Re: Glass Caps

To: tesla-at-pupman-dot-com
Subject: Re: Glass Caps
From: Wells Campbell <wellscampbell-at-erols-dot-com> (by way of Terry Fritz <twf-at-verinet-dot-com>)
Date: Fri, 12 Mar 1999 12:33:20 -0700
Approved: twf-at-verinet-dot-com

Tesla List wrote:
> 
> Original Poster: NickandSim-at-aol-dot-com
> 
> To All,
>           I have just built my first glass plate cap.  I have been told that
> they are fine running in air.  Is this true or should I oil bath it?
> 
> Thanks in advance
> Nick Field

I would say that if you can, dunk it. I ran my first tabletop coil on an
air/glass cap, and it failed consistently over time. Corona sparks will
travel along the surface of the glass, and etch lines for surprising
distances around the ends of the glass plates. These become more
conductive, and eventually sustain a full power arc, which will usually
crack the glass.  Oil would limit these corona effects, but would do
nothing about the lossy nature of the glass. It would still heat
considerably. If you are going to dunk something in oil, it might as
well be a rolled or stacked polyethlene unit. In any case, good luck
with your cap.

Wells