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Helium(?) gap test.



Hi All,
	I repeated my spark gap voltage test with helium from a balloon filling
kit sold at the party store today.  As Bill mentioned a few days ago, this
stuff is NOT pure helium.  It will allow contact burning.  I don't know
what the other gasses are but they do cause gap damage.  This gas also has
very different properties from the argon.  Instead of having a clean arc at
the gaps, it tends to have more of a plasma glow.  The losses are very
high.  Helium has a very high heat capacity that may account for the loss.
Since this gas is not pure I can't say too much as to how pure helium will
behave.  Also the leak rate of helium is very high which is not desirable
in my case.  For now, I think the welding grade of argon is the best gas to
use.  Helium may work but my admittedly flawed tests today suggest it may
have problems too.

Here are the gap voltages but don't take them too seriously since the gas
is contaminated.

Gap Width (mil)		Firing Voltage
4				550
8				620
12				850
16				920
20				1090
24				1200
28				1250


	Terry Fritz