Bi-Ionized Space Charges Generated by Means of Corona

Due to the extensive usage of unipolar corona in electrostatic precipitators, electrostatic painting, mineral ore separation, and other applications, most of the past studies of particle charging and electric fields in space-charge regions have focused on the unipolar corona. As such, while the basic equations for particle charging in bi-ionized fields are known, relatively little experimental work may be found in the literature. A test chamber and a wire probe assembly have been constructed allowing the investigation of electric fields in the bi-ionized space between parallel wire coronas for various gas mixtures, pressures, and spacings. Results are presented for experiments in air, CO2, and CO2-nitrogen mixtures, and they seem to indicate that a substantial amount of recombination of positive and negative ions occurs. The resulting average electric field intensity over a large section of the bi-ionized space between the corona wires was found to be uniform.