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Re: Optimal Topload?

Subject:  Re: Optimal Topload?
  Date:   Wed, 14 May 1997 19:57:33 -0400
  From:  "Thomas McGahee" <tom_mcgahee-at-sigmais-dot-com>
    To:   "Tesla List" <tesla-at-pupman-dot-com>
    CC:   <rwstephens-at-headwaters-dot-com>



> Subject:  Re: Optimal Topload?
>   Date:   Sun, 11 May 1997 12:19:35 -0500
>   From:  "Robert W. Stephens" <rwstephens-at-headwaters-dot-com>
>     To:   Tesla List <tesla-at-pupman-dot-com>
> 

HUMONGOUSLY HUGE SNIP

> Fr. Tom,
> 
> What kind of cigars do you smoke? : )
> 
> Your idea of the optimum topload employing an inverted cone
starting 
> with a rolled edge (bottom toroid) near the top of the secondary
and 
> only slightly larger than the secondary diameter, and then becoming
a 
> large overall diameter terminating in a large R.O.C. toroid (rolled

> edge) on the top is indeed the idea I have successfully employed. 

Hey, it feels GOOD to win the cigar!

My coming up with that shape was based on the consideration of what
kind of large radius of curvature shape would be EASIEST for a coiler
to manufacture. Yeah, there is a little figuring to get the shape
drawn on a flat material such that when you make it into a cone it is
a somewhat PROPER cone, but it ain't that hard.
 
more snips

> 
> I think that such a technique, to use a conical field control
shield 
> at the bottom of a classical two coil design may be the answer to 
> exceeding 3-4 times the secondary length in streamer activity, but 
> this bottom shape will be hard to implement without A). being a
shorted 
> turn, and B). still permitting optimum coupling of the primary,
since 
> ideally the cone should launch off the bottom end of the coil. 
I've 
> actually prototyped a very small tabletop unit employing such an 
> idea, but it does not outperform a regular coil, and that could 
> easily be because tiny tesla coils are just not that successful 
> anyhow.  I need to make a normal, (as in large) test model to
really 
> see if there are advantages to be found in this direction.  This is

> experiment number 2,027 to be tried next.

On the BOTTOM you *absolutely* do not want it to be a shorted turn! I
am talking here about the SECONDARY. The base of an Extra Coil in a
Magnifier is a whole 'nother story. BUT, why do you even NEED such a
beast at the base of a standard Tesla secondary??? The base of the
secondary should ideally be at a very LOW voltage (like ground...)

You might be able to get some added counterpoise action here that
would stiffen up the local ground at the base, but I don't think you
need any e-field shaping here.

SNIP

> 
> What I'm trying to figure out is how to build one of these shapes 
> that are maybe 24-30 feet in diameter, 15 feet or so tall, and be
able
> to transport
> one in an 8 foot wide trailer.
> 
> rwstephens

Don't laugh. Such a thing is possible. When the size of the top load
increases, it becomes more tolerant of deviations in the surface
smoothness. Don't think perfectly toroidal. Think of something with
say sixteen identical STRAIGHT sections that link together to form a
large toroid-LIKE shape (not unlike some of the furnace pipe toroids
I have seen used by some of the members of this list). The huge size
of the e-field will help smooth things out electrostatically, so it
will "act" smoother than it looks. The same goes for the cone part.
Make it up of say sixteen sections that assemble together.

Are you aware of the fact that if you made a toroid out of metal
screen door mesh (that stuff that keeps the flies out) that it would
actually work quite well as a toroid? Yep, the individual e-field
COMPONENTS merge wonderfully, and it quickly becomes a nice even
e-field. Does THAT give you any lightweight ideas for huge toroids
and cones??? Think in terms of having the parts to build a
lightweight wooden inner framing upon which the mesh panels can be
hung. VOILA! the 8 foot trailer, she fits!

Hope some of the ideas help someone out there!
Fr. Tom McGahee