Improvement of the spreading effect of atmospheric pressure microplasma jet treatment through shielding-gas-controlled focusing

The spreading effect of atmospheric pressure microplasma jets (APμPJ) on the surface of materials will increase the etching area, and controlling the diameter of the jet can improve the precision of surface treatment. In this work, a two-dimensional axisymmetric simulation model is established to analyze the effect of nitrogen (N₂) shielding gas on helium (He) from gas dynamics. In addition, by etching the polyethylene terephthalate film, the relationship between the etching effect and aerodynamic analysis is verified. The simulation results are similar to the experimental results, indicating that N₂ shielding gas has a focusing effect which is related to the N₂ flow rate, distance difference between the inner and outer tubes, and outer tube nozzle diameter. It is hoped that the results of this work can provide a certain reference for the use of shielding gas to control the jet flow of APμPJ.