Modeling Study on the Generation of Reactive Oxygen Species in Atmospheric Radio‐Frequency Helium–Oxygen Discharges

Abstract

Atmospheric radio‐frequency (rf) plasmas have attracted an increasing amount of attention due to its unparalleled capability for production of chemically reactive oxygen species (ROS). In this paper, we explore a one‐dimensional fluid model, incorporating 17 species and 65 key reactions, to investigate the generation mechanism of ROS in atmospheric He/O2 rf discharges. From the computational data the atomic oxygen density is almost linearly dependent on the power density and its largest value was observed at the oxygen admixture of 0.6% while altering the oxygen admixture at a constant power density, and an optimal oxygen admixture level of 0.3% is also found to produce the largest density of single delta oxygen (SDO) at a given power density.The dominant production and destruction reactions of ROS are also discussed based on the simulation results.

Uncertainty and error in complex plasma chemistry models

“…Recent interest in helium-oxygen chemistry has been stimulated by applications in chemical lasers (where excitation of the O 2 (a 1 ∆ u ) state is the primary concern) and biomedicine [132,139,77,81,100,142,50,95]. As we have already noted, plasma chemistry models are typically derived by complicated paths, and we will not try to follow these historical developments in detail.…”

Numerical Simulation on the Production of Reactive Oxygen Species in Atmospheric Pulse-Modulated RF Discharges with He/O2 Mixtures

“…[25,15] An optimal oxygen admixture of about 0.6%, at which the ground state atomic oxygen density could get the maximum value under a constant power or applied voltage condition, has been observed. [6,7,15] To investigate the influence of duty cycle and modulation frequency on the production of ROS, the oxygen admixture used in present study is fixed as 0.6%.…”

“…[22] The used model and reaction set has been validated in refs. [15,22] by comparing with the experimental measurements. …”

“…[17][18][19] The simulations based on the fluid description also have been developed, usually with simplified reaction set that selected by the global model, to greatly reduce the computational load. [14,15,20] In our previous report, we have presented a fluid model to tailor and optimize the pure helium plasmas generated in a pulse-modulated RF discharge. [12] In this study, the fluid model incorporated with a simplified He/O 2 reaction set is explored to examine the generation of ROS in a pulsemodulated RF discharge, we focus on the influences of duty cycle and modulation frequency on the generation of ROS, which would provide interesting and useful information for many applications.…”

“…[6,8] To gain more details on the production and destruction of reactive species, numerical modeling, usually based on some simplified assumptions, is an effective way to identify the key pathways of ROS and RNS, this can markedly deepen the insights of plasma chemistry in atmospheric RF discharges. [14,15] Due to the high computational efficiency by neglecting the spatial gradients, global model always is adopted to study the plasma chemistry even with tens of species and hundreds of reactions, to further clarify the key reactive species and reactions. [17][18][19] The simulations based on the fluid description also have been developed, usually with simplified reaction set that selected by the global model, to greatly reduce the computational load.…”