When the aircraft is moving in the atmosphere at a very high speed, the aircraft and the surrounding atmosphere will violently friction, which causes the air to ionize and produce a plasma flow field around it. Plasma is constantly generated on the windward side of the aircraft and flows backwards. The velocity of plasma is different from that of the aircraft. In addition to the dispersion characteristics of the plasma and the non-uniform distribution around the target, the plasma flow field will produce amplitude, frequency and phase modulation effects on the incident radar wave, which will change the electromagnetic scattering characteristics of the target.
In order to reproduce the non-uniform Doppler phenomenon in the flow field under electromagnetic wave irradiation, this paper carried out the plasma echo spectrum measurement experiment in the JF-10 wind tunnel of the Institute of Mechanics, the Chinese Academy of Sciences. The echo spectrum data of S and C bands were obtained by the measurement system composed of signal source, circulator, antenna and spectrometer, based on the measured data, the one-dimensional range profile of the plasma coated target is simulated, and the results show that the plasma flow field has spectrum modulation effect on the target; When the speed of the flow field cannot be compensated accurately, the spectral modulation effect will further cause defocusing of the one-dimensional range profile, which will affect the detection and tracking ability of the radar. The preliminary analysis shows that the effect is mainly caused by the inhomogeneous velocity distribution of plasma flow field and the sudden change of medium parameters when the shock wave arrives. This experiment can provide data support for the verification of electromagnetic characteristics modeling method of plasma flow field.
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