Characteristics of chemical products under the NO_<i>x</i> mode of dielectric barrier discharge: comprehensive effects of specific energy input and magnetic field

The reactive nitrogen species generated under the NO_<i>x</i> mode of dielectric barrier discharge have attracted widespread attention in biomedical applications, with the crucial factor for their utilization being the regulation of the species proportion. In this work, we investigated the variation of NO_<i>x</i> mode products in an AC-driven coaxial dielectric barrier discharge system under different specific energy inputs (SEIs) controlled by voltages and gas flow rates in the presence and absence of a magnetic field as a method for combinatorial multiparameter regulation. Our findings demonstrated that the effect of SEIs on products was closely related to the discharge conditions. Under constant conditions, increasing the SEI led to the promotion of NO and N₂O, suppression of NO₂, and stabilization of ONOO^-. When the SEI was varied by adjusting the voltage, the product trend followed the same pattern as described above. However, when the SEI was varied by adjusting the gas flow rate, the product trend appeared to differ. As the gas flow rate increased, the discharge power remained almost unchanged, while the SEI decreased significantly, leading to the suppression of NO, N₂O, NO₂, and ONOO^- production. The magnetic field did not significantly alter the SEI, but it affected the products. Introducing a 0.2 T magnetic field under constant conditions promoted the production of NO while suppressing N₂O, NO₂ and ONOO^- formation. To understand the microscopic physicochemical mechanisms of product variations under multiple discharge parameters, we analyzed the chemical reaction network, presenting an overview of the effects of multiparameters on the generation of reactive nitrogen species. These insights hold significant value for plasma applications within the realm of biomedicine, where the regulated generation of reactive nitrogen species is pivotal in attaining the desired plasma performance.