Ground-Shielded Dual-Type High-Voltage Electrode for Corona Charging Applications

Corona discharge generated by various electrode arrangements is commonly employed for several electrostatic applications, such as charging nonwoven fabrics for air filters and insulating granules in electrostatic separators. The aim of this paper is to analyze the effects of the presence of a grounded metallic shield in the proximity of a high-voltage corona electrode facing a grounded plate electrode. The metallic shield was found to increase the current intensity and decrease the inception voltage of the corona discharge generated by this electrode arrangement, both in the absence and in the presence of a layer of insulating particles at the surface of the plate electrode. With the shield, the current density measured at the surface of the collecting electrode is higher and distributed on a larger area. As a consequence, the charge acquired by millimeter-sized HDPE particles forming a monolayer at the surface of the grounded plate electrode is twice as high as in the absence of the shield. These experiments are discussed in relation with the results of the numerical analysis of the electric field generated by the wire-plate configuration with and without shield.