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Research directions
Hello all,
Although much of TC theory is now understood, probably the greatest
mysteries still lie within the area of streamer dynamics; how the
streamers grow as a result of various TC configurations, and why the
sparks branch in various ways.
We know that a higher break rate will tend to coalesce the sparks and
cause spark growth due to the re-ignition of streamer ion channels.
What is unknown is what the best break rate might be. Some have
said that each TC requires its own best break rate. This may be true,
but is not quite what I mean. What I mean is; of all the possible TC
designs and break rates can be be utilized, which is the absolute best
for obtaining max spark lengths using minimum input power. However,
one would not want to reduce the break rate to the point where the
sparks appear to be intermittent or pulsed because this would be
"cheating". Certainly one could pulse a coil once a year, and say it
was "very efficient". (please see below for how I'm defining efficiency
here)
Everytime I write what I'm writing here, someone responds by saying
that their sparks got longer as they raised the break rate. This is not
what I'm refering to.
I have done some tests at relatively low power levels that suggest that
a break rate of around 120 bps is best. Higher break rates may give a
brighter or fuller spark for the same spark length, but more power was
then needed. As I increased the break rate, the TC became less and
less efficient. I am defining efficiency here from a practical standpoint
of spark length vs input power. I am not refering to charging efficiency,
but solely to effects occuring once the capacitor is already charged,
and measuring wattages based on cap joules and bps. Gap losses,
and other losses come into play here too.
The performances of Greg leyh's two large TC's were very interesting,
as well as awe-inspiring. His older coil had a somewhat linear break
rate vs spark length relationship; If you doubled the break rate, the
spark length would tend to double. In contrast, his Electrum TC, was
less dependent on break rate. Almost full spark length was achieved
at a relatively low break rate, and higher break rates added mostly to
the fullness of the streamers rather than their lengths. It had been
suggested that a larger TC can tolerate a lower break rate.
It is easiest for these kinds of comparisons, if the coils being tested can
provide a variable break rate along with a constant bang-size (as Greg's
TC's did). DC coils of various types tend to fit the bill nicely here;
systems such as Greg's rectified 3 phase system, Larry Robertson's
H-drive, or Marco's solid state TC driver.
Much may also be learned from running pulsed CW systems.
Much work to be done,
Cheers,
John Freau