Re: Q about E-tesla-6

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

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

I would venture to say that there is no convenient closed form solution for
a toroid.  A decent approximation based on EM modeling or empirical
measurements perhaps.  I base this on the fact that there isn't a closed
form solution for the field a sphere-sphere or a sphere-plane gap, only for
sphere in free space (where it is trivial).

For the real case of object working against a plane or another identical
object (really, the same problem, because the plane just creates an image),
the typical approach is to calculate what the field from one electrode looks
like on the other one, calculate the charge distribution, calculate the
field on the other electroide, calculate its charge distribution, and
successively refine the distributions as an infinite series of images of
each electrode in the other.  Gets real nasty, real fast, hence the
popularity of numerical or empirical methods.

The Feynman Lectures on Physics (I don't recall which volume, probably 1 or
2) has a very good description of the process.


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, September 13, 2001 9:31 PM
Subject: RE: Q about E-tesla-6


> Original poster: "Johnson, Jeffrey D -at- PWC by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <jeffrey.d.johnson-at-l-3com-dot-com>
>
> I am far from an expert on numerical electromagnetics but I wrote some
> Matlab code in school to solve for the charge distribution on simple
> geometries.  It seems like a toroid, being symmetrical, may not be too
hard
> to simulate.  I'll have to dig out the books but it may be easier than
> finding a closed-form solution (then again, it may not).
>
> Jeff Johnson
> SLC, USA
>
> -----Original Message-----
> From: Tesla list [mailto:tesla-at-pupman-dot-com]
> Sent: Thursday, September 13, 2001 11:43 AM
> To: tesla-at-pupman-dot-com
> Subject: RE: Q about E-tesla-6
>
>
> Original poster: "Loudner, Godfrey by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <gloudner-at-SINTE.EDU>
>
> Hi Peter
>
> I