An investigation was carried out on the factors determining the corona charging characteristics of 200μm-thick particle layers consisting of micron-order insulative fine particles. When particle layers were charged using a corona charging device with a grid electrode, the surface potential of the particle layers reached the grid potential in a low grid potential range (range A). In a potential range above the range A (range B), however, the surface potential of the particle layers can no longer reached the grid potential. In this range, a pulsed electric current was observed with an ammeter connected to the conductive plate supporting the particle layers. For both range A and B, the charges from the device existed only on the particle layer surface, and therefore, the charge quantity of the particle layer was approximately proportional to the surface potential. These results led us to infer that in range B discrete small discharges occur in the air-filled spaces between the particles. These discharges were caused by the electric field within the particle layer generated by the charges adhering to the particle layer surface. The relaxation caused by these discharges determines the maximum charge quantity. In this paper, we explain the charging rate and a model for the electric relaxation phenomenon.
Furukawa Kazuhiko, Nishio Shigeru, Toyoshima Tetsuro, Okuda Tooru, "The Charging Characteristics of Fine Particle Layers with Corona-Charge" in Proc. IS&T Int'l Conf. on Digital Printing Technologies (NIP17), 2001, pp 619 - 623, https://doi.org/10.2352/ISSN.2169-4451.2001.17.1.art00041_2