感性耦合夹层等离子体隐身天线罩电磁散射分析

Electromagnetic scattering analysis of stealth radome with inductively coupled plasma in interlayer chamber

设计了一种石英夹层感性耦合等离子体(ICP)隐身天线罩模型,采用有限元与Z变换时域有限差分(ZTFDTD)联合仿真的方法,建立了ICP放电的流体模型,得到不同气压及功率下与电磁散射相关的电子密度空间分布,在此基础上建立Z变换时域有限差分法模型,对石英夹层等离子体隐身天线罩的宽频段后向散射进行计算,同时利用微波干涉法及XFDTD软件对算法及程序进行验证。结果表明:感性耦合等离子体可产生较高密度等离子体,能有效实现雷达散射截面(RCS)的减缩,在气压为2Pa时,碰撞衰减较弱,等离子体密度分布较均匀,衰减带宽集中在等离子体振荡频率附近,功率增加会使衰减峰值向高频方向移动,气压为20Pa时,碰撞衰减增强,且等离子体密度分布有较大梯度,衰减带宽有效增加,同时RCS曲线的波动特性加强。

A stealth radome model with Inductively Coupled Plasma（ICP）in the interlayer chamber is designed.A two-dimensional fluid model of ICP discharge is built by integrating the finite element method and the ZT-FDTD method.The electron density distribution related to the electromagnetic scattering with different power and pressure is obtained.The FDTD method for Z transformation is established to calculate the backscatter of the plasma radome on the broadband.Microwave interference diagnosis and XFDTD software are used to validate the calculation.The results show that the ICP can produce high density plasma,and can effectively achieve the reduction of the Radar Cross Section（RCS）.At 2 Pa air pressure,the electron density distribution is uniform,the collisional absorption of plasma is relatively weak,the bandwidth of the attenuation of RCS is concentrated near the plasma frequency,and the attenuation peak will move to high frequency zone with the increase of the power.At 20 Pa air pressure,the collisional absorption of the plasma is obviously improved to have larger gradient in density distribution of electrons,the bandwidth of the attenuation of RCS increases effectively,and the wave characteristics of the RCS profile is strengthened at the same time.