Method and device for calculating electromagnetic property of plasma coated target

Abstract

The invention discloses a method and a device for calculating electromagnetic characteristics of a plasma coated target. The method comprises the following steps: determining a ray trajectory and a deflection point of electromagnetic waves propagating in plasma based on a ray tracing method; dividing a transmission area of the electromagnetic wave into three areas based on the ray trajectory and the deflection point; the first area is from the starting point to the deflection point of the ray trajectory, and the second area is from the deflection point to the target surface; the third area is from the deflection point to the end point of the ray trajectory; calculating electromagnetic characteristics of the first area based on a ray tracing method to obtain first electromagnetic data at the deflection point; calculating second electromagnetic data of the second area based on a transmission line method; enabling the second electromagnetic data to be equivalent to the deflection point, and obtaining equivalent electromagnetic data at the deflection point; and taking the equivalent electromagnetic data as initial data of the third region, and calculating the electromagnetic property of the third region based on a ray tracing method to obtain the electromagnetic property of the plasma coated target. According to the invention, the calculated electromagnetic characteristics of the plasma coated target are more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic property calculation, and in particular to a method and device for calculating the electromagnetic property of a plasma-coated target. Background Art

[0002] When an aircraft moves at a very high speed in the atmosphere, it will have intense friction with the atmosphere, generating a plasma flow field surrounding 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 targets. Therefore, in order to stably track and identify high-speed moving aircraft, it is necessary to accurately calculate the electromagnetic characteristics of the plasma-encapsulated target.

[0003] The complexity of the electromagnetic scattering modeling method of plasma-coated targets is much higher than that of ideal conductor targets. When electromagnetic waves irradiate the plasma flow field, they will penetrate into the flow field, and there will be reflection and refraction phenomena. As an electromagnetic loss medium, it will also attenuate the electromagnetic waves. The study of theoretical modeling methods for plasma flow fields has always been one of the difficulties in the field of electromagnetic characteristics modeling. At present, the commonly used modeling method in the high-frequency region is based on the ray tracing method, which uses the propagation path of rays in the plasma to track and calculate the frequency shift and energy transfer of electromagnetic waves to obtain the electromagnetic scattering characteristics of the target. However, in the process of calculating the ray propagation path, the path of the ray is calculated only according to the plasma parameters, and the ray may not be able to reach the thin plasma layer on the target surface. When the thickness of the plasma layer is thin, some of the energy of the electromagnetic wave can actually pass through this part of the plasma. The electromagnetic characteristics information of this part of the plasma is lost during the simulation calculation. The electromagnetic characteristic parameters of this part of the plasma are generally strong, and the impact on the overall electromagnetic characteristics of the plasma flow field cannot be ignored.

[0004] Therefore, there is an urgent need for a method and device for calculating the electromagnetic properties of a plasma-coated target. Summary of the invention

[0005] The present invention provides a method and device for calculating the electromagnetic characteristics of a plasma-coated target, which can take the thin plasma layer between the deflection point and the target surface into account in the overall electromagnetic characteristic calculation, making the electromagnetic characteristic calculation result more accurate. The technical solution is as follows:

[0006] In one aspect, a method for calculating electromagnetic properties of a plasma-coated target is provided, the method comprising:

[0007] Determine the ray trajectory and deflection point of electromagnetic waves propagating in plasma based on ray tracing method;

[0008] Based on the ray trajectory and the deflection point, the transmission area of ​​the electromagnetic wave in the plasma is divided into three areas; the first area is from the starting point of the ray trajectory to the deflection point, the second area is from the deflection point to the target surface; the third area is from the deflection point to the end point of the ray trajectory;

[0009] Calculate the electromagnetic characteristics of the first region based on a ray tracing method to obtain first electromagnetic data at the deflection point;

[0010] Calculating second electromagnetic data of the second region based on a transmission line method;

[0011] Based on the first electromagnetic data, the second electromagnetic data is equivalent to the deflection point to obtain equivalent electromagnetic data at the deflection point;

[0012] The equivalent electromagnetic data is used as the starting data of the third region, and the electromagnetic characteristics of the third region are calculated based on a ray tracing method to obtain the electromagnetic characteristics of the plasma-coated target.

