Model for corona modes in point-to-plane device with coated electrodes

A corona device with point-to-plane electrode geometry is used to simulate electrical operating conditions in industrial electrostatic precipitators. The particular aspect investigated is the effect of electrode coating by precipitated particulates of high resistivity, and as simulated by layers of porous insulating materials. The typical measured d.c.characteristics and square-wave response of the device are presented and discussed. The corona modes are identified from measurements, and the device performance is represented by a lumped-element circuit model based on a spatial systematisation of corona phenomena into four regions described as the primary-ionisation, accumulation, transport, and secondary-ionisation regions. The lumped parameters of the circuit model are used for a semiquantitative formulation of criteria for typical corona modes and corresponding electrical characteristics. Further, the circuit model is implemented in the design of a simple solid-state analogue, which can simulate the negative-corona characteristics of the device under different operating conditions.