Magnetically controlled spark gap for Wireless Transmitter

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Original poster: "David Thomson" <dwt@xxxxxxxxxxxx>

Does anybody here have experience working with the magnetically controlled
spark gap mentioned in this article?
http://www.iop.org/EJ/abstract/0950-7671/40/9/118

I'm building one for my wireless power transmission project and was curious
as to why nobody else seems to have noticed this.  Essentially, the spark
gap is a concentric cylinder copper spark gap that serves as the core of an
electromagnet.  The electromagnet is pulsed at the desired break rate.
According to the article, this particular gap arrangement also works as a
diode for rectifying the current.

At first I thought it would only produce a half wave rectification, but then
I thought about John Freau's concentric spheres.  He uses concentric spheres
for his top load, and without any other adjustments, the concentric spheres
double the streamer length.  This makes me think that not only does the
concentric geometry cause half wave rectification, but it also doubles the
potential.  At least, that is what John's results suggest.

To further capitalize on the rectification, I built the outer tube of the
concentric spark gap to also be the inner tube of a concentric cylinder
capacitor.  I was amazed at how precise the concentric cylinder capacitor
equation was for predicting the capacitance, too.  It was spot on.

I'm hoping this magnetically controlled spark gap will allow break rate
tuning with my signal generator.  I've got a solid state relay I built from
a couple heavy duty transistors in parallel.  Don't worry, I have several
backup generators in case it gets fried.  However, the article didn't
mention anything about stray currents destroying their pulse generator.

Another feature of the magnetically controlled spark gap I'm hoping to see
is the distributed area of the gap allowing for spark-less breaks at high
break rates.  I note that Marconi used a concentric cylinder antenna on his
radios.  It seems the cylinders would have added potential to the photon
radiation, just as John Freau's concentric spheres add potential to the
electron streamer.  I'm wondering whether the break could take place
entirely as a photon transmission and reception, which would eliminate the
need for sparks.  With no sparking, but successful current transmission,
this could allow for a more efficient operation of the coil.  I'm also
providing air quenching in the gap just in case it does work by electron
sparking.

Also, if the gap does work at the rate set by the frequency generator, and I
can get it to work at 2500 bps, or more, it may make the coil work entirely
as a high frequency sine wave generator.  It seems it may be possible since
the concentric cylinders are rectifying the current.

I'm putting the primary capacitor just before the inner most turn of the
primary coil and grounding the circuit with capacitor terminal closest to
the spark gap (shared cylinder).  If I tap the outer most turn of the spiral
coil to the opposite side of the spark gap, this should make the primary
circuit act as a one-wire oscillator.

The power supply is a 10KV 23mA OBIT and all the connections are super
insulated.  The secondary coil is a flat spiral.  The ground wires of the
secondary coil, primary capacitor, and extra coil all meet just below the
extra coil in a wye formation.  The extra coil and its top load are jacketed
in oil.  There is also a "hood" placed over the top, which is a 3" aluminum
sphere isolated and at the center of an 8" aluminum hemisphere (not quite a
concentric sphere setup).  The hemisphere is grounded to the same connection
as the others.  This is one of the setups provided by Leland Anderson from
images of Tesla's Wardencliffe system, which he reprinted from the Belgrade
Museum.

I have already operated this coil with rough tuning and a makeshift power
supply using a standard four point static spark gap.  I was surprised to see
the broad sparking activity in four static spark gaps.  I didn't expect this
with such a small power supply.  When the new polypropylene snubbers come
in, I'll finish making the custom MMC capacitor to complete the system and
be ready for a test drive.  With any luck, I'll be collecting Terry's $100
prize soon.  I also hope to show Soljacic that Tesla's system works just
fine for power transmission, and his proposal is essentially the same thing
as Tesla's.

Dave