Numerical Study On Atmospheric Pressure Dielectric Barrier Discharge In Argon-Oxygen Mixture

In recent years, studies on atmospheric pressure non-thermal plasma applications in biomedicine are becoming more widely. Many studies have shown that active particles of the plasma play a dominant role in the applications of sterilization, wound healing, skin disease treatment, accelerating cancer cells' death et al. Especially, it has been confirmed that reactive oxygen species (ROS) play a key role in it. The atmospheric pressure dielectric barrier discharge in the gas mixed oxygen is the main way to produce ROS, and it has been widely used in biomedical research at present. Due to the lack of diagnosis methods of ROS, ROS generation and consumption mechanism in the atmospheric pressure dielectric barrier discharge is still not clear, there are many basic problems which need to be investigated. Numerical simulation method is advantageous to analyze ROS generation and consumption mechanism and provides some reference for experiments. In this thesis, atmospheric pressure dielectric barrier discharge in argon-oxygen mixture has been systematically investigated by means of numerical simulation with the use of a one-dimensional fluid model. The main contents and results are as follows.1. Assuming the oxygen concentration is constant, the characteristics of single pulse and multi-pulse atmospheric pressure dielectric barrier discharge in argon-oxygen mixture have been obtained. By calculating the electric field, charged particle density and other physical quantities, the spatial distribution of oxygen particle density has been analyzed. In the discharge space, the ground state oxygen atoms density is always maintained at high level.2. The effects of oxygen concentration on the single pulse and multi-pulse atmospheric pressure dielectric barrier discharge in argon-oxygen mixture have been discussed. With the oxygen concentration increasing. The densities of electrons, argon atomic ions, resonance state argon atoms, metastable state argon atoms and excited state argon atoms all show a trend of decline. The oxygen molecular ions density is high and little influenced by the oxygen concentration. Ground state oxygen atoms density tends to increase before falling. The ozone density increases significantly. The effects of oxygen concentration on the single pulse and multi-pulse atmospheric pressure dielectric barrier discharge in argon-oxygen mixture are similar.3. The effects of oxygen concentration on the discharge mode have been analyzed. With the oxygen concentration increasing, the discharge mode begins to change gradually from the glow discharge mode to Townsend discharge mode, and the electrons density decreases. With the increase of applied voltage, the discharge mode of multi-pulse discharge begins to change from Townsend discharge mode to glow discharge.4. The reaction rate of ROS with the change of oxygen concentration has been investigated. The evolution mechanism of ROS has been systematically analyzed. The ROS evolution mechanism of single pulse and multi-pulse atmospheric pressure dielectric barrier discharge in argon-oxygen mixture is similar.