The effect of polarity on dc arc development over an ice surface

Electrical/optical measurements have been carried out to study the dynamic behaviour of discharge on an ice surface. Significant differences in behaviour between positive and negative arcs have been revealed during discharge propagation. Also, its root structure, shape and velocity were found to be strongly polarity dependent. High-speed photography of the decays observed during discharge propagation showed two different patterns for dc positive and negative. Using simultaneous analysis of the captured pictures along with the current measurements at anode and cathode a mechanism describing the observed patterns is proposed. The effect of space charge regions observed around the main discharge channel is also discussed.