Microscopic Discharge Characteristics and Experimental Investigation of Atmospheric-Pressure Air Dielectric Barrier Discharge

To elucidate the microscopic evolution characteristics of atmospheric-pressure air dielectric barrier discharge (DBD) under different voltage amplitudes, this study systematically investigates the discharge behavior of an atmospheric-pressure air DBD with a double-dielectric parallel-plate configuration by combining equivalent-circuit analysis, fluid-based numerical simulation, and experimental measurements. First, an equivalent-circuit model of the DBD, incorporating the dielectric capacitance, gap capacitance, and time-varying plasma resistance, is established to analyze the dynamic relationships among the applied voltage, gap voltage, and conduction current. Subsequently, a one-dimensional N2/O2 fluid plasma model is developed in COMSOL Multiphysics to systematically examine the effects of voltage amplitudes of 10, 12, 14, 16, and 18 kV on the spatiotemporal distributions of electron density, as well as on the gap voltage, conduction current, electric field strength in the gap, and electron temperature. The results show that, with increasing applied voltage, electron avalanche ionization is significantly enhanced, and both the electron density and current peak increase overall, although their marginal gains gradually diminish. At 14 kV, the region of high electron density effectively extends from the dielectric interface to most of the discharge gap, and the discharge exhibits a higher plasma filling degree and good cycle-to-cycle repeatability. Further analysis based on normalized curves and the Kneedle knee-point criterion reveals that the critical transition points of both the peak gap voltage and the peak conduction current are located at 14 kV, indicating that this condition represents a characteristic operating point within the investigated voltage range. Finally, a spatiotemporal evolution analysis of a single steady-state microdischarge pulse demonstrates that the DBD undergoes the stages of pre-ionization, avalanche ionization, electric-field reconstruction, surface charge deposition, and afterglow decay, and that the coupled effects of space charge and surface charge constitute the key mechanism governing discharge stability. The experimental results are in good agreement with the simulation findings, providing a theoretical basis for the parametric optimization and design of atmospheric-pressure air DBD systems.