[AMPS] Another arc question

[Rich Measures]

>OK, 
>
>Thanks to those who responded to my seemingly dumb question about why no 
>carbonization marks exist around tubes which supposedly had an arc-over 
>in them.  Specifically this is in regards to the bent filament helix 
>phenomena in the 3-500Z's.
>
>So here's a follow up question:
>
>Several people pointed out that you wouldn't get carbon scoring from an 
>arc because the tube is evacuated and therefore there is nothing that 
>would cause carbonization (OK, maybe that's not the scientific 
>explanation, but you know what I mean).  

--  i.e., arc cratering does not involve carbon.  

>However, if there were no gas of 
>any kind inside the tube, then how did the arc occur?  Doesn't an arc 
>occur when the voltage potential across a gas is so large that the 
>molecules in the gas break down, turn into a plasma and thereby creat a 
>low resistance path for current to flow?  

electrons are temporarily ripped off.

>If there is no gas then why is 
>one theory called the Gas Discharge Theory or whatever?  If there IS some 
>sort of gas, then isn't it possible that carbonization could occur due to 
>the arc?  Or is it the wrong type of gas (ie:  needs to contain carbon)?
>
Oxygen gas and/or  nitrogen gas become conductors when enough potential 
gradient exists to free their electrons.  In a partial vacuum, relatively 
low potentials are needed to accomplish this and create an arc.  
>........

cheers
Rich...

R. L. Measures, 805-386-3734, AG6K   


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