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Re: [TCML] ELECTROMETERS
Not so sure the physics is that interesting. Charge will leak faster from a
negatively charged electrode than a positive one. So an AC charged object
that is not sparking will tend to charge up with some DC component.
Check out the corona from these DC electrodes at 100kV. The electrode tips
are asymmetrical but the negative (earth) on the right has more corona on
the uprights.
https://plus.google.com/u/0/108941983487083451766/posts/CA547s9vtnq
Peter
Tesladownunder.com
-----Original Message-----
From: David Thomson
Sent: Monday, June 04, 2012 9:41 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] ELECTROMETERS
Hi Mike,
I have built several jacketed secondary coils. The coils were wound on PVC
and then a second PVC pipe slipped over the wound coil and sealed at both
ends and filled with transformer oil. The dielectric was extreme. During
the run, the coils produced intense DC electrostatic fields. You could
feel it very clearly across the room. The strong residual charge on the
PVC would last for several days.
After doing research on dielectrics, I came to the conclusion that it was
the oil and plastic that was arranging the charge particles (charged dust,
polarized water vapor, electrons, etc) in the environment. The high
potential inside the coil apparently arranges dipoles in the dielectric. It
is as though the empty valence holes in the dielectric atoms and molecules
become fixed in such a way as to draw charged particles from the
environment without allowing them to change the dielectric's structure.
Perhaps the outer layers of atoms and molecules of the dielectric are
affected by charge contact, but the inner layers retain their ability to
organize charge. The outer layers act like a buffer. Thus the thicker the
dielectric, the stronger will be the residual charge and the longer it will
last.
I believe there are a lot of undiscovered and interesting electrical
effects that can be accomplished by engineering different types of
dielectrics under conditions of high potentials and high currents. Bert
Hickman makes beautiful art by stressing dielectrics, and there are likely
many other uses.
Dave
On Sun, Jun 3, 2012 at 8:17 PM, Peggy Day <mmjday@xxxxxxx> wrote:
I've experienced the same ever year when I run my coil outside during
Halloween. Currently, the coil I'm using has about a 1/4 inch of epoxy
coating the surface. Even after 1/2 hour or more after a Halloween run,
the
static build-up on the surface of the coil can be startling, if you are
not
prepared. This happens year after year, and is independent of what coil I
happen to run. I always find it a bit odd, given that the humidity around
Washington DC is usually fairly high. I would expect the charge to bleed
off quickly.
I always wanted to know if it was always the same polarity or if it was a
positive or negative charge. Possibly more important, why is there a
residual parasitic charge? I speculate that it is due to the fact that
the
Earth is charged with respect to the ionosphere, though I suppose that it
could also be a residual parasitic charge resulting from coronal
rectification, whatever that is. I also wonder if other people experience
the same when they run coils indoors, or is this just something that
happens
when outside?
Mike
On 6/3/12 5:09 PM, "Tesla" <tesla@xxxxxxxxxxxxxxx> wrote:
>
> Yes a real phenomenon
>
> Have received one good fright from static left on the surface of the
> secondary after use. Left coil for 10 min before disassembly and got a
> static shock off it after carrying it.
>
> Secondary is coated with polyurethane and is on 25 cm PVC tube
>
> ted in NZ
>
>
------------------------------------------------------------------------------
> --
> -----Original Message-----
> From: ED
> Sent: Monday, June 04, 2012 1:42 AM
> To: Tesla Coil Mailing List
> Subject: [TCML] ELECTROMETERS
>
> One of the subjects he
> investigated was the charges left in the insulation on the surface of
> TC's after operation and I'd like to repeat his tests.
>
> SNIP
>
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
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