Re: Spheres on toroids

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

Original poster: "Antonio Carlos M. de Queiroz" <acmq-at-compuland-dot-com.br> 

Tesla list wrote:
 >
 > Original poster: Thomas <tom-at-pwrcom-dot-com.au>
 >
 > I too modelled the phi spiral to get this:
 >
 > http://www.webclot-dot-com//high_volt/images/inca/phi1a.jpg
 >
 > With a (sort of) secondary coil field it looks like this:
 >
 > http://www.webclot-dot-com//high_volt/images/inca/phi1c_zoom.jpg
 >
 > This is what I really did to get that field plot:
 >
 > http://www.webclot-dot-com//high_volt/images/inca/phi1c.jpg
 >
 > not sure if it is really valid. But I could not model a real secondary.

A good approximation would be to place a series of cylinders below the
terminal, progressively reducing their voltage. Use just one ring for
each cylinder, to have what a linear (or how you want it) gradient.
To make the ground, you can use a flat disk at zero voltage. A large
counterpoise as you used works too, but set it to zero volts.

 > After modelling 785 turns of a 6" secondary in excel and ultraedit (got to
 > love the "column edit" feature in that program) and pasting into inca only
 > to be told "too many elements", I was a bit frustrated, and went for the
 > approximation shown in 1c.

Not so many rings. The program has a limit of 400 rings. I could use
large
numbers, but the solution time grows with the cube of the number of
rings.

 > The distributed voltage line would be so handy!
 >
 > Antonio, is this possible?

Yes, it is. But I will be away for the next two weeks. I will work on
this after returning. For awhile, distributed voltages must be specified
ring by ring.

 > But assuming that the plot is approximately valid, it looks like a neat top
 > load to try (streamers mostly on top).
 >
 > Next question - how to make such a shape? High density polystyrene foam and
 > some sort of shaping jig?

Note that the top is a regular hemisphere, and the part of the bottom
that
really matters is a half toroid.

Antonio Carlos M. de Queiroz