Coupling Of Temporal Symmetry And Spatial Symmetry Of Patterns In Dielectric Barrier Discharge

The formation of the square superlattice pattern and the pattern scenario in the formation of square superlattice pattern in a dielectric barrier discharge by using a device with water electrodes are studied from the macroscopical and microscopical point of view. It mainly concentrates on the investigation of the temporal symmetry of individual filaments in different spatial symmetry filaments patterns through optical methods.The formation of the square superlattice pattern is investigated firstly in a dielectric barrier discharge in the mixture of argon and air. It is found that the bifurcation scenario of the patterns follows as square pattern, quasisuperlattice pattern, square superlattice pattern, and stripe pattern or hexagonal pattern. Their spatial Fourier spectra are analyzed and the variation of the wave vector as a function of the applied voltage is given. In addition, two types of square superlattice pattern with different spatial scale are observed with the applied voltage increasing. They all satisfy the standing wave condition. The influence of experimental parameters such as width of gas gap, gas pressure and gas components, etc. on the formation of patterns has been studied.Further, the temporal symmetry of individual filaments in different spatial symmetry filaments patterns is investigated on the basis of the bifurcation scenarios of square pattern and square superlattice pattern. It is found that there is a certain correlation between the spatial symmetry of pattern and the temporal symmetry of individual filaments. The enhancement (or reduction) of the spatial symmetry of pattern would lead to the reduction (or enhancement) of the temporal symmetry of the filaments. When the filaments arrange from the stochastic state to a square structure, the spatial symmetry of the system is enhanced but the temporal symmetry of individual filaments is reduced due to the interaction of the filaments and the effect of the wall charges. Comparatively, as the square superlattice pattern bifurcates from the square pattern, the spatial symmetry of the system is broken. Meantime, the temporal symmetry of the filaments is enhanced. Further increasing the applied voltage, the bifurcation of the square superlattice pattern to a hexagonal pattern makes the enhancement of the spatial symmetry of the system, while leads to the reduction of the temporal symmetry of the filaments. The temporal and spatial symmetry couple with each other and their product should keep constant in some extent in the self-organization processes of filaments.The period doubling and chaotic behavior have been observed firstly in dielectric barrier discharge. It is found that the ordinary filaments evolved into circular-ring-shaped filaments with the decrease of the applied voltage. Meanwhile, the period doubling of the intensity of the pulses in the light signals is observed in the progress. The discharge sequence is T→2T→4T.