Square superlattice pattern with discharge holes due to direction-selective surface discharges in dielectric barrier discharge.

We report a square superlattice pattern with discharge holes due to direction-selective surface discharges (SDs) in a dielectric barrier discharge system for the first time. The instantaneous images with an exposure time of 10 μs (half cycle of voltage) taken using a high-speed video camera show that the directions of surface discharges (SDs) of the small spots are selective, which are different from the directions of SDs of the large spots diffused in all directions. In each positive half cycle of voltage, the graphs captured using an intensified charge-coupled device show that the large spot discharges after the small spots and locates at the center of the square formed by the SDs induced by small spots but not their cross point. In each negative half cycle of voltage, the large spots discharge before the small spot and press the SD of the small spot to stretch along the midperpendicular of two adjacent large spots. In a word, the direction-selective surface discharges play a crucial role for the formation of the pattern with the discharge holes in the dielectric barrier discharge system. [ABSTRACT FROM AUTHOR]