Re: A LUA file for BELA (a help to build electrostatic model of TC)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Finn Hammer <f-h@xxxx>

DC,

Toroids are great and classic devices in the quest for a more uniform field.

A tertiary magnifier coil is a good example, where the potentials of 
both ends of the resonater are above ground level, and the field 
strength is aligned in the coils axial direction. A toroid in both 
ends of this coil is mandatory, to avoid corona loss. This applies 
particularly to the bottom end. In the other end we do of course not 
only accepy, but ultimately rather desire corona loss.
In the example you put forth, where  discontinuities exist on a 
conductor at high potential, a toroid is also advisable at each discontinuity.

I do however fail to grasp, what a toroid at the bottom of the coil 
in question would acheive in the line of field controll, since both 
coils at the bottom are terminated at ground potential.
The field strength in this example is aligned in the radial direction 
of the space btwn. both coils.

How do you expect to smooth a _radial_ field with toroids?

Cheers, Finn Hammer

Tesla list wrote:

> Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>
>
>
>
> One impovement to this design would be using a toroid on the bottom 
> of the coil as well as on the top.  Just using one on top shapes the 
> field but the smaller dia copper tubing in the base area does not 
> provide effective electrostatic field control in this area.  Using a 
> toroid on the bottom as well as on the top will help provide better 
> control of the fields and reduces the insulation required.  As you 
> noted just using more insulation does not give good uniform field 
> control.  You need to shape the fields with proper electrostatic 
> shielding techniques.
>
> These principles are used in very high potential 60 Hz xmfrs used 
> for research work.  A nice toroid is placed in the case entry area 
> and many times actually inside the case near both the bushing tip 
> and also near the area when the bushing departs the case.
>
> Dr. Resonance
>
>
>
>
>
>
> > Original poster: Ed Phillips <evp@xxxxxxxxxxx>
> >
> >
> > People who work with tightly coupled transformers for high voltage 
> > know it already, but I have only recently found out:
> > I cannot insulate my way out of a corona problem. The more 
> > dielectric I stuff into the gap, the more severe the corona gets in 
> > the remaining air.
> >
> > Ain't that the truth..."
> >
> >    Of course; "it has to be that way".  The more (higher 
> > dielectric constant than air) material you put in the gap the 
> > greater the voltage drop across the remaining air and hence more 
> > corona.  IF you completely fill the gap and IF you exclude all 
> > residual air the corona will be suppressed.  If a little air 
> > remains somewhere it will break down due to corona and may very 
> > well result in breakdown of the associated dielectric 
> > material.  Major failure mechanism for capacitors operated at high AC voltages.
> >
> > Ed