A dual-channel wave-absorbing device based on a plasma composite material

Abstract

The application discloses a kind of dual-channel wave-absorbing devices based on plasma composite material, it is related to plasma application field, device includes: metal base, first wave-absorbing material layer, plasma array, second wave-absorbing material layer, first isolation protection layer and second isolation protection layer;First wave-absorbing material layer is set on the upper surface of metal base;First wave-absorbing material layer top is equipped with plasma array;The top of plasma array is equipped with second wave-absorbing material layer;First isolation protection layer and second isolation protection layer are set on the two sides of plasma array;Two wave-absorbing material layers and two isolation protection layers constitute cavity structure;Plasma array is set in cavity structure, so that plasma array is in the cavity formed by wave-absorbing material layer, conducive to the generation and maintenance of plasma electron density, to improve wave-absorbing effect and wave-absorbing performance, in addition, using plasma and wave-absorbing material layer combination forms composite dual-channel wave-absorbing structure, greatly improve wave-absorbing performance.

Description

Technical Field

[0001] This invention relates to the field of low-temperature plasma application technology, and in particular to a dual-channel absorbing device based on plasma composite materials. Background Technology

[0002] The widespread use of radar in modern military applications has made it an important detection tool. Radar stealth has naturally become an important stealth technology, and it has always been a research hotspot in the field of space exploration. Plasma stealth technology is gradually moving from the laboratory to practical application, and its applications are expanding from the aviation field to stealth for naval vessels and ground weapons.

[0003] Achieving low observability of targets in increasingly complex electromagnetic environments is a crucial issue that must be considered when designing various equipment systems. The key to radar stealth is primarily reducing the target's radar cross-section to a level undetectable by radar receivers. Common methods for reducing radar cross-section include loading radar-absorbing materials onto the target surface to reduce detection echoes or modifying the object's geometry to redirect scattered waves away from the backscattering direction.

[0004] Achieving radar stealth through target reshaping is an extremely challenging engineering project with very high design costs. It is often only applicable to a small number of critical devices, and the shape design does not effectively achieve stealth at lower frequencies. Applying radar-absorbing materials to the target surface is a common method to reduce radar cross-section. Traditional ferrite and carbon-based radar-absorbing materials can only effectively absorb electromagnetic waves in specific frequency bands and angles. Furthermore, radar-absorbing material coatings are very thick, making it difficult to absorb X-band microwaves. Therefore, thin-layer radar-absorbing materials are not suitable for reducing radar cross-section over a wide frequency range. Since plasma can absorb electromagnetic waves over a wide frequency range and is easy to control, plasma stealth is used to reduce the electromagnetic wave reflection of targets.

[0005] Much of the research on plasma stealth revolves around open-plate plasma covering metal plates. However, due to the short lifetime of plasma in open environments, it is difficult to generate and maintain an ideally distributed plasma electron density. Therefore, the application of open-plate plasma for radar stealth is currently ineffective. Summary of the Invention

[0006] The purpose of this invention is to provide a dual-channel absorbing device based on plasma composite materials. By setting absorbing material layers on the upper and lower sides of the plasma array and setting isolation protective layers on two opposite sides, the plasma array is placed in the cavity formed by the absorbing material layers, which is conducive to the generation and maintenance of plasma electron density, thereby improving the absorbing effect and absorbing performance. In addition, the combination of plasma and absorbing material layers forms a composite dual-channel absorbing structure, which can greatly improve the absorbing performance.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] A dual-channel microwave absorbing device based on plasma composite material, the device comprising: a metal substrate, a first microwave absorbing material layer, a plasma array, a second microwave absorbing material layer, a first isolation protective layer, and a second isolation protective layer;

[0009] The first absorbing material layer is disposed on the upper surface of the metal substrate; a plasma array is disposed above the first absorbing material layer; and a second absorbing material layer is disposed above the plasma array.

[0010] The first isolation protective layer and the second isolation protective layer are disposed on both sides of the plasma array;

[0011] The first absorbing material layer, the second absorbing material layer, the first isolation protection layer, and the second isolation protection layer constitute a cavity structure; the plasma array is disposed in the cavity structure.

[0012] Optionally, the first absorbing material layer includes a third insulating protective layer and a first ITO layer;

[0013] The third isolation and protective layer is disposed on the upper surface of the metal substrate;

[0014] The first ITO layer is disposed on the upper surface of the third isolation protective layer.

