Re: Illegal?

To: tesla-at-pupman-dot-com
Subject: Re: Illegal?
From: Richard Hull <hullr-at-whitlock-dot-com>
Date: Fri, 20 Sep 1996 10:39:19 -0700
Tesla List wrote:
> 
> >From pjp-at-compulink.grThu Sep 19 22:33:21 1996
> Date: Thu, 19 Sep 1996 16:50:40 -0700
> From: "Peter J. Papadopoulos" <pjp-at-compulink.gr>
> To: tesla-at-pupman-dot-com
> Subject: Re: Illegal?
> 
> Tesla List wrote:
> > Most of the magnetic field
> > associated with The tesla coil is pretty low. (milligauss)  The "E" field
> > can be quite high (megavolts/meter) and again, a special meter is
> > required to determine this accurately.  There is lotsa' stuff goin' on
> > around a TC running at full tilt.  If it even slightly concerns you,
> > forget Tesla coils and turn on the TV.
> >
> > Richard Hull, TCBOR
> 
> Just to clarify this.
>         EMF =
>          ElectroMagnetic Field and
>          ElectroMotive Force (electric potential)
>         ELF = Extremely Low Frequency (0-300 Hz)
>         EF = Electric Field (the 'E' field)
>         MF = Magnetic Field (the 'M' field)
> 
> I would agree for the EF. It may reach MV/meter.
> I would disagree for the MF. Discharging a capacitor in msec produces high currents,
> and high MF (for msecs). I would like discussion on this.
> 
> Peter.

Peter,

The average really giant Tesla coil (10KW)  might see 500 amps of peak 
current in a 6 turn primary.  This system would, therefore, have a pulsed 
magnetic field strength at the rather widely spaced primary turns of 3000 
amp turns.  This is not a very heavy magnetic field in air u=1 and would 
rapidly fall off in intensity. (simple relay solenoids and motor 
armatures often have this intensity)  About 25% of this magnetic energy 
is coupled and consumed by the secondary.  About another 15% is lost in 
the ground and nearby metallic items.  Most folks when in the vicinity of 
such a coil are a minimum of 15 feet away.  (more like 20')  The magnetic 
fields at these distances are back down in the 1g-100mg range. These 
magnetic pulses are in the 500hz rep rate range. 

 I am much more interested in the rather intense E fields, which are 
still quite high at these ranges.  The peak pulsed power of such a system 
can be in the 10-20 megawatt range.  A small coil of 12" diameter with 
100 turns at 15 feet from my 7KW system gives a .3 volt AC signal due to 
coupled 500 hz magnetic energy (verified by 90 degree rotation). A 12" 
diameter aluminum plate shows a 12KV DC potential in seconds 
(electrostatic voltmeter) and a 1/2" continuos RF AC arc can be drawn to 
ground!  If I use an electrometer for this test, I get a reading of 650 
volts DC on a 1" diameter ball.

The Tesla coil is a device which trades off Magnetic fields (locked up in 
the vicinity of the coils themselves, for E fields both electrostatic and 
electrodynamic pushed out to great distances.

Richard Hull, TCBOR