Electromagnetic Characteristics And Experimental Study Of Plasma Based On The Correction Of Electron Energy Distribution Function

Plasma is a complex multi-particle system.There are many phenomena of research significance in the transmission of electromagnetic wave in plasma.Great progress has been made in the interaction between electromagnetic wave and plasma over the years,so the research on this aspect has become a hot topic in the field of plasma and electromagnetic transmission.Electrons play a major role in the interaction between electromagnetic wave and plasma,and the Electron Energy Distribution Function(EEDF)is an important physical parameter to describe plasma,which determines the relationship between current and electric field in plasma.This determines the dielectric properties of the plasma.In laboratory studies,we generally assume that electrons are in thermal equilibrium,and the electron distribution function is Maxwellian distribution.If Maxwellian hypothesis is not valid,Boltzmann equation must be used to solve the electron distribution function.It is only an idealized assumption that electrons in plasma meet Maxwell distribution.Plasmas often deviate from Maxwell distribution in practical experiments,so it is impossible to simply use Maxwell distribution to deal with practical problems.This article is based on analysis of plasma EEDF,EEDF influence on electron energy plasma electromagnetic characteristics,combined with the actual experiments to verify this theory and numerical simulation,the focus on plasma EEDF effect on the conductivity and dielectric constant and the experimental verification,the plasma EEDF effects on the electromagnetic wave transmission coefficient and the experimental verification.Research work on transmission characteristics of plasma antenna and the influence of EEDF on transmission characteristics,the specific research contents are as follows:Firstly,based on the general form of plasma conductivity and dielectric constant obtained by plasma kinetic theory,a correction factor was introduced to modify the form.Four typical EEDF were used to compare the modified results,and the effects of different EEDF on the conductivity and dielectric constant were analyzed.Based on the above theory and numerical simulation,carried out the experimental research,the design of the cylindrical microwave cavity,the cavity perturbation method,the conductivity and dielectric constant expression to the perturbation theory,atmospheric pressure was obtained under different discharge form helium jet plasma electron density value,and by using several typical EEDF has given the experiment results were corrected.The modified results were in good agreement with the existing results in the literature,and the specific form of describing helium jet plasma EEDF was obtained.Secondly,a physical model of the interaction between electromagnetic wave and plasma has been build and several typical EEDF under the condition of the electromagnetic wave incident to plasma reflection,transmission and absorption characteristics were studied,and several EEDF were explored at different collision frequency,discharge pressure,under the condition of electron density and thickness of the plasma,the influence on the electromagnetic wave propagation properties.On this basis,the use of coaxial hollow cathode discharge device grid,ionized argon and helium gas,the two kinds of plasma,and used the vector network analyzer on the transmission rate of transmission of electromagnetic wave in plasma were measured,will get the transmission coefficient of the experimental results and give the theoretical results of several different EEDF were compared.It is found that the argon plasma produced in the experiment conforms to the Druyvesteyn distribution and the helium plasma conforms to the Bi-Maxwellian distribution.Finally,based on EEDF theory,the plasma antenna is studied experimentally.An array plasma antenna system is constructed and its characteristics are measured.The antenna direction patterns at different discharge currents are obtained.The results showed that in some cases,the plasma antenna will present highly directional radiation phenomenon.The electron density of the plasma antenna and the transmission coefficient of electromagnetic wave in the antenna were further measured at different discharge currents.On this basis,the effects of different EEDF on the relative amplitude and additional phase of plasma antennas are compared.It is found that EEDF has a great effect on the amplitude variation of the plasma antenna system,but a relatively small effect on the phase variation.