Gap Arc Voltage Was: Natural streamer

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

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Carlos, All,

Sorry to post this so late on this subject (of sorts), but I've been
thinking about coilers spark gaps and arc
voltages. Typically, a coiler will use either electrodes with a large
radius (of which the ball-ball equation fits
nicely as per my own experimentation and works for ball-ball safety gaps),
but there are coilers which use electrodes
with a flat edge as well. I'd like to think a plane-plane gap equation
would suffice, but considering the electrodes
are typically 1/2" down to 1/8", I'm not sure a plane-plane arc voltage
equation would work well (then again, to a
spark, that small flat might appear pretty large). I guess I'm curious for
thoughts on the subject from you or anyone.

Thanks,
Bart.

Tesla list wrote:

> Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>
>
> Tesla list wrote:
> >
> > Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <evp-at-pacbell-dot-net>
>
> >         The last scheme is OK in principal, if you had a large source
of very
> > high resistance devices, which you'd probably have to run in oil for
> > corona protection.  I don't consider that easy.
>
> Spark length to a grounded ball with the same curvature of the terminal
> (another terminal) gives a good value, provided that the spark is not
> too long compared to the radius of the ball. Use the formula:
>
> V=E*4*d/(d/R+1+sqrt((d/R+1)^2+8));
>
> Where E=30000 V/cm, d is the spark length (cm), and R is the radius
> of the ball (cm).
>
> Or, using a small ball, with radius R much smaller than the radius
> of the terminal :
>
> V=E*4*d/(2*d/R+1+sqrt((2*d/R+1)^2+8));
>
> The same formula applies (more exactly) to a spark to a large plane,
> with R being the radius of the terminal.
>
> Formulas from the "North Report".
>
> The first formula gives results for my double VDG that are in the
> expected range. The second I didn't try.
>
> Antonio Carlos M. de Queiroz