高/低气压氩气感应耦合等离子体电磁波衰减效果建模研究及实验验证

Simulation and Mesurement of Electromagnetic Wave Attenuation by Inductively Coupled Ar-Plasma

设计了一种雷达舱共形的电感耦合等离子体(ICP)发生装置,开展了ICP放电的流体模型研究,获得在高低气压及不同放电功率对ICP的电子密度分布的影响,据此得出与电磁散射相关的介电常数空间分布,在此基础上利用Z变换时域有限差分方法建立了电磁波在ICP中的传播模型,得出了在不同放电条件下ICP对电磁波的宽频段散射参量。同时开展实验,对该模型的结果进行验证。研究表明,气压为10 Pa时,ICP对电磁波的衰减带宽主要为6~8 GHz,平均反射率为-21dB左右。气压为150 Pa时,衰减带宽为13~15 GHz,此时碰撞吸收效果会增强,但由于等离子体轴向体积的压缩导致衰减效果相比于5 Pa下没有明显增强。

The interaction of the electromagnetic（ EM） wave and the argon inductively coupled plasma（ ICP）,generated by the newly-developed radar-capsule conformal source,was mathematically modeled with fluidfield,theoretically analyzed,numerically simulated with software Z-FDTD,and experimentally evaluated. The influence of the discharge power and pressure on the electron density distribution of Ar-ICP and EM-wave attenuation was investigated. The calculated results show that the discharge power and pressure strongly affect the EM-wave attenuation. For example,at 10 Pa,the EM-wave attenuation occurred,with an average reflectance about-21 d B in6 - 8 GHz band,because of the resonant absorption and weak scattering; a larger discharge power shifted the peak of attenuation rate to a higher frequency. At 150 Pa,the scattering absorption of EM-wave increased in 13 - 15 GHz band; however,the attenuation was not better than that at 5 Pa,possibly because of the axial compressionof plasma. The simulated and measured results were in good agreement.