A three-dimensional inhomogeneous plasma electromagnetic vortex scattering characteristics measurement system

Abstract

The present invention discloses a three-dimensional non-uniform plasma electromagnetic vortex scattering characteristic measurement system, comprising: a plasma generator; a control system connected to the plasma generator and configured to set discharge parameters of the plasma generator and transmit control commands to the plasma generator; the plasma generator generates a three-dimensional non-uniformly distributed plasma according to the received control commands; a vortex electromagnetic wave transmitting system configured to transmit a vortex electromagnetic wave transmission signal to the plasma generator; a vortex electromagnetic wave receiving system, wherein the vortex electromagnetic wave transmitting system and the vortex electromagnetic wave receiving system are located on the same side of the plasma generator; and the vortex electromagnetic wave receiving system is configured to receive the scattered signal of the fed-back vortex electromagnetic wave and obtain the scattering parameters of the plasma based on the scattered signal. The present invention can simulate the distribution of non-uniform plasma and obtain the influence of complex plasma on the propagation of vortex electromagnetic waves.

Description

Technical Field

[0001] The present invention relates to the technical field of measuring vortex electromagnetic wave scattering characteristics, and in particular to a three-dimensional non-uniform plasma electromagnetic vortex scattering characteristic measuring system. Background Art

[0002] While plasma appears electrically neutral overall, its charged particles (primarily free electrons) absorb, reflect, and scatter electromagnetic waves, producing an effect similar to metal shielding, causing electromagnetic signal attenuation, phase shifts, and dispersion. These effects can severely attenuate and shift the microwave signal amplitude, leading to interruptions in the transmission link and detection signal. The complex properties of inhomogeneous plasma are a significant factor in degrading detection and identification quality. Even in the absence of inhomogeneous plasma, electromagnetic waves passing through a dynamically changing random medium can cause signal quality degradation. Inhomogeneous plasma exhibits complex properties due to factors such as target maneuvers, incident angle variations, complex flow field changes, thermal shielding material ablation, and random environmental variations. These complex properties can cause the electromagnetic signal to experience severe amplitude jitter (amplitude noise) and phase jitter (phase noise). This can also alter the antenna's impedance and radiation characteristics, potentially causing the acquisition and tracking loops in the information receiving system to fail, leading to information transmission interruptions similar to blackouts.

[0003] Currently, there are several main ways to simulate plasma sheaths. One is the high cost of wind tunnels, ballistic targets and other tests, but there is no way to build a complex plasma sheath environment; another is the glow discharge plasma ground simulation device, but due to the limitations of the cavity, it is impossible to simulate the characteristics of the non-uniform distribution of electron density in the plasma sheath, which is suitable for studying and verifying some basic characteristics of plasma; and there is also a plasma cannon, which can build a high-speed moving plasma environment, but it is difficult to detect high-speed moving plasma clusters. Summary of the Invention

[0004] The purpose of the present invention is to provide a three-dimensional inhomogeneous plasma electromagnetic vortex scattering characteristics measurement system that can measure the scattering parameters of vortex electromagnetic waves in inhomogeneous complex plasmas, thereby obtaining the influence of complex plasma on the propagation of vortex electromagnetic waves.

[0005] In order to achieve the above objectives, the present invention is implemented through the following technical solutions:

[0006] A three-dimensional non-uniform plasma electromagnetic vortex scattering characteristic measurement system comprises: a plasma generator; a control system connected to the plasma generator and configured to set discharge parameters of the plasma generator and transmit control commands to the plasma generator; the plasma generator generates a three-dimensional non-uniformly distributed plasma according to the received control commands; a vortex electromagnetic wave transmitting system configured to transmit a vortex electromagnetic wave transmission signal to the plasma generator; and a vortex electromagnetic wave receiving system, the vortex electromagnetic wave transmitting system and the vortex electromagnetic wave receiving system being located on the same side of the plasma generator; the vortex electromagnetic wave receiving system configured to receive a feedback vortex electromagnetic wave scattering signal and, based on the scattering signal, obtain a scattering parameter of the vortex electromagnetic wave transmission signal in the plasma.

[0007] Optionally, the plasma generator includes: a blunt cone target, which is divided into a head and a tail along its axial direction; a first annular plasma tube group, which is nested on the surface of the head; and a second annular plasma tube group, which is nested on the surface of the tail.

