Study On Microwave Propagation In Dusty Plasma

In many communication problems,the plasma interacting with microwave usually contains nano-micron dust particles,such as abnormal attenuation of microwave in rocket exhaust,plasma sheath in aircraft reentry,PMSE and so on.Dusty plasma is to describe those plasmas including dust particles,which is a more complex system owing to the interaction between dust particles and other plasma particles.The mechanism by which dusty plasma affects microwave is not clear yet.Some related studies lack the support of experimental results.In view of this situation,this paper has studied the influence of various parameters of dusty plasma on the microwave transmission through ground experiments,and simulates the microwave transmission under experimental conditions by using the finite difference time domain method based on Z transform.Firstly,coaxial mesh annular electrodes are used to produce large area plasma with uniform diffusion.Dust particles are continuously added to plasma by electronically controlled vibrating screen.The energy transmittance of 1.5-8 GHz microwave through dusty plasma was measured,where dust with different amounts and types was sprinkled.The spectrum curve characteristics of the results are analyzed,and the experimental results of adding different kinds of particles are discussed according to the charging theory of dust particles.Secondly,the dust particles are levitated in the plasma due to the striated structure of the long DC column discharge.And the microwave transmission of the striated dusty plasma is measured by use of the axial mode helical antennas.We have obtained the energy transmittance of 1-4 GHz microwave in dusty plasma at different pressure and voltage.The electron density is calculated by the microwave phase difference,which is considered with discharge voltage and current in analysis of the reasult.It's showed that the effects of dust particles on plasma with different parameters are obviously different.Finally,the experimental process is simulated by Z-FDTD method.Taking the change of air pressure as an example,the microwave transmittance is calculated,which agrees with the experimental results.In the simulation,the parameters reflecting the effect of dust are the electron density measured by microwave diagnosis.The experimental and simulation results show that the total number density of effective electrons in plasma is affected by dust particles through adsorbing electrons,which indirectly affects the microwave transmittance.