RE: Torroids

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Hajdrowski, Leo T." <leo.hajdrowski@xxxxxxx>

Hello Christoph,

Thank you for that explanation.

Leo



-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Wednesday, March 08, 2006 8:07 PM
To: tesla@xxxxxxxxxx
Subject: Re: Torroids

Original poster: "Christoph Bohr" <cb@xxxxxxxxxxxxxxx>

Hello Leo.


 > Why does the top torroid have to be smooth?
hm, has to is realtive. It is usually preferred to be and this is for
some good reasons. If you think of an capacitance to ground, the
smoothness of the topload seems not very important.
But as a HV loading terminal you want to minimize corona leakage in the
first place which would be introduced by any sharp edges.
When streamers form, they tend to attach in these places, hindering the
streamer from wandering around the toroid. Further, the total breakdown
voltage will be lower than calculated  for the same size, which might
mess your design up, because the wrinkles of the foil are hard to
predict. The good new is, "smooth" usually means smooth compared to the
toriod size. A 1" bump in a 6" toroid will cause a single breakout
point. A 1" bump on a 10 feet toroid will hardly be noticable.
You usually want the voltage to rise as high as possible with a toroid /
coil combination that can just break out, or even can not break out on
its own and uses a breakout point for longest streamer performace.
Of course there are asthetic reasons to.

 > Why can't you take a two foot in diameter beach ball and cover it
with  > tin foil, aluminum tape, or copper flashing to make a large
torroid?
Hm, to point out the obvious: because a ball is not a toroid..
Ok, I can be really annoying ... If you meant topload, this can and has
be done, tough a toroid proves advantagous in most designs for its field
shaping propperties. Aluminium tape can be applied very smooth like with
Gary Lau's great foam toroid:
http://www.laushaus.com/tesla/foamtoroid.htm

However, a ball or even nothing at all will work, just nor very well.

best regards

Christoph Bohr