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Argon Gap Voltages and progress

Hi All,

	I set up a test argon gap with various gap widths and tested it for
breakdown voltage.  The gap had no forced cooling.  I spaced the gaps with
pieces of 4.0 mil paper to get gaps that were 4, 8, 12, 16, 20, 24 and 28
mil.  I put it in a plastic bag with leads and filled the bag with argon.
The temperature was ~75F and I live at 5300 feet above sea level.  There
was some jitter and the gaps were not perfectly spaced but I took three
readings at each level with a calibrated fiber optic probe.  The firing
frequency was 120 BPS and I let it run for few seconds before it took the
readings.  The gaps were connected to a primary cap and inductor but there
was no secondary present.  The gap was made from 3 inch long sections of
3/4 inch copper pipe glued to a board.  The actual firing voltage was
measured with the scope cursor.  The voltages were as follows:

Gap Width	Voltage
4		530
8		700
12		800
16		980
20		1130
24		1210
28		1360

Since I want an 800 volt breakdown, I will use 12 mil gaps for my argon gap.

I then tapped the inductor to a much lower value to increase the gap
current and cranked up the power.  I let it run for a few minutes.  It
seemed like the small gap sections heated up just as much as the large gap
sections which would suggest that the gaps dissipate the same amount of
heat regardless of the gap width.  The gap was quite beautiful.  The argon
has a turquoise glow and was really neat to watch cooking away.

After the hard run, I removed the gap from the bag and examined it for
wear.  The gaps showed zero signs for burning or fouling.  The surfaces had
a dull copper appearance but they were pure clean copper.  In fact they
appeared much cleaner than the original slightly oxidized surfaces.
Apparently, the arc is hot enough to melt the copper but the copper
redeposits back onto the surfaces.

All in all, a very successful experiment! 


The gap work is going very well.

Argon may not be the best gas to use but the chamber can easily be filled
with any gas or a combination of gasses.  I definitely want to stay away
from toxic and flammable gases.  Too dangerous if many others follow in my
foot steps (or craters :-))  Since I have lots of argon around the house,
it is my first choice.  I'll snap digital photos and such of my testing and
make a report for the group on what happens.

The cost is:

Glass $35 (I let the glass shop cut all the pieces to size) 
Copper $10  (20 feet of 3/4 inch copper pipe)
Silicon Sealant $5
Powerful Fan $75  (new)
Gas  $2  (lots of purging)
Misc. stuff $3  (bits of wood, copper straps, line cord)

For a total of $130.  Not bad for a real nice gap.  The expensive fan is
probably overkill but if this doesn't work, I have other plans for it. 

The fun continues.....

	Terry Fritz