[0008] Optionally, the first annular plasma tube group includes multiple layers of first annular plasma tubes, which are arranged in a radially stacked manner along the head; the second annular plasma tube group includes a single layer of second annular plasma tubes, which are arranged axially along the tail; the diameter of the first annular plasma tube is smaller than the diameter of the second annular plasma tube; each of the first annular plasma tubes and each of the second annular plasma tubes is connected to the control system.

[0009] Optionally, the discharge parameters are set according to plasma density distribution, including the discharge current, discharge power and discharge voltage of each of the first annular plasma tubes and each of the second annular plasma tubes.

[0010] Optionally, the plasma generator further comprises: a vacuum pump, an air chamber, an electrode, a probe and a three-way pipe fitting; and the control system comprises an atmosphere mode control system, a control power supply and a computer terminal; each of the first annular plasma tubes and each of the second annular plasma tubes is provided with a gas injection port; one of the pipe openings of the three-way pipe fitting is connected to the gas injection port, and the other two pipe openings are respectively connected to the vacuum pump and the air inlet of the air chamber; the vacuum pump is used to adjust the air pressure in the corresponding first annular plasma tube or the second annular plasma tube to a preset value; the air chamber is connected to the atmosphere mode control system, and the atmosphere mode control system is used to control the discharge gas and air pressure introduced into the air chamber, so as to obtain a gas in the air chamber. A mixed gas having a mixing ratio that meets a preset value is introduced into the corresponding first annular plasma tube and the second annular plasma tube; the electrodes and the probe are provided at both ends of each of the first annular plasma tube and each of the second annular plasma tubes; the electrodes are connected to the control power supply, and the control power supply controls the electrode discharge according to preset discharge parameters to ionize the discharge gas in the corresponding first annular plasma tube or the second annular plasma tube to generate the plasma; the probe is connected to the computer terminal, and the probe is used to collect the plasma density in the corresponding first annular plasma tube or the second annular plasma tube and send it to the computer terminal for display.

[0011] Optionally, the air inlet of the air chamber is provided with ablative diffusion powder, and the ablative diffusion powder can be brought into the corresponding first or second annular plasma tube by the air flow in the air chamber.

[0012] Optionally, it also includes: a control machine, which is connected to the vortex electromagnetic wave transmitting system and the vortex electromagnetic wave receiving system respectively, and the control machine is used to control the vortex electromagnetic wave transmitting system to generate a vortex electromagnetic wave transmitting signal of a preset mode in real time; it is also used to collect the scattered signal received by the vortex electromagnetic wave receiving system in real time, and calculate the scattering parameter based on the scattered signal.

[0013] Optionally, the vortex electromagnetic wave transmitting system and the vortex electromagnetic wave receiving system are separated by a distance of 2.5 m from the plasma generator.

[0014] Optionally, it further includes: a focusing lens, which is arranged between the vortex electromagnetic wave emission system and the plasma generator, and the focusing lens is used to focus the vortex electromagnetic wave emission signal.

[0015] Optionally, the ratio of the axial length of the head portion to the axial length of the tail portion is 1:2.

[0016] The present invention has at least one of the following advantages:

[0017] The present invention provides a three-dimensional non-uniform plasma electromagnetic vortex scattering characteristic measurement system, the main function of which is to use vortex electromagnetic waves to detect non-uniform complex plasma environments, and to detect and identify non-uniform plasma sheaths by measuring the scattering parameters of vortex electromagnetic waves in complex plasmas. Based on a fully digital multi-channel controlled plasma generator, different targets are covered to achieve the construction of a non-uniform complex plasma environment (the detection of complex plasmas is real-time, non-uniform, dynamic, and complex). At the same time, vortex electromagnetic waves are used to detect targets, and different non-uniform plasma sheath distributions are achieved by adjusting parameters such as the discharge parameters, discharge atmosphere mode, and discharge power of the plasma generator. The measurement of the scattering parameters of vortex electromagnetic waves in complex plasmas is studied, that is, dynamic simulation measurement of the scattering characteristics of electromagnetic vortex waves in three-dimensional non-uniform plasmas is achieved, thereby obtaining the influence of complex plasma on the propagation of vortex electromagnetic waves.

