Re: Skin effect, was Complete destruction if the Geeks perfectly good p133...

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

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

Actually, what Jason describes isn't skin effect...which DOES require the
thing to be at least somewhat conductive.

This is an example of surface breakdown or creeping discharge, for which
there are two things happening. First, the dielectric constant of glass (or
some arbitrary insulator) is different than that of air, which means that
the field does not distribute evenly across the interface.  This is
particularly important if the interface is sharply curved, because uneven
distribution generally implies higher fields in some places than others,
which generally makes the breakdown voltage (for a given distance) less.

Secondly, and probably more important, is that as the voltage along the
surface rises, charge accumulates on the surface, causing the field to
increase, resulting in breakdown.

These effects are the genesis of the general rule of thumb that the
breakdown voltage along an insulator's surface is 1/3 that of the same
distance in air, and is why HV insulators have ribs and corrugations... To
make the creepage distance > 3 times the air distance.

For a very impressive effect, put a big sheet of metal down, covered by a
sheet of plastic or glass (or a tray of deionized water). Then hook your
handy HV source (i.e. NST or TC) (referenced to the gound plate) to an
electrode on the top surface of the insulator...



----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, July 07, 2001 9:02 AM
Subject: Skin effect, was Complete destruction if the Geeks perfectly good
p133...


> Original poster: "Jason Petrou by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<jasonp-at-btinternet-dot-com>
>
> Mark,
>
> > Skin effect is only valid for good conductors.  Last time I checked, the
> > ceramic casing of a chip was not too conductive.
>
> I dont think so... Take a glass rod with big copper things on each end.
Make
> sure the rod is shorter than the streamers from your TC. Then, set it up
as
> a ground rod, and hit the one end with TC streamers, while the other end
is
> just grounded. The electricity will run over the surface of the glass. The
> reason for this is that the electron 'junction' between the glasss and the
> air (different electron densities) causes the rod to become a capacitor...
> and as you know, capacitors conduct at high frequencies :)
>
> Regards,
> Jason
>
> Geek # 1139 Rank G-1
> www.thegeekgroup-dot-org
>
>
>
>
>