Research On Low Power Microwave Microplasma Source Based On Metamaterial Structure

Metamaterials have many prospective applications on smart antennas,terahertz holographic imaging and electromagnetic stealth,ect.Metamaterials which are characteristic of negative magnetic permeability act extremely as suitable carriers for exciting high-density micro-plasma.The micro-plasma with small discharge scale and stable discharge performance can be used in chemical analysis,environmental protection and material processing and so on.Therefore,it is of great practical significance to research microwave micro-plasma sources based on metamaterial structures.According to the basic structure of metamaterial,some low-power microwave micro-plasma sources based on single and double split ring resonators operating at 2.45 GHz are studied in this thesis,including rectangular single split ring resonator(SSRR),circular single split ring resonator(SSRR),rectangular double split ring slot resonator(DSRR),circular double split ring resonator(DSRR)and binary rectangular double split ring resonator.Firstly,5 kinds of single and double split ring resonators are designed and optimized with HFSS simulation software,and the effects of the size of related structures on S parameters,resonant frequency and electromagnetic field distribution are analyzed.Secondly,the microwave micro-plasma sources based on single and double split ring resonators were fabricated,and its S parameters were tested.Finally,an experimental system was established to study the effects of input power and gas pressure on excitation,discharge intensity and spectrum of microwave microplasma in air and argon.The optical emission spectrum of microwave micro-plasma was analyzed with the relative intensity comparison method and the Stark broadening effect,and the electron temperature and electron density of microwave micro-plasma were estimated.The experimental research shows that the micro-plasma discharge area increases with input power when gas pressure is constant,and increases with gas pressure when input power is constant.For the binary rectangular double split ring resonator,the microwave micro-plasma can be ignited at both the inner and outer ring gaps when the input power is 2.1W and gas pressure is 1140 Pa in argon.It is testified that the electron temperature and electron density in air is higher than that in argon,and the electron temperature and electron density of the rectangular structure is higher than that of the circular structure.When the micro-plasma is ignited at both the inner and outer ring gaps of DSRR,its electron density and electron temperature are higher than that of SSRR.While the micro-plasma is excited only at the outer ring gap of DSRR,its electron density and electron temperature are lower than that of SSRR.The discharge shows obvious contamination to the surface of split ring resonators.This work provides a reference for research of miniaturized microwave micro-plasma sources based on metamaterial structures.