[0018] The three-dimensional non-uniform plasma electromagnetic vortex scattering characteristic measurement system provided by the present invention has the advantages of controllable ionization process, long process maintenance time, controllable electron density, non-destructiveness and low cost, which provides a basis for the study of the electromagnetic characteristics of the plasma of ultra-high sound speed target ablation diffusion. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic structural diagram of a system for measuring electromagnetic vortex scattering characteristics of a three-dimensional non-uniform plasma according to one embodiment of the present invention;

[0020] Figure 2 A schematic structural diagram of a plasma generator provided in one embodiment of the present invention;

[0021] Figure 3 A schematic structural diagram of a fully digital multi-channel control system provided by one embodiment of the present invention;

[0022] Figure 4 A schematic diagram showing changes in electron density at the center of a plasma tube as a function of discharge voltage according to an embodiment of the present invention;

[0023] Figure 5 An embodiment of the present invention adopts Figure 1 The diagram shows a flow chart of the method for using the three-dimensional non-uniform plasma electromagnetic vortex scattering characteristics measurement system. DETAILED DESCRIPTION

[0024] The following is a further detailed description of a three-dimensional non-uniform plasma electromagnetic vortex scattering characteristic measurement system proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the drawings are in a very simplified form and all use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purposes, features and advantages of the present invention more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no technical significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose that can be achieved by the present invention.

[0025] Vortex electromagnetic waves radiate not only linear momentum but also angular momentum, providing a new, orthogonal, infinite dimension of electromagnetic waves beyond the time, frequency, spatial, or polarization domains. Unlike traditional electromagnetic wavefronts, vortex electromagnetic wavefronts exhibit a spatial spiral equiphase distribution, enhancing the electromagnetic wave's ability to transmit and acquire information. Therefore, the present invention can leverage the unique spatial distribution of vortex electromagnetic waves to measure the scattering properties of inhomogeneous, complex plasmas.

[0026] Plasma sheaths significantly impact electromagnetic signals, preventing accurate target detection and identification. When a non-uniform plasma sheath interacts with vortex electromagnetic waves, it exhibits unique scattering properties. This principle of azimuth imaging of targets by vortex electromagnetic waves can be exploited to detect non-uniform and complex plasmas. Complex non-uniform plasma sheaths reflect, refract, and absorb incident vortex electromagnetic waves. Therefore, building a non-uniform plasma electromagnetic vortex scattering property measurement system can enable detection and identification of non-uniform and complex plasma environments using vortex electromagnetic waves.

[0027] like Figure 1 As shown, this embodiment provides a three-dimensional non-uniform plasma electromagnetic vortex scattering characteristic measurement system, including: a plasma generator 100; a control system connected to the plasma generator 100, which is used to set the discharge parameters of the plasma generator 100 and send control commands to the plasma generator 100; the plasma generator 100 generates a three-dimensional non-uniformly distributed plasma according to the received control commands.

[0028] The vortex electromagnetic wave transmitting system 201 is used to transmit a vortex electromagnetic wave transmitting signal to the plasma generator 100 .

[0029] The vortex electromagnetic wave receiving system 202 is located on the same side of the plasma generator 100 as the vortex electromagnetic wave transmitting system 201. The vortex electromagnetic wave receiving system 202 is configured to receive the scattered signal of the feedback vortex electromagnetic wave and obtain the scattering parameters based on the scattered signal. In this embodiment, plasma is generated by plasma tube discharge. The vortex electromagnetic wave transmitting and receiving antennas are placed on the same side of the plasma generator. By processing the received signal, clutter signals can be effectively eliminated and the scattered signal of the plasma can be extracted.

[0030] Please continue to refer to Figure 1 As shown, this embodiment also includes: a control machine 203, which is connected to the vortex electromagnetic wave transmitting system 201 and the vortex electromagnetic wave receiving system 202 respectively, and the control machine 203 is used to control the vortex electromagnetic wave transmitting system 201 to generate a vortex electromagnetic wave transmitting signal of a preset mode in real time; the control machine 203 is also used to collect the scattered signal received by the vortex electromagnetic wave receiving system 202 in real time, and calculate the scattering parameter of the vortex electromagnetic wave (it can be understood that the vortex electromagnetic wave and the vortex electromagnetic wave transmitting signal are the same, and the vortex electromagnetic wave transmitting signal is called the vortex electromagnetic wave transmitting signal only to illustrate that it is the emitted vortex electromagnetic wave) in the plasma (the complex plasma simulated by the plasma generator 100) according to the scattered signal. According to the scattering parameter, the influence of the complex plasma on the propagation of the vortex electromagnetic wave is obtained.

