[TCML] Would a Tesla coil work in a vaccum?
yurtle_t at yahoo.com
Mon Apr 19 04:22:43 MDT 2010
As to your camera not matching what you see, I'm assuming you're using a digital camera. Digital cameras often have trouble with colors if the light source isn't incandescent or the sun. Most digital cameras have trouble with fluorescent, mercury, or sodium vapor lamps. They usually have a setting for one or more of these under "white balance" or you can set them manually with something white. You can also save the photos in raw mode and correct them in Photoshop.
--- On Sat, 4/17/10, Scott Bogard <sdbogard at gmail.com> wrote:
> From: Scott Bogard <sdbogard at gmail.com>
> Subject: Re: [TCML] Would a Tesla coil work in a vaccum?
> To: "Tesla Coil Mailing List" <tesla at pupman.com>
> Date: Saturday, April 17, 2010, 8:51 PM
> Hi Greg,
> I can chime in here, the color of discharge
> is greatly effected by the humidity and particulate content
> of the air, as well as current density of the arc.
> Allow me to explain the basic mechanics by which sparks make
> light, the atoms in the air are floating around with all
> their electrons in their lowest orbital states, when they
> are energized (by heat like with fire, or in this case raw
> electricity) the outer electrons shift orbitals to a higher
> energy level. When they lose that energy (which they
> inevitably do) the electrons come back down to where they
> belong and emit a photon of an exact frequency.
> Different elements emit different frequencies based on
> energy input (hotter fire, or more current.) Dirt in
> the air will burn encouraging a more orange color (maybe)
> and humidity will favor a more blue color (probably.)
> Another very interesting thing to note, is that fire is
> orange because of the ionized carbon/wood/smoke in it, and
> if you use high enough current you can ionize and vaporize
> the metal electrodes (aluminum makes a brilliant aqua blue,
> and lead solder is dark blue (use ventilation...))
> Your grounded arcs have higher current and so the electrons
> shift higher and the result is brighter. Your Jacob's
> ladder arc is billowy and thick because high current and
> high "on time" (most of the time the tesla coil arc is off,
> so the current stays in a thin bright streamer and does not
> have time to spread, if you take an instantaneous picture of
> a Jacob's arc ladder forming it is also a narrow bright
> channel, which almost immediately spreads out to allow
> greater current.) This is also why some tube and solid
> state coil sparks are thick and bushy, they have a higher
> duty cycle than a disruptive TC so the arc has time to
> grow. As for photographs the
> difference is because the camera isn't sensitive to all the
> frequencies the human eye is, and since sparks emit definite
> frequencies instead of a broad band like sunlight, if the
> camera isn't sensitive to one it looks wrong. I
> explain this a bit here on my Plasma globe webpage.
> Scott Bogard.
> G Hunter wrote:
> > 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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> > Tesla at pupman.com
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