Abstract
We make experiments charging a polyethylene-terephthalate sheet with a metal roller, and observe discharges that occur in the gap between the roller and the sheet. The pattern of the charge distribution, made visible by sprinkling color-powders onto the sheet surface after the electrification, appears when applied voltage (DC) to the roller exceed a threshold value. This threshold coincides with threshold of appearance of the discharge pulses. The threshold is independent of the polarity of applied voltage, but the shapes of the patterns depends upon the polarity. The pattern is star-like with positive voltage, and round with negative electrification. Length of the discharge light along the sheet is approximately same as the spatial repetition distance of the charge pattern. Therefore the non-uniform electrification is ascribed to the discharges. We can predict the threshold voltage calculating the voltage across the gap using the partial capacitance model and Paschen's law.
