Computational estimation of ESD conditions between charged particles and grounded surfaces

The paper examines the conditions in which a discharge occurs between charg ed spherical particles and grounded surfaces, in air, at atmospheric pressu re. The study is of interest to a large group of electrostatic applications which involve the processing of particulate matter: separation of granular mixtures, precipitation of dust, and spraying of powders, At the same time , this simple physical model simulates a class of hazardous situations quit e often met in the operation of electronic circuits, Boundary-element metho d was employed for the computation of the electric field in the gap of leng th x between a charged conductive spherical particle of radius R and a grou nded plate. The data on held distribution represented the input data of an original program which employed Pedersen's criterion for estimating the bre akdown conditions of that air-gap. The study was carried out for spheres of various sizes (radii: 0.01-1 mm), Some computations were performed for the case when the grounded plate was covered with an insulating layer of known permittivity. The computational results were in good agreement with,with t he experimental data for both long (x/R > 10) and short (x/R < 0.1) gaps.