# Re: Minimum arc voltage of air was: Definitions of High Voltage

```Original poster: "Jolyon Vater Cox by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>

Surely this has a potential application the chemical analysis of gases,
doesn't it?
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, October 05, 2002 12:26 AM
Subject: Re: Minimum arc voltage of air was: Definitions of High Voltage

> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Kidd6488-at-aol-dot-com>
>
> Somebody should try this.  You could rig up some fine thread bolts as
> electrodes, and hook up a variac with a DMM to a 12kV neon (12kV units are
> 1:100) and feed it 34.00 volts. I may try this, but not for a little
while.
>
> ---------------------------------------
> Jonathon Reinhart
> hot-streamer-dot-com/jonathon
>
> >
> > >
> > > Interesting is the fact that bellow 300-400 V in a
> > > very narrow gap there is still no gas discharge before
> > > metal to metal touch (standard atm. conditions).
> >
> > Yes, it is interesting. North states that 340 is the "absolute minimum"
> > (in air), therefore, anything below this value should not arc a gap
> > regardless of eletrode size, shape, gap distance, or barometric
> > pressure. He goes on to say that breakdown voltage decreases as pressure
> > decreases until the 340V minimum is reached, due to the fact that as the
> > melocular density of air is reduced, there is greater likelihood that a
> > free ion can traverse the space between electrodes without running into
> > something. But (here's the thing), as pressure is further reduced, the
> > required voltage for breakdown increases once again because a more
> > limited number of air molecules make ionization more difficult. So, we
> > have a dip and it's value is 340V. Thus, it's the physical makeup of air
> > and pressure that give us this minimum voltage.
> >
> > Take care,
> > Bart
>
>
>
>
>

```