Chemistry of atmospheric pressure low temperature plasma jets for different experimental parameters

Abstract

The chemistry of atmospheric pressure low temperature plasma jets (APLTPJs) is investigated by a spatio-temporally resolved optical emission spectroscopy (OES) method for different experimental parameters. APLTPJs' chemical makeup is important for biomedical applications because it is their reactive species that undergo interaction with the biological systems under treatment. The behaviors of emitting species are studied for different HV pulse amplitudes, pulse widths, repetition rates, and gas flow rates. These species include N 2 SPS (0–0) band at 337 nm, N 2 + FNS (0–0) band at 391 nm, OH (A- X) at 308 nm, He (23P-33S) at 706 nm, and O (35S-35P) at 777 nm. The effect of argon admixture on APLTPJ kinetic mechanism was found to enhance the plasma chemistry during applications. Accordingly, even a small amount of argon admixture significantly increases the intensity of N 2 SPS while decreasing that of N 2 + FNS dramatically. As already reported in several publications [1–3], the plasma jet is not a continuous medium but rather consists of plasma bullets that are launched from the reactor with each HV pulse. Spatio-temporally resolved distributions of excited species offer great insights into the plasma bullet's propagation mechanism for pure helium and helium/argon admixture working gases. Hence, excited states reach their maxima around 12 mm away from the reactor. In addition, the plasma bullet velocity in helium/argon mixtures is about twice as fast compared to pure helium. The donut-shaped structure of the plasma bullets is also observed for different emitting species, axial positions, HV pulse amplitudes, and argon admixtures.