Study On Characteristics Of Microwave Microplasma Linear Array Based On Microstripe Resonator

Microplasma is a plasma that is confined to a limited space,and the discharge dimension is generally in the millimeter or micron level.Due to the reduction of discharge dimension,the characteristics of microplasma are different from the ordinary plasma.Firstly,microplasma can be ignited and sustained stably at atmospheric pressure,and has a high plasma density and good stability.Secondly,microplasma consumes less gas and energy than ordinary plasma,which reduces the cost of its use.Besides,smaller dimension makes microplasma device portable and easy to be integrated.Therefore,microplasma has potential applications on nano materials synthesis,micromachinery system,microchemical analysis,photonic devices and biological materials processing and other fields.Based on the microstrip resonator array,the characteristics of the microplasma linear array ignited in air are explored in this thesis.At first,the basic theory of microplasma,the principal of microstrip resonator and coupled mode theory are introduced.Secondly,the multimode resonant frequencies between 0Hz and 20GHz can be obtained with HFSS.The effect of the Teflon covered over the gap on the electric field of gap is also simulated.Finally,the experimental results show that the S parameter,the resonant frequency,ignition of microplasma array,discharge area and strength and optical emission spectra are closely related with the air pressure,the signal frequency and input power.In addition,the electron temperature and electron density can be calculated approximately using the optical emission spectra detected in experiments.The simulated results show that except for the domain resonant frequency of 2.45GHz,there are still 6 multimode resonant frequencies of 7.3GHz,8.21GHz,10.35GHz,13.94GHz,15.74GHz and 17.95GHz between 0Hz and 20GHz.In addition,the electric field of gap is distributed much more uniformly while the gap is coated withTelflon sheet.With the increase of air pressure,the discharge area reduces,the microplasma array is broken,the brightness of microplasma becomes weaker,and the electron temperature and electron density decrease.Between the pressure of 6.2Torr and 45Torr,the |S11| is minimum of 0.274 at the same input power when the air pressure is 17.9Torr.When the air pressure is raised to 6.2Torr,there are 8 elements of microwave microplasma linear array ignited,the discharge area and brightness have maximum,and the electron temperature and electron density are 0.61eV(7078K)and 7.97*1017cm-3 respectively.When the air pressure is raised to 45Torr,the microwave microplasma linear array is extinguished.At the air pressure of 3.3Torr,there are 8 elements of microwave microplasma linear array are successfully ignited when the input power is 21.73W,while the input power is reduced to 20.4W,the microwave microplasma linear array is broken,and the microwave microplasma linear array is extinguished when the input power is below 18.6W.After the microwave microplasma linear array is excited,the domain resonant frequency of the microwave microplasma linear array increases from 2472MHz to 2487MHz and 2495MHz whose bandwidth is 125MHz.