Small HV Insulators was Re: New 4" coil: R.Hull and CSN, Secondary Varnish

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

Original poster: "Mark Fergerson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <mfergerson1-at-cox-dot-net>

Tesla list wrote:
> 
> Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<jimlux-at-earthlink-dot-net>
> 
> Actually, given the power levels in a typical TC (hundreds, if not
> thousands, of watts, compared to milliwatts in an electrostatic generator),
> a bit of conductivity is probably good.. It helps make the field nice and
> uniform.

  I hadn't considered that, even after
looking at some websites describing
serious HV stuff for particle
accelerators etc.; they use epoxy to
make a smooth transition from wiring to
electrode supports. Now I see why the
slight (?) conductivity of epoxy would
be a good thing. The word "tradeoff"
comes to mind.

  But finding just _how_ slight that
conductivity might be for a given epoxy
is extremely difficult, as I'm sure your
average epoxy manufacturer, who intends
their product _not_ be used
electrically, just doesn't have specs
available. I sure don't have the
hardware to check for milliohms -at- multi
kV.

  Not that the accelerator crowd uses
off-the-shelf epoxies, but still it'd be
nice if manufacturers would spec their
stuff. Sigh.

  Well, I mentioned I'm trying to see
how small a Magnifier can be made, with
"good" performance (-at- not quite 100W).
I've been having all sorts of fun
turning insulators out of various
plastics on a Dremel and like that,
hoping I don't have to try _glass_. Also
hoping something better than Plumber's
Goop exists for non-symmetrical shapes
(it droops a bit). No joy AFAICT.

  BTW, does anyone know of design
equations for what used to be called
spiderweb coils? I've wound several and
none are quite the values I'd expected.
I've decided (out of sheer perversity,
apparently) the pri/sec circuitry of my
micro-Magnifier will be best arranged
that way.

  Mark L. Fergerson

> ----- Original Message -----
> From: "Tesla list" <tesla-at-pupman-dot-com>
> To: <tesla-at-pupman-dot-com>
> Sent: Sunday, September 01, 2002 6:50 PM
> Subject: Re: New 4" coil: R.Hull and CSN, Secondary Varnish
> 
> > Original poster: "Mark Fergerson by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <mfergerson1-at-cox-dot-net>
> >> > Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz
> > > > Original poster: "Jeff W. Parisse by way of Terry Fritz
> > > All the epoxy resins that I have seen are poor insulators. Maybe
> > > good enough for Tesla coil insulation, and even advantageous for
> > > safely draining static charges. Epoxy doesn't retain static
> > > charges for long (seconds) periods. It can't even be electrized by
> > > friction. A big no-no for electrostatics.
> >
> >   So off-the-shelf epoxy would make a
> > poor electret? (reminiscing the
> > "mysterious shocks" thread here)