Numerical Study On The Mode Transition Of Atmospheric Dbd Plasma And Its Interaction With Cells

Atmospheric pressure cold plasma can generate lots of reactive species with the gas at room temperate,and it don't need expensive,complex vacuum equipments,so it has a wide application.After plasma applied to material processing successfully,people began to research using plasma processing life tissues and cells,such as used for sterilization,inducing cancer cell apoptosis.It could get better treatment effect with plasma instead of drugs or auxiliary.Cell is the basic unit of organism structure and function,the research of the interaction of plasma and cell is the important basis of plasma medicine,and it is of great significance to reveal the inner mechanism of the plasma medicine.In this thesis,we first introduce the research background of plasma itself.By means of the fluid simulation,we numerically studied all kinds of discharge modes in atmospheric pressure dielectric barrier discharges with helium as working gas as the excitation frequency increases from kHz to MHz range,and the computational data show a good agreement with the experimental measurement.Then we coupled the fluid model of plasma with the multi-layer dielectric model of cell,and researched the interactions of atmospheric pressure dielectric barrier discharge plasma and cells.Get the following main conclusions:The discharge mode of atmospheric pressure dielectric barrier discharge plasma can be divided into a low power mode and a high power mode in each frequency range.In the low frequency range,there is a Townsend discharge mode and a glow discharge mode.In the medium frequency range,there is an ? mode and a hybrid mode.In the high frequency range,there is an ? model and an a mode.The hybrid mode has mixing characteristics of glow discharge mode and a mode.The discharge structure of hybrid mode is not as stable as glow discharge mode or a mode.With the increase of frequency or voltage,the characteristics of a mode become more significant in the discharge structure of hybrid mode.In high power modes,the position of the largest ionization located in the sheaths,while in low power modes,the position of the largest ionization located in the middle of the gas gap.Under the action of atmospheric pressure dielectric barrier discharge plasma,the voltage of cell membrane occupied most parts of the cell voltage,the voltage of other layers is relatively very small and has a peak in the form of pulse during the discharge.When increasing the amplitude or frequency of applied voltage,the voltage of each layer will increase.When raising voltage amplitude,the cell membrane voltage will increase faster than the nucleus membrane voltage,when raising frequency,the cell membrane voltage will increase slower than the nucleus membrane voltage.Compared normal cells with tumor cells,we find that the voltage of normal cell is smaller than tumor cell's,this leads to tumor cell membrane more easily breakdown.For intracellular membrane voltage,normal cell's is smaller than tumor cell's during the discharge,but normal cell's is larger than tumor cell's during the time does not discharge.This feature is beneficial to normal cell's intracellular membrane not to be breakdown.The membrane of tumor cells is more easily breakdown than the membrane of normal cells,so we can achieve selective electroporation by selecting the parameters.