Re: Conductive paint?

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

Original poster: "Dr. Duncan Cadd by way of Terry Fritz <twftesla-at-uswest-dot-net>" <dunckx-at-freeuk-dot-com>

Hi Marc, All!

>i've tried spray graphite lube on a couple toploads with pretty good
>success? even though the graphite megs out real high resistance in a
>half inch distance, the streamers didn't seem all that much shorter,
>just many more at once.


Now *THAT* I find fascinating.  It implies that the spark length is
simply controlled by the total net charge and that, if there's
sufficient resistance on the surface, breakout at one spot can't drain
all the charge fast enough to regain equilibrium.  So you get more
breakouts in order to reach equilibrium between the charging rate and
the discharging rate.  Are the individual streamers from a
graphite-coated topload less intense than the fewer sparks you get
from a metallic topload of the same size?

>i've often wondered if the dc resistance really comes into play with
the
>topc charge being at such a high frequency?

Don't see why not.  It's a thin coating, so the skin effect isn't
going to alter much, and Ohm's law is still Ohm's law.

>is the charge of the topc
>being held on the conductor or in the dielectric?

Gauss' theorem suggests on the conductor, when the conductor is
outside the dielectric as in a coated topload.

>i wondered if the
>hf\hv wouldn't just jump across the points of all the fine graphite
>particles?

I would assume it does, but if they're in contact anyhow, there may be
little jumping involved.  Also, particles in contact will "cohere"
very efficiently considering the circumstances!

>the spray graphite never flaked off but i did notice that
>once in a while the clear poly spray i put over one, seemed to burn
in a
>fine point as one streamer would get stuck there, showing a very
bright
>pinpoint at the base. i never could see a pinhole on it though?


Maybe it carbonises a mini-breakout spike in the poly coating.

>just thinking again,


Dangerous that!  What manner of spray-on goop is this?  I know you've
mentioned it before, but it sounds like a specialised sort of product.
Where might you find it?

Dunckx