Re: Torroid and sphere terminal magnetic/eddy loss (fwd)

---------- Forwarded message ----------
Date: Fri, 19 Dec 1997 18:00:46 +1200
From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Torroid and sphere terminal magnetic/eddy loss (fwd)

Hi Scott,
         Good thinkin' but.....

> Date: Thu, 18 Dec 1997 06:29:15 -0700
> From: Scott Stephens <stephens-at-enteract-dot-com>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Torroid and sphere terminal magnetic/eddy loss
> It has occured to me, (as other's no doubt) that torroids may be better than
> spheres, in part, because the concentrated flux that exits the secondary
> solendoid induces eddy current losses in a sphere; where with a torroid, the
> flux does not cut the conductor.
> This could have the effect of cutting a section of coil off the top equal to
> the squar of the coil diameter.
> My hypothesis could be tested by suspending a turn of wire with a lightbulb
> between the ends, over the coil to see how much it glows, and by putting an
> insulative gap in torroids/spheres. But who wants to cut a slit in their
> sphere, or in their torroid? 

It has been done - by me.  The effect on inductance is negligible. 

> The voltage accross the slit would be low (step down transformer link) and
> the current high.

The top end of the coil would only have a significant current (prior 
to spark production) if the topload was pretty large. It really 
doesn't seem to matter.