Images of Striations in Large-Gap Plasma Display Panels

Abstract

Striations in large-gap coplanar dielectric barrier discharge (DBD) are investigated both experimentally and theoretically. We show the striations in a large-gap coplanar DBD. The time-resolved images of discharge were obtained by macrocell experiment and PIC-MCC simulation. Two series of striations appear in the cell during the discharge developing between the faced electrodes and the coplanar electrodes. The simulation is in accordance with the stratified potential in the space.Index Terms-Coplanar discharge, pattern, plasma display panel, striation, wall charge.T HE MECHANISMS of striation formation in discharge plasma have been one of the subjects of theoretical and experimental studies. Research works have been done on striations both in dielectric barrier discharge (DBD) and dc glow positive column under different conditions. Striations in DBD show similar characteristics at high and low pressures. However, the mechanism of striation formation is still not clear [1].Detailed physical models [2], [3] and diagnostics [4] of DBD cell have been developed in order to better understand the parameters that control the striation formation. We employ a macroscopic cell (in dimensions of 9 × 3 × 1 cm 3 ). The filling gas is a mixture of 96% Ne and 4% Xe at 5 torr. The gap of coplanar electrodes is 5 cm. A detailed experimental set was described in [4]. A square-wave voltage of 290 V/100 Hz is applied on the coplanar electrodes to excite the discharge. We used an intensified charge-coupled device (ICCD) to measure the 823-nm emission which corresponds to the decay of Xe * excited levels to metastable and resonance state. The images at different times are shown in Fig. 1. The discharge has also been simulated by using a PIC-MCC method in a similar microcell with dimensions of 900 × 300 × 100 µm 3 . The Xe * distribution and the potential at different times are shown in Fig. 2. The excited atom Xe * distribution corresponds to the luminous image in the experiment.The results in Figs. 1 and 2 are as follows. At the beginning, the electric field between A and X is stronger than that between X and Y, and the breakdown occurs first between them ( Fig. 1 at 9.9 µs and Fig. 2 at 63 ns). The electrons move toward the address electrode A, and the atoms are ionized or excited. An equipotential area is formed before the surface of the dielectric layer near electrode A. The discharge is ignited between electrodes X and A. Because of the accumulated wall charges, electrons expand along the address electrode, and striations occur at 11.5 µs in Fig. 1 and at 70 ns in Fig. 2. Accompanying the plasma expansion, luminous striations appear one after another (Fig. 1 at 12.3 µs and Fig. 2 at 76 ns).Then, the discharge between coplanar electrodes is triggered, and a coplanar plasma channel is formed. The striations of Xe * and potential hold their positions when the discharge channel X-A-Y is forming. The density of Xe * increases remarkably in the plasma channel (see Fig. 1 at 12.7 µs and Fig. 2 at 79 ns). After the coplanar discharge cha...

Simultaneous formation of striations and patterns in surface dielectric barrier discharge

“…The accumulated knowledge about striations and progress achieved in the past decades was well reviewed in [2]. Striations may also be observed in dielectric barrier discharge (DBD) (e.g., pixels of coplanar plasma display panels or PDPs) when plasma expanding on the dielectric surface above anode at both high pressure in micro-cells [3][4][5][6] and low pressures (a) E-mail: jtouyang@bit.edu.cn in macro-cells [6][7][8][9][10]. The scaling laws suggest that striations in micro-discharges at high pressure should resemble striations in classical low-pressure glow.…”

“…Especially, recent experiments and simulations [15][16][17] show that the space charges play the most important role for the pattern formation, although the surface charges on the dielectric surface are also important to sustain the glow DBD. Actually DBD becomes an excellent nonlinear system for both pattern and striation formation [3][4][5][6][7][8][9][10][12][13][14][15][16][17][18][19][20], although it is well known for its industrial applications [21]. However, patterns and striations in DBD system are two different instabilities.…”