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Re: streamer hit



Tesla List wrote:

> Original Poster: "Gregory R. Hunter" <ghunter-at-enterprise-dot-net>
>
> As a teen, I tinkered with two or three little table top coils powered by
> automobile ignition coils.  Power input was under 100 Watts.  The little
> coils probably ran at rather high frequency due to the small secondary
> diameter and short winding length.  They gave a bright purple brush
> discharge and I often drew sparks off them up to 3 or 4 inches with a metal
> object (key, metal ruler, etc.).  I repeated this act at least 100 times
> over the course of a year or two with no I'll effects now or then (I'm 36).
>
> In 1983 I was bitten by a 10 Watt UHF transceiver I was bench testing.  My
> knuckle happened to brush against the shell of a coax connector on a faulty
> cable while the transmitter was keyed.  It felt like a bee sting--raised a
> small blister too!  This incident permanently colored my attitude about RF
> shock, (and about electricity in general) and I've had little desire to be
> within striking range of an operating Tesla coil ever since.
>
> Greg
>
> ----------
> From:   Tesla List[SMTP:tesla-at-pupman-dot-com]
> Sent:   Friday, November 13, 1998 7:01 PM
> To:     tesla-at-pupman-dot-com
> Subject:        RE: streamer hit
>
> Original Poster: "Coiler" <mycroft-at-access1-dot-net>
>
> Terry: I am not certain it was due to my coil.. but I wonder.
> I am an apherisis donor.. so I get a hand workout every two weeks, for
> 90 minutes I sqeeze a ball to force the blood into the machine. When
> I was fooling around taking hits from my 360VA 3.5" coil, I would have
> pain in my joints during the donation. Now that I am running at 1.4KVA
> (and soon to move up to 3KVA or more ) I don't go near the coil. I also
> don't have the pain in my hands during my donation.
> The pain was localized to the joints.
> Was it the coil? Dunno. But I don't intend to be a target anymore anyway.
> I have my requisite RF scar on the back of one hand to remind me. (another
> story)
>
> Michael Baumann
> Coiler, Homebrewer, Nerd. mycroft-at-access1-dot-net
>
>
> > -----Original Message-----
> > From: Tesla List [mailto:tesla-at-pupman-dot-com]
> > Sent: Thursday, November 12, 1998 4:44 PM
> > To: tesla-at-pupman-dot-com
> > Subject: Re: streamer hit
> >
> >
> > Original Poster: Terry Fritz <terryf-at-verinet-dot-com>
> >
> > At 10:51 PM 11/11/98 -0600, you wrote:
> > >Tesla List wrote:
> > >snip>
> > >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 --
> > >
> > >
> >
> > Thanks Bert,
> >
> >       I had heard the skin effect stuff for so long I really
> > didn't question it
> > till recently.  I think you pretty much hit everything right on the head.
> > I never was a big fan of getting shocked or taking arcs.  The fact that
> > these high frequency currents travel through ones guts and all is pretty
> > important to understand.  Just like X-rays, we need to know as much about
> > our risks as possible.  Large coils are pretty ominous when operating and
> > not too many people run TOWARD them :-))  Smaller coils don't have the
> > freight factor to keep us away and we need to be aware of what they are
> > doing to those of use who like to "play" with the arcs.
> >       It would be interesting to know is anyone has noticed any long term
> > affects of arcs through the body aside from the obvious burns and the
> > mentioned short term tingling muscles?
> >
> >       Terry

This thread started a separate communication between myself and Kristian
Ukkonnen concerning the E field and RF generated from an operating TC. My
assertion was that although you could shield the electromagnetic radiation
from an operating x-ray tube it would be difficult to shield the observer from
the RF of a TC. My conclusion was that the best possible protection would be
the use of the inverse square law (field intensity diminishes as the square of
the distance.) Kristian countered (and prbably rightly so!) that the ground
plane transmission is probably more significant than the air transmission and
therefore the decrease is linear rather than quadratic.

This raises the question: Is there any way to shield the body from the ground
plane RF field? Would non-conductive sole boots be of any use or would they
merely act like capacitors and light up the whole body? Any takers? I know
that some you you guys are RF guru's, what do you think?

My experience with RF is limited to the radiobiological effects and I don't
have the savvy to make the kind of prediction about the ground plane
transmission that this would require.

Kristian suggested that the effects experienced by Michael may have been
associated with noxious gasses such as O3 (ozone) or NOX's, which might be
possible, however I think the gasses are more commonly related to lung damage
and less commonly to the neurological effects like numbness, pain or tingling.
These findings are common with RF exposure and even with high intensity E
fields. Everybody knows about the hazards of x-rays, but it's because of the
hundreds of tragedies which occured in the early part of this century. Let's
not let that happen in the TC arena. Keep a healthy respect for the power in
you hands or it will burn you.

A note of caution is probably in order to all coilers; in radiology, we keep
everybody clear of the field. We use multiple layers of shielding if we have
to be in the room. If distance is your only protection from RF, it's wise to
get a lot of it. I'll defer the effectiveness about insulated lineman's boots
to others with that understanding, but I will be waiting for the answer
myself.

Bryan Kaufman, MD, MS
Radiologist