Experimental and simulated investigation of microdischarge characteristics in a pin-to-pin dielectric barrier discharge (DBD) reactor

Abstract

Both experimental and simulated studies of the micro-discharge (MD) are carried out in a DBD with a pin-to-pin gap of 3.5 mm, ignited by a sinusoidal voltage with a peak voltage of 10 kV and a driving frequency of 5 kHz. A statistical result has shown that the probability of the single current pulse in the positive half-period (HP) reaches 73.6% under these conditions. Experimental results show that the great intensity of the luminous is concentrated on the dielectric surface and the tip of the metal electrode. A one-dimensional (1D) plasma fluid model is implemented by coupling the species continuity equations, electron energy density equations, Poisson equation, and Helmholtz equations to analyze the MD dynamics on the micro-scale. The simulated results are in good qualitative agreement with the experimental results. The simulated results show that the MD dynamics can be divided into three phases: the Townsend phase, the streamer propagation phase, and the discharge decay phase. During the streamer propagation phase, the electric field and electron density increase with the streamer propagation from the anode to the cathode, and their maximal values reach 625.48 Td and 2.31×1019 m−3 as well as 790.13 Td and 3.58×1019 m−3 in the positive and negative HP, respectively. Furthermore, a transient glow-like discharge is detected around the anode during the same period of the streamer propagation. The formation of transient glow-like discharge is attributed to electrons drifting back to the anode, which is driven by the residual voltage between the air gap.

Experimental and numerical study on atmospheric‐pressure air dielectric barrier discharge via 50 Hz/5000 Hz dual‐frequency excitation

“…Moreover, the discharge area on the dielectric surface is much larger than the section area of the electrodes. Therefore, one of the reasons for the discrepancy between the simulation results and experimental ones is the dynamic variation of the discharge area during the breakdown process [38, 50].…”

“…Therefore, a 1D PFM with photoionisation is implemented in this study by COMSOL Multiphysics software with a built‐in plasma module and Helmholtz equation solver to compare the discharge dynamics at different periods in the DF discharge. As the detailed description of PFM has already been presented in a previous paper [38], a brief description of the model is presented in this work. The governing equations of the fluid model are listed below, $$$\frac{\partial \left({n}_{\text{e,i,uc}}\right)}{\partial t}+\nabla \cdot {{\Gamma }}_{\text{e,i,uc}}={S}_{\text{e,i,uc}}$$$ $$$\frac{\partial \left({n}_{\varepsilon }\right)}{\partial t}+\nabla \cdot {{\Gamma }}_{\varepsilon }={S}_{\varepsilon }$$$ $$$\nabla \cdot \left({\varepsilon }_{0}{\varepsilon }_{r}\boldsymbol{E}\right)={\rho }_{\mathrm{q}}$$$ in these equations, the subscripts e, i, uc, and ɛ represent the electrons, ions, uncharged neutral species, and electron energy, respectively.…”

“…Therefore, a 1D PFM with photoionisation is implemented in this study by COMSOL Multiphysics software with a built-in plasma module and Helmholtz equation solver to compare the discharge dynamics at different periods in the DF discharge. As the detailed description of PFM has already been presented in a previous paper [38], a brief description of the model is presented in this work. The governing equations of the fluid model are listed below,…”