Study On Electromagnetic Wave Propagation Characteristics In Plasma Sheath Based On HMM Method

When the reentry vehicle enters the atmosphere,it will strongly rub against the atmosphere,forming a plasma sheath around the vehicle.The plasma sheath causes attenuation and scattering of electromagnetic waves,which interferes with the communication function between the reentry vehicle and the ground,and even causes signal interruption,this is the"blackout".Studying the propagation characteristics of electromagnetic wave in plasma sheaths is of great significance for alleviating the"blackout" problem.In this paper,we use the Hybrid Matrix Method(HMM)to analyze the propagation properties of electromagnetic wave in the plasma sheath under steady-state electron density and random electron density.The research content of the paper is as follows:1.Based on the plasma sheath stratification model,the arbitrary magnetic fields plasma dielectric constant tensor ? and the coupling matrix C are derived by combining the Maxwell equation with the hydrodynamic equation of the plasma.The definition of Hybrid Matrix(H matrix)and the calculation method of single layer H matrix and stacked H matrix are given.2.The reflection coefficient and transmission coefficient of electromagnetic wave propagating in the plasma sheath are derived by Snell's law and Hybrid matrix,and the propagation characteristics of electromagnetic wave in the plasma sheath under the conditions of the same direction,vertical direction and existence angle of the applied magnetic field with the electromagnetic wave are analyzed respectively.The results show that the applied magnetic field can improve the transmission of the GPS signal,and with the increase of the applied magnetic field,the stop band of the transmission coefficient gradually moves to the high frequency direction,and the transmission coefficient of the low frequency is improved under the applied magnetic field.This conclusion provides a theoretical reference for mitigating the"blackout".3.Combining HMM with Monte Carlo method,and using the random electron density model to analyze the statistical properties of the transmission coefficient of electromagnetic wave propagating in the plasma sheath with random electron density under non-magnetized state and magnetization state.The results show that the higher the collision frequency,the more stable the variation of the transmission coefficient amplitude and phase standard deviation of the electromagnetic wave.In addition,increasing the frequency of the incident wave can reduce the influence of electron density on the transmission coefficient.