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

[mddeming@xxxxxxx]

Hi Greg,

If the air were perfectly homogeneous, and the temperature, pressure, and humidity in each case were identical, then, if the potential, frequency, and current of every discharge were identical, the colors would all be the same. The color perceived depends upon the energy of the photons, which are emitted when the electrons bound to the atoms of the ionized gases return to lower energy levels, strike the retina of the eye. The color perceived in a photograph depends on the energy of the photons from the light source which are reflected from the photograph. Since the distribution of energies in the photons emitted from the arcs and streamers in not the same as the energies of those falling on, and reflected from the photo, the colors perceived will not be identical.  To answer your last question, a free electron is emitting no energy and thus has no intrinsic "color".

Matt D.






-----Original Message-----
From: G Hunter <dogbrain_39560@xxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Sat, Apr 17, 2010 3:48 pm
Subject: Re: [TCML] Would a Tesla coil work in a vaccum?


> 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, 
iddle-aged brain.  For example, why are Tesla coil sparks the color they are?  
resumably, ionized air contributes the color.  But if that's all there is to 
t, why aren't all TC sparks the same color?  Even in my own coils, I've 
bserved discharges of violet, violet-white, purple, blue, and various shades of 
lue-white.  Likewise, Jacob's ladder sparks are orange and flaming, while TC 
park gap sparks are intense blue-white.  How can an ionized 80/20 
itrogen/Oxygen mix at 1 atm glow at so many different colors?  Is it just a 
atter of temperature?  What about impurities?  I suppose the JL uprights might 
ontribute metal ions and metal vapor, which could explain the dramatic color 
ifference.
Oddly, what the camera sees and what I see don't always agree.  Sparks that look 
lue-white to me may render as violet in photographs, or vice-versa.  This is 
roubling as my cameras and I tend to agree very well on the colors of other 
ubjects.  Why the disagreement on the color of TC discharges?
Regarding the ultra-high vacuum situation:  what about a thermionic electron 
ube?  Is a visible discharge inside such a tube possible?  I'm assuming the 
nswer is "no", but what about a very high current through a hard vacuum?  Still 
nvisible?  I guess I'm just fishing around for an answer to the ultimate 
uestion:  What color is an electron???
Greg

     
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