[0031] Preferably, the straight-line distance between the vortex electromagnetic wave transmitting system 201 , the vortex electromagnetic wave receiving system 202 and the plasma generator 100 is 2.5 m.

[0032] In some embodiments, the vortex electromagnetic wave transmitting antenna in the vortex electromagnetic wave transmitting system 201 and the vortex electromagnetic wave receiving antenna in the vortex electromagnetic wave receiving system 202 are placed on the same side of the plasma generator 100, 2.5 meters away from the plasma generator. The vortex electromagnetic wave transmitting antenna and receiving antenna can each be composed of eight circular array antennas, which can generate multi-modal vortex electromagnetic waves.

[0033] Please continue to refer to Figure 1 As shown, this embodiment further includes placing a focusing lens 300 in front of the transmitting antenna to focus the antenna signal (vortex electromagnetic wave transmission signal) emitted by the transmitting antenna. The focusing lens 300 is placed between the transmitting antenna and the plasma generator 100 to focus the transmission signal. By adjusting the position of the focusing lens 300 and observing the changes in the received signal, the plasma generator 100 is ensured to be at the focus of the focusing lens 300.

[0034] The distance between the vortex electromagnetic wave receiving antenna and the transmitting antenna, as well as the distance between the transmitting antenna, the receiving antenna and the plasma generator 100 are initially adjusted. By processing the received signal, a distance image is obtained. Compared with the position of the plasma generator 100, the positions of the transmitting antenna and the receiving antenna are adjusted again to determine that the received signal is the scattered signal.

[0035] Combine Figure 1 and Figure 2 As shown, the plasma generator 100 includes a blunt cone target 120, which is divided into a head portion and a tail portion along its axial direction. Preferably, the ratio of the axial length L1 of the head portion to the axial length L2 of the tail portion is 1:2; a first annular plasma tube group 121, which is embedded on the surface of the head portion; and a second annular plasma tube group 122, which is embedded on the surface of the tail portion.

[0036] In this embodiment, the first annular plasma tube group includes multiple layers of first annular plasma tubes, which are stacked radially along the head; the second annular plasma tube group includes a single layer of second annular plasma tubes, which are arranged axially along the tail; the diameter of the first annular plasma tube is smaller than the diameter of the second annular plasma tube; each of the first annular plasma tubes and each of the second annular plasma tubes is connected to the control system.

[0037] Since the plasma density is unevenly distributed, a multi-layer annular plasma tube is arranged at the blunt cone target head, and a single-layer annular plasma tube is arranged at the rest of the target according to the density distribution. The discharge state in the tube is set according to the density distribution. The electron density at the center of the annular plasma tube changes with the discharge voltage as shown in the following figure: Figure 4 As shown: the greater the power, the greater the plasma electron density produced.

[0038] Due to the distribution characteristics of the plasma sheath, the electron density is higher at the head, so a two-layer plasma tube is set, but the plasma tube diameter is 1 cm; the electron density is lower at the middle and tail ends, so a single-layer plasma tube is set, and the plasma tube diameter is 3 cm. This shows that according to the distribution characteristics of the plasma sheath, multi-layer plasma tubes are set in areas with higher electron density, and single-layer plasma tubes are set in areas with lower electron density, and the diameter of the plasma tubes in these areas is larger than that in areas with higher electron density.

[0039] In this embodiment, the discharge parameters are set according to the plasma density distribution, including the discharge current, discharge power and discharge voltage of each of the first annular plasma tubes and each of the second annular plasma tubes.

[0040] Specifically, based on the previous flow field simulation calculation results, the spatial distribution of non-uniform complex plasma electron density is obtained, the mean plasma density in each plasma tube area is obtained according to the grid division, and the corresponding discharge current, discharge power and discharge voltage are set.

