A multi-electrode RF capacitively coupled He/O2 plasma jet — Experimental and simulation study

Atmospheric pressure plasma jets (APPJs) have attracted a great deal of attention recently since they do not need expensive vacuum system, enabling a wide variety of application such as surface modification or bio-medical treatments, etc. In this work we developed arf (13.56 MHz) capacitively coupled APPJ where a multi-figure type electrode structure is adopted in order to enhance the plasma discharge volume while maintaining low ingition voltage/power. Experiments with O2/He gas mixture have been conducted. Characteristics of the discharge were investigated by optical emission spectroscopy analysis and I/V probe measurements. To further understand the physical and chemical mechanisms occurring in the plasma discharge, as well as the effluence region, numerical simulations have been carried out with a 2-D fluid model (CFD-ACE+, ESI Corp.), where 15 gas phase species and 82 reactions are considered in the analysis. Simulation results show that the electron density is around 1017 1/m3, electron temperature is around 1.2 eV and sheath thickness is around 0.6 mm between two electrodes in APPJ. Moreover, the particle densities between the electrodes and along the dielectric tube are solved, we found out that the main active species are O, O2∗ and O3. Furthermore, the fluxes of these species incident on the grounded electrode placed at 1.5 cm away from the exit of nozzle are around 109 kg/m2-s (O), 108 kg/m2-s (O2∗) and 109 kg/m2-s (O3), while the gas temperature is around 306 K. Parametric analysis from the simulation analysis along with experimental measurements will be presented.