Study on the D<sub>2h</sub> superlattice pattern in dielectric barrier discharge

Abstract

We observed on a D2h superlattice pattern in the dielectric barrier discharge for the first time. Its spatiotemporal structure investigated by an intensified charge-coupled device shows that it is an interleaving of three different sublattices, which are hexagonal sublattice, halos and square sublattice, respectively. With increasing driving parameter, the discharge sequence is hexagonal sublattice-halos-square sublattice in each half cycle of applied voltage. The evolution sequence of the symmetry is D4h-the mixed state of both D4h and D6h-D2h-D2h by analyzing a series of patterns occurred in the evolution process. The symmetry of the hexagonal sublattice, the square sublattice and the halos belong to D2h point group by analyzing the symmetry of the three sublattices. The emission line of the second positive band system (C3∏u→B3∏g) of the nitrogen molecule (N2) and the emission line at 696.57 nm (2P2→1S5) of the argon atom were collected by using emission spectroscopy. The molecular vibration temperature and electron density of three different substructures in the D2h superlattice pattern are obtained. The results show that the molecular vibration temperature and electron density of the three different substructures are similar, which indicates that the plasma states of the three different substructures are the same. The formation of the D2h superlattice pattern is analyzed by the wall charges.