Analysis and simulation of spark path shapes for point/plane gaps

Analysis of data derived from sparks in point/plane gaps ranging from 45 to 400 mm has shown the similarity of the probability functions determining the shape of the spark paths. This is true, regardless of gap width, when each path is divided up into equal steps, here equal to 2% of the gap width. This implies the leader step lengths are nearly proportional to gap width. The probability functions were used to develop improved simulations of the spark paths which were found not only to reproduce them visually but, more importantly, to give closely similar values for the small amount by which the spark paths are, on average, displaced when the pointed electrode is tilted. The same agreement was found for the degree of scatter of the spark paths about the mean. It is anticipated that the simulations can be generalised to a variety of geometries and scaled up to simulate and predict lightning strike probabilities