Development And Experimental Study Of Atmospheric Pressure Pulsed Microwave Low Temperature Plasma Jet Device

Atmospheric pressure microwave plasma is widely used in plasma assisted combustion,material processing and plasma biomedical fields.Different applications require plasma jets with different parameters to make them suitable for practical applications and achieve optimal treatment results.Atmospheric pressure microwave plasma jets treat materials that are not resistant to high temperature or directly contact the surface of organisms,which require plasma jets at room temperature or lower temperatures.However,the atmospheric pressure low temperature plasma jet formed by the existing discharge device has the problems of high temperature,excessive ozone generation and low plasma density,which limits its application fields.In view of this,an atmospheric pressure pulsed microwave low temperature plasma jet device is developed in this paper.The atmospheric pressure plasma jet generated by pulsed microwave can effectively avoid the above problems.The device uses argon,nitrogen and even air as working gases,respectively,and can discharge in the air environment to produce microwave low-temperature plasma jet.The main research contents of this paper are as follows :(1)Firstly,the working principles of four typical microwave discharge devices are analyzed,and the coaxial line resonator with simple structure and low loss is selected as the basic configuration of the discharge device developed in this paper by comparison.Then the basic theory of coaxial resonator is described,and the coaxial resonator meeting the discharge requirements is designed according to the theoretical basis.(2)The high frequency electromagnetic simulation software Ansoft HFSS is used to simulate and model the designed coaxial resonator.The purpose is to optimize the structural parameters of the coaxial resonator,so that the optimized coaxial resonator has the characteristics of stable discharge and high microwave energy utilization.(3)The atmospheric pressure pulsed microwave plasma jet discharge experimental system was built.Firstly,the discharge performance of the designed coaxial resonator is verified.Under the premise of meeting the discharge requirements,argon,nitrogen and air are used for discharge experiments.The results show that the atmospheric pressure pulse microwave low temperature plasma jet can be produced by changing the discharge parameters of the three gases in the air environment.(4)The morphology and parameters of atmospheric pressure pulse microwave low temperature plasma jet produced by three kinds of gas discharge were recorded by high speed ICCD camera,optical fiber spectrometer and microwave Rayleigh scattering device.Through the comprehensive analysis of the evolution process of electron density,transient discharge image and electromagnetic simulation results,the mechanism and characteristics of atmospheric pressure pulse microwave low-temperature plasma jet ionization process are obtained.