Study On The Discharge And Electromagnetic Characteristics Of Array Plasma

Plasma is a substance composed of electrons and ions of a large amount of motion,which is electrically neutral to the outside.Due to its own special way of existence,the plasma has unique electromagnetic properties.When the plasma is arranged periodically,the plasma that has a periodic structure becomes another material,which is called plasma photonic crystals(PPCs).In PPCs,the propagation of electromagnetic waves will show many new phenomena due to the existence of plasma.For example,tunable forbidden band and surface plasmon polaritons.These characteristics enable RF / microwave devices based on plasma photonic crystals to quickly adapt to the growing modern communication system.Studying the interaction between array plasma and electromagnetic wave can give us a better understanding of the effect of plasma on electromagnetic waves,and grasp the general law of using plasma to control the transmission of electromagnetic wave and the profound meaning behind it.This has an important guiding significance for the fabrication of RF / microwave devices based on PPCs.Based on our predecessors' work and combined with the physical theory of PPCs,we have studied basic properties and characteristics of PPCs from simulation and experiments in this paper.The effect of the parameters of plasma and the geometric parameters of the array on the PBG is analyzed.The main achievements and innovations of this paper are as follows:1?Through the finite element simulation software COMSOL and the preliminary experiment,we have studied the properties of TM polarized wave propagation in one dimension plasma array.And the effects of the lattice constant,the radius ratio of the medium,the number of medium,the plasma density and the collision frequency on the PBG are also discussed.At the same time,the EM characteristics of the one dimensional array plasma are studied under the TE wave mode.Unlike single plasma,the study shows that when the TE wave propagates in one-dimensional array plasma,the tunable passband and negative PBG structure appear in the cut-off band which below the plasma frequency.And the negative PBG is often accompanied by the appearance of surface plasma waves.With the increase of the plasma density,these bands will gradually become stronger.All of the bands can be regulated by the density of the plasma.2?Through simulation and experiment,we studied the effect of plasma on the defect mode in the TM mode.The influence of the plasma density on the quality factor(Q)of the resonator and the frequency of the resonant peak is analyzed by simulation.In the experiment,two dimensional alumina ceramic photonic crystal with defects was used to form the resonant cavity.The plasma column was produced by low temperature glow discharge with low pressure mercury lamp,and the plasma column was placed in the resonant cavity.The Q and the resonant frequency of the resonant cavity are measured and calculated under different current.By comparing the difference of the relation between the resonant frequency and the plasma density in the theory and experiment,the range of change of the plasma density in the experiment is deduced.At the same time,the results also show that the plasma change the Q value and resonant frequency of the resonator by plasma density.However,a higher collision frequency will cause a decrease in the Q value.The plasma density and collision frequency determine the change of the Q value.3?We use a glow discharge to form a two-dimensional plasma column array in a closed space.And the influence of plasma density,duty cycle of plasma,lattice constant and dielectric constant of wrapped medium on the forbidden band which produced by the twodimensional plasma column array under different electromagnetic modes is discussed through simulation analysis.The results show that the propagation of TM wave and TE wave in the two-dimensional plasma array has very different properties.The cut-off band caused by plasma is produced at low frequency at TM and TE wave,but the cut-off frequency is obviously lower than the plasma frequency.Besides,TM wave is more likely to generate complete forbidden band than TE wave,and increasing dielectric constant of wrapped medium can significantly enhance the scattering effect,resulting in complete forbidden band.In contrast,the TE wave has a series of flat band structures associated with surface plasma waves,as well as the related Fano mode.The plasma density has a significant influence on all the PBG structure in these two modes.