[0013] In another aspect, a device for calculating electromagnetic properties of a plasma-coated target is provided, the device comprising:

[0014] A determination unit, used for determining the ray trajectory and deflection point of the electromagnetic wave propagating in the plasma based on the ray tracing method;

[0015] A dividing unit, for dividing the transmission area of ​​the electromagnetic wave in the plasma into three areas based on the ray trajectory and the deflection point; the first area is from the starting point of the ray trajectory to the deflection point, the second area is from the deflection point to the target surface; the third area is from the deflection point to the end point of the ray trajectory;

[0016] A first calculation unit, configured to calculate the electromagnetic characteristics of the first region based on a ray tracing method to obtain first electromagnetic data at the deflection point;

[0017] A second calculation unit, configured to calculate second electromagnetic data of the second region based on a transmission line method;

[0018] A third calculation unit is used for, based on the first electromagnetic data, converting the second electromagnetic data into equivalent electromagnetic data at the deflection point to obtain equivalent electromagnetic data at the deflection point;

[0019] The fourth calculation unit is used to use the equivalent electromagnetic data as the starting data of the third region, calculate the electromagnetic characteristics of the third region based on the ray tracing method, and obtain the electromagnetic characteristics of the plasma-coated target.

[0020] On the other hand, a computer device is provided, which includes a memory and a processor, wherein the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory to implement the steps of the above-mentioned method for calculating the electromagnetic properties of a plasma-coated target.

[0021] On the other hand, a computer-readable storage medium is provided, wherein a computer program is stored in the storage medium, and when the computer program is executed by a processor, the steps of the method for calculating the electromagnetic properties of a plasma-coated target are implemented.

[0022] On the other hand, a computer program product is provided, comprising a computer program, wherein when the computer program is executed by a processor, the steps of the method for calculating electromagnetic properties of a plasma-coated target described above are implemented.

[0023] The embodiment of the present invention provides a method for calculating the electromagnetic characteristics of a plasma-coated target. After determining the outgoing ray trajectory and the deflection point, the transmission area of ​​the electromagnetic wave in the plasma is divided into three areas, wherein the first area and the third area are separated by the deflection point, and the second area is from the deflection point to the target surface, that is, the plasma layer on the target surface. After the electromagnetic characteristics of the first area and the second area are calculated respectively, on the basis of the calculation results of the first area, the calculation results of the second area are equivalent to the deflection point, and the equivalent electromagnetic data at the deflection point can be obtained. Finally, when calculating the electromagnetic characteristics of the third area, the equivalent electromagnetic data of the deflection point is used as the starting data, so that the electromagnetic characteristics of the thin layer of plasma on the target surface are taken into account in the overall electromagnetic characteristics calculation, and the final plasma-coated target electromagnetic characteristics are obtained. It can be seen from this that the present application can also take into account the thin layer of plasma between the deflection point and the target surface in the overall electromagnetic characteristics calculation, so that the electromagnetic characteristics calculation results are more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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.

[0025] Figure 1 It is a flow chart of a method for calculating electromagnetic characteristics of a plasma-coated target provided by one embodiment of the present invention;

[0026] Figure 2 It is a structural diagram of a device for calculating electromagnetic characteristics of a plasma-coated target provided by one embodiment of the present invention;

[0027] Figure 3is a hardware architecture diagram of a computer device provided by an embodiment of the present invention;

[0028] Figure 4 is a curve showing a change in transmittance with electromagnetic wave frequency for different plasma layer thicknesses provided by an embodiment of the present invention;

[0029] Figure 5 is a schematic diagram of the propagation trajectory of rays in electromagnetic waves provided by an embodiment of the present invention;

[0030] Figure 6 It is a schematic diagram of second area unit division and electromagnetic wave transmission provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0031] 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.

[0032] like Figure 4 As shown in the figure, the curve of the transmittance of electromagnetic waves in the plasma layer changes with the frequency of electromagnetic waves under different plasma layer thicknesses calculated by the inventor. It can be seen from the figure that when the plasma layer thickness is thin, some of the electromagnetic wave energy can actually pass through this part of the plasma, and the electromagnetic characteristic parameters of this part of the plasma are generally stronger. Therefore, if the electromagnetic characteristic information of this part of the plasma is lost during the simulation calculation, it will have a greater impact on the calculation of the overall electromagnetic characteristics of the plasma flow field.

[0033] Based on this, the inventors proposed that the electromagnetic characteristics of the plasma layer from the deflection point to the target surface can be equivalent to the deflection point to ensure the accuracy of the calculation results.

[0034] The specific implementation of the above concept is described below.

