We report the observation of a square superlattice pattern in a dielectric barrier discharge system. The correlation measurements indicate that the square superlattice pattern is an interleaving of two different transient square sublattices. The interplay between the charge pattern and the discharge filament pattern is discussed.

A rich variety of spiral patterns such as single-armed spiral, dipole spirals, target pattern, multiarmed spiral, and spiral defect chaos state have been observed in ac-driven atmospheric pressure gas discharge. The confined and free boundary conditions are defined by means of whether there is a sidewall in the discharge domain or not, respectively. In the free boundary condition, the spiral pattern arises when the stripe pattern undergoes core instability or notching instability. In the confined boundary condition, the spiral pattern is formed by sidewall forcing. The spiral drifts upward in the free boundary condition and meanders in the confined boundary condition. The topological charge of the spiral pattern can be changed when the spiral interacts with the dislocations. The spiral wavelength (average distance between two consecutive rolls) is a function of gas composition and decreases rapidly with increase of air concentration in discharge gas.

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We report on a honeycomb hexagon pattern in dielectric barrier discharge. It bifurcates from a square pattern as the applied voltage is increased. A phase diagram of the pattern types as a function of the gas component and applied voltage is presented. The spatial Fourier spectrum of the honeycomb hexagon pattern is a hexagonal superstructure with three wave vectors k[over ]_{1};{h} , k[over ]_{2};{s} and k[over ]_{3};{s} at least, demonstrating that the pattern is a superlattice pattern. Measurements of the correlation between discharge filaments indicate that the honeycomb hexagon pattern is an interleaving of three different transient hexagonal sublattices, whose spatial wave vectors are exactly equal to k[over ]_{1};{h} , k[over ]_{2};{s} and k[over ]_{3};{s} , respectively. These three wave modes fulfill a triad resonance condition k[over ]_{3};{s}-k[over ]_{2};{s}=k[over ]_{1};{h} .

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