Atmospheric Pressure Air Plasma Uniformity Study

With the development of low temperature plasma technology generated by gas discharge,the application demand of uniform plasma is increasing day by day.The use of inert gases or low-pressure environments for the generation of uniform plasma has limited industrial applications due to its heavy reliance on complex gas path devices and vacuum environments.The generation of uniform plasma without discharge filaments in open atmospheric pressure air environment has become a research hotspot.In this thesis,an atmospheric pressure air plasma generator is developed,an air discharge experimental platform is built,and a uniform dispersion plasma without discharge filaments is generated in the air without external airflow,and the application of material surface modification is explored.The structure of atmospheric pressure air plasma generator is designed.The flat electrode structure,needle-ring electrode structure and needle-plate electrode structure are studied and analyzed.The discharge characteristics of each electrode structure in air are compared.The needle-plate dielectric barrier generator structure suitable for generating uniform plasma in air is selected.The appropriate power supply circuit is selected to drive the transformer to generate a plasma power supply with a peak-to-peak value of 25 k V.At the same time,an electrical and optical measurement system is built,and an atmospheric pressure air plasma experimental platform is established.The air discharge experiment is carried out in the indoor air environment,and the uniformly dispersed air plasma is generated when the discharge spacing is 10 mm.The discharge analysis is carried out in combination with electrical and optical images.On the basis of the existing plasma uniformity detection method,the egg inner membrane surface treatment method is proposed.The uniformity of air plasma is determined by image shooting and egg membrane treatment.The argon plasma jet is used as a comparison,and the results are determined by discharge image,optical magnifying glass and optical microscope.The uniformity of air discharge with different spacing is studied experimentally.The results show that the argon plasma jet is in the form of filamentary discharge.The discharge images have obvious filamentary discharge and causes perforation damage to the egg inner membrane,while the air plasma discharge image has no discharge filaments and no damage to the egg membrane after treatment,which proves the uniformity of the air plasma.When the spacing is5 mm,it will develop into arc discharge,and when the spacing is 12 mm,the discharge only shows corona mode.The spectral composition of the air spectrum and the reaction form of the internal particles are analyzed.The species and intensity changes of the particles in the air plasma at different stages of discharge are explored.It is found that the spectrum has a good correspondence with the experimental phenomena.The surface modification treatment of hydrophobic non-woven fabrics is explored.The air plasma did not cause damage to non-woven fabrics and after 60 s,the surface wettability of non-woven fabrics is greatly increased.