Fanciful spark-augmenter

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

Original poster: "Kennan C Herrick by way of Terry Fritz <twftesla-at-qwest-dot-net>" <kcha1-at-juno-dot-com>

Ref:

http://hot-streamer-dot-com/temp/Tcbigspk1.pcx
http://hot-streamer-dot-com/temp/Tcbigspk1.gif and
 
http://hot-streamer-dot-com/temp/Tcbgspk2.gif
http://hot-streamer-dot-com/temp/Tcbgspk2.pcx:

It occurs to me that this notion--absent a fundamental flaw which, if
present, I hope someone will point out--might be useful for many of you
spark-gappers.

My basic idea is this:

1.  Interpose a coil/capacitor/spark-gap apparatus between an
electronically-driven primary coil and a conventional secondary.

2.  Configure the new apparatus so that it has a) a portion of its coil
resonating with a high-voltage/high-current capacitor and b) another
portion of the coil arrayed so as to be put in anti-parallel with the
first portion via a series spark-gap.

3.  Choose the first coil-part and the capacitor to resonate at a
frequency perhaps 15% lower than that of the secondary coil plus top
electrode.

4.  Choose the second part of the coil such that, when it becomes
connected across the first part via the gap, its inductance causes the
resonant frequency of that first part + the capacitor + the second part
to increase so as to equal the resonant frequency of the secondary.

5.  The way it is to work:

5.1  The gap being off, excite the apparatus from the primary at the
resonant frequency of coil-first-part and capacitor; the capacitor's
voltage rises cycle-per-cycle toward its ultimate value.

5.2  By induction, the voltage across the second part of the coil also
rises, free to do so because the gap is off.

5.3  The secondary absorbs little energy since its resonant frequency is
higher.

5.4  The gap fires.  At this instant, a) the capacitor/coil-first-part
voltage begins to decline because the frequency shifts and b) the
operating frequency becomes that of the secondary's resonant frequency.

5.5  Now, the secondary commences to absorb energy from the interposed
apparatus, just the same as it would have done from a conventional
spark-gap primary.

5.6  The secondary/electrode produces its spark, the gap extinguishes and
the cycle repeats.

It seems that the above might offer a way to get around the use of
dangerous mains-frequency voltages in the primary apparatus (as my s.s.
system does) while at the same time achieve the (presumed) advantage, as
to spark length, of a spark-gap system.  The key factor is the initial
phase of operation at a somewhat lower frequency than the secondary's Fr.
 Because of that, the interposed resonant system may be brought up to a
high voltage--but a voltage only at a much higher frequency than that of
the mains--relatively gradually from a relatively low-voltage s.s.
driver, utilizing resonance in the same way as does the secondary.  Then,
the requisite very large dV/dT is made available to the secondary by the
shift in frequency while the gap is fired.

A further refinement could be to obtain the driver's excitation as a
function of the voltage in the coil-first-part.  That could readily be
done with a suitably-located ground-&-tap connection (since the whole
aparatus otherwise "floats").  That way, one tuning requirement would be
eliminated: that between the driver and the new apparatus.  The single
tuning requirement would then be that between the apparatus and the
secondary--essentially the same as in a conventional gap-system.

The refinement could allow for the primary to continue delivering energy
into the secondary while the secondary's spark exists, as my system does,
perhaps making the spark fatter while at the same time it has been made
longer by the action of the new apparatus.

...and I claimed that I was no longer of an age to remain interested in
spark-length!  Maybe there's "snow on the roof but still a fire in the
furnace".

Ken Herrick
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