RE: A new idea? ...different geometries in coil construction more efficient?

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

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-compaq-dot-com>

Where did the notion that primaries are "best" at 18.36 degrees come from?
What defines "best"?

How about a 4-sided pyramid shape for a primary?  I'm sure the ancient
Egyptians must have been on to something there.  Can it be mere coincidence
that my lucky energy crystal also has a pyramid shape?

OK, cynical mode OFF.

Goodness of a primary must be related to how long a spark can be achieved
off of the secondary.  There are two known factors relating to the primary
here.

One is primary losses.  The shape of the primary may have a small influence
here, as it may relate to the recent discussions about inner-turn primary
heating.  The primary Q is surely related to shape, but no one has yet
actually shown that better performance may result from one geometry over an
other.  It may be that the differences are too small to have any observable
effect.

The other is strike distance from the top load.  A conical primary has it's
outer turn closer to the top load than would a flat primary of the same
inductance, and the closer distance makes primary strikes more likely,
limiting the maximum achievable streamer length.

What is not significant to coil performance is the maximum achievable
coupling between primary & secondary.  Now, coupling itself IS important.
If it is too low, performance will be poor.  But any primary shape can be
adjusted to deliver the proper coupling.

Gary Lau
MA, USA

 -----Original Message-----
From: 	Tesla list [mailto:tesla-at-pupman-dot-com] 
Sent:	Friday, April 05, 2002 1:33 PM
To:	tesla-at-pupman-dot-com
Subject:	A new idea? ...different geometries in coil construction more
efficient?

Original poster: "Matt Woody Meyer by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <meyerml-at-stolaf.edu>

Well, for once, I'm not going to bother you all with engineering questions
(not yet, anyway) :), but while putting off some E&M Field Theory homework,
I came up with something I wanted to run by you all...

I've been tinkering with primary coil inductance based on setting everything
else except the hypotenuse as variables wrt theta (angle of rise).  Looks
like the best inductance is right around 18.36 degrees (small peak).  Now
this isn't anything new, but, has anybody ever tinked around with coil
designs using a geometry other than a linear coil? (in essence, cones,
solenoids, spirals are linear in cross  section).  Although the engineering
could become a real pain in the rear with these different shapes, but maybe
there is something out there that could be more efficient than the common
shapes used.

Had the idea sitting in the back of my head for a while... wanted to start
looking at it after seeing that amazing flat secondary (amazing how good it
looks!)

Man, this stuff is so much more interesting than "the field of a polarized
object" :)

><>Matt