[0015] Optionally, the second absorbing material layer includes a fourth isolation protective layer and a second ITO layer;

[0016] The fourth isolation and protection layer is disposed above the plasma array;

[0017] The second ITO layer is disposed on the lower surface of the fourth isolation and protective layer.

[0018] Optionally, the first isolation protection layer, the second isolation protection layer, the third isolation protection layer, and the fourth isolation protection layer are all FOAM layers.

[0019] Optionally, the opening and closing functions of each plasma unit in the plasma array are set independently.

[0020] Optionally, the plasma frequency of each plasma unit is adjustable.

[0021] Optionally, the plasma elements with different plasma frequencies are distributed alternately.

[0022] Optionally, the plasma array includes multiple sets of gas discharge tubes with black tubular closed cavities; the multiple sets of gas discharge tubes are arranged in parallel.

[0023] Optionally, the third and fourth isolation protective layers are parallel to the axis of the gas discharge tube.

[0024] Optionally, the gas discharge tube is filled with a low-pressure mixture of inert gas and mercury; the pressure inside the gas discharge tube is 500-1500 Pa; and the diameter of the gas discharge tube is 15 mm.

[0025] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0026] This invention provides a dual-channel absorbing device based on plasma composite materials. By setting absorbing material layers on the upper and lower sides of the plasma array and setting isolation protective layers on two opposite sides, the plasma array is placed in the cavity formed by the absorbing material layers, which is conducive to the generation and maintenance of plasma electron density, thereby improving the absorbing effect and absorbing performance. In addition, the combination of plasma and absorbing material layers forms a composite dual-channel absorbing structure, which can greatly improve the absorbing performance. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 A structural diagram of a dual-channel microwave absorption device based on plasma composite material provided in an embodiment of the present invention;

[0029] Figure 2 Plasma distribution diagrams under three modes provided in embodiments of the present invention;

[0030] Figure 3 A comparison chart of the absorption rates of plasma and radar absorbing materials with three different distribution patterns provided in the embodiments of the present invention. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The purpose of this invention is to provide a dual-channel absorbing device based on plasma composite materials. By setting absorbing material layers on the upper and lower sides of the plasma array and setting isolation protective layers on two opposite sides, the plasma array is placed in the cavity formed by the absorbing material layers, which is conducive to the generation and maintenance of plasma electron density, thereby improving the absorbing effect and absorbing performance. In addition, the combination of plasma and absorbing material layers forms a composite dual-channel absorbing structure, which can greatly improve the absorbing performance.

[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Example

[0035] like Figure 1 As shown, this embodiment provides a dual-channel radar-absorbing device based on plasma composite materials. This invention aims to broaden the microwave stealth capabilities of radar-absorbing materials in the X-band, while simultaneously achieving tunable electromagnetic absorption. It is generally considered that when the electromagnetic wave frequency is higher than the plasma frequency, electromagnetic waves cannot propagate within the plasma in certain frequency bands, i.e., the photonic bandgap; while when the electromagnetic wave frequency is lower than the plasma frequency, electromagnetic waves cannot propagate within the plasma, which is called the cutoff frequency. Generally, Wp / 2π (Hz) is considered the cutoff frequency for electromagnetic wave propagation within the plasma. Electromagnetic waves below this frequency will be totally reflected and cannot enter the plasma. Since the plasma density inside the gas discharge tube exhibits a radial Gaussian distribution, meaning the plasma frequency at the tube wall is lower than the plasma frequency at the tube center, when electromagnetic waves couple into a large-scale plasma array, electromagnetic diffraction and other phenomena will not occur. (Refer to...) Figure 2 As shown, the thin plasmas arranged in Mode 2 and Mode 3 are relatively uniformly distributed and can only transmit electromagnetic waves in specific frequency bands. Therefore, by arranging the thin plasmas in a non-uniform manner, more electromagnetic waves can be coupled into the plasma layer, thereby increasing the possibility of electromagnetic wave multiple scattering, dissipating electromagnetic energy, and improving the electromagnetic wave absorption rate.

