Study Of Of Vortex Electromagnetic Wave Propagation In Plasma

The vortex electromagnetic wave is an electromagnetic wave with a unique spatial spiral structure that carries the orbital angular momentum.It also has a broad application background in the field of radar detection and communication.The theoretical and numerical simulations of the interaction between plane electromagnetic waves and plasma have tended to be perfect,but there are relatively few theoretical and experimental studies on the interaction between vortex electromagnetic waves and plasma.In this thesis,the reflection and radiation characteristics of vortex electromagnetic waves in plasma are studied based on the plasma propagation of planar electromagnetic waves.On this basis,the subject also conducted experimental research on the propagation of planar electromagnetic waves and vortex electromagnetic waves in plasma.First,this thesis describes the basic characteristics of the plasma and the parameters that mainly affect its characteristics.A test system with uniform ion density and weak ionization impact plasma is presented.The entire system includes the intake section,the vacuum section,and the external power supply section.The plasma generation step in the experiment is described,and the approximate correspondence between the applied voltage and the plasma density is analyzed.Secondly,by using the WKB method of electromagnetic field,the effects of electron density and plasma collision frequency on the transmission characteristics of electromagnetic waves in homogeneous and inhomogeneous plasmas are studied,providing theoretical guidance for the experimental research on the interaction between plane electromagnetic waves and plasmas.On the numerical simulation analysis.The three-dimensional model of the transmission interaction between electromagnetic wave and plasma is established.The electromagnetic wave reflection coefficient and transmission coefficient under different discharge powers are simulated and compared with experimental measurements.Finally,the expression of the vortex electromagnetic wave field solution is solved in this thesis,and the basic propagation characteristics of the vortex electromagnetic wave are analyzed.In this thesis,a circular array antenna is designed to generate vortexelectromagnetic waves,and different modes of the vortex electromagnetic waves are generated by controlling the feed phase.Based on the interaction between the plane wave and the plasma,the influence of the sampling radius and sampling angle on the receiving mode is analyzed by simulation during the propagation of the vortex electromagnetic wave in the plasma.Based on the simulation,experiments are conducted on the interaction between plasma and the vortex electromagnetic waves in different states.The experiments and simulations are mainly focused on mode 0 and mode 1,and they are performed from three aspects: different modes,different distances,and different plasma densities.The array transmission studies and compares the vortex wave transmission in the plasma with that in air.