled to perform part or all of the actual operations, thereby realizing the functions of any of the above-mentioned embodiments.

[0154] It should be noted that, in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical factors in the process, method, article or device including the elements.

[0155] A person of ordinary skill in the art can understand that all or part of the steps of implementing the above method embodiments can be completed by hardware related to program instructions, and the aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it executes the steps of the above method embodiments; and the aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk, etc., various media that can store program codes.

[0156] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for acquiring electromagnetic characteristics of a target covered by a plasma flow field, characterized in that: include: Determine the scattering center data of the target body based on a high-frequency electromagnetic modeling method; wherein the scattering center data includes the coordinates and field strength of the scattering center point; Performing ray tracing on the plasma sheath generated by the target body to determine the trajectory of the ray; Determine the intersection point of the trajectory of the ray and the target body; When the intersection point includes the scattering center point, the two-way attenuation and phase shift generated by the ray at the intersection point on the propagation path are superimposed on the scattering center point to obtain the coupled field strength of the scattering center after the electromagnetic properties of the plasma are modulated; According to the coordinates of the scattering center point and the post-coupling field strength, the electromagnetic characteristic data of the plasma flow field covering the target body are determined.

2. The method according to claim 1, characterized in that: The method of determining the scattering center data of the target body based on the high-frequency electromagnetic modeling method includes: According to the three-dimensional geometric model of the target body and the preset radar observation condition parameters, the scattering field data of the target body is calculated based on the bouncing ray method; Generating a three-dimensional ISAR image of the target body using a ray integral imaging method according to the scattering field data; An iterative peak search algorithm is used to extract three-dimensional scattering center data of the target body under the preset radar observation condition parameters from the three-dimensional ISAR image; wherein the three-dimensional scattering center data includes the coordinates and field intensity of the scattering center point.

3. The method according to claim 1, characterized in that The step of performing ray tracing on the plasma sheath generated by the target body to determine the trajectory of the ray includes: The three-dimensional geometric model of the target body and the plasma sheath are segmented to obtain a plurality of grids; The Haselgrove equation in the plasma is used to solve the trajectory of the ray; the trajectory includes the coordinates of the first grid that the trajectory passes through.

4. The method according to claim 3, characterized in that Determining the intersection point between the trajectory of the ray and the target body includes: Determine a first grid parameter of the first grid and a second grid parameter of a second grid through which the target body passes; Determine whether the first grid parameter is the same as the second grid parameter; If the judgment result is yes, the trajectory of the ray is intersected with the target body, and the intersection point is determined in the first grid corresponding to the first grid parameter.

5. The method according to claim 1, characterized in that When the intersection point includes the scattering center point, the two-way attenuation and phase shift generated by the ray at the intersection point on the propagation path are superimposed on the scattering center point to obtain the coupled field strength of the scattering center after the electromagnetic properties of the plasma are modulated, including: The three-dimensional geometric model of the target body and the plasma sheath are segmented to obtain a plurality of grids; Determine the target grid where the intersection point is located; Determine whether there are coordinates in the target grid that are the same as the coordinates of the scattering center point; If the judgment result is yes, it is determined that the intersection point includes the scattering center point, and a two-way attenuation constant and a phase shift constant are calculated according to the acquired electromagnetic wave frequency, plasma collision frequency, plasma resonance frequency and magnetic permeability in vacuum; The post-coupling field intensity of the scattering center point included in the intersection point is obtained according to the two-way attenuation constant and the phase shift constant.

6. The method according to claim 5, characterized in that The two-way attenuation constant is calculated by the following formula: The phase shift constant is calculated by the following formula: Wherein, α is the two-way attenuation constant; β is the phase shift constant; ω is the electromagnetic wave frequency; ν is the plasma collision frequency; ω p is the plasma resonance frequency; μ0 is the magnetic permeability in vacuum; ε0 is the dielectric constant in vacuum; The post-coupling field strength is calculated by the following formula: E=E0e -αz-jβz Wherein, E is the field strength after coupling; E0 is the field strength at the scattering center point, Z is the transmission distance, and j is an imaginary unit.

7. The method according to any one of claims 1 to 6, characterized in that: Determining electromagnetic characteristic data of the plasma flow field covering the target body according to the coordinates of the scattering center point and the post-coupling field strength includes: Using the coordinates of the scattering center point and the post-coupling field strength, coupled scattering center data is obtained; The coupled scattering center data is input into a geometric diffraction theory model, and the electromagnetic characteristic data of the plasma flow field covering the target body is output.

8. A device for acquiring electromagnetic characteristics of a target covered by a plasma flow field, characterized in that: include: A computing module, used to determine the scattering center data of the target body based on a high-frequency electromagnetic modeling method; wherein the scattering center data includes the coordinates and field strength of the scattering center point; A trajectory determination module, used for ray tracing of the plasma sheath generated by the target body to determine the trajectory of the ray; A coupling module is used to determine the intersection point of the trajectory of the ray and the target body; and when the intersection point contains the scattering center point, the two-way attenuation and phase shift generated by the ray at the intersection point on the propagation path are superimposed on the scattering center point to obtain the coupled field strength of the scattering center after the electromagnetic characteristics of the plasma are modulated; The operation module is also used to determine the electromagnetic characteristic data of the plasma flow field covering the target body according to the coordinates of the scattering center point and the post-coupling field strength.

9. A computing device, comprising a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the method according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, which, when executed in a computer, causes the computer to execute the method according to any one of claims 1 to 7.

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