[0036] Furthermore, when an electromagnetic wave is incident normally onto a plasma absorber, the low-frequency electromagnetic wave propagates within the low-electron-density plasma, as referenced. Figure 2As shown, the plasma unit with an electron density of Ne1 strongly couples with low-frequency electromagnetic waves. As the electromagnetic wave frequency increases, more electromagnetic energy can couple into the high-electron-density plasma, resulting in a stronger coupling effect between high-frequency electromagnetic waves and the plasma with an electron density of Ne2. Electromagnetic waves in the X-KU band can completely couple into the plasma layer and be dissipated and absorbed by the RAM. The electromagnetic waves react with the RAM, and the radar-absorbing material on the metal surface exhibits an induced electric field. This indicates that such radar-absorbing materials have good absorption performance for high-frequency electromagnetic waves. As the frequency increases, electromagnetic energy is concentrated in the gaps between the plasma units. Electromagnetic waves undergo multiple scattering between the gas discharge tube and the radar-absorbing material and are dissipated and absorbed.

[0037] Based on the above theory, alternating plasma frequencies on radar absorbing materials can form a novel composite absorbing material that exhibits extremely excellent absorbing performance. Specifically, the device includes: a metal substrate, a first absorbing material layer, a plasma array, a second absorbing material layer, a first isolation protection layer, and a second isolation protection layer.

[0038] The first absorbing material layer is disposed on the upper surface of the metal substrate; a plasma array is disposed above the first absorbing material layer; and a second absorbing material layer is disposed above the plasma array.

[0039] In this embodiment, a metal substrate can be selected as the copper substrate, that is... Figure 1 The copper shown is attached to the bottom of a metal substrate on the surface of the proposed electromagnetic shielding device. The proposed electromagnetic shielding device includes stealth-enabled weapons and equipment or important radar antenna components for land, sea, and air applications. Such radars are not easily stealthed by their shape; protruding parts cannot effectively achieve radar stealth. Traditional radar absorbing materials applied to radar antennas cannot achieve wide-band absorption. This invention, combining plasma and radar absorbing materials, can achieve this effectively. For flying targets where stealth is difficult to achieve, such as landing gear and aircraft engines, the stealth method of this invention can also be used.

[0040] The first absorbing material layer includes a third isolation and protection layer (corresponding to...) Figure 1 Foam Layer 3 and the first ITO layer (corresponding to) Figure 1 (ITOLayer1 in the text). That is, the first absorbing material layer is composed of an ultra-thin ITO layer and a FOAM layer. The third isolation and protective layer serves as the dielectric substrate between the absorbing device and the metal substrate.

[0041] The third protective layer is disposed on the upper surface of the metal substrate.

[0042] The first ITO layer is disposed on the upper surface of the third isolation protective layer.

[0043] The first absorbing material layer serves as the foundation for high-frequency electromagnetic absorption materials, playing a basic absorbing role.

[0044] The second absorbing material layer includes a fourth isolation and protection layer (corresponding to...). Figure 1 Foam Layer 4) and the second ITO layer (corresponding to Figure 1 The second absorbing material layer (ITOLayer2) is composed of an ultra-thin ITO layer and a FOAM layer, which plays a basic absorbing role. The fourth isolation protective layer serves as the substrate of the second ITO layer.

[0045] The fourth isolation and protection layer is disposed on the plasma array (corresponding to) Figure 1 Above the Plasma tunable tube.

[0046] The second ITO layer is disposed on the lower surface of the fourth isolation and protective layer.

[0047] The first isolation protection layer, the second isolation protection layer, the third isolation protection layer and the fourth isolation protection layer are all Foam layers.

[0048] The first and second isolation protective layers are disposed on both sides of the plasma array. Figure 1 As shown, the third and fourth isolation protection layers are parallel to the axis of the gas discharge tube constituting the plasma array. The first and second isolation protection layers serve as basic isolation protection for the absorbing device.

[0049] The first absorbing material layer, the second absorbing material layer, the first isolation protection layer, and the second isolation protection layer constitute a cavity structure; the plasma array is disposed in the cavity structure.

[0050] For plasma arrays, the opening and closing functions of each plasma unit in the plasma array are set independently.

[0051] The plasma frequency of each plasma unit is adjustable. Furthermore, plasma units with different plasma frequencies are alternately distributed, with the frequencies of the alternating plasma distribution within the gas discharge tube being 2.36 × 10⁻⁶. 10 rad / s and 4.15×10 10 rad / s. Therefore, after excitation, the plasma array forms a combined plasma layer; the plasma frequency within the plasma layer exhibits an alternating distribution of high and low frequencies.

