A Simulation Model for Dielectric Barrier Discharge Considering Finite Trap Density

A simulation model for dielectric barrier discharge considering the finite trap density is established to investigate the discharge characteristics and the variation of trap electrons in He and N2 discharges. Instead of a constant, secondary electrons emission coefficient γ varying with trap electron filling is obtained by Auger electron theory. In addition to the gas ionization degree, the secondary electron emission coefficient might also be the reason for the different discharge characteristics of He and N2. Compared to He+ and He2+ ions, the γ of N2+ and N4+ are very small and cannot emit intrinsic electrons in the valence band of the dielectric. However, due to the existence of localized energy levels, N2+ and N4+ can emit the electrons in the traps, causing γ ≠ 0. It is found that the cathode trap density gradually decreases during the discharge process in N2 discharge, while keeps 100% filling in He discharge. Changing the band gap width of the dielectric does not effectively regulate the discharge characteristics of N2 discharge. However, reducing the band gap width of the dielectric can effectively increase the secondary electron emission coefficient in He discharge, thus increasing the seed electron density and allowing the discharge to occur at lower gap electric fields, which is beneficial for uniform discharge. Therefore, for glow and Townsend type dielectric barrier discharge, targeted optimization of dielectric material properties should be combined with discharge mechanisms to achieve uniform discharge.