Comparision study of dielectric barrier discharge in inert gases at atmospheric pressure

To deeply understand dielectric barrier discharge in inert gases at atmospheric pressure, we investigated the breakdown voltage, the discharge mode, and evolution of DBD in a parallel gap by means of electrical measurements and fast photography in helium, neon, and argon at atmospheric pressure. Homogenous discharges could be easily produced in 2~8 mm gaps in helium and neon, and they were attributed to glow discharge. Compared to that in helium or neon, the homogenous DBD often covered only a part of the electrode in 2 mm-argon using the high frequency power. And with a small increase of the applied voltage, it would turn into a pattern mode. When the argon width was no less than 3 mm, the DBD always resulted in bright filamentary streamers in which the current density could reach 7.5 A/cm 2. High-speed time-resolved photographs of the homogenous discharge in helium, neon and argon were taken using an ICCD camera. Side-view photographs showed an evolution from Townsend discharge to glow discharge. The end-view photographs exhibited a radial development. The spectroscopic diagnosis showed that the penning ionization between energetic metastabilty and impurities was the most important reason leading to a homogenous discharge. The N 2 + first negative system (B 2Σ u + →X 2Σ g +), existing in helium discharge, could not be observed in the neon or argon, as was due to the lower energy level of metastable neon and argon states. Instead, the emission spectral lines of N 2 second positive band system (C 3Π u→B 3Π g) were observed in neon and argon.