Positive corona discharge in a three-electrode system

Abstract

Positive corona discharge in a two-electrode system in air at atmospheric pressure always starts with burst pulses. The transition from burst pulse to streamer or to glow depends on the gap geometry. However, the modes of corona discharge will differ in the presence of a third electrode (grid) because of the role played by grids in controlling the potential gradient distribution in the gaps. The modes of corona discharge in point-to-plane air gaps, which are commonly used in corona and breakdown studies, are experimentally examined with the addition of a grid. The appearance or disappearance of certain corona modes is dependent on grid geometry, grid potential, as well as grid relative position. However, the stability of the glow mode as well as its range depend to a great extent on the grid potential. The optimum grid potential and position that lead to a minimum potential gradient and at the same time favour the stability of positive glow, are theoretically obtained using the charge simulation technique. A theoretical model is suggested to analyse the corona inception modes of discharge on a three-electrode system. A comparison between theoretical and experimental findings is presented for a better understanding of the role played by the grid in deciding the discharge development.