[0035] Please refer to Figure 1 , an embodiment of the present invention provides a method for calculating electromagnetic characteristics of a plasma-coated target, the method comprising:

[0036] Step 100, determining the ray trajectory and deflection point of the electromagnetic wave propagating in the plasma based on the ray tracing method;

[0037] Step 102, based on the ray trajectory and the deflection point, the transmission area of ​​the electromagnetic wave in the plasma is divided into three areas; the first area is from the starting point of the ray trajectory to the deflection point, the second area is from the deflection point to the target surface; the third area is from the deflection point to the end point of the ray trajectory;

[0038] Step 104, calculating the electromagnetic characteristics of the first region based on a ray tracing method to obtain first electromagnetic data at the deflection point;

[0039] Step 106, calculating second electromagnetic data of the second region based on the transmission line method;

[0040] Step 108, based on the first electromagnetic data, equate the second electromagnetic data to the deflection point to obtain equivalent electromagnetic data at the deflection point;

[0041] Step 110: Using the equivalent electromagnetic data as the starting data of the third region, and calculating the electromagnetic characteristics of the third region based on a ray tracing method to obtain the electromagnetic characteristics of the plasma-coated target.

[0042] In an embodiment of the present invention, after determining the outgoing ray trajectory and the deflection point, the transmission area of ​​the electromagnetic wave in the plasma is divided into three areas, wherein the first area and the third area are separated by the deflection point, and the second area is from the deflection point to the target surface, that is, the plasma layer on the target surface. After the electromagnetic characteristics of the first area and the second area are calculated respectively, on the basis of the calculation results of the first area, the calculation results of the second area are equivalent to the deflection point, and the equivalent electromagnetic data at the deflection point can be obtained. Finally, when calculating the electromagnetic characteristics of the third area, the equivalent electromagnetic data of the deflection point is used as the starting data, so that the electromagnetic characteristics of the thin layer of plasma on the target surface are taken into account in the overall electromagnetic characteristics calculation, and the final plasma-coated target electromagnetic characteristics are obtained. It can be seen from this that the present application can cover the electromagnetic characteristics of the thin layer of plasma on the target surface, and the calculated plasma-coated target electromagnetic characteristics are more accurate.

[0043] Described below Figure 1 How the various steps are performed.

[0044] First, step 100 includes:

[0045] Based on the flight altitude and flight speed of the target, the plasma parameters of the target are calculated based on a preset simulation model, and the plasma parameters include electron density and expansion frequency;

[0046] Based on the plasma parameters, the variation gradient of the plasma parameters on the ray path is calculated;

[0047] Determine the ray trajectory of the electromagnetic wave propagating in the plasma based on the frequency of the electromagnetic wave and the gradient of the change of the plasma parameters on the ray path;

[0048] The deflection point is determined based on the initial direction of the ray and the threshold of the gradient of the plasma parameter change on the ray path.

[0049] In this step, since the propagation path of the ray in the plasma is determined by the frequency of the electromagnetic wave and the change in the gradient of the plasma parameters on the ray path, it is necessary to first calculate the plasma parameters of the target based on the simulation model. Once the plasma parameters are determined, the gradient of the plasma parameters on the ray path can be determined, and then the ray trajectory of the electromagnetic wave propagating in the plasma can be determined. In addition, when the gradient change of the plasma parameters on the ray propagation path reaches a certain threshold, the ray propagation direction will be significantly deflected or even reversed. The point of obvious deflection is the deflection point. Figure 5 The figure shows a schematic diagram of the ray propagation trajectory.

[0050] In addition, in some embodiments, the Haselgrove equation in the plasma may be used to solve the ray propagation trajectory, that is, the following set of equations may be used to solve the ray trajectory:

[0051]

[0052] In the formula, x' is the propagation trajectory of the ray; P is the intermediate parameter, P = 1-n 2 , n is the refractive index of plasma; c is the speed of light in vacuum; ω is the frequency of electromagnetic wave; r, θ and They are the values ​​of the three coordinate axes in the spherical coordinate system, k r , k θ and They are the projections of the electromagnetic wave vector on the three coordinate axes of the spherical coordinate system.

[0053] For steps 104 to 110:

[0054] from Figure 5 It can be seen that based on the ray tracing method, the ray changes direction after reaching the deflection point, and will not pass through the area from the deflection point to the target surface. It is also impossible to calculate the electromagnetic characteristics of the area from the deflection point to the target surface, which affects the accuracy of the electromagnetic characteristic calculation results. Therefore, this application needs to separately calculate the electromagnetic characteristics of the area from the deflection point to the target surface, that is, the second area, and equate the calculation results to the deflection point. After the equivalence, continue to calculate the electromagnetic characteristics between the deflection point and the end point of the trajectory.

