A Study Related To Electromagnetic Wave Scattering By Charged Particles

Electromagnetic(EM)wave technology is rapidly developed to be widely used in many fields.For example,EM wave must be propagating in extreme environments such as dust storms,fog and haze weather and EM wave technology is also used to monitor the composition of atmosphere particles in these weather.The properties of particles,such as the charge of particles,can affect the scattering of EM waves,and thus affect the quality of signal transmission and monitoring results.In this thesis,based on the EM scattering properties of charged particle,the scattering phase function of a charged particle was investigated,and the properties and charge of charged particle were reversely calculated and the effect of charged particle systems on the capability of radar atmospheric detection was studied.The main work includes as following:First,we deduced out the scattering phase function(SPF)of a charged spherical particle,which is significantly different from the SPF of uncharged spherical sphere.The difference between the SPF of a charged spherical particle and the SPF of an uncharged spherical sphere is related to the surface conductivity,particle size parameter,the frequency of the EM waves and the refractive index of the particle.The surface charges carried by the particle makes the backward scattering of EM waves increasing.Given the EM wave frequency and the refractive index,there is a threshold of surface conductivity for each particle size number,beyond which SPF mainly depend on the surface conductivity.Second,we derived the amplitude ratio and phase difference of the transverse components of the scattered electric field.We found that in the direction perpendicular to the incident direction of the EM waves,the amplitude ratio and phase difference are linearly dependent on the surface potential.For particulate systems,the surface electric potential and relative refractive index of a charged particle are mathematically expressed by amplitude ratio and phase difference,and a method to estimate the surface potential and the relative refractive index was proposed based on the observation of EM wave's signals.Finally,we investigated the radar ratio of charged particles system combining the extinction coefficient and backscattering coefficient of charged particle.The results show that there are significant differences in the ability of detecting the charged particle system with different bands radar.For the sand and dust particles system,the effect of charged particles on laser band radar detection is minimal.Compared with other band radars,the advantage of laser-band radar measurement of charged particle system is significant.In addition,radar detection capability will also depend on the charge of particles and particle properties.