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Re: Water As Dielectric


From: 	Alfred C. Erpel[SMTP:aerpel-at-Op.Net]
Sent: 	Monday, November 10, 1997 7:30 PM
To: 	Tesla List
Subject: 	Re: Water As Dielectric

AE>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>     Is distilled water considered to be a viable dielectric material for a
>plate capacitor? High voltage vs. low voltage? DC vs. RF?  Since it's k=80+
>it would seem to be a good choice.  As a toolmaker, I would have no problem
>making a sealed, watertight plexiglas cube, void of air, with evenly spaced
>copper plates inside, and I would like to do this if someone doesn't tell
me
>it is a dumb idea.
>     What is water's dielectic strength? I did a search on the internet for
>this value and the only thing I kept finding was it's dielectric constant.
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<AE

DD>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Another fluid used in research is Glycerin, it's dielectric constant is
about
40, as compared to water's 80.
I've seen water used as a dielectric fluid and coolent, but only by running
it with a pump through a small ion-exchange bed, to pick up the
contamanents.
Of course the general rule of thumb is that losses go up in propotion to the
dielectric constant, so you might be shooting yourself in the foot, trying
to use a high constant fluid.
What we really need to find out is how dielectric loss is related to
dielectric constant. Is it directly related to the polar nature of most
of the high constant fluids, or does the complexity of the molecular
structure enter into the equation ?
If the former, we can lay to rest useing any high constant fluids forever
and concentrate on building really nice vacuum caps for the ultimate in
low loss.
If the latter, we can search for, and perhaps engineer a proper low-loss
fluid to do the trick.
Anyone out there with a background in Physical Chemistry ?
Daryl (who is dreaming of cheap, low loss, homemade caps...)
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<DD

    Ok, I think I've been convinced of the folly of using water as a
dielectric, but now I am intrigued about glycerin. Can anyone report on the
dielectric strength of glycerin or otherwise shoot down its potential
efficacy as a dielectric? Again, my intent is to use it in a sturdily,
machined/assembled, liquid tight, polycarbonate container .032 copper plates
parallel and flat withing .002, with .010 to .030 even gaps between plates
 depending on desired voltage/capacitance combination). Also what about
ethyl alchohol as dielectric, which is between 35-40 k?

    Also, while on the topic of capacitors, I can't wait until I'm retired
so I can build my 48" cube, 1 farad capacitor in my basement.  I'd charge
that sucker up to 10,000 volts and go to sleep resting easy that I had 13.9
kilowatt hrs. stored away in case I needed it.
<seg>

Regards,
Alfred



    Regarding capacitors in general