Re: Airtight Coil form

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

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

It's not so much arcing through the air, but along the surface of the inside
of the form.  The breakdown voltage along a surface is typically 1/3 that of
the same free air distance.  So, for instance, if the distance inside the
form were 2 feet, in free air that would hold off up to 1400 kV (actually,
almost never that high, because that's for a perfect uniform field). But,
along the surface it would be around 500 kV, which is a typical number for a
TC topload voltage (give or take 50%).  The 500 kV would flashover along the
surface, unless you've made the surface distance longer... (This is why HV
insulators have ribs.. or the ones on power lines are made up of a bunch of
stacked disks or bells)
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, March 13, 2001 9:28 PM
Subject: Airtight Coil form


> Original poster: "Stolz, Mark by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<Mark.Stolz-at-st-systems-dot-com>
>
> Hi all,
>
> My name is Mark and I'm beginning to get started into coiling.  I've been
> reading lots from this list, and there is A LOT to read, and I've been
> reading at tons of TC websites.  I haven't been able to find an answer to
> the question of why does the coil form need to be airtight.  I thought it
> might be due to internal arcing, but that didn't make sense since arcs can
> still happen in a vacuum.  I figured this would be the best place to get
an
> answer from, since a majority of you are what I would consider experts.
> Thanks!
>
>
>