基于Fokker-Planck-Landau碰撞模型的非均匀尘埃等离子体目标散射特性

Scattering characteristics of non-uniform dusty plasma targets based on Fokker-Planck-Landau collision model

从玻尔兹曼方程出发,推导了全电离非均匀尘埃等离子体的Fokker-Planck-Landau碰撞模型下时域有限差分的迭代表达式.结合尘埃等离子体的碰撞效应和充电效应,得到了Fokker-Planck-Landau碰撞模型下全电离尘埃等离子体的电导率表达式.利用Z变换时域有限差分(Z-FDTD)法计算了二维情况下尘埃等离子体涂覆金属钝头锥的雷达散射截面.分析了尘埃粒子密度、尘埃粒子半径、电子密度与尘埃粒子密度比值、尘埃粒子充电频率以及电磁波的入射角对钝头锥散射特性的影响.结果表明,在全电离空间非均匀尘埃等离子体中,随着尘埃粒子半径的增大会削弱德拜屏蔽效应,导致雷达散射截面增大;此外,受到尘埃等离子体的碰撞效应和充电效应产生影响,会对目标的雷达散射截面有较大的影响.这些结果对研究空间非均匀尘埃等离子体的电磁波散射特性以及近地空间的通信问题提供了理论依据.

Dusty plasma is a multi-particle system of dust particles suspended in plasma,which is generally composed of free electrons,ions,and dust particles.It is widely found in natural space and aerospace equipment,such as the Earth’s ionosphere,rocket tail flame,and sheath of the hypersonic vehicle.The dust particles will interact with free electrons and ions in the plasma so that the dust particles are charged.They also significantly change the characteristics of dusty plasma,showing some phenomena different from those in ordinary plasma,such as dust acoustic solitary waves and dust void.Electromagnetic(EM)waves will interact with dusty plasma,which results in the attenuation of EM wave signal and the change of phase and other serious effects,and the phenomenon of“blackout”appears.This is very unfavorable for the guidance and control system of the vehicle.The generation of“blackout”is related to the dynamics of dusty plasma and the analysis and research of EM characteristics,so studying the scattering characteristics of dusty plasma is of great significance.First,starting from the Boltzmann equation,the iterative expression of finite-difference time-domain under the Fokker-Planck-Landau(FPL)collision model of fully ionized non-uniform dusty plasma is derived.The expression of the conductivity of the fully ionized dusty plasma under the FPL collision model is obtained by combining the collision effect and charging effect of the dusty plasma.By using the Z-transform finite-difference time-domain method,the radar cross section(RCS)of the dusty plasma coated metal blunt cone in two dimensions is calculated.The effects of dust particle density,dust particle radius,ratio of electron density to dust particle density,dust particle charging frequency,and EM wave incident angle on the scattering characteristics of the mental blunt cone are analyzed.The results show that the Debye shielding effect is weakened and RCS is increased with the increase of the radius of dust particles in the fully ionized non-uniform dusty plasma.In addition,it is affected by the collision effect and charging effect of dusty plasma,which will have a great influence on the RCS of the target.These results provide a theoretical basis for studying the EM waves scattering problem of fully ionized non-uniform dusty plasma and the communication problems in near space.