[0041] Please continue to refer to Figure 1 As shown, the plasma generator 100 further includes: a vacuum pump ( Figure 1 Not shown), air chamber ( Figure 1 Not shown), electrodes ( Figure 1 Not shown), probe ( Figure 1 Not shown) and tee fittings ( Figure 1 and the control system includes a digital control system 102 (digital control system 102 includes an atmosphere mode control system ( Figure 1 Not shown) and control power supply ( Figure 1 ) and a computer terminal 103. Figure 1 Components not shown in the figure may use components existing in the prior art, and the present invention is not limited thereto.

[0042] Each of the first annular plasma tubes and each of the second annular plasma tubes is provided with a gas injection port; one of the pipe ports in the three-way pipe fitting is connected to the gas injection port, and the other two pipe ports are respectively connected to the vacuum pump and the gas inlet of the gas chamber.

[0043] The vacuum pump is used to adjust the gas pressure in the corresponding first annular plasma tube or the second annular plasma tube to a preset value.

[0044] The gas chamber is connected to the atmosphere mode control system, and the atmosphere mode control system is used to control the discharge gas and air pressure introduced into the gas chamber, so as to obtain a mixed gas in the gas chamber with a mixing ratio that meets a preset value, and the mixed gas is introduced into the corresponding first annular plasma tube and the second annular plasma tube.

[0045] The electrodes and the probe are provided at both ends of each of the first annular plasma tubes and each of the second annular plasma tubes.

[0046] The electrode is connected to the control power supply, and the control power supply controls the electrode to discharge according to preset discharge parameters to ionize the discharge gas in the corresponding first annular plasma tube or the second annular plasma tube to generate the plasma.

[0047] The probe is connected to the computer terminal 103 , and is used to collect the plasma density in the corresponding first annular plasma tube or the second annular plasma tube, and send it to the computer terminal 103 for display.

[0048] Each annular plasma tube is enclosed, with electrodes, air tubes, and probes on either side. The electrodes are connected to the control power supply via wires, the air tubes to the vacuum pump, and the probes to the probe computer terminal 103. Each plasma tube is independent, nestled above a blunt cone target. The plasma tubes are not interconnected, but are each connected separately to the control power supply. The air tubes are directly connected to the vacuum pump, and the probes are also connected separately to the computer terminal 103. The control power supply switches all annular plasma tubes on and off.

[0049] In this or other embodiments, the air inlet of the gas chamber is provided with ablative diffusion powder, which can be carried by the airflow within the gas chamber into the corresponding first or second annular plasma tube. The ablative diffusion particles are rapidly charged in the discharge annular plasma tube, affecting the incidence of the vortex electromagnetic wave.

[0050] In order to simulate the impact of the products of surface thermal protection material ablation on plasma when the target is in high-speed flight, ablative diffusion powder can be placed at the gas injection port of the gas chamber. The ablative material can be brought into the plasma generator during the movement of the airflow, thereby realizing the construction of a complex ablative diffusion plasma environment.

[0051] Specifically, the powder is pressed into a thin sheet using a mold (not too much pressure, just enough to form the sheet). The diameter of the sheet is the same as the diameter of the gas injection port in the gas chamber. After placing it in the gas injection port, the air pump is turned on. Due to the pressure difference between the inside and outside, the gas enters the annular plasma tube of the plasma generator, dragging the powder into it. (Understandably, this pressure difference is quite large, and the instantaneous pressure is very high, which can instantly break the powder sheet and drag it into the air tube.)

[0052] Please continue to refer to Figure 1 As shown, 1 to n refer to the annular plasma tubes, the 1st, 2nd, and nth. The annular plasma tubes are connected in parallel, and the control system can control each annular plasma tube, including parameters such as switching, discharge power, and gas pressure.

[0053] like Figure 3 As shown, the digital control system 102 includes an atmosphere mode control system ( Figure 1 Not shown) and control power supply ( Figure 3 The power module 1021 and the power chip 1022 in the computer terminal 103.

[0054] Specifically, the digital control system 102 further includes: a digital-to-analog converter 1023, an analog-to-digital converter 1025 and an operational amplifier 1024;

[0055] The power module 1021 is electrically connected to each annular plasma tube in the plasma generator 100;

[0056] The power chip 1022 is connected to the power module 1021 and the digital-to-analog converter 1023 respectively; the digital-to-analog converter 1023 is connected to the computer terminal 103;

[0057] The operational amplifier 1024 is connected to the power chip 1022 and the analog-to-digital converter 1025 respectively, and the analog-to-digital converter 1025 is connected to the computer terminal 103 .

