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| Paschen's law - spark gap distance at high pressures |
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| honeybadger:
Hi, I "need" to know breakdown voltage of air at 8 bar pressure. I spent 2 hour of googling and found nothing. I just need a simple graph of "air breakdown voltage VS air pressure". There is a lot of these charts: https://en.wikipedia.org/wiki/Paschen's_law#/media/File:Paschen_curves.svg I don't understand them... vertical scale is in "V" , not "V/m". And then there is the Paschen's law... can anybody understand that? Where can I find all these constants? |
| mikerj:
Check the horizontal scale pd i.e. pressure multiplied by electrode separation. |
| honeybadger:
mikerj: thanks, it makes sense now. So if "pd = pressure x electrode gap" remains constant -> this means breakdown voltage must remain constant. Twice the pressure -> 1/2 electrode gap = same breakdown voltage. Is it really this simple? :palm: If at 1 bar (absolute) I need 3kV per mm -> at 10 bar (absolute) I would need 3kV per 0.1mm, which is 30kV/mm. Am I correct? |
| floobydust:
I thought Paschen's law is more about the non-linearities on the low end (low pressures, very small µm gaps) but larger gaps/higher pressures behave more linearly. 8 bar is around 116 PSI or close to automotive compression stroke pressure. You can see this on sparkplug testers that take shop compressed air and apply that to a chamber with a sparkplug mounted in it. 1mm spark gap is around 30kV, although turbulence, electrode geometry, ozone, polarity matter. |
| Le_Bassiste:
fyi, http://home.earthlink.net/~jimlux/hv/hvmain.htm especially, http://home.earthlink.net/~jimlux/hv/paschen.htm |
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