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Spark Gap Gasses Experiment
Hi All,
I was working with my primary circuit today and a simple static gap. I
was blowing different gases across the gap to see what would happen. The
results were very interesting. The scope photos of the primary voltage
ringdown with various gasses are at:
www.peakpeak-dot-com/~terryf/tesla/misc/
The scope was hooked across the primary cap with a fiber-optic high voltage
probe. The variac setting, gap width, etc. were all the same for each
picture. Only the gas flowing into the gap was different. The scale is
2kV/div in all photos.
gapair.jpg and gapair1.jpg - These photos show the ringdown with just air
flowing into the gap. I did not see much difference with and without air
flow. The firing voltage was about 4000 volts and the gap rang down in
about 150uS.
gapar.jpg - With argon flowing into the gap, the change was dramatic! The
firing voltage dropped to about 2200 volts. The arc actually moved
aggressively toward the gas flow. Apparently argon reduces the firing
voltage to about 1/2 what it is in air.
gapdg.jpg and gapdg1.jpg - The gas is 1,1,1,2-Tetrafluoroethane which is
the environmentally safe gas used in Beseler dust of cans used to blow dust
off photographic equipment. Basically a freon type gas.
!!! NOTE!!! This gas produces extremely TOXIC gases when exposed to an
electric arc. I had fans and lots of fresh air and only fired the gap long
enough to get the photos. Do not repeat this experiment yourself or use
this gas in a real coil.!!!
With this gas, the firing voltage increased to around 5000 volts. The arc
itself became smaller and looked more efficient. The scope pictures show
that the primary rang for about 350us with this gas (the time was longer
due to the higher voltage also).
gapexp.jpg - shows the setup of the equipment.
I am not sure this is real useful but it is interesting none the less.
Terry Fritz