[0058] The computer terminal 103 issues a control command, and the digital-to-analog converter 1023 converts the digital signal of the control command into an analog signal (electrical signal). The power chip 1022 controls the switch of the power module according to the received electrical signal, thereby controlling the switch of each corresponding annular plasma tube and controlling the density of the plasma in the tube.

[0059] The operational amplifier 1024 is used to amplify the electrical signal of the control end, and the analog-to-digital converter 1025 is used to perform analog-to-digital conversion on the amplified electrical signal and send it to the computer terminal 103; the computer terminal 103 is used to control the parameters of the plasma generator 100 according to the electrical signal after the analog-to-digital conversion.

[0060] like Figure 5 As shown in the figure, a plasma environment created by a fully digital multi-channel controlled plasma generator was tested. First, the electromagnetic characteristics of a single-layer plasma tube were analyzed. The digital control system controlled the plasma tube output power to various values, varying from 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0 of the total power, to simulate the electromagnetic characteristics of the plasma environment. Reference data was also tested with the plasma tube in the off state. Based on the equivalent formula for the plasma dielectric constant, the minimum error fitting method was used to obtain the relationships between the plasma frequency, collision frequency, and equivalent electron density parameters.

[0061] A double-layer plasma tube was placed at the head of the blunt cone target (but the present invention is not limited to this), and electromagnetic testing in a simulated plasma environment was also conducted using a digital control system. Because the plasma density at the head is higher than at the tail of the blunt cone, the discharge power of the double-layer plasma tube at the head is the highest, while the discharge power of the single-layer plasma tube at the tail is the lowest.

[0062] The specific operations are as follows:

[0063] Step S1: Turn on the control power of the plasma generator and check the working status of each part of the plasma generator.

[0064] Step S2: Open the gas cylinder, open the gas chamber valve, and inject gas into the gas chamber.

[0065] Step S3: If a mixed gas is selected, the gas chamber needs to be pre-vacuumed. After injecting one gas, it is evacuated to a preset value, and then the second gas is injected. Then the pressure is reduced to the preset value, and the third gas is injected, and so on, until the mixing ratio meets the predetermined value.

[0066] Step S4, turn on the vacuum pump, pre-evacuate the corresponding annular plasma tube, and inject the gas in the gas chamber after the air pressure in the tube reaches the lower limit. To ensure that no air remains in the annular plasma tube, the above operation can be repeated (specifically, step S4 can be repeated) until all the impurity gases in the annular plasma tube are discharged.

[0067] Step S5: Setting the discharge parameters of the corresponding annular plasma tubes. Specifically, the discharge current, discharge power, and discharge voltage of each annular plasma tube are set in the computer terminal.

[0068] The step S5 includes: obtaining the non-uniform complex plasma electron density spatial distribution based on the previous flow field simulation calculation results, obtaining the mean plasma density in each plasma tube area based on grid division, and setting the corresponding discharge current, discharge power and discharge voltage of each annular plasma tube. The corresponding plasma generator can form a corresponding non-uniform complex plasma electron density spatial distribution.

[0069] Step S6: Turn on the control machine of the vortex electromagnetic wave antenna, check the status of the transmitting antenna and the receiving antenna, and after confirming that the connection is normal, select the mode, frequency band and other parameters of the transmitted vortex electromagnetic wave in the control bar of the control machine, and set the receiving antenna parameters at the same time to remove background signals and other clutter signals.

[0070] Step S7: Place the focusing lens between the transmitting antenna and the plasma generator to focus the transmitting signal. By adjusting the position of the focusing lens and observing the change of the received signal, ensure that the position of the plasma generator is at the focus.

[0071] Step S8: Preliminary adjustment is performed on the distance between the incident antenna and the transmitting antenna of the vortex electromagnetic wave, as well as the distance between the antenna and the plasma generator. By processing the received signal, a distance image is obtained, which is compared with the position of the plasma generator. The antenna position is adjusted again to determine that the received signal is a scattered signal.

