Hi Paul,

This is a bit off topic for this mailing list. You may wish to consider
joining the Tesla Coil Mailing List (TCML) at www.pupman.com for
extended Tesla Coiling information/dialog.

Once you cool down the gap electrodes, they will (re)fire at a higher
voltage, providing more energy to your tank circuit each time your gap
(re)fires. This creates longer and hotter output sparks from your
bipolar Tesla coil. The "S" shaped discharge might be due to electrical
field effects, but it's more likely due to stray air currents from your
vacuum cleaner "blowing" the Tesla Coil sparks.

Bert
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mrapol wrote:
> 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
>