More THOR Expts

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

Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz> 

Hi Marco, all,
                A question that needs to be answered is "what
determines what the useful maximum breakrate is?", "useful" being
defined as the breakrate beyond which no further increase in spark
length results. Some thought led to the hypothesis that the useful
breakrate will scale with secondary charge storage (i.e. capacitance).
I devised some expts which will hopefully prove or disprove this.
There is weak evidence already that supports this hypothesis, mainly
the results obtained by Richard Hull in his extensive work. My own
observations with a range of coil sizes also suggests this might be
true.

Noting the highest useful breakrate for the current THOR
configuration:

#1 - increase Ctop while maintaining the same ROC, and maintain the
same theoretical Vout by suitably increasing Cp or Vp (i.e. Ep). An
increased useful BPS would indicate a charge-available dependence.

#2 - decrease Ctop while maintaining the same ROC and same Vout
(reducing Ep to maintain this). If the useful BPS increases, that
would throw my hypothesis out. If useful BPS decreases, there is
supporting evidence for the hypothesis.

#3 - decrease Ctop while maintaining Ep to increase Vout (at this
point, I am not sure whether increasing or maintaining the same ROC
is the way to go - for completeness' sake it would be worth doing
both). Does the useful BPS change and if so, higher or lower?
If higher, it again negates the hypothesis.

#4 - increase Ctop while maintaining Ep to reduce Vout (ROC may have
to be reduced to allow breakout). If useful BPS remains the same, it
would provide more support for the hypothesis.

This list is by no means complete but should be a useful guide to
devising a complete set of tests. Some of these questions may already
have been answered but what I would like to see is the full gamut of
tests and results presented all at once. A key question I would like
to see answered is the degree to which sparklength depends on output
voltage and, separately, charge availability. My guess is that there
is a dependence on both but that charge availability is the more
dominant of the two. The enormous discharge from the 5MV Russian Marx
bank plus the behaviour of lightning seems to indicate this also.

     The purpose of all this is to refine the design criteria for a
spark-producing coil, a goal I'm sure we'd all welcome being reached.
The general approach at present seems to be equivalent to grabbing
whatever components one has available and building something that
works. In the engineering world however, one does as much as is
needed to fulfil a design goal and no more (safety margins
nothwithstanding), size, weight and economics being the arbiters.
     This is also what I'd consider to be a rigorous (scientific if
you like) approach to coil building. Why throw a 20 x 5" toroid on
top of a coil just because it happens to be lying around if it makes
the finished product bulkier and heavier without actually
contributing to the performance? I think anyone building coils for
commercial gain (I am NOT one of them) would appreciate this way of
doing things.

Malcolm