Re: Spark-gap sparks vs. solid-state sparks

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

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

I've seen but 1 or 2 comments on my conjecture of 4/19 regarding the
spark-delay mechanism, to wit:

It has been asserted that a delay occurs between the time the top
electrode's potential reaches the initial spark break-out level and the
onset, or extension, of the spark.  I do not see any electrical mechanism
present that could account for such a delay.  Thus I postulate that the
delay--and I do believe it exists though I have never measured it--has a
mechanical cause.

I think that the cause lies in the inertia of the air that the spark must
push aside, i.e. heat up, for it (the spark) to advance.  As I wrote,
that's the same mechanism that allows nuclear bombs to work (and aren't
we thus in fine company?).

I've concluded that, since that's the case and such delay is of
relatively short duration, one must apply a relatively high initial
rate-of-rise of primary excitation for that delay to be a) measurable and
b) useful for "coilers".

How the delay is useful lies in its effect in lengthening the spark: 
With a sufficiently high initial rate-of-rise of electrode voltage, that
voltage will rise significantly beyond the level necessary to initiate
spark break-out before the spark can have time to propagate.  Having so
risen, the voltage--the accumulation of electrons on the electrode--is
then sufficient to propel the spark to a greater length than it would
otherwise reach. I believe that that is the reason, often asserted and
certainly applying to my own coil, that neither solid-state not tube-type
coils can achieve the spark lengths of spark-gap coils, other factors
being comparable.  Such circuit elements cannot conduct the high but
short-duration primary currents that are necessary; only spark gaps can
do that.

If my secondary's voltage rises to break-out in, say, 40 cycles while a
comparable spark-gap-secondary's voltage rises in 2 cycles, then the
exciting magnetic fields must rise by the same factor, of 1:20.  In order
to get that 20X increase in field rate-of-rise, one needs 20X the current
in the primary--from 20X the voltage applied.  Of course, that 20X
current doesn't get applied for very long; not nearly so long as my ~7 ms
per spark for example (Otherwise, coilers would be moving from California
in droves.).

Any comments from those more skilled in the art?

Ken Herrick
________________________________________________________________
GET INTERNET ACCESS FROM JUNO!
Juno offers FREE or PREMIUM Internet access for less!
Join Juno today!  For your FREE software, visit:
http://dl.www.juno-dot-com/get/tagj.