[0055] The specific process is as follows: along the ray trajectory, the electromagnetic characteristics of the first area are first calculated. When the ray propagates to the deflection point, the ray tracing path is first suspended. Then the electromagnetic characteristics of the second area, that is, between the deflection point and the target surface, are calculated, and the calculation results are equivalent to the deflection point, thereby obtaining the equivalent electromagnetic data at the deflection point. Finally, after the electromagnetic characteristics of the plasma thin layer are equivalent to the deflection point, the calculated reflected electric field intensity, phase shift and Doppler information are used as the initial data, and the deflection point is used as the starting point. The electromagnetic characteristics of the third area are continued to be calculated according to the ray tracing method, and the electromagnetic characteristics of the plasma-coated target can be obtained.

[0056] Specifically, with respect to step 106, calculating second electromagnetic data of the second region based on the transmission line method includes:

[0057] Taking the deflection point as the starting point, let the ray propagate along a straight line from the normal direction of the tangent plane of the deflection point to the target surface;

[0058] Along the propagation thickness direction of the ray, every two plasma layers are regarded as a unit;

[0059] For each unit, the following steps are performed: taking the movement speed of the second layer of plasma as the overall speed of the unit, taking the incident angle as 0°, and calculating the reflectivity and transmittance of the electromagnetic wave in the unit based on the transmission line method; based on the reflectivity and transmittance, calculating the reflected electric field intensity, phase shift and Doppler information of the unit;

[0060] The calculation is completed until the last unit is completed, and second electromagnetic data of the second area is obtained.

[0061] In this step, if Figure 6 As shown in the figure, it is a schematic diagram of the second area unit division and electromagnetic wave transmission. It can be seen from the figure that the right arrow represents the incident wave, the black dotted arrow is a schematic diagram of the reflection of the electromagnetic wave at the interface of each plasma layer, and the left arrow represents the incident unit reflected wave. Each unit includes two plasma layers. For each unit, the transmission line method is introduced to calculate the reflectivity and transmittance of the electromagnetic wave in the unit, so that the reflection characteristics of the plasma layer between the deflection point and the target surface can be obtained.

[0062] In some embodiments, the thickness of each plasma is equal to the step size of the ray tracing method.

[0063] In some embodiments, when the number of plasma layers in the second region is odd, the second plasma layer of the last unit is replaced by a metal layer, and the movement speed of the second plasma layer is the target movement speed.

[0064] This application has completed the improvement of the plasma-clad target modeling method based on ray tracing. Through the improvement, the thin plasma layer between the deflection point and the target surface can also be taken into account in the overall electromagnetic property calculation, making the electromagnetic property calculation results more accurate.

[0065] like Figure 2 , Figure 3 As shown, an embodiment of the present invention provides a device for calculating the electromagnetic properties of a plasma-coated target. The device embodiment can be implemented by software, or by hardware or a combination of software and hardware. From the hardware level, Figure 2 As shown, a hardware architecture diagram of a computing device where a computing device for calculating electromagnetic properties of a plasma-coated target provided by an embodiment of the present invention is located, except Figure 2 In 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 3 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 internal memory and runs it.

[0066] Please refer to Figure 3 , an embodiment of the present invention provides a device for calculating electromagnetic properties of a plasma-coated target, the device comprising:

[0067] A determination unit 300, for determining a ray trajectory and a deflection point of an electromagnetic wave propagating in a plasma based on a ray tracing method;

[0068] A division unit 302 is used to divide the transmission area of ​​the electromagnetic wave in the plasma into three areas based on the ray trajectory and the deflection point; the first area is from the starting point of the ray trajectory to the deflection point, the second area is from the deflection point to the target surface; and the third area is from the deflection point to the end point of the ray trajectory;

[0069] A first calculation unit 304 is used to calculate the electromagnetic characteristics of the first region based on a ray tracing method to obtain first electromagnetic data at a deflection point;

[0070] A second calculation unit 306, configured to calculate second electromagnetic data of a second region based on a transmission line method;

[0071] The third calculation unit 308 is used to convert the second electromagnetic data into equivalent electromagnetic data at the deflection point based on the first electromagnetic data, so as to obtain equivalent electromagnetic data at the deflection point;

[0072] The fourth calculation unit 310 is used to use the equivalent electromagnetic data as the starting data of the third region, calculate the electromagnetic characteristics of the third region based on the ray tracing method, and obtain the electromagnetic characteristics of the plasma-coated target.

