Re: Surface Arcing Photo/man inside top electrode

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

Original poster: "boris petkovic by way of Terry Fritz <teslalist-at-qwest-dot-net>" <petkovic7-at-yahoo-dot-com>




 > I'm sure he's ok... although the ozone may have
 > affected his sanity.
 >
 > Regarding the magnetic field component, the website
 > mentions:
 > The currents in the top winding are about 50A peak
 > The # of turns per meter in the secondary is about
 > 200.
 >
 > The basic equation for a solenoidal field is:
 > B = 4pi*10^-7 * N/m * I
 >
 > which yields:
 >
 > B = 4pi*10^-7 * 200 * 50
 > B = 0.01256(tesla) = 126(gauss)
 >
 > 126G is not much of a field to start with, and the
 > conductive cage
 > of the sphere attenuates it considerably further
 > from there, given
 > the high frequency of the magnetic field.  An
 > attenuation of as little
 > as 44dB would bring it down to the Earth's field
 > level.

Greg,all,
One digression here.
Sinusoidal CW fields 1mT -at- 40 kHz in space,are already
within nerve stimulation zone for humans!
Refering just to a field strenght without frequency
range is meaningless.
Treshold of perception for CW fields at 60 kHz is
about
1 mT (0.001 T).
Having mentioned that,for 6000 Hz the threshold is
about 0.1 mT,and for 60 Hz the same is 2mT.
These are all rms values, bellow t. of any thermical
effect (and above some 100 khz there's no neural
response to SCW,given strong fields whatsoever.Only
perception of warmth if the fields are strong enough).
Concerning just thermical effects most disruptively
operated TCs generate too weak rms magnetic fields to
heat human tissue.
One might want to calculate current induced in human
body due to external magnetic field in order to
compare them with stimulation tresholds for given
frequency.For instance,where a human body linear low
conductivity piece of material,current density induced
at 60 kHz would be 1000X higher than at 60 hz (for
same B).
But here comes the problem .The body is far from being
linear in electrical therms.It is a coctail of various
tissues having various conductivities and
permeabilities depending on frequency.
For those who want to deal with models data in
JavaScipt form in interval 10 hz-10 ghz can be
displayed at
http://safeemf.iroe.fi.cnr.it/tissprop

To return to the orginal question:what is the cause
that Greg in Electrum didn't feel anything strange
(well except smell of ozone and its side effects
latter)?
Two things come to my mind:
1. TCs are impulsive,disruptivelly discharged devices
and I suppose (not being an expert in all this matter)
that stimulation via magnetic field in 40kHz-60 kHz
range is roughly proportional to rms value of field
taken over much longer interval of time that just
during TC duty cycle.
Judging by Electrum duty cycle,despite 10mT+ peaks an
effective rms value is well bellow 1 mT.
Thus no perception of magnetic field induction.

2.Second thing is presence of well conducting sphere.
The sphere silents average field level inside its
cavity(althought it doesn't completely eliminate it at
all),and acts kinda imperfect passive magnetic field
shield.

BTW,I recall sombody else on this list mentioned
standing in big coil while it was operating,and
experienced only external electrical fields effects
(hair,skin etc).


cheers,
Boris

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