Corona plating

The field strength is uniform between parallel plates, whereas it varies in the space between concentric cylinders, being highest at the surface of the central cylinder. After corona sets in, the current flow will become appreciable. The field strength near the center electrode will be less than given by Eq. (17-18) and that in the major portion of the clearance space will be greater and more uniform [see Eqs. (17-23) and (17-24)]. 

Low resistivity can sometimes be a problem, if the resistivity is below lO" n-cm, the collected particles are so conductive that their charges leak to ground faster than they are replenished bv the corona. The particles are no longer electrostatically pinned to the plate, and... 

Two-stage precipitators consist of separate sections for particle charing and collection. Particle charging is realized with corona wires between grounded metal plates. The collection of particles rakes place in a system of parallel plate electrodes of opposite polarities. Two-stage precipitators are typically used in indoor air cleaning and light industrial applications. 

Figure 12.1. Electrode geometries for corona discharges (A) pin-to-plate (B) wire-cylinder (C) wire-plane.

Kim, Y.-H. and Hong, S.H. (2002) Two-dimensional simulation images of pulsed corona discharges in a wire-plate reactor, IEEE Trans. PI. Sci. 30, 168-9. 

Figure 4. Most studied electrode geometry in liquid corona discharge reactors (A) point-to-plane and (B) plate-to-plane.

A second effect of high fly ash resistivity is observed when the difference in potential across the collected dust layer rises to too high a value. A back corona can form as the EMF differential breaks down due to sparking across the dust layer. High currents flow between the wire cathode and plate anode thereby destroying the ability of the ESP to charge particulates. 

The sample on the conducting plate is charged by the corona discharge up to the surface potential V0 in the first method. Under the action of the strongly absorbed light one can observe the change of the surface potential due to the discharge current... 

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