Study Of Electromagnetic Transmission Characteristics Of Magnetized Sheath Layer Based On SMM Method

When the vehicle is flying at hypersonic speed,a plasma sheath layer will be formed around its fuselage,and electromagnetic communication waves need to pass through the plasma sheath layer to reach the antenna window.Due to the characteristics of the plasma itself,its internal high-density electronic movement will reflect and absorb electromagnetic signals to a large extent,resulting in significant interference with communication signals.This hinders the precise control of the vehicle from the ground and the need for uninterrupted communication during the spacecraft’s return to the atmosphere.In order to investigate the transmission mechanism of electromagnetic waves in the plasma sheath,numerical simulations and analysis of several characteristic parameters based on the scattering matrix method(SMM)have been carried out in this paper,and the following are the main research works.Firstly,the scattering matrix method(SMM)for electromagnetic waves incident on a non-homogeneous medium is introduced in this paper.The interaction of terahertz waves with magnetization,collision,and non-homogeneous plasma is analyzed theoretically.Since terahertz waves possess better penetration and interference resistance than microwaves,the paper focuses on the transmission mechanism of the sheath THz band.Analyzes the effects of key parameters such as the electron density maximum,electron density distribution,collision frequency,electron cyclotron frequency and thickness of the plasma on the normalized reflected power,transmitted power and absorbed power of electromagnetic waves.In addition,the effect of the applied magnetic field on electron motion and the consumption of electrons by the applied electric field are also methods that can improve sheath transmission to some extent.In this paper,the transmission characteristics of terahertz waves under the electromagnetic window are explored by introducing the applied magnetic and electric fields.These results provide a theoretical basis for the reception or blocking of electromagnetic waves in the sheath to a certain extent.Second,based on the conventional SMM,two improved scattering matrix methods,ISMM and MSMM,are introduced in this paper,improving the singularity and divergence problems encountered during the numerical calculations.Moreover,based on these two methods,a computational analysis of plasma sheaths with higher electron densities is carried out.Finally,considering the actual ultra-high speed flight of the vehicle,there will be very violent ablation of the thermal insulation material on the surface of the airframe,which will release high-density fine metal particles during the ablation process,and then form a dusty complex plasma sheath layer on the surface of the airframe,making the electromagnetic wave transmission process in it more complicated.In this paper,based on the BGK collision model,the transmission characteristics of terahertz waves in dust plasma are calculated and analyzed when the parameters of dust particle density,dust particle radius,effective collision frequency,and charging frequency are varied.