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Re: streamer hit

Tesla List wrote:
> 
> Original Poster: Terry Fritz <terryf-at-verinet-dot-com>
> 
> At 10:31 AM 11/11/98 -0600, you wrote:
> snip>
> >Hi,
> >
> > I personally don't know what 80+ sparks feel like hitting your hand.
> >But I can say that I have held my hand up to my coil and it gives off
> >~3 foot streamers. It isn't really painful but it makes your muscles
> >contract and feel really weird. By the way if anyone is wondering I did
> >have myself insulated from ground and drew the sparks to me by using a
> >12 inch copper pipe.
> >
> >Chris
> >
> >
> 
> I always wanted to do this experiment but never got around to it.  I would
> like to take a thick piece of meat, like ham, and put neon bulbs or leds
> inside it with their leads along the current path.  This should indicate
> the currents in the interior of the meat (I would make little holes so I
> could see the lights).  This would indicate if the Tesla coil currents flow
> on the outside of ones body or uniformaly throughout the body.  Perhaps
> someone already has done this or knows the answer??
> 
>         Terry

The distribution of RF current in a field is a subject of some
considerable interest to those in the antenna business, as well as in
the RF safety area. There is a huge amount of literature on the
penetration of RF into resistive conducting bodies. You could take any
of the Finite Element EM modeling programs (some are shareware, so
relatively inexpensive, though slow) and model this quite easily.

Alternately, if you have a mathmatical bent, you could assume that your
arm (or the equivalent) is a cylinder of uniform characteristics, and do
an analytical solution of Maxwell's equations. For what it is worth, the
current penetrates according to the magnetic permeability (i would
assume free space) and resistivity, and has a distribution as a Bessel
function. For a very large diameter cylinder and shallow penetration,
you could assume it is a flat plate (that happens to be in the form of a
cylinder) and the penetration would be exponential (classic skin depth
equation) However, as the skin depth (defined as the penetration to
current being 1/2.71828 on a flat infinite surface) gets to be a
significant fraction of the diameter, the distribution is more of a
Bessel function, for which there isn't a simple expresssion.  Hence
those tables of skin depth vs frequency and wire diameter.

If you start to assume a non homogenous body (i.e. bone and blood
vessels) then the modelling becomes substatially more complex.

Try the neon bulbs in a roast approach... (although, the wire in the
bulbs may perturb the field)
-- 
Jim Lux                               Jet Propulsion Laboratory
ofc: 818/354-2075     114-B16         Mail Stop 161-213
lab: 818/354-2954     161-110         4800 Oak Grove Drive
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