[0073] In some implementations, the determining unit 300 is configured to perform the following operations:

[0074] Based on the flight altitude and flight speed of the target, the plasma parameters of the target are calculated based on a preset simulation model, and the plasma parameters include electron density and expansion frequency;

[0075] Based on the plasma parameters, the variation gradient of the plasma parameters on the ray path is calculated;

[0076] Determine the ray trajectory of the electromagnetic wave propagating in the plasma based on the frequency of the electromagnetic wave and the gradient of the change of the plasma parameters on the ray path;

[0077] The deflection point is determined based on the initial direction of the ray and the threshold of the gradient of the plasma parameter change on the ray path.

[0078] In some embodiments, the ray trajectories of electromagnetic waves propagating in plasma are obtained by solving the following set of equations:

[0079]

[0080] In the formula, x' is the propagation trajectory of the ray; P is the intermediate parameter, P = 1-n 2 , n is the refractive index of plasma; c is the speed of light in vacuum; ω is the frequency of electromagnetic wave; r, θ and They are the values ​​of the three coordinate axes in the spherical coordinate system, k r , k θ and They are the projections of the electromagnetic wave vector on the three coordinate axes of the spherical coordinate system.

[0081] In some implementations, the second computing unit 306 is configured to perform the following operations:

[0082] Taking the deflection point as the starting point, let the ray propagate along a straight line from the normal direction of the tangent plane of the deflection point to the target surface;

[0083] Along the propagation thickness direction of the ray, every two plasma layers are regarded as a unit;

[0084] For each unit, the following steps are performed: taking the movement speed of the second layer of plasma as the overall speed of the unit, taking the incident angle as 0°, and calculating the reflectivity and transmittance of the electromagnetic wave in the unit based on the transmission line method; based on the reflectivity and transmittance, calculating the reflected electric field intensity, phase shift and Doppler information of the unit;

[0085] The calculation is completed until the last unit is completed, and second electromagnetic data of the second area is obtained.

[0086] In some embodiments, the thickness of each plasma is equal to the step size of the ray tracing method.

[0087] In some embodiments, when the number of plasma layers in the second region is odd, the second plasma layer of the last unit is replaced by a metal layer, and the movement speed of the second plasma layer is the target movement speed.

[0088] It should be noted that: the device for calculating the electromagnetic characteristics of the plasma-coated target provided in the above embodiment is only illustrated by the division of the above functional modules. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above. In addition, the device for calculating the electromagnetic characteristics of the plasma-coated target provided in the above embodiment and the method for calculating the electromagnetic characteristics of the plasma-coated target are of the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.

[0089] The embodiment of the present application also provides a computer device, please refer to Figure 3 The computer device includes a processor and a memory, wherein the memory stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, at least one program, a code set or an instruction set is loaded and executed by the processor to implement the method for calculating the electromagnetic properties of a plasma-coated target provided by the above-mentioned method embodiments.

[0090] An embodiment of the present application also provides a computer-readable storage medium, on which is stored at least one instruction, at least one program, code set or instruction set, and the at least one instruction, at least one program, code set or instruction set is loaded and executed by a processor to implement the method for calculating the electromagnetic properties of a plasma-coated target provided by the above-mentioned method embodiments.

[0091] 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 the method for calculating the electromagnetic properties of a plasma-coated target as described in any of the above embodiments.

[0092] For the convenience of description, the above system or device is described by dividing it into various modules or units according to its functions. Of course, when implementing the present application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0093] It can be known from the description of the above implementation methods that those skilled in the art can clearly understand that the present application can be implemented by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of the present application can be essentially or partly contributed to the prior art in the form of a software product, which can be stored in a storage medium such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in the various embodiments of the present application or certain parts of the embodiments.

[0094] Finally, it should be noted that, in this article, relational terms such as first, second, third and fourth 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 elements in the process, method, article or device including the elements.

