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Re: [TCML] If He Starts Nodding Off, Try Another Million Volts - Vasodilation



On 10/8/12 2:16 PM, David Thomson wrote:
Hi Jim,

On Mon, Oct 8, 2012 at 2:41 PM, Jim Lux <jimlux@xxxxxxxxxxxxx> wrote:

On 10/8/12 11:56 AM, David Thomson wrote:

You guys need to be careful about prolonged exposure to Tesla coils.

http://www.ncbi.nlm.nih.gov/**pubmed/16875980<http://www.ncbi.nlm.nih.gov/pubmed/16875980>



That paper is about *ultrasound*, not RF or electromagnetic fields.


The paper is about ultrasound, which is a mechanical vibration.  The E
field of a Tesla coil is also a mechanical vibration when the air is
electrostatically charged.  If you are sensitive enough, you can feel the
electrostatic vibration of the air molecules.




The paper refers to power flux densities of >1 W/square centimeter. That's huge.

yes, an oscillatory electric field will move charged particles, but I don't think that's the case here. Consider the following back of the envelope calculation..

While there may be some ions floating around, in general, the net effect will be neutral (that is, there's as many positive as negative ions, so for a given instant of E-field polarity, half push towards and half push away). At atmospheric pressure, the mean free path is on the order of 100 nm.. that is, the moving ion will hit another air molecule after it's moved less than 100 nm.

But let's for the sake of argument assume there is a net charge positive or negative. I found some literature that says net ion densities of 2.7E6 ions/cm3 had some effect on Seasonal Affective Disorder (ion production is a more likely cause of any physiological or psychological effect from a tesla coil or plasma sphere by the way)

But, I'm not worried about the effect of the ions, per se, but what's a reasonable density.. (obviously, the air isn't glowing, so it's not all that high)..


So, let's take a cc of that ionized air and see what the force would be from a field of, say, 10kV/meter (a field that won't make the hair on your skin stand up, but is probably noticeable otherwise).

assume the ions have a charge of one electron, so we have F = qE...

q is the charge in coulombs (1 C = 6.24E18 electrons.) our cc of air has about 1E-12 coulombs charge
In a field of 1E4 V/m, the force is 1E-8 Newton.

Somehow, I don't think you can feel 1 E-8 Newton. Heck, if you had a whole liter of air (1000 cc) that would only bring it up to 1E-5N.



In any case, as previously mentioned, the energy density from the EM field is much too low to produce a sensible effect.



if you are noticing any physiological or psychological effects from plasma globes or tesla coils, I'd start looking for thermal effects (absorption of the EM field heating you up, as in diathermy treatment) or for the effects of net positive or negative ion concentrations (for which there is a fair amount of literature).

I could easily imagine a TC (or plasma globe, especially, since they use flyback supplies with a very asymmetric waveform) having incidental rectification and generating a surplus of positive or negative ions. The fact that they develop a surface charge and attract dust is ample evidence of this.


You might also have some direct nerve stimulation, or, more likely, the hairs on your skin are standing up and providing the stimulation (anyone who has been in close proximity to lightning strikes will know what this is.. or who's been charged in proximity to a Van deGraaff generator). But those are pretty strong fields.. I don't know what field is needed, but I'm going to guess in the tens of kV/meter are needed, maybe as much as a 100kV/meter (a fairly small VDG will get hair to stand on end, and the human probably has a radius of curvature around 10cm.. so the max voltage is going to be 300kV (at 3MV/meter), and you're nowhere near having corona off your head.. probably more like 10-15kV..





I can assure you from personal experience that the vasodilation does occur
from mechanical vibrations of the air.

Dave
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