The Study Of The Propagation Of Microwaves In Plasmas With Dust Grains

The research of microwave interactions with plasma is getting more and more complete.However,the influence of dust grains in plasma on microwave propagation has attracked more attention when some problems like the microwave attenuation of rocket plume,PMSE and black barrier effect are studied further.There is no good way to introduce dust grains in microwave propagation problems and the influence mechanism of dust grains is not studied well.Therefore,this paper plans to introduce the effect of dust grains in Drude model and studies the influence of different parameters of dust grains on microwave propagation by RC-FDTD method.Meanwhile,the influence machanism of dust grains and the propagation characteristics of microwave in inhomogeneous plasma are investigated.Firstly,the interactions between electrons and dust grains which are fully charged are discussed from the OML theory.There are two processes which include direct collisions and Coulomb scattering collisions resulting momentum transfer between electrons and dust grains.The collision frequency expression between electrons and dust grains is derived,and we study that the collision frequency is affected by the radius and number density of dust grains.Then,the collision frequency between electrons and dust grains is considered in electron total collision frequency of Drude model.So the electron total collision frequency contains collisions between electrons and neutral molecules,ions and dust grains.The electron density of Drude model is also influenced by dust grains.By the means of numerical simulation,the influence of plasma ionization degree,dust radius,dust number density and dust quantity of charge on electromagnetic waves propagation is investigated,and the reasons are analysed.The studies have shown that adding dust grains to plasma,changing electron density and dust parameters will affect microwave propagation characteristics remarkably.Finally,the inhomogeneous plasma models are established,and the influence of the plasma density distributions on electromagnetic waves propagation is studied.Along the direction of microwave propagation,the plasma layer with linear increase electron density has good absorption to microwave near its rear surface.On the contary,the plasma layer with linear decrease electron density has good reflection to microwave near its front surface.