[0095] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for calculating electromagnetic properties of a plasma-coated target, characterized in that: The method comprises: Determine the ray trajectory and deflection point of electromagnetic waves propagating in plasma based on ray tracing method; Based on the ray trajectory and the deflection point, the transmission area of ​​the electromagnetic wave in the plasma is divided into three areas; the first area is from the starting point of the ray trajectory to the deflection point, the second area is from the deflection point to the target surface; the third area is from the deflection point to the end point of the ray trajectory; Calculate the electromagnetic characteristics of the first region based on a ray tracing method to obtain first electromagnetic data at the deflection point; Calculating second electromagnetic data of the second region based on a transmission line method; Based on the first electromagnetic data, the second electromagnetic data is equivalent to the deflection point to obtain equivalent electromagnetic data at the deflection point; The equivalent electromagnetic data is used as the starting data of the third region, and the electromagnetic characteristics of the third region are calculated based on a ray tracing method to obtain the electromagnetic characteristics of the plasma-coated target.

2. The method according to claim 1, characterized in that The method of determining the ray trajectory and deflection point of electromagnetic waves propagating in plasma based on the ray tracing method includes: Based on the flight height and flight speed of the target, the plasma parameters covering the target are calculated based on a preset simulation model, wherein the plasma parameters include electron density and expansion frequency; Based on the plasma parameters, calculating the change gradient of the plasma parameters on the ray path; Determining a ray trajectory of the electromagnetic wave propagating in the plasma based on the frequency of the electromagnetic wave and a change gradient of a plasma parameter on the ray path; The deflection point is determined based on the initial direction of the ray and the threshold of the gradient of the plasma parameter change on the ray path.

3. The method according to claim 1, characterized in that The ray trajectories of electromagnetic waves propagating in plasma are obtained by solving the following set of equations: Where x' is the propagation trajectory of the ray; P is the intermediate parameter, P = 1-n 2 , n is the refractive index of plasma; c is the speed of light in vacuum; ω is the frequency of electromagnetic wave; r, θ and They are the values ​​of the three coordinate axes in the spherical coordinate system, k r , k θ and They are the projections of the electromagnetic wave vector on the three coordinate axes of the spherical coordinate system.

4. The method according to claim 1, characterized in that The calculating the second electromagnetic data of the second area based on the transmission line method includes: Taking the deflection point as the starting point, the ray is propagated along a straight line from the normal direction of the tangent plane of the deflection point to the target surface; Along the propagation thickness direction of the ray, every two plasma layers are regarded as a unit; For each of the units, the following steps are performed: taking the movement speed of the second layer of plasma as the overall speed of the unit, taking the incident angle as 0°, and calculating the reflectivity and transmittance of the electromagnetic wave in the unit based on the transmission line method; and calculating the reflected electric field intensity, phase shift and Doppler information of the unit based on the reflectivity and the transmittance; After the last unit is calculated, the second electromagnetic data of the second area is obtained.

5. The method according to claim 4, characterized in that The thickness of each plasma is equal to the step size of the ray tracing method.

6. The method according to claim 5, characterized in that When the number of plasma layers in the second region is odd, the second plasma layer of the last unit is replaced by a metal layer, and the movement speed of the second plasma layer is the movement speed of the target.

7. A device for calculating electromagnetic properties of a plasma-coated target, characterized in that: The device comprises: A determination unit, used for determining the ray trajectory and deflection point of the electromagnetic wave propagating in the plasma based on the ray tracing method; A dividing unit, for dividing the transmission area of ​​the electromagnetic wave in the plasma into three areas based on the ray trajectory and the deflection point; the first area is from the starting point of the ray trajectory to the deflection point, the second area is from the deflection point to the target surface; the third area is from the deflection point to the end point of the ray trajectory; A first calculation unit, configured to calculate the electromagnetic characteristics of the first region based on a ray tracing method to obtain first electromagnetic data at the deflection point; A second calculation unit, configured to calculate second electromagnetic data of the second region based on a transmission line method; A third calculation unit is used for, based on the first electromagnetic data, converting the second electromagnetic data into equivalent electromagnetic data at the deflection point to obtain equivalent electromagnetic data at the deflection point; The fourth calculation unit is used to use the equivalent electromagnetic data as the starting data of the third region, calculate the electromagnetic characteristics of the third region based on the ray tracing method, and obtain the electromagnetic characteristics of the plasma-coated target.

8. A computer device, characterized in that: The computer device includes a memory and a processor, the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory to implement the steps of any one of the methods described in claims 1-6.

9. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method described in any one of claims 1 to 6 are implemented.

10. A computer program product, characterized in that The method comprises a computer program, wherein when the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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