For purpose of the electromagnetic pulse (EMP) protection research, a double-layer barrier of cylindrical plasma array was designed, and its protective performance to 6GHz high-power microwave (HPM) was conducted experimentally. Combining the distribution of the discharge plasma array, the shielding effectiveness of the double-layer plasma on 6GHz HPM pulse was studied. The main research contents and conclusions are as follows: The transmission energy of HPM decreased as the increase of plasma electron density, indicating an improved protection effect, with both double-layer and single-layer plasma array. Besides, the results showed that the transmission attenuation of HPM in double-layer structure was greater than that in single-layer structure because of the interlayer reflection. In addition, an interesting phenomenon was discovered during the experiment, which was that the boundary plasma units had a significant impact on the HPM transmission. The shielding effect of HPM was better with opening seven plasma units than that with opening whole plasma array. Finally, the spectral characteristics and transmission coefficients of the HPM were presented by Fourier transform, and the results of the protective performance were consistent with the above-mentioned time-domain analysis. The experiment results in this paper are of great significance in protecting against HPM based on plasma.
The transmission of High-Power Microwave (HPM) with a frequency of 1 GHz in a plasma double-line induced by intense femtosecond laser pulses is discussed by CST software. The influence of plasma electron density and collision frequency on HPM transmission performance is analyzed especially. The simulation results indicate that, the influence of plasma electron density on the transmission performance of HPM along the double-line is slight when the electron density is in the range of 1015 cm-3 ~1017 cm-3. It can also be obtained that the incident EM wave can propagate around the plasma double-line rather than in the over-dense plasma. We also discover that the attenuation value of the EM wave increases significantly with increasing the plasma collision frequency. Meanwhile, the attenuation value of the EM along the plasma transmission line can be calculated at approximately 0.94 dB/m and 1.56 dB/m when the plasma collision frequencies are 6×109 Hz and 1.5×1011 Hz, respectively. As can be seen, it is not necessary to increase the electron density of femtosecond laser plasma for achieving a high HPM transmission performance in the future applications.
The transmission of high-power microwave (HPM) with a frequency of 1 GHz in a plasma double-line induced by intense femtosecond laser pulses is discussed by CST software. The simulation results indicate that the EM wave can propagate around the plasma double-line rather than in the over-dense plasma with a velocity near the speed of light. It can also be obtained that the time evolution of the electric field is consistent with the duration of the incident HPM. We also discover that the electric field increases monotonically with increasing the line radius. Meanwhile, the electric field is inversely proportional to the propagation distance along the plasma double-line and the spacing between two lines. Furthermore, the attenuation value of the EM wave in the plasma transmission line can be calculated at approximately 0.03 dB/m in a double-line with an effective plasma electron density of 1016 cm–3 .
To solve the problem of real-time recognition of large quantities of ISAR data with multi-platform and multi equipment, especially the issue of adaptive feature extraction of ISAR data, an ISAR target recognition system based on artificial intelligence is proposed. The system consists of three arrangements: data layer, recognition analysis layer, and presentation layer. The data layer extracts ISAR data according to different application scenarios; the recognition and analysis layer introduces deep learning algorithm for adaptively feature extraction, model training and optimizing, comprehensive identification and evaluation results analyzing. The presentation layer establishes stable and efficient information service based on the Web service framework and realizes a full cross-platform display of recognition results and feature information. By practice, the system improves the identification speed significantly and achieves real-time recognition of ISAR data, information push, and display across multi-platform, to effectively assist users in decision making and evaluation judgment.
In order to verify the heat dissipation characteristics of selective low emissivity materials, the traditional low emissivity materials and selective low emissivity materials were coated on the oxidized steel surface, and the heat transfer model between the target and the dark room was established. Finally, the heat dissipation characteristics of selective low emissivity materials were simulated, and the effects of the emissivity and the darkroom temperature on the heat dissipation characteristics of selective low emissivity materials were analyzed. The results showed that for high temperature targets, selective low emissivity materials had better heat dissipation characteristics than traditional low emissivity materials. The lower the emissivity in mid-far infrared bands, the better the heat dissipation characteristics of selective low emissivity materials. When the ambient temperature of the dark room fell from 30°C to -30°C, the lower the temperature, the better heat dissipation characteristics of selective low emissivity materials.
As a kind of special electromagnetic medium, femtosecond laser plasma has the potential of transmitting the electromagnetic wave. In this paper, a theoretical study on 6 GHz EM wave guiding performance of the plasma filament is carried out with the software XFDTD. Then, an experimental setup for the interaction between the EM wave and the plasma filaments is established. Based on the data measured by oscilloscope, the transmission properties of the EM wave along the filament are obtained. The results show the electric field is enhanced out of the waveguide with the plasma filament. The guiding performance of the plasma filament on the TE polarization wave is better than that on the TM one, which is consistent with the experimental results. For TE polarization wave, the plasma filament can reduce the transmission pulse energy greatly and the attenuation is up to 3.5 dB in the experiment. The research results show that the laser plasma filament can provide efficient transmission of the EM wave energy.
