Re: cryogenic spark gap?

To: "'Tesla List'" <tesla-at-poodle.pupman-dot-com>
Subject: Re: cryogenic spark gap?
From: Tesla List <tesla-at-stic-dot-net>
Date: Thu, 6 Nov 1997 21:43:41 -0600
Approved: tesla-at-stic-dot-net

From: 	Robert W. Stephens[SMTP:rwstephens-at-headwaters-dot-com]
Reply To: 	rwstephens-at-headwaters-dot-com
Sent: 	Thursday, November 06, 1997 8:18 PM
To: 	Tesla List
Subject: 	Re: cryogenic spark gap?

> 
> From: 	David Huffman[SMTP:huffman-at-FNAL.GOV]
> Sent: 	Wednesday, November 05, 1997 8:33 AM
> To: 	Tesla List
> Subject: 	cryogenic spark gap?
> 
> Has anyone ever tried putting a spark gap in LN2?
> D. Huffman
> 
Dave,

I don't have my cryo reference books handy but I recall LN2 expands 
something like 700 or 1000 times in volume going from liquid to gas state.  By 
pumping real energy through your gap, this phase change would be 
inevitable.  I'm afraid you'd have a dangerous explosion situation.
There is an undesireable condition which can occur within certain 
cryo dewars employed to store liquid gasses at near room pressure.  
Something is placed at the bottom of the dewar like a dab of vacuum 
grease to form a continuous string of rising gas bubbles.  If this is not employed 
the entire volume of liquified gas, LN2 for example can spontaneously go from a 
liquid to gas state causing that undesired explosion effect.  Imagine 
a gallon of LN2 converting instantaneously to gas state.  Your lab 
would look like the Federal Building at Oklahoma.

rwstephens