The Segments controls change the appearance (structure) of the individual segments in the bolt.

The Number slider controls the number of segments in the bolt. An arc typically consists of only one segment.

The Erraticness slider controls how chaotic the segments are. At the extreme values, 0% erraticness results in straight-lined segments and 100% erraticness results in completely unpredictable segments that may even contain loops.

The Spiral slider controls how much the segments twist around themselves. At the extreme values, 0% spiral results in a two dimensional object (you'll have to rotate the bolt around to see this); 100% spiral results in the segments twisting as much as possible (i.e., as three dimensional as possible).

The Flicker cycle slider controls how much the segments flicker (change in appearance over time). It is useful when animating the movement of the segments, especially for electrical arcs. At 0% and 100%, the segments are identical, so that seamless looping of the animation is possible.