Re: SSTC Dangers - E Fields / Radiation

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>

Hi Dan,

At 06:38 PM 6/11/2003 -0400, you wrote:
>I know this has been discussed before, but the question really was never
>assessed too well or answered.
>
>First the Facts:
>
>All of us who built SSTC coils know the field generated by them is very
>strong, easily producing RF currents on anything metallic in the vicinity
>producing strong RF burns when contacting
>any of these metallic objects.
>
>Now the questions . . .
>
>1.  Is the RF field generated by SSTCs much stronger (power for power) than
>conventional tesla coils???  It would seem so, but then again, maybe we feel
>safer around SSTCs and will more
>readily approach them (closer) than when running similarily sized
>conventional coils.

I have a 900 watt conventional coil and a 900 watt CW coil.  The disruptive 
coil packs a much larger punch but only has a 5% duty cycle.  Basically, 
they are both "just" 900 watts...  The CW coil has far lower voltages but 
20 times the duty cycle...  My guess would be to consider them the same for 
such purposes...



>2.  How dangerous is this RF field??  If I can get scorching RF burns from
>objects up to five feet away from my SSTC running (CW) mode, then the RF
>field must be hazardous.  The question is,
>how hazardous.  Will prolonged exposure (say a few minutes once a week
>around these things cause significant tissue damage / cancer / etc...) over
>a few years  ? ? ?

If it hurts, that is getting to be too much.  You should avoid getting 
burned or directly hurt in all cases.  I know there are all kinds of odd 
claims about RF field exposure, but none are made by people that really 
know about RF fields ;-))  Like alpha radiation, the fields stop at the 
surface of the skin...  If you want to live longer, eat right, excercise, 
don't smoke, don't drink, fasten you seat belt....  But limiting you 
exposure to the RF fields of Tesla coils is going to do zero to extend you 
life...  One does not want to stand in front of a high power radar or tan 
in a microwave oven, but the dangers of RF field exposer from TC's is about 
zero.  If you have a pacemaker or something, that's different...


>3.  Nature of the RF field?  What exactly is the nature of this RF field?
>The resonant frequency of the SSTC maybe around 150kHz to 300kHz, but is
>this the predominant RF generated by the coil, or are the other higher
>harmonics (way up into the MHz and beyond) created by the SSTC a large
>factor in this field and thereby more dangerous?

High voltage gradient E-fields with little real power behind them.  The 
fields "die" at the surface of a conductor like skin.  Robert reports no 
damage after 25 years and his exposure is about 1000000++X that of a casual 
bystander:

http://www.krampf-dot-com/p_images/fp_ele_sparks.jpg

BTW - Don't try this!!  Robert knows what his is doing ;-))

There is some pulse >1MHz noise but nothing that would do damage.


>4.  I did attempt to measure my coil using a NARDA RF sniffer, but the probe
>end was geared more towards 300MHz up into the GHz range.  HOWEVER, at about
>6 feet distance I was getting number of 25-45 mW/cm^2 which to me is a lot.
>However, this number was bounching around a bit, so I'm not sure if the
>field was interfering with the probe.  But you would think the probe was
>designed to withstand fields like this during measurement !

The poor little probe does not stand a chance ;-))  It was just spazing out 
from the noise.



>SSTCs are relatively a new thing on the block in the tesla community.  And
>from just the proximity effects I'm witnessing (hair standing up, strong RF
>burns off nearby objects, etc...) makes me think
>these might be much more dangerous (in the terms of RF fields generated),
>than conventional coils.  I think we really need to look into this much more
>carefully.

Think of it as a ~300kHz RF transmitter and start from there.  At close 
range, that is about what you have and there should really be "real" 
information on that.  However, the field current is far far weaker and I 
think the RF current does the real damage.  The current (NOT the voltage) 
is what get's "into" you.  That current is small...  What you really need 
to do is measure the current flowing in the body when standing close to the 
coil.  The voltage just does not count.

Cheers,

         Terry


>Any thoughts or comments ? ? ?
>
>The Captain