Two-dimensional simulation of the evolution of radial discharge columns in an atmospheric argon dielectric barrier discharge.

A two-dimensional model is employed to investigate the evolution of radial discharge columns (or filamentary channels) and the potential mechanism in an atmospheric argon dielectric barrier discharge (DBD). As the applied voltage amplitude increases, the number of discharge columns first increases and then deceases, and finally, the discharge evolves into the diffuse mode. With a lower voltage amplitude range, the more uniform distribution of surface charge density makes the original discharge column move outwards, providing a wider inner space to increase the filament number. A similar filamentation process is also observed in atmospheric helium. However, when the voltage amplitude is further increased, considering the lower ionization threshold of argon, even the relatively small amount of residual electrons diffusing from filaments to adjacent regions can serve as seed electrons to activate the former inhibition positions, which makes the filament number further increase. Moreover, influenced by the stronger radial electric field between the central column and its neighborhoods, more electrons located at the column near the middle position will drift toward the center. As a result, once charged particles move over the inhibition region with voltage amplitude rising further, the two discrete discharge columns will merge, causing the decrease in the filament number. Finally, it is revealed in our simulations that when the voltage amplitude exceeds one certain level, seed electrons of the preionization stage get harder to gather and all discharge columns vanish. These results may help to provide a new perspective on the evolution of radial filamentary channels in an atmospheric argon DBD. [ABSTRACT FROM AUTHOR]