Numerical study on propagation mechanism and bio-medicine applications of plasma jet

摘要

In this study, the propagation mechanism of plasma jet and some bio-medical applications are investigated by two-dimensional numerical model. The key equations of plasma physics and chemistry related with plasma jet are firstly introduced. The simulation results suggest that the sheath forms near the dielectric tube inner surface, which results in the plasma channel to shrink in the radial direction inside the dielectric tube. The photoionisation of air species plays a crucial role in the transition from the localised discharge to streamer. The Penning ionisation increases the electric conductivity of the plasma channel and facilitates the formation of ring-shaped plasma bullet. For the plasma jet in the open air, electron-impact dissociation of H2O, electron neutralisation of H2O+, as well as dissociation of H2O by O(1D) are found to be the main reactions to produce OH. For micro plasma jet, the higher ignition voltage as the tube diameter decreased is attributed to the deceasing pre-avalanche electron density inside the tube. The simulation of plasma treatment of bacteria biofilm indicates that the mean free path of charged species in µm scale permitted the plasma penetrate into the cavity of the biofilm, and the structure of the biofilm results in the non-uniform distribution of ROS and RNS. The simulation of plasma treatment of cells immersed in liquid suggests that the HO2 generated by plasma aqueous species is the only way for superoxide to penetrate cell membrane and damage cytosolic fumarase B.