Re: streamer length = volts ?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>" <jimlux-at-earthlink-dot-net>

Sadly, no formula exists for this relationship.  In a non-uniform field, the
length isn't particularly well correlated with the voltage.  Of considerably
more importance is the amount of energy or charge available to support the
growth of the streamer.

In a uniform field, the accepted value is around 30 kV/cm (70 kV/inch).
However, taking lightning for an example, the overall field just before the
leader starts is around 10 kV/meter or 100 V/cm, some 300 times less.  A TC
that puts out a 10 foot spark (120 inches) doesn't have a voltage of 8.4
Megavolts, but is probably more around 500 kV to a Megavolt.

If you want a rough estimate of the voltage on your TC...If there is NO
breakout, the voltage is probably less than 30 kV/cm of the smallest radius.
However, this really only applies with very smooth surfaces.  Any surface
bumps or edges (like the corrugations in your dryer duct toroid) reduce the
maximum voltage quite a bit (and will promote the growth of streamers).
This rule of thumb is probably better for things like smooth Van deGraaff
electrodes, for instance.

A better length measure is the Freau equation length(inches) = 1.7*sqrt(VA).
This is an emprically derived formula which seems to work over a fairly wide
range.  It is also an optimum in that your sparks will likely be shorter.

So, a 15kV at 30 mA NST, nominally around 450 VA, should produce sparks up
to around 36 inches long.  24 inches would be a nice reasonable number, and
if you aren't getting 12 inches, something is seriously wrong.



----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, April 20, 2001 6:29 PM
Subject: streamer length = volts ?


> Original poster: "hoggwild89 by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<hoggwild89-at-netzero-dot-net>
>
> Drawing an arc x inches off the secondary...equals xxxx volts per inch ???
>
>
> Whats the formula ??
>
>
>
>