Charging of Polymeric Surfaces by Positive Impulse Corona

Abstract

This paper focuses on analysis of charging of polymeric surfaces by means of impulse corona discharges in air. Internal (space charge densities and electric fields) as well as external (circuit current) characteristics of corona in a point-plane electrode configuration are investigated by means of computer simulations. Two types of onset positive corona modes, namely positive glow corona and burst pulse corona are identified. The developed and verified computer model is further used to study corona charging of a 2 mm thick polymeric material sample. Both the mechanism of charge deposition and distribution of deposited charges on the surface are dependent on the mode of the corona discharge used. In the case of glow corona, charge generation is limited to the anode region and the generated charges move towards the sample surface under applied electric field. Thereafter the deposited charge cloud expands radially along a portion of the surface with fairly constant concentration. In the case of burst pulse corona, series of positive charge clouds start from the anode and move towards the sample surface in a wave-like manner. Each burst contributes to the deposited charge, which spreads over the surface less extensively than that observed during glow corona charging.