针对飞机进气道等离子体隐身问题, 建立了三维筒形进气道模型, 采用有限元求解波动方程, 计算了腔体内壁覆盖均匀等离子体时的雷达散射截面。研究表明: 腔体内覆盖等离子体时可以有效吸收入射电磁波能量；吸收随电磁波频率增加而减弱, 但由于腔体结构作用, 会存在几个吸收峰；吸收随电子数密度增加而增强, 但电子数密度过高时, 吸收效果会变差；最佳碰撞频率虽然与电磁波频率和电子数密度有关, 但其值可约为9 GHz；吸收随等离子体厚度增加而变大, 但在较大电子数密度时, 由于电磁波在等离子体与空气交界面处反射导致厚度增加, 从而使得吸收变小；选取合适的入射角度和等离子体数密度可以在1~3 GHz频段实现明显的隐身效果。

Aiming at the problem of plasma stealth for aircraft inlet, we create a three-dimensional model for cylindrical inlet. A finite element model is used to solve the wave equation to gain the RCS (radar cross section) of inlet whose inner wall is covered with uniform plasmas. The model operates at a collision frequency of 1-100 GHz, an electron number density of 1016-1018 m-3, a microwave frequency of 1-3 GHz, and an incident angle of 0°-80°. The results show that the attenuation is significant when the inlet is covered with plasmas and decreases with the microwave frequency; there are several attenuation peaks because of the cavity geometry structure; the attenuation increases with the electron density, but it can deteriorate while the electron density is too high; the optimum collision frequency is related with the microwave frequency and the electron density, but it is generally about 9 GHz; the attenuation increases with the thickness of plasma, but it can deteriorate because of the reflection on the interface between the plasma and the air while the electron density is too high; the attenuation can be significant in whole microwave band (1-3 GHz) at the appropriate incident angle and plasma density, which is important for designing plasma source to applied the plasma stealth.