Re: toroid question

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Marc,

On 30 Jan 2002, at 8:22, Tesla list wrote:

> Original poster: "Metlicka Marc by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <mystuffs-at-orwell-dot-net>
> 
> 
> 
> Tesla list wrote:
> > 
> > Original poster: "Malcolm Watts by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>
> > 
> > Hi Allan,
> > 
> > On 27 Jan 2002, at 23:30, Tesla list wrote:
> > 
> > > Original poster: "Allanh by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> > <allanh-at-starband-dot-net>
> > >
> > > It has occured to me that using a toroid with no conducting material
in the
> > > center in effect places a
> > > shorted turn in the magnetic field and would cause
> > > very high current to flow. Upon testing my theory on
> > > my coil, I found very little difference in the two types.
> > > I would like to know why the shorted turn toroid doesn't
> > > consume great quantities of power.
> > >
> > > any ideas?
> 
> Malcolm, all
> 
> > 
> > Why should having no conducting material in the centre be worse? You
> > could view either form of construction as being a shorted turn,
> > possibly worse in the case of a central conductor since it is closer
> > to the windings.
> 
> I don't think i agree here, I see the toroid as more of a horizontal
> conductive disk with the outer ridge of a large ROC. Even with a toroid
> that has no conductive center, you still must run the top turn out to
> connect, this makes it still a horizontal disk with a large ROC outer
> ridge. I would think that a cut toroid would tend to break out at the
> edges of the cut, but since i haven't tried this i couldn't say
> positive?

I don't think a wire running to a toroidal ring has any bearing on 
where and to what degree currents are induced in the ring. Does it?? 
I was leaving considerations of breakout well to one side since the 
original question appeared to be addressing inductive effects. I have 
performed the expts I allude to below the corona inception point FWIW.

>  In fact, the requirement for anything to consume
> > power is that it must be somewhat resistive. Most terminals are close
> > to perfectly conducting. There can't be much doubt that the
> > arrangement modifies the operating properties of the resonator to
> > some degree, but then connecting something to the top of the windings
> > does that anyway.
> 
>  But more due to adding top c then anything?

It would appear so.
 
>   Since cutting a slit in the toroid so that a
> > shorted turn no longer exists has little effect on Fr (it tends to go
> > up a bit if you do this), it must be telling you something about the
> > way the resonator operates (how currents are distributed for example)
> > and how the two interact.
> 
> It seems to me that at some point the toroid can become to big around in
> relation to the coil, I find this on my little test coil, If i put the
> toroid that is almost as large of outer diameter as the coil is tall.
> I think that at a point the topload will start to couple with the
> primaries field, this causes some real strange effects and then i think
> it looks like a shorted turn?

Too big = too big a drop in output voltage (for breakout). The 
coupling between primary and toroid is pretty well negligible given 
their physical separation (like < 10% of Ksys). I have measured this 
too. Needless to say, the exact figure is dependent on physical 
parameters so varies from coil to coil.

>  I'm not sure if this has been covered in
> > the tssp project yet. Perhaps Paul Nicholson might care to comment?
> 
> I remember mentioning this to Paul in that with this large topload the
> first streamer always broke towards the primary and contacting the upper
> two thirds secondary windings, almost at right angles then they extended
> to air as normal.
> Take care,
> Marc M.

I think we may be addressing two different issues? Sorry if I've 
misunderstood.

Regards,
Malcolm