Investigation of impulse spark trajectory in air between hemispherically-ended rod and plane electrode

A video camera and image processing technique have been used to analyse images of spark trajectories. The sparks consist of several short straight segments. The number of segments per spark falls as the applied overvoltage is increased. At any voltage level the distribution of sparks having one to five segments is determined by the mean number of segments per spark. The experimental results are discussed in terms of prebreakdown corona and streamers, and theoretical distribution for the spark types is derived