On The Diagnostics And Optimization Of Hydroxyl Radicals And Atomic Oxygen In Atmospheric Pressure Plasma Jets

Non-equilibrium atmospheric pressure plasma jets(N-APPJs)could generates low temperature plasmas in the open space rather in a confined gap.With simple operation,easy configurations and rich reactive species,N-APPJs draw a lot of attentions by scholars around the world in the fields of biomedical engineering,material processing and surface modification.In this work,aiming at two key reactive oxygen species in N-APPJs(hydroxyl and atomic oxygen),laser induced fluorescence spectrometry is applied to study their calibration methods,density distributions,space and temporally resolved variations and optimizing techniques.The dissertation is arranged as follows:1.Two dimensional hydroxyl(OH)density distribution is measured by one-photon absorption laser induced fluorescence with high space and time revolution.A kinetic chemical model is developed by fitting OH-LIF decay in the afterglow to calibrate absolute OH density;Donut shape distribution of OH radicals is found;Gas flow effects on the donut shape distribution is investigated;Discharge and gas parameters on OH density distribution is studied;Multi-ring structures on optimizing OH density is discussed and testified by sterilization experiments.2.Atomic oxygen(O)density distribution is detected by two-photon laser induced fluorescence with high space and time revolution.The calibration is applied by comparing the similar transition of O atoms and Xe without discharge.Ring-shape distribution of O atoms is first time found to author's knowledge;Discharge and gas parameters on O density distribution is studied;The production of O atoms with distance to electrode tip is investigated;It is suggested to adopt suitable devices and seed gas content to optimize O concentration in APPJs.3.Five widely used plasma jet devices are carefully selected to compare with each other on their generation of reactive oxygen species(ROS: OH/O).OH/O density map is plotted under same conditions;Discharge and gas parameters on OH/O density distribution for each devices is studied;It is found that the structure with naked pin electrode and ring electrodes could generate highest OH/O density,which provide great guidance for kinds of applications.