Simulation And Experimental Study On Electromagnetic Wave Propagation Characteristics In Non-uniform Plasma

As a special medium,plasma has various parameters that change with the external conditions and has many unique properties.Therefore,plasma is widely used in both civil and military fields.Since the plasma in practical applications is often time-varying and non-uniform,it will generate absorb,refract,scatter and other physical phenomena of electromagnetic waves.The interaction between the time-varying dust plasma containing dust particles and electromagnetic waves has important practical application value for exploring the communication interruption phenomenon in the reentry process.This thesis will systematically study the electromagnetic wave propagation characteristics in non-uniform time-varying plasma from the aspects of numerical simulation and experiment.The specific work is as follows:The DI-FDTD algorithm for the propagation characteristics of one-dimensional nonuniform time-varying plasma electromagnetic waves is established.In the cavity model,the propagation characteristics of the microwave frequency band in non-uniform time-varying plasma are studied.Through the simulation of different frequency bands,the frequency drift phenomenon of non-uniform time-varying plasma is found.The speed of the t non-uniform time-varying plasma and the effect of the frequency of the electromagnetic wave on the frequency drift are analyzed.The results show that after the non-uniform time-varying plasma is generated,a new resonant frequency is generated in the resonant cavity.The faster the timevarying plasma is generated,the larger the frequency drift.When the non-uniform time-varying plasma is generated at the same speed,the lower the frequency of the wave,the greater the amount of frequency drift.The simulation and experimental research on the interaction between non-uniform timevarying plasma and electromagnetic wave are carried out.In the simulation results,the plasma time-varying period is consistent with the position of the first side lobes.In the case of the same time-varying period,the modulation intensity is inversely proportional to the frequency.The intensity of the modulation of the electromagnetic wave amplitude by the plasma decreases as the frequency of the electromagnetic wave increases.In the steady-state discharge plasma transmission experiment,the attenuation characteristics of the electromagnetic wave in different frequency bands and the attenuation characteristics of the electromagnetic wave are obtained when the discharge pressure is different.In the non-uniform time-varying plasma transmission experiment,the effect of plasma on the amplitude and phase modulation of electromagnetic waves is verified,and the correctness of the simulation results is proved.The effect of non-uniform time-varying dust plasma parameters on electromagnetic wave propagation characteristics is studied by SO-FDTD method.Different dust plasma parameters: the concentration of dust particles,the radius of dust particles,the electron density,and the rate of change of electron density on the propagation characteristics of electromagnetic waves in a non-uniform time-varying dust plasma are calculated.The results show that the dust concentration and dust radius in the dust plasma have a slight influence on the electromagnetic wave propagation characteristics,and the maximum electron density and electron density change rate in the dust plasma have a great influence on the electromagnetic wave propagation characteristics.In addition,as the frequency of the incident wave increases,the influence of various parameters in the dust plasma on the electromagnetic wave propagation will be weakened.At the same time,it will reduce the absorption of electromagnetic wave energy by the entire dust plasma layer and enhance the ability of electromagnetic waves to penetrate the plasma layer.