[TCML] Would a Tesla coil work in a vaccum?

[Bill Noble]

crawling WAAAY out on a limb here - I would speculate that spark color is 
based on what gas gets ionized and to what level it gets ionized - so spark 
energy can make a difference, as can moisture

I would further speculate that if you looked at the spectra of nitrogen, 
oxygen and CO2, you might find most of the colors you see

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From: "G Hunter" <dogbrain_39560 at yahoo.com>
Sent: Saturday, April 17, 2010 12:48 PM
To: "Tesla Coil Mailing List" <tesla at pupman.com>
Subject: Re: [TCML] Would a Tesla coil work in a vaccum?

>> From: Bill Noble <william_b_noble at msn.com>
>> sparks can  only be visible when
>> there is matter in the intervening space to be
>> ionized.  In a perfect vacuum, there would be no
>> visible sparks or plasma
>>
>> --------------------------------------------------
>
> Hi Bill,
>
> Interesting stuff, which raised still more questions in my slowly 
> calcifying, middle-aged brain.  For example, why are Tesla coil sparks the 
> color they are?  Presumably, ionized air contributes the color.  But if 
> that's all there is to it, why aren't all TC sparks the same color?  Even 
> in my own coils, I've observed discharges of violet, violet-white, purple, 
> blue, and various shades of blue-white.  Likewise, Jacob's ladder sparks 
> are orange and flaming, while TC spark gap sparks are intense blue-white. 
> How can an ionized 80/20 Nitrogen/Oxygen mix at 1 atm glow at so many 
> different colors?  Is it just a matter of temperature?  What about 
> impurities?  I suppose the JL uprights might contribute metal ions and 
> metal vapor, which could explain the dramatic color difference.
>
> Oddly, what the camera sees and what I see don't always agree.  Sparks 
> that look blue-white to me may render as violet in photographs, or 
> vice-versa.  This is troubling as my cameras and I tend to agree very well 
> on the colors of other subjects.  Why the disagreement on the color of TC 
> discharges?
>
> Regarding the ultra-high vacuum situation:  what about a thermionic 
> electron tube?  Is a visible discharge inside such a tube possible?  I'm 
> assuming the answer is "no", but what about a very high current through a 
> hard vacuum?  Still invisible?  I guess I'm just fishing around for an 
> answer to the ultimate question:  What color is an electron???
>
> Greg
>
>
>
>
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