[0072] Step S9, click "discharge" switch on the cabinet of control power supply, corresponding annular plasma tube discharges, and ionizes the discharge gas in the tube to produce plasma. After the discharge state is stable, the received signal of vortex electromagnetic wave is observed. According to the received signal received by the vortex electromagnetic wave receiving antenna, vortex electromagnetic wave near-field scattering parameters are measured. It can be seen from this that, based on the plasma generator of full digital multi-channel control, different targets are covered, and non-uniform complex plasma environment is constructed, while vortex electromagnetic wave is used to detect target, by adjusting the parameters such as discharge parameter, discharge atmosphere mode and discharge power of plasma generator, different non-uniform plasma sheaths are distributed, and the scattering parameter measurement of vortex electromagnetic wave in complex plasma is studied.

[0073] Step S10: Click the "Discharge" switch again to stop the annular plasma tube from discharging. Close the gas chamber valve and the vacuum pump. After the pressure in the annular plasma tube returns to normal atmospheric pressure, open the gas chamber and place weighed ablation diffusion powder at the gas injection port of the gas chamber. The powder has been ablated and sieved, and its particle size and density are the same as those of the ablation diffusion in the actual test environment. Close the gas injection port of the gas chamber.

[0074] Repeating steps S2-S9, the ablated diffusion particles now enter the plasma generator along with the airflow from the gas chamber. In the discharged plasma, they are rapidly charged, affecting the incidence of the vortex electromagnetic wave. This creates a complex ablated diffusion plasma environment, and the near-field scattering parameters of the vortex electromagnetic wave are measured based on the received signal from the vortex electromagnetic wave receiving antenna.

[0075] Next, the process proceeds to steps S10 and S11. Step S10 shuts down the plasma generator, while step S11 opens the air chamber for cleaning. Any remaining ablation and diffusion powder is removed. After cleaning, the plasma generator is turned on again, and air is used to remove any remaining ablation and diffusion particles from the annular plasma tube, eliminating any potential impact on the next test.

[0076] In summary, the three-dimensional non-uniform plasma electromagnetic vortex scattering characteristic measurement system provided in this embodiment has the main function of using vortex electromagnetic waves to detect non-uniform complex plasma environments, and by measuring the vortex electromagnetic wave scattering parameters, the detection and identification of non-uniform plasma sheaths can be achieved. Based on a fully digital multi-channel controlled plasma generator, different targets are covered to achieve the construction of a non-uniform complex plasma environment. At the same time, vortex electromagnetic waves are used to detect targets. By adjusting the discharge parameters, discharge atmosphere mode, and discharge power of the plasma generator, different non-uniform plasma sheath distributions are achieved, and the measurement of the scattering parameters of vortex electromagnetic waves in complex plasmas is studied. That is, the dynamic simulation measurement of the scattering characteristics of electromagnetic vortex waves of three-dimensional non-uniform plasmas is realized, thereby obtaining the influence of complex plasma on the propagation of vortex electromagnetic waves.

[0077] That is, this embodiment provides a plasma generator based on fully digital multi-channel control and builds a vortex electromagnetic wave scattering parameter measurement system in complex plasma, thereby realizing the detection of non-uniform complex plasma by vortex electromagnetic waves.

[0078] The three-dimensional non-uniform plasma electromagnetic vortex scattering characteristic measurement system provided in this embodiment has the advantages of controllable ionization process, long process maintenance time, controllable electron density, non-destructiveness and low cost, and provides a basis for the study of the electromagnetic characteristics of the plasma of ultra-high sound speed target ablation diffusion.

[0079] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0080] In the description of the present invention, it should be understood that the terms "center," "height," "thickness," "up," "down," "vertical," "horizontal," "top," "bottom," "inside," "outside," "axial," "radial," "circumferential," and the like, indicating positions or location relationships, are based on the positions or location relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0081] In the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0082] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0083] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A three-dimensional non-uniform plasma electromagnetic vortex scattering characteristics measurement system, characterized in that: include: plasma generator; a control system connected to the plasma generator and configured to set discharge parameters of the plasma generator and transmit control commands to the plasma generator; The plasma generator generates three-dimensional non-uniformly distributed plasma according to the received control command; A vortex electromagnetic wave transmitting system, used for transmitting a vortex electromagnetic wave transmitting signal to the plasma generator; A vortex electromagnetic wave receiving system, wherein the vortex electromagnetic wave transmitting system and the vortex electromagnetic wave receiving system are located on the same side of the plasma generator; The vortex electromagnetic wave receiving system is used to receive the scattered signal of the fed-back vortex electromagnetic wave, and obtain the scattering parameter of the vortex electromagnetic wave emission signal in the plasma according to the scattered signal; A control machine, which is connected to the vortex electromagnetic wave transmitting system and the vortex electromagnetic wave receiving system respectively, and is used to control the vortex electromagnetic wave transmitting system to generate a vortex electromagnetic wave transmitting signal of a preset mode in real time; It is also used to collect the scattered signals received by the vortex electromagnetic wave receiving system in real time, and calculate the scattering parameters according to the scattered signals.

