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The enhancement of plasma generation in atmospheric pressure dielectric barrier discharge (DBD) is gaining increasing interest for various plasma applications. In this paper, the effect of surface charges moving with the rotating dielectric plate on improving the generation of streamer channels is investigated by a statistical analysis of electrical measurements, optical diagnostics, and numerical simulation in a needle-plate DBD device with a rotating dielectric plate. Results suggest that rotating the dielectric plate can improve the spatiotemporal distribution of streamer channels by inducing a bending of the streamer channels and an increase in the number of discharges. Statistical results show that the number of current pulse and discharge energy are increased by 20% and 47%, respectively, at the rotating speed of 160 rps (revolution per second). Based on the interaction between the applied electric field and the electric field induced by surface charges, a formula is proposed to govern the effect of rotating the dielectric plate on the discharge energy and streamer bending. To further understand the mechanism of the influence of rotating the dielectric plate on plasma properties, a 2D fluid model is implemented, and the reduced electric field and streamer propagation are analyzed. Results show that the effective transfer and reuse of surface charges play an important role in the enhancement of plasma generation. [ABSTRACT FROM AUTHOR]

Exotic polarization domain configurations in BiFeO3 nanoislands have recently been achieved, promising for exploring next-generation nanoelectronics. Here, different from the earlier reported BiFeO3 nanoislands with a very thin cross-shaped domain wall on LaAlO3 substrates, we observed the cross-shaped domains with a downward polarization separating quad-domains with an upward polarization, which is confirmed by spherical aberration corrected scanning transmission electron microscopy and piezoresponse force microscopy. Interestingly, the cross- and quad-domains show diode-like transport behaviors but with different rectification directions owing to their different polarization orientations. Specifically, an intriguing two-step ferroelectric polarization switching can be realized, which locally results in a tri-state nonvolatile memory. These results broaden the understanding of the interesting polarization configurations in BiFeO3 nanoislands and highlight their potential as high-density information storage. [ABSTRACT FROM AUTHOR]

We present the triangular lattice pattern with the invisible Kagome lattice in the dielectric barrier discharge system with two water electrodes for the first time. The spatio-temporal dynamics studied by an intensified charge-coupled device (ICCD) show that the complex pattern is composed of four different sublattices: Kagome lattice, halos, and big and small spots (B and S). The invisible Kagome lattice is similar to the dark discharge because of its spatio-temporal randomness. Based on the novel discharges (B and S) occurring at the falling edge of applied voltage, the dynamics of surface charges is investigated and demonstrated with a high speed video camera and photomultiplier tubes. Furthermore, the formation of restricted random structures is considered to be the effect of previous discharges which rearrange the surface charges. [ABSTRACT FROM AUTHOR]

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]

The snowflake pattern which consists of bright spots and dim lines is investigated in a dielectric barrier discharge system. Visually, dim lines straightforwardly converge to the center of three bright spots. The spatiotemporal dynamics shows that the bright spots are formed by the volume discharges (VDs), and the dim lines are formed by the surface discharges (SDs). The snowflake pattern is the result of VD induced SD and SD transfer surface charges. The emission spectra of the N2 second positive band (C3Πu→B3Πu) and the spectral lines of Ar I (2P2→1S5) of VD and SD are collected and analyzed, respectively. It is found that the ratio values of emission intensity of VD to SD at 696. 5 nm and 380. 4 nm are 4.4 and 1.3, respectively. It indicates that the number of electrons that can excite Ar and N2 to emit the optical spectrum in VD is more than that of SD. A new method of differentiating VD and SD is suggested. [ABSTRACT FROM AUTHOR]

We report a dot-line square super-lattice pattern with surface discharge (DLSSPSD) in a dielectric barrier discharge system and show for the first time that the surface discharge can promote the formation of volume discharge (VD). The pattern consists of three different discharge morphologies, namely, bright spots, dim spots, and bright lines. The spatiotemporal dynamics of the DLSSPSD are studied using an intensified charge-coupled device camera, a photomultiplier, and a high-speed video camera. The results show that the VD located at the dim spots and bright lines is generated on both the rising and falling edges of the voltage. It is found that the high surface charge density transferred by the surface discharge of the bright spots promotes the formation of VD at the dim spots and bright lines. [ABSTRACT FROM AUTHOR]

We report on a novel dielectric barrier discharge (DBD) instrument with asymmetrical electrodes. It consists of three water electrodes, one big electrode faces to two small electrodes placed side by side, any one of two small electrodes connects with a high-voltage diode which can control on or off of applied power. Using this DBD experimental setup, the phenomenon of forming two kinds of different patterns at the different parts of discharge gap simultaneously is investigated for the first time. The spatio-temporal characteristic of these different patterns limited by the boundary which contains two connected same circles is studied. It is shown that although the power source is applied on one part of the discharge gap at a half period because of existence of high voltage photodiode, the discharge occurs at both areas in each half period of the applied voltage. Results have prospective applications for studying the discharge mechanism and different characteristic of positive and negative charges in forming of pattern. [ABSTRACT FROM AUTHOR]

The linear-zigzag transition is observed and studied in dielectric barrier discharge with rectangular frames for the first time by two photomultipliers, an intensified charge-coupled device, and a high-speed video camera. The unstable linear spot pattern transforms into a stable zigzag superlattice pattern with increasing voltage. The zigzag superlattice pattern is made up of dim spots at each corner, light spots between dim spots, and a zigzag line which is composed of moving spots and zigzag halos. All the spots in the linear spot pattern discharge simultaneously, and they have equal electric quantities, while the discharge sequence in the zigzag superlattice pattern is light spots, dim spots, halos, moving spots, and electric quantities of light spots are more than that of dim spots. The difference in the electric quantities leads to the formation of zigzag halos. In a word, the zigzag superlattice pattern results from unequal wall charge quantities of different sublattices and statistical self-organization of moving spots. [ABSTRACT FROM AUTHOR]