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Re: Toroid Design .

Tesla List wrote:
> 
> Original Poster: bertpool-at-ticnet-dot-com
> 
> Date forwarded:         Sat, 19 Dec 1998 14:00:43 -0700

> The inside of a spherical or toroidal discharge electrode has zero volts
> charge inside.

Whoops, charge isn't measured in volts. Charge is, of course, measured
in Coulombs (or electrons, for small charges), not volts. However, it is
true that there is no net charge inside a conducting object (it is all
on the outer surface).  The voltage that an object is at (relative to
something else, of course), has to do with the force (Electromotive
Force = EMF (measured in volts) required to get an additional charge to
the object. The higher the voltage, the harder you have to push that
incremental charge. This is why a Van deGraaf motor slows down as the
the upper electrode voltage increases: it has to work harder to
transport the charge to the electrode.


  It does not matter whether you fill the inside with balls of
> aluminum foil or even with Greg Leyhs (see his web site for a good
> example), they will have no charge on them.  The surrounding electrode
> effectively shields them.  The Tesla coil does not see anything inside the
> toroid.  The outside, however is a different matter.  Hemispheres on the
> surface of a toroid just may increase the effective capacitance (Tesla
> constructed his largest top this way).

I think that Tesla was using small hemispheres as a construction aid,
not because a bumpy surface has higher C. He commented in several places
that you can construct something of large effective radius (for higher
voltage before breakdown) by combining things of smaller radius close
together. Electrostatic field calculations, although tedious for any
practical system, will confirm this. Some more modern practical
applications include the construction of huge toroids used for testing
at the IREC HV research center in Canada, field control rings on EHV
transmission line terminations, and, of course, Greg Leyh's top load
made from tubing welded into a sphere.
> 

> Bert Pool

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