Re: Spark Gap Gasses Experiment

Terry Fritz wrote:

>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.

Interesting.  I wonder if perhaps the purpose of the airflow is to cool 
the metallic faces to keep hot "cathode spots" from forming.  Once a hot 
spot would form, the breakdown voltage would be greatly reduced (just my 
guess) since the hot spot would then be maintained via metallic arc 
(since all the energy would continue to flow through that location).  
This operation is opposed to the conventional wisdom that the air blast 
interrupts the damped waveform (which, according to Terry's 
measurements, is not the case)...

Comments anyone?  Let the flaming (or arcing) begin! :)

>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.

A good measurement.  It's always fun to see an "inert" gas change the 
breakdown potential so dramatically.  Note that "Inert" does not imply 
"Difficult to ionize"!

Does anyone think that a gap run entirely under argon (probably fan 
circulated) would have any advantages over the traditional air-cooled 
units?  I would think the corrosion problem would be 
reduced/eliminated...  I'd always wanted to try this but never did!

Thank you, Terry, for some intriguing measurements,

-Bill the arcstarter
Starting arcs in Cinci, OH

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