Re: Distilled water as a dielectric?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Mike" <mike.marcum@xxxxxxxxxxxx>

In the pre-mmc days people used 4-mil polyethylene from a hardware store 
and aluminum flashing from the same store for the plates. Size depends 
mostly on the voltage rating. PE has a dielectric strength of around 1200 
vdc/mil (200vac/mil for reliable tc use) and a constant of around 2.3 and 
low RF loss. These types of caps aren't made much these days other than for 
bragging rights since mmc's are much easier to make (no oil/vacuum 
pump/container needed for one). Several years ago (pre-list days, going by 
Brent Turner's tc book) I made a .01uF 15kvac one for a 15/60 nst and irrc 
the thing weighed close to 60lb and was messy to make and keep the plates 
where I wanted them, especially while bolting down the stack and having the 
plates shift (oily pe is slippery). After CD's 942c20p15k's I'm never doing 
that again.

Mike
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Tuesday, May 31, 2005 9:23 PM
Subject: Re: Distilled water as a dielectric?


> Original poster: Greg Morris <gbmorris@xxxxxxxxx>
>
> Alright, thanks guys, that's exactly what I wanted to know. Any 
> suggestions on what I should use for a dielectric, that would be cheap, 
> easily obtained and work well? How big do parallel plate caps usually have 
> to be anyway? Has anyone here made any?
>
> On 5/31/05, Tesla list <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx> wrote:
> > Original poster: dave pierson <<mailto:davep@xxxxxxxx>davep@xxxxxxxx>
> >
> >
> >
> > >The problem is that it is hard to make deionised water stay
> > >deionised.  Once you put ordinary metal contacts in the water and pass a
> > >current you start to get ions.  There are dissolved gases such as CO2 >that
> > >dissociate into H+ and HCO3- that can combine with metals.
> > >In some casual HV experiments with deionised water open to the air the
> > >conductivity increased over a day or two.
> >
> >     Just so.
> >     I've mentioned visiting the HVDC power inverter: they chop MW of 
> > +/-500KVDC
> >     back to AC for the net (including some of what i use to send
> > this....).  The
> >     main insulator/cooler  is 99.999ifergethowmany9s water.  The
> > purifier/deionizer runs
> >     constantly stripping the stray ions back out...
> >
> >     best
> >        dwp