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

[G Hunter <dogbrain_39560@xxxxxxxxx>]

> From: Bill Noble <william_b_noble@xxxxxxx>
> 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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