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Re: streamer hit

Tesla List wrote:
> 
> Original Poster: Terry Fritz <terryf-at-verinet-dot-com>
> 
> Original Poster: Terry Fritz <terryf-at-verinet-dot-com>
> >snip
> >>
> >> 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
> 
> Wow! Sounds like a neat experiment to determine if the RF currents really
> are going through our internal organs and such (as opposed to the skin
> effect which suggest they just flow on the outer surface of the skin).
> However, It would be easier and cheaper to use clear Jello type gelatine
> with some salt added to simulate the human body rather than expensive meat
> (works fine for bullet testing).  The neon bulbs or LEDs would be very easy
> to see and it would be very easy to encase them uniformly in the Jello.  I
> always have wondered if RF currents arcing to our heads would pass through
> our brains??  If so, arcs to the head may not be a good idea!
> 
>         Terry :-)

Terry and all,

I've been reading the many interesting posts on this topic! Lots of
rather exotic methods of estimating the current distributions. However,
you can get a quick estimate of skin effect by using the operating
frequency of a typical operating Tesla Coil by using the permeability
and conductivity of sea water to model the EM inside of your body.

The bottom line: 
===============
At the relatively low operating frequencies used in Tesla Coils, there's
virtually NO "skin effect" at work - the effective "skin depth" of your
body is "deeper" than you are thick! For example, the RF current from a
100 kHz system has a "skin depth" of about 31 inches inside your body.
Unlike a good conductor, the current will NOT be confined only to the
outer surface of you body.

The fact that you may not "feel" the RF current (particularly from a CW
coil) does NOT mean that it won't do any physical damage - your nerves
are simply not responding to the RF current - sort of like being unable
to hear a damaging level of ultrasonic sound. Any current flowing
through your body (once it penetrates your skin), will be concentrated
through the best conducting portions of your body - your nervous and
circulatory systems. And make no mistake, excessive/prolonged current
flow can result in temporary or long-term nerve or organ damage. 

Worse yet, if you happen to be grounded through an accidental flashover
to some other part of your body (toes, elbows or kneecaps...), the
discharge from a fully-charged topload and coil self-C is actually a
direct current capacitor discharge through your body. Taking a "hit"
from a multi-Joule coil will most definately "smart"... a hit from a
larger system can kill! Ao, don't buy into the old skin effect folklore,
guys - it ain't true!!

And, SAFE coilin' to you!

-- Bert --