Re: SSTC Dangers - E Fields / Radiation

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

Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

 >
 > 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.

Probably a "peak/average" issue comes into play... They're both about the
same when it comes to wallplug watts in, to watts out...
The other issue is how many watts going to heating air (i.e. making sparks)
and how many watts get radiated

 >
 > 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  ? ? ?

RF field safety limits are well known, particularly for low frequencies...
Check the archives.. The main risks at low frequencies are heating, burns,
and shocks.  As for "athermal" effects..


 >
 > 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?

Higher frequencies might radiate better, so the field at some distance might
have accentuated harmonics...   However, even if you look at the 10th
harmonic of a 300 kHz coil, it's still only 3 MHz..

 >
 > 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 !

You're very much in the near field, so an isotropic radiator approximation
isn't really valid, but... 50 mW/cm^2 over a 2 meter radius sphere (4 * pi *
200^2 = 500,000 cm^2) is about 25 kW...
 >
 > 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.
 >
 > Any thoughts or comments ? ? ?
 >
 > The Captain
 >
 >