Research on Reflection Mechanism of Nonuniform Plasma

The surface of the near-space hypersonic vehicle is covered with a plasma sheath (PSh) with fluid properties. During the radar detection of hypersonic vehicles, the spatial distribution characteristics of PSh parameters affect the reflected wave intensity and the position of the maximum reflection layer of plasma in the vehicle's different areas, resulting in significant differences in the intensity and frequency offset of echo signals in various areas. In order to further study the reflection characteristics of nonuniform plasma, this article uses the equivalent wave impedance method to calculate the reflection and transmission coefficients of each layer of plasma, analyzes the reflection intensity distribution mechanism of nonuniform plasma, and reveals the EM shielding effect (ES-effect) of plasma. Based on the typical carrier frequency, collision frequency, electron density, and electron density distribution gradient, the variation law of maximum reflection position and maximum reflection intensity in nonuniform plasma is revealed. The research results lay a theoretical foundation for analyzing echo signal characteristics of the PSh-covered target, radar detection anomaly suppression, and EM stealth.