Transition mechanisms between selective O₃ and NO x generation modes in atmospheric-pressure plasmas: decoupling specific discharge energy and gas temperature effects

Two modes of the atmospheric-pressure plasma discharge, distinguished by the dominant O 3 and NO x species are studied numerically and experimentally. To investigate the mode transition mechanisms, here we develop a global chemical kinetics model for the atmospheric-pressure dielectric barrier discharge involving 63 species and 750 reactions. Validated by the experimental results, the model accurately describes the mode transition. The N, O, O 2 (a), and O 2 (b) are the essential transient intermediate species for the O 3 and NO x production and loss reactions. The individual and synergistic effects of the specific discharge energy and the gas temperature on the species density and the relative contributions of the dominant reactions are quantified under the increasing discharge voltage conditions. The modeling results indicate that the gas temperature and specific discharge energy both contributed to the discharge mode transition, while the decisive factors affecting the change of the O 3 and NO x density are different in the respective modes. These insights contribute to diverse plasma applications in biomedicine, agriculture, food, and other fields where selective and controlled production of O 3 and NO x species is the key for the desired plasma performance.