Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: taregg on 20/01/2012 14:02:55

Title: which gas has the higher breakdown voltage helium or oxygen ?
Post by: taregg on 20/01/2012 14:02:55

for light tube gas discharge

Title: Re: which gas has the higher breakdown voltage helium or oxygen ?
Post by: taregg on 21/01/2012 07:17:18

can you answer  quickly

Title: Re: which gas has the higher breakdown voltage helium or oxygen ?
Post by: Bored chemist on 21/01/2012 17:40:00

It depends
http://en.wikipedia.org/wiki/Paschen's_law

Title: Re: which gas has the higher breakdown voltage helium or oxygen ?
Post by: taregg on 23/01/2012 09:31:07

‏  can you explain depends of what.......

Title: Re: which gas has the higher breakdown voltage helium or oxygen ?
Post by: CliffordK on 23/01/2012 09:54:57

If you look at the graph from the Wikipedia that BC gave.

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2Fthumb%2F8%2F82%2FPaschen_Curves.PNG%2F601px-Paschen_Curves.PNG&hash=8a55f4b8ab49cd047edfd13ba0f1a1d4)

O₂ is not listed. 
However, compare the curves for N₂ and He.

The X axis of the graph shows a product of the (pressure * distance) separating the electrode plates.

For all higher pressures and wider gaps, Helium hits the bottom of the list.  I.E.  The lowest breakdown voltage.

However, there is a point with low pressures and narrow gaps, that Helium performs better than most other gases, except for Hydrogen.

Title: Re: which gas has the higher breakdown voltage helium or oxygen ?
Post by: taregg on 23/01/2012 21:09:39

what makes elements of gases low or high  break down voltage from same of atom structure...

Title: Re: which gas has the higher breakdown voltage helium or oxygen ?
Post by: CliffordK on 23/01/2012 22:40:06

BC will have to give a better answer.

It appears as if the chart on the left side is dominated by atomic/molecular size.

On the right, it appears to be dominated more by electronegative, and "free" electrons, but I would need more data to confirm.  Surprisingly the Helium which is one of the least electronegative elements is at the bottom of the graph.

I would be curious about more gases, chlorine, fluorine, oxygen, methane, and etc.