Formation of white-eye patterns with microdischarge in an air dielectric-barrier-discharge system

We report on the observation of a white-eye pattern in an air dielectric barrier discharge. The patterned discharges undergo a development as follows: random spots-quasihexagonal pattern-hexagonal pattern (type I)-hexagonal pattern (type II)-white-eye pattern-chaos, as the voltage is increased. The spatiotemporal characteristics of the patterned discharges are investigated by using an optical method. Results show that the two discharge modes, uniform mode and filamentary mode, are actually two different spatial presentations of the same origin: the microdischarge. From the viewpoint of pattern dynamics, the white-eye pattern results from a three-wave resonance interaction.