Development of a semi-empirical 1.5D plasma fluid model for a single microdischarge in atmospheric pressure dielectric barrier discharges

In this work, a semi-empirical 1.5D plasma fluid model (PFM) is proposed to model a single microdischarge (MD) in atmospheric pressure air dielectric barrier discharges (APADBDs). The species continuity equations and the electron energy density equation are solved in one-dimensional domain, while the Poisson equation is solved in the axisymmetric domain to capture the enhancement of the electric field in front of the streamer. The framework of air chemistry is considered and the effect of photoionization is modeled in the axisymmetric domain. The accumulation factor (AF) is introduced and determined by experimental data to model the accumulation of charged particles on the dielectric surface. The simulated results in two gaps are compared with experimental measurements. In the gap of 1.4 mm, the simulated electric current reaches 72 mA, which is close to the typically measured electric current. The simulated maximum wave velocity is around 1.7 x 10(6) m s(-1), which is close to the available experimental data. The change of simulated charge density implies that the average accumulation of charged particles on the dielectric surface during each half period (HP) is around 40 nC cm(-2), which is in the same order of magnitude as the average charge density evaluated in the previous measurements as 51.5 nC cm(-2). The effect of AF is studied and shows that the AF determines both peak and duration of the electric current. In the gap of 2.0 mm, the simulated current reaches 113 mA, which is close to the typically measured current. Although the gap voltage of the 2.0 mm gap is higher than that of the 1.4 mm gap, the average electric field of the 2.0 mm gap is lower than that of the 1.4 mm gap before breakdown due to larger gap distance. The maximum wave velocity is faster than that simulated in the gap of 1.4 mm due to the longer gap distance for developing higher wave velocity as 2.4 x 10(6) m s(-1). During each HP, the average accumulation of charge density on the dielectric surface reaches around 40 nC cm(-2) which is almost identical to that simulated in the gap of 1.4 mm as observed experimentally. In general, the proposed semi-empirical 1.5D PFM captures the dynamics of a single MD in APADBDs.