Re: Water sparks (fwd)

[Steven Roys <sroys@xxxxxxxx>]

---------- Forwarded message ----------
Date: Thu, 7 Aug 2003 09:13:04 -0700
From: Sean Taylor <sean.s.taylor@xxxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: Water sparks (fwd)

Hi Terry,

I think our thought processes are almost exactly the same!  Just yesterday I
tried pure (tap) water rather than with salt that I had tried before, and
that alone increased the spark distance significantly.  I'm using a 0.188 uF
maxwell cap, and getting about 1.5" arcs from the center electrode.

I then decided to add an inductor (0.4 mH, air core - check out
http://www.madisound.com/3way.html for some really cheap small inductors),
for a resonance of about 18 kHz (please check my math . . . I'm drawing a
complete blank on rad/sec -> Hz for some reason).  There really wasn't a
huge noticable difference.  The arcs got a little bit "hairer" - i.e. they
branched out more, and got a little bit longer, but the RF envelope died out
fairly quickly, most likely because of the high resistance of the water
(need to get the scope out and the HV probe!)

Anyhow, I don't want to test this too extensively because of the huge
voltage reversal that these caps are most likely seeing when running with
the inductor (it's probably actually higher without the inductor, with much
higher frequency!), but I am going to be using two of these (in series) in a
pig powered coil, so maybe I shouldn't worry about it too much :-).

BTW - I originally had just a galvanized nail in the water, then later
switched to a copper plate directly below the terminal.  With the water
being relatively high resistance, it didn't seem to matter that much.
However, the hardware on the copper plate to hold the wire to it just
corroded over night, even though it was supposedly galvanized.  Probably had
to do with a small nick in the galvanization, or the fact that I had it
hooked up to copper, and that whole electrolysis thing and potential
difference thing happened between the zinc and copper!

Sean Taylor
----- Original Message -----
From: "High Voltage list" <hvlist@xxxxxxxxxx>
To: <hvlist@xxxxxxxxxx>
Sent: Thursday, August 07, 2003 8:42 AM
Subject: Re: Water sparks (fwd)


> Original poster: Steven Roys <sroys@xxxxxxxx>
>
>
>
> ---------- Forwarded message ----------
> Date: Wed, 06 Aug 2003 11:46:25 -0600
> From: Terrell W. Fritz <terrellf@xxxxxxxxx>
> To: High Voltage list <hvlist@xxxxxxxxxx>
> Subject: Re: Water sparks (fwd)
>
> Hi Sean,
>
> The water in the Z-Machine is constantly filtered, purified, deionized,
> etc. to keep its electrical reistance as high as possible (the water is
> being used as an insulator).  So, your water should be very pure like
> distilled water from the grocery.  The more of an insulator it is, the
> longer the arcs will travel before being bleed off into the water.
>
> Tou may want to try a small ground for the water too.  Rather than having
> say a metal pan, try just a small exposed wire end in the water, that will
> further decrease the leakage current of the spark.
>
> It may be interesting to put a large series inductor inline with the cap
> too.  that would make the spark have a heavy RF content which may produce
> interesting results.
>
> You may also just try a metal pan and salt water to insure that the spark
> is very tiny in that case.  With some experimenting, I am sure you will be
> able to determine what is best for cool sparks.
>
> Cheers,
>
> Terry
>
> At 08:19 AM 8/6/2003 -0600, you wrote:
> >Original poster: Steven Roys <sroys@xxxxxxxx>
> >
> >
> >
> >---------- Forwarded message ----------
> >Date: Tue, 5 Aug 2003 09:35:41 -0700
> >From: Sean Taylor <sean.s.taylor@xxxxxxxxxxx>
> >To: High Voltage list <hvlist@xxxxxxxxxx>
> >Subject: Water sparks
> >
> >Hi all:
> >
> >A while back, there were several posts on the Tesla list about creeping
arc
> >discharges along water surface.  It was all started by a picture of the Z
> >machine at Sandia. Anyhow - I have been trying to do this, and first I
used
> >a 10 kV DC PS I had, and just depended on the filter cap for the
discharge
> >(bad idea, I know, but it was just a test) and it worked pretty well.  I
had
> >about 1 inchor so of arcs going out from the electrode (brass drawer
pull).
> >I recently just tried it again with a couple maxwell pusle caps, with
higher
> >voltage and more energy storage( 0.188 uF, ~15 kV) than the DC power
supply.
> >Results were quite disappointing though - only about 1/2" max creeping
> >discharge, but plenty of noise.  There were more arcs across the surface,
> >but not nearly the same length.  So, here's the question/my theory:  Are
the
> >Maxwell pulse caps too good, and the current dies out too quickly so the
> >arcs don't have time to form? Or is something else going on?
> >
> >Thanks for the help!
> >Sean Taylor
> >
> >
>
>