Effects of Oxygen Concentration on the Reactive Oxygen Species Density Under Different Operating Conditions in Atmospheric-Pressure Helium/Oxygen Pulsed Dielectric Barrier Discharge

In this paper, a numerical investigation on the effects of oxygen concentration on the reactive oxygen species (ROS) density under different operating conditions in the atmospheric-pressure helium/oxygen pulsed dielectric barrier discharge (DBD) has been performed by means of a one-dimensional (1-D) fluid model. The involved ROS are ground state oxygen atom O, excited state oxygen atom O(
¹
D), single delta metastable oxygen O
₂
(
¹
Δg) (SDO), and ozone molecule O
₃
. The present work gives the following significant results. For a given operating condition, the averaged O density is evidently larger than the other three ROS densities. There exist characteristic oxygen concentrations where the averaged densities of O and SDO reach their maximum with the increase in the oxygen concentration, respectively. The averaged O
₃
density increases with the oxygen concentration, but the reverse is true for the averaged O(1D) density. In addition, the ROS density is increased when increasing the applied voltage amplitude Va, decreasing the rising time of the applied voltage pulse t
_r
, or reducing the frequency of the applied voltage pulse f. Also, the characteristic oxygen concentrations for the averaged densities of both the O and SDO move towards the higher oxygen concentration when increasing the V
_a
, decreasing the t
_r
, or increasing the f. The effect of the operating conditions on the averaged O
₃
density is weak under lower oxygen concentrations, and it is increasingly affected by the operating conditions with the increasing oxygen concentration. However, the variation trend of the averaged O(
¹
D) density versus oxygen concentration is hardly affected by the operating conditions.