Re: Tesla's large pancake coil

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: William Beaty <billb@xxxxxxxxxx>

On Sun, 1 Oct 2006, Tesla list wrote:

> Original poster: Ed Phillips <evp@xxxxxxxxxxx>
>
>    QUESTION:  If we actually build a large pancake-style TC secondary, and
>    mount a sphere terminal on the end of a central rod, then does the
>    discharge tend to occupy a fairly narrow cone which is directed
>    outwards from the pancake coil?     Yes or no."
>
>     NO.  The discharge tends to follow the electric field lines back
> to the periphery of the coil.

Ah, so you have run simulations (etc.) that show the shape of the pancake
coil's field lines?

If not, then a firm and confident "no" is totally out of place.

WIth a pancake secondary, the e-field lines in the center near the
windings are vertical, while the field lines of a sphere terminal distant
from other objects are radial, so at some spacings of a sphere terminal
and a flat secondary, the field lines radiating from the sphere would
mostly point away from the coil in a fan-shaped cone.  At other spacings
the coil would have little effect on the sphere, so the sphere's field
lines would be radial.  The drawing might be made from imagination, or it
may contain accurate details.

On a pancake-secondary and sphere terminal with the geometry shown in that
drawing, what shape would the many arcs have if they were following the
field lines?


Also something suspicious in the drawing:  I'd be suprised if the arcs
from the pancake TC terminal appeared as depicted.  The drawing looks like
it was not made from life, but from a long-exposure photograph.  There's a
small chance that the drawing is actually a heavily-retouched version of a
photograph, where the original photo was far too poorly made to be
published.  That would explain the almost superrealist "look" of those two
photos in the article.

And I still wonder if a big pancake TC is different than a tall
cylindrical TC in that the pancake has some large "safe zones" where arcs
never go, and where a human can safely sit.   It might be worthwhile
building a big wall-mount pancake secondary just for that reason, eh?



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William J. Beaty                            SCIENCE HOBBYIST website
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