Effect of gas flow on transport of O (3Pj) atoms produced in ac power excited non-equilibrium atmospheric-pressure O2/Ar plasma jet

The Spatial distribution of O ( 3 P j ) atoms emitted from a non-equilibrium atmospheric-pressure O 2 /Ar plasma jet in ambient N 2 gas has been measured by using the vacuum ultraviolet absorption spectroscopy. In remote regions of the plasma, the absolute density of O ( 3 P j ) atoms for a total gas flow rate of 1 slm decreased from 4.1 × 10 14 to 1.5 × 10 13 cm −3 as the distance from the main discharge region increased from 10 to 16 mm and that for 5 slm decreased from 7.7 × 10 14 to 2.0 × 10 14 cm −3 . The reduction ratio thus changed from 0.037 to 0.259 with increasing total gas flow rate. Although loss of O ( 3 P j ) atoms occurs frequently due to the influence of N 2 or nitrogen oxide species produced by the inflow of ambient gas, it is found that the gas flow velocity is a very important factor for the transport of the active species to longer distances from the plasma, and it determines the material processing performance for a non-equilibrium atmospheric-pressure O 2 /Ar plasma jet.