[TCML] Proper VTTC Coupling?

[futuret at aol.com]

Does anyone have any suggestions for the best coupling value
for a small VTTC?  I usually use something around 0.2 or 0.18
but those figures may have actually been lower.  I did some
experiments at k = 0.3 or so, but a flashover destroyed the
primary and secondary.  Has anyone loosened the coupling to
0.10 or so and seen any reduction in spark length?

Has anyone noticed if the spark characteristics change with
various couplings?  I saw some evidence that too tight coupling
ruins the sword-like spark effect.  Not sure though.  I'm
aware of Steve Ward's work in which he found that a too-low
frequency killed the sword-sparks.  In my own work, I found
the sword sparks to be affected by various parameters and
adjustments.  I never attempted to verify the frequency idea.

Thanks,
John