Re: S.s.t.c. "booster" proposal

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Kchdlh-at-aol-dot-com>

Terry note:  For some reason I never got John Freau's and Antonio de Queiroz's
responses to my original posting.  I've downloaded them from the archive. 
AOL's machinations again, do you suppose? >>As far as I know, everything is
fine on the list side.  Probably an AOL "thing"<<

I think they are in the main right in pointing out that I am wrong.  The
voltage that will exist across my "booster" coil just prior to its gap's firing
will have, in effect, a high internal impedance--being generated due to a
coupled magnetic field from the secondary.  The same voltage that would exist
within the capacitor of a conventional capacitor-gap-coil circuit would be
associated with, on the other hand, a vastly lower impedance--the impedance of
the capacitor at Fr.

As to John's comments on pulse-burst rate and duration:  He's quite right as to
my ~5 ms pulse-burst duration brightening the spark but not increasing the
length (substantially).  But I don't think that decreasing that duration and at
the same time increasing the burst-rate does much for the spark length. As I've
mentioned before, initially I went to some trouble to devise a circuit that
would detect when the spark broke out and end the excitation 50 us or so after
that--thinking that I would thereby avoid wasting input power.  That scheme
worked fine but the sparks ended up looking very pallid indeed.  When I
extended the duration I got much more impressive sparks but the length didn't
change a whole lot.

I have this imperfect understanding of the overall situation:  With sparks
going off into the air and not hitting any grounded conductor, there exists
this series-circuit of impedances:  (spark)-(toroid)-(secondary
coil)-(primary:secondary coupling)-(primary), strung between ground and the
primary's voltage-source--the toroid's impedance being 0.  The only way to
increase the voltage drop across "spark", in a given coil assembly, and thereby
to increase its length, is to increase the driving voltage at the "other end". 
That's the reason that spark-gap coils do better in that regard than s.s. or
tube coils.  Or most of the reason, in case my notion as to the air's thermal
inertia has any merit at all.

A variation of what I proposed might have some value for s.s. or tube coilers: 
Add a rectifier diode string across the gap of the "booster" assembly so that
the capacitor becomes charged during the relatively slow build-up of toroid
voltage.  Space the gap so that it fires before the break-out from the toroid
would otherwise occur.  In effect, that adds a higher-voltage spark-gap primary
into the circuit.

The effect on the s.s. or tube primary would have, of course, to be
considered.  I think that in my case there would be no harm since my primary is
essentially a short-circuit for induced voltages in excess of the sum of its
supply voltages.  Said short-circuit would dissipate relatively little power
during the spark-gap firing interval.

One might well ask, of course, "Why, then, bother with s.s. or tube drive at
all?  Just be conventional."  That would be a good question and were it to be
asked, I would work on an answer.

Ken Herrick