Strong electromagnetic pulse (EMP) may lead to serious damage once it is coupled into the interior of the electronic system. As a kind of special electromagnetic medium, plasma has the ability of shielding strong EMP. Therefore, EMP protection technology based on the plasma is of pratical significance. The experimental setup of the interaction between the nuclear electromagnetic pulse (NEMP) and the plasma based on a one-layer cylindrical plasma array is built. Combined with the density distribution characteristics, the protection performance of the plasma array against the NEMP is studied. The results indicate that the protection performance of the plasma array against the TE polarization NEMP is better than that against the TM one. For both TE and TM polarization NEMP, the one-layer cylindrical plasma array can reduce the transmission pulse energy greatly and the energy attenuation is up to 10dB when the electron density is 8.5×1016 m-3.
In order to study the effect of the ratio of oxidizing agent to reducing agent on the performance of the trilead tetraoxide/ Teflon/magnesium (Pb3O4/PTFE/Mg) powder decoy compounding agent, 5 different pharmaceutical formulations are designed by maintaining constant oxidant formula and changing the ratio of oxidant agent and reducing agent. Then the mixed powder is pressed into a powder by a table press. The combustion process of the drug column was measured with an 8-14 micron infrared thermal imager, and the burning time, mass burning rate, radiation area, radiance, and radiation intensity of each sample were calculated. The results show that with the increase of the proportion of reducing agent, the burninging time of the sample becomes shorter and the mass burninging rate becomes larger. The maximum temperature of the flame increased with the proportion of reducing agent first and then decreased. When the ratio of oxidant agent to reducing agent is 1.5:1, the maximum temperature of sample combustion reaches a maximum of 1503°C. The radiance increases first and then decreases with increasing proportion of reducing agent, and When the ratio of oxidant agent to reducing agent is 1:1.5, the infrared radiance is the maximum, which is 2510 W·m-2·Sr-1.Radiation intensity increases as the proportion of reducing agent increases. It can be seen that in the 8-14 micron band, when the ratio of oxidant agent to reducing agent is 1:1.5, the radiation characteristics of the sample is best and the sample is the best one as infrared decoy.
By using the electromagnetic wave reflection characteristics of the plasma,
the plasma can be used to design the reflector antenna. the paper designs a metal
parabolic cylindrical antenna and a plasma luminescence parabolic cylindrical
antenna, and uses CST software calculating the radiative properties of them,
analysising the key parameters of plasma luminescence parabolic cylindrical antenna
radiation and scattered radiation resistance. Simulation results show that selecting
appropriate plasma column spacing, plasma frequency, collision frequency, the
plasma luminescence parabolic cylindrical antenna has the same radiation
performance with metal parabolic antenna, at the same time, the RCS of plasma
antenna in working and not working are smaller compared with the metal antenna,
especially in plasma does not work ,the bistatic RCS reduced to a greater extent than
the previous related literature design.
For the safety of electronic equipment, a double-layer barrier of cylindrical plasma array was designed, and its protective performance to high-power microwave (HPM) were analyzed and the protective performance experiment was conducted. Combining the density distribution characteristic of the discharge plasma, the shielding effectiveness of the double-layer plasma on 6GHz HPM pulse was studied. The experiment results indicate that the protective effectiveness of two layers plasma array is better than that of one layer. Two layers plasma array can make the peak electric field of transmission waveform less than interference threshold of electronic equipment to achieve better protection effectiveness. Transmission attenuation of one layer and two layers plasma array to HPM can reach -6.6066dB and -24.9357dB. The results also show that for the existence of multiple reflection, even the plasma electron density is not high enough, it can realize a strong attenuation. The experiment results in this paper are of great significance in protecting against HPM and electromagnetic pulse.
Firstly, the dispersion equation of a plane electromagnetic wave in homogeneous and non-magnetized discharge plasma was established. According to the different frequency of electromagnetic wave and plasma parameters, the characteristics were discussed when the plasma interacted with electromagnetic waves. Then the gas discharge approach was put forward according to characteristics of plasma generated by different methods and their advantages and disadvantages. The possibility of using non-magnetized discharge plasma for the military purpose was analyzed. In the end, the principle and characteristics of the application of the non-magnetized discharge plasma were studied in the fields of stealth and protection against strong electromagnetic pulse.
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