[AMPS] Arcing in air vs. arcing in a vacuum

[Jon Ogden]

Hi all,

I got a question.  I had a discussion with a ham friend of mine on our 
way to Dayton this weekend.  We were talking about the *gas* theories in 
tubes and tube arcing.  His comment was that from his experience, he has 
determined that the voltage breakdown potential of a vacuum is LESS than 
that of the voltage breakdown potential in air.  He said that while doing 
some EMC testing of a product he has designed for his company, he found 
this to be the case.  He had to simulate lightning strikes at high 
altitude and thinner air.  The breakdown potential was much less at 
higher altitude (thinner air) than at the thicker air of sea level.  The 
arcs happened at less voltage at high altitude.  So he has made the 
conclusion that if the breakdown potential of thin air is less than 
regular air, the breakdown potential of a vacuum is less still.  I don't 
know if this jump can be made.

Can someone help explain this?  All my instincts tell me that a vacuum 
has the highest breakdown withstanding potential.  I seem to remember 
hearing once though that thin air ionizes easier than "thick" air so 
perhaps that explains it.

Thanks a lot.

73,

Jon
KE9NA


--------------------------------------------------------------------------
The Second Amendment is NOT about duck hunting!


Jon Ogden

jono@enteract.com
www.qsl.net/ke9na

"A life lived in fear is a life half lived."


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