Re: Water capacitor, was: Re: General Questions

["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 Mark, Terry, All!

I was interested to read of your experiences re designing one of these
things, Mark.

>The other problem is actually getting the parts clean.  EVERYTHING
that goes
>into the water (including the "tub") must be THOROUGHLY washed.  This
means
>soap and water, alcohol, MANY rinses, and then just letting things
soak for
>several weeks, and changing the water every day.  The problem is that
only a
>VERY few particles are needed to destroy the insulating properties of
the
>water. Soaking allows the "crud" to leech out of the plastic, metal,
etc.


Yes, that would be a real pain.  However, there is a far worse one.

The water molecule has a permanent net electric dipole.

This means that when placed in an electric field, the water molecule
tends to line up with the electric field lines like a magnet does with
magnetic field lines.  If the field oscillates, the molecules try to
follow the oscillation.  Moving water molecules takes energy, and the
dissipation factor of pure water at 20C at 1Mc/s is around 0,05 which
is 100x worse than a good TC cap material, or in other words, water is
lossy at rf, as Gary Johnson's recent experiments have confirmed.
(Mind you, ice at 3x10^9c/s has a dissipation factor of only 0,0009
(hence the low power "defrost" setting on the microwave oven) so for
that *really* tiny tc . . .)  Many rf heating applications e.g. timber
drying, industrial gluing operations, medical diathermy etc depend on
the dielectric loss of water to generate heat from the applied rf
field thereby drying the timber, setting the glue, heating the patient
or whatever.

For a pulse cap where generating rf is not an issue, this hardly
matters, and in fact a bit of built-in rf damping might even be
desirable depending on the application, but IMHO not a good choice for
a TC primary cap.  The rf performance is not going to be impressive.
An expensive way of brewing the coffee!  Sorry!

However, were it not for that permanent electric dipole, the protein
molecules in my body would be a different shape, to mention but one
consequence.  I think I'll forgive the dielectric loss under the
circumstances ;-)

Dunckx