2. The three-dimensional inhomogeneous plasma electromagnetic vortex scattering characteristics measurement system according to claim 1, characterized in that: The plasma generator comprises: a blunt cone target, wherein the blunt cone target is divided into a head portion and a tail portion along its axial direction; a first annular plasma tube group nested on the surface of the head; A second annular plasma tube group is nested on the surface of the tail portion.

3. The three-dimensional non-uniform plasma electromagnetic vortex scattering characteristics measurement system according to claim 2, characterized in that: The first annular plasma tube group includes multiple layers of first annular plasma tubes, and the multiple layers of first annular plasma tubes are stacked and arranged along the radial direction of the head; The second annular plasma tube group includes a single-layer second annular plasma tube, and the single-layer second annular plasma tube is arranged along the axial direction of the tail; The diameter of the first annular plasma tube is smaller than the diameter of the second annular plasma tube; Each of the first annular plasma tubes and each of the second annular plasma tubes is connected to the control system.

4. The three-dimensional non-uniform plasma electromagnetic vortex scattering characteristics measurement system according to claim 3, characterized in that: The discharge parameters are set according to the plasma density distribution, including the discharge current, discharge power and discharge voltage of each of the first annular plasma tubes and each of the second annular plasma tubes.

5. The three-dimensional non-uniform plasma electromagnetic vortex scattering characteristics measurement system according to claim 4, characterized in that: The plasma generator further comprises: a vacuum pump, a gas chamber, an electrode, a probe and a three-way pipe fitting; and the control system comprises an atmosphere mode control system, a control power supply and a computer terminal; Each of the first annular plasma tubes and each of the second annular plasma tubes is provided with a gas injection port; One of the three-way pipe openings is connected to the gas injection port, and the other two openings are connected to the vacuum pump and the gas inlet of the gas chamber respectively; The vacuum pump is used to adjust the gas pressure in the corresponding first annular plasma tube or the second annular plasma tube to a preset value; The gas chamber is connected to the atmosphere mode control system, and the atmosphere mode control system is used to control the discharge gas and gas pressure introduced into the gas chamber, so as to obtain a mixed gas in the gas chamber with a mixing ratio that meets a preset value, and to introduce the mixed gas into the corresponding first annular plasma tube and the second annular plasma tube; The electrodes and the probe are provided at both ends of each of the first annular plasma tubes and each of the second annular plasma tubes; The electrode is connected to the control power supply, and the control power supply controls the electrode to discharge according to preset discharge parameters to ionize the discharge gas in the corresponding first annular plasma tube or the second annular plasma tube to generate the plasma; The probe is connected to the computer terminal, and is used to collect the plasma density in the corresponding first annular plasma tube or the second annular plasma tube, and send it to the computer terminal for display.

6. The three-dimensional non-uniform plasma electromagnetic vortex scattering characteristics measurement system according to claim 5, characterized in that: The air inlet of the air chamber is provided with ablative diffusion powder, and the ablative diffusion powder can be brought into the corresponding first annular plasma tube or second annular plasma tube by the air flow in the air chamber.

7. The three-dimensional non-uniform plasma electromagnetic vortex scattering characteristics measurement system according to claim 1, characterized in that: The vortex electromagnetic wave transmitting system and the vortex electromagnetic wave receiving system are separated by a distance of 2.5 m from the plasma generator.

8. The three-dimensional non-uniform plasma electromagnetic vortex scattering characteristics measurement system according to claim 1, characterized in that: Also includes: A focusing lens is provided between the vortex electromagnetic wave emission system and the plasma generator, and is used for focusing the vortex electromagnetic wave emission signal.

9. The three-dimensional non-uniform plasma electromagnetic vortex scattering characteristic measurement system according to claim 2, characterized in that: The ratio of the axial length of the head portion to the axial length of the tail portion is 1:2.

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