Re: Pseudo Toroid Design

To: "'Tesla List'" <tesla-at-poodle.pupman-dot-com>
Subject: Re: Pseudo Toroid Design
From: Tesla List <tesla-at-stic-dot-net>
Date: Sun, 9 Nov 1997 23:26:25 -0600
Approved: tesla-at-stic-dot-net

From: 	BertPool[SMTP:Bert.Pool-at-flash-dot-net]
Reply To: 	bertpool-at-flash-dot-net
Sent: 	Sunday, November 09, 1997 4:04 PM
To: 	Tesla List
Subject: 	Re: Pseudo Toroid Design


> 
> From: 	Thomas McGahee[SMTP:tom_mcgahee-at-sigmais-dot-com]
> Sent: 	Sunday, November 09, 1997 2:16 PM
> To: 	Tesla List
> Subject: 	Pseudo Toroid Design
> 
> 
> 
> > From: 	Chuck Curran[SMTP:ccurran-at-execpc-dot-com]
> > Sent: 	Saturday, November 08, 1997 12:09 PM
> > To: 	tesla-at-pupman-dot-com
> > Subject: 	Toroid Design Features
> > 
> > Hello All:
> > 
> > I'm in the process of deciding on how to prioritize coil improvements for
> > the next few winter months.  Near the top of the list is the toroid.  I am
> > going to get pricing for a spun aluminum toroid and that is where a question
> > pop's up right away.
> > 
> > Many of us have made a toroid using a similar set of design features.

[rather large snip]

> > Chuck Curran
> > 


>>Friar Thomas McGahee replied:
> > 
> Chuck, 
> What makes a toroid so good for TC use is its ability to shape the e-fields 
> so that breakout is supressed at the top and bottom, and instead tends to 
> occur at the outer rim of the toroid.
> 
> The inside of the toroid actually contributes next to nothing to the toroid's 
> characteristics. In fact, if you look at Tesla's patent drawings you will find
> that he leaves the inner section out completely. He also shows the toroid's
> surface as being composed of many small half-spheres. The interesting thing is
> that the mutual action of the surface e-field shapes of a toroid-like structure
> is such that it will tolerate a fair amount of surface irregularity and still 
> act as if it were perfectly smooth.
> 
> Simplification: Concentrate on making the outer rim and enough of the top and
> bottom of the toroid shape smooth enough to be useful. Do not worry about the
> inner part of the topload, as it adds nothing to the toroid's usefulness in
> TCs.
> 

[very large snip]

I have to take issue with the good Friar's comment that the inner 
part of the top load not being important or "useful".  Without an 
inner disk, the toroid forms a perfect single turn short, which can 
absorb a huge amount of your coil's energy.  The disk "shorts" out 
this single turn and prevents the toroid from acting as a short as 
seen by the coil. We found this out on the extra coil on our large 
magnifier. The resonator coil was driven with a transmission line, so 
we didn't think a solid metal disk was important.  We were wrong.  
The toroid at the bottom of the coil (for field shaping) got so hot 
it melted hot glue!  Richard Hull had about the same thing happen 
(Richard, correct me if my memory is wrong on this.)  I always make 
sure that I have a solid metal disk in the center of all toroids now, 
regardless of size.  Especially on magnifiers.  The disk contributes 
little or nothing to field shaping, but it *does* play an important 
part of the toroid assembly.

Smokin' them toroids in Ft. Worth,

Bert Pool
TCBFW
bertpool-at-flash-dot-net