[0052] Each plasma unit in the plasma array can be turned on and off arbitrarily. By adjusting the parameters of the plasma, the absorption frequency band can be made adjustable. By controlling the on and off of the plasma units, the spatial distribution of the plasma can be changed, thereby adjusting the attenuation bandgap and attenuation amplitude.

[0053] Plasma arrays can control plasma on / off states and related operating properties by setting their associated plasma frequencies and collision frequencies.

[0054] To achieve an absorption rate of over 90% for microwaves in the 3-7GHz and 12-16GHz bands, and to leave channels in the 8-12GHz and 16-20GHz bands for device communication, the absorber should also achieve large-angle, tunable electromagnetic absorption within these bands. Furthermore, it should be possible to adjust the absorption band to suit different scenarios by arbitrarily turning each plasma unit in the plasma array on and off. Adjustment of the absorption band can be achieved by controlling the plasma parameters. By controlling the on / off state of the plasma units, the spatial distribution of the plasma can be altered, thus adjusting the attenuation bandgap and attenuation amplitude.

[0055] Furthermore, existing open-type plasmas emit visible light, making them easily detectable by photoelectric detection systems. Therefore, such open-type plasmas cannot be directly used for practical stealth applications. For this reason, closed-cavity plasmas have been introduced into stealth technology. Closed-cavity plasmas are typically generated using inductively coupled coils or discharge electrodes. Closed-cavity plasmas can maintain stable electron density and controllable plasma distribution. Inductively coupled coil-generated plasmas suffer from uneven distribution and large device size, making them unsuitable for large-area plasma stealth applications. Therefore, in this invention, the plasma array is generated by a tubular closed-cavity low-pressure plasma generator; the tubular closed-cavity low-pressure plasma generator consists of multiple sets of gas discharge tubes with black tubular closed cavities. That is, the plasma array includes multiple sets of gas discharge tubes with black tubular closed cavities; these gas discharge tubes are arranged in parallel. Each plasma unit is a gas discharge tube. The gas discharge tubes are filled with a low-pressure mixture of inert gas and mercury; the pressure inside the gas discharge tubes is 500-1500 Pa; the diameter of the gas discharge tubes is 15 mm. The plasma excitation module is controlled by a ballast. This will, in turn, limit the frequency of the plasma.

[0056] The plasma cylindrical array is assumed to be infinitely distributed on a perfect electrical conductor (metal plate) covered with a conventional radar absorbing material. By adjusting the rectifier voltage, plasmas with different electron densities can be obtained. To analyze the influence of plasma spatial distribution on radar absorption, refer to... Figure 2As shown, the distributions of two plasmas with different frequencies were tested in three different modes (single low-electron-density plasma, single high-electron-density plasma, and alternating distributions of the two densities). (Ne1 and Ne2 represent the corresponding plasma electron densities). The electron collision frequency at this point was taken as a fixed value of 1.256 × 10⁻⁶. 10 rad / s, according to Figure 2 The simulation results show that the plasma frequency inside the gas discharge tube is 4.15 × 10⁻⁶. 10 rad / s (high electron density plasma corresponding to Ne2), 2.36 × 10 10 rad / s (Ne1 corresponds to low electron density plasma). Adjusting the voltage can change the electron density of the plasma, thereby changing the plasma frequency.

[0057] Comparison of the absorption rates of three plasma stealth devices with different distribution patterns and radar absorbing materials (reference) Figure 3 As shown, when the plasma frequency of the plasma absorber is distributed in alternating high and low bands, it can effectively absorb low-frequency electromagnetic waves, and the passband is clearly visible. Furthermore, as the plasma frequency changes, the strong resonant point of the passband also changes, achieving an adjustable resonant passband for device communication.

[0058] Proposed process for preparing resistivity ITO thin films (ITO thin film resistivity is 150-300 Ohm / m) 2 :

[0059] ITO nanoparticles were prepared using In(NO3)3·5H2O and SnCl4·5H2O as inorganic reactants, citric acid as a complexing agent, ethylene glycol as a polymerization agent, and double-distilled water and anhydrous ethanol as dispersing solvents.

[0060] (1) ITO nanopowder was prepared by PC sol-gel method.

[0061] 1. Dissolve In(NO3)3·5H2O and SnCl4·5H2O in equal weight proportions of double-distilled water and anhydrous ethanol.

