Re: pure water capacitor?

To: tesla-at-pupman-dot-com
Subject: Re: pure water capacitor?
From: "Jeff Metschuleit" <jeff-at-lumitron-dot-com> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Thu, 17 Feb 2000 08:15:47 -0700
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Mark,
Your information about water is correct, it makes an excellent insulator
when it is pure.  Unfortunately water is also an excellent solvent and
becomes unpure over time when touching almost anything.  In water cooled
setups involving high voltages the water is typically circulated through a
deionizer to maintain its insulating properties, this obviously complicates
the construction of a plate capacitor.

Jeff Metschuleit
-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Wednesday, February 16, 2000 1:43 PM
Subject: pure water capacitor?


>Original Poster: "Mark Broker" <broker-at-uwplatt.edu>
>
>I'm a very new member to the TC community.  I've been interested in
>building one, or two for quite some time, but have never had the
>opportunity ($$$, tools, ect) until recently.
>
>I'm a senior majoring in Engineering Phyisics (don't ask....) and am
>involved with the SPS (Society of Physics Students).  The SPS occasionally
>gives physics demos to local schools.  We have a POS 250kV 1/2 wave TC that
>must be 20 years old.  I thought that a nice medium-sized 1/4 TC might make
>an excellent "gift" to the SPS as a going-away gift.
>
>I've been trying to do some research regarding design issues, when I came
>across a list of dielectrics for some materials for use in capacitors.  The
>dielectric constant for pure water is around 85 with an infinite breakdown
>voltage!  This means that two 12" x 12" plates spaced 1/8" apart will give
>a capacitance of .020uF!  I thought it would be a pretty sweet idea: a pure
>water cap in a plexiglass (or lexan (?)) box.  But, I have NEVER seen this
>mentioned anywhere I've looked.  The only problem I can see is
>contamination: everything has to be 110% clean before adding water.  This
>is do-able.
>
>Are there any reasons why I shouldn't try to use this?
>
>For the record, I'm looking at a 15kV/120mA+ NST.
>
>Thanks
>
>Mark
>
>