OK, so now I've seen something I've never heard of or seen before. The simple
two post spark gap I made for my bipolar Tesla coil runs hot (not surprising),
so I was casting about for a simple way to cool. I got a small vacuum cleaner
with a reversible hose, and I switched it from intake to outtake. It blows a
fairly strong stream of air out. I fired up the coil and directed the stream of
air at the spark gap.

Whoa! The buzzing, flickering spark turned into a bright, steady fireball, and
the coil's discharge took on a distinctly thicker, brighter spark--in the shape
of a sideways S, or sine wave! Is this typical for a forced air gap coil? It's
very striking, a blazing hot purple S sizzling between the terminals.

Paul