[0062] 2. Add citric acid and ethylene glycol, and stir at 40°C for 40 minutes.

[0063] 3. Reflux the stirred solution at 120°C for 3 hours.

[0064] 4. Slowly heat the obtained sol in an open oil bath for 18 hours, with the oil bath temperature at around 90°C.

[0065] 5. The obtained wet gel is directly heated at 140°C for 4 hours.

[0066] 6. Then heat at 200℃ for 30 minutes to dry.

[0067] 7. The obtained dry gel is placed in a natural air chamber at 350°C for one hour, and then allowed to slowly cool to room temperature. This yields the desired ITO nanoparticles.

[0068] (2) Magnetron sputtering is used to deposit the film using the principle of cathode sputtering. SiO2 is used as the substrate, and the film particles originate from the cathode sputtering effect of argon ions on the ITO target material during glow discharge. After the argon ions sputter the target atoms, ionic oxygen bombards the ITO film whose resistance value needs to be improved. This causes a secondary reaction between the ionic oxygen and the ITO film, resulting in an ITO film with the desired resistance value, which is then deposited onto the substrate surface to form the desired ITO film shape.

[0069] In this embodiment, the present invention utilizes a tubular closed low-pressure plasma generator to generate plasma. The FOAM layer substrate and ITO thin film material together constitute a dual-channel absorbing device (electromagnetic stealth device). The tubular closed cavity is made of black glass tube, which can effectively block the visible light generated by the plasma from diffusing outside the cavity. The present invention combines plasma with absorbing materials to form a novel composite absorbing material that exhibits extremely excellent absorbing performance. It can absorb radar waves over a wide frequency band. When the plasma density presents an alternating high and low distribution pattern, the absorber can achieve an absorption rate of over 90% for microwaves in the 2.2-4.2GHz, 9.8-12.3GHz, and 18-20GHz bands. It also leaves two channels with lower absorption rates next to the band gap for equipment communication. In addition, by changing the type of radar absorbing material and the on / off state of the plasma unit, different absorption frequency bands can be adjusted for different scenario requirements. Ultimately, wide-bandwidth, large-angle, tunable electromagnetic absorption within the specified frequency band can be achieved.

[0070] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A dual-channel microwave absorbing device based on plasma composite materials, characterized in that, The device includes: a metal substrate, a first absorbing material layer, a plasma array, a second absorbing material layer, a first isolation protection layer, and a second isolation protection layer; The first absorbing material layer is disposed on the upper surface of the metal substrate; the plasma array is disposed above the first absorbing material layer; the second absorbing material layer is disposed above the plasma array. The first isolation protective layer and the second isolation protective layer are disposed on both sides of the plasma array; The first absorbing material layer, the second absorbing material layer, the first isolation protective layer, and the second isolation protective layer constitute a cavity structure; the plasma array is disposed in the cavity structure. The first absorbing material layer includes a third insulating protective layer and a first ITO layer; The third isolation and protective layer is disposed on the upper surface of the metal substrate; The first ITO layer is disposed on the upper surface of the third isolation protective layer.

2. The apparatus according to claim 1, characterized in that, The second absorbing material layer includes a fourth isolation protective layer and a second ITO layer; The fourth isolation and protection layer is disposed above the plasma array; The second ITO layer is disposed on the lower surface of the fourth isolation and protective layer.

3. The apparatus according to claim 2, characterized in that, The first isolation protection layer, the second isolation protection layer, the third isolation protection layer, and the fourth isolation protection layer are all FOAM layers.

4. The apparatus according to claim 1, characterized in that, The opening and closing function of each plasma unit in the plasma array is set independently.

5. The apparatus according to claim 4, characterized in that, The plasma frequency of each plasma unit is adjustable.

6. The apparatus according to claim 5, characterized in that, The plasma units with different plasma frequencies are distributed alternately.

7. The apparatus according to claim 3, characterized in that, The plasma array includes multiple sets of gas discharge tubes with black tubular closed cavities; the multiple sets of gas discharge tubes are arranged in parallel.

8. The apparatus according to claim 7, characterized in that, The third and fourth isolation protective layers are parallel to the axis of the gas discharge tube.

9. The apparatus according to claim 8, characterized in that, The gas discharge tube is filled with a low-pressure mixture of inert gas and mercury; the pressure inside the gas discharge tube is 500-1500 Pa; and the diameter of the gas discharge tube is 15 mm.

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