RE: TC Spark Energy

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

Original poster: "Steve Conner" <steve.conner-at-optosci-dot-com> 

 >To my
 >knowledge no coiler (see below) has ever determined the TC input energy
 >(joules) per spark for these comparisons. Do any coilers know how this
could
 >be best accomplished?

I have done it for all of my coils. The conventional one I did by turning my
variac down till it was only firing about once every three seconds.
(Resonant tank cap with static gap) It gave about 10" between the topload
and a grounded point for roughly 2 joules input.

The OLTCs I did by just turning the break rate down to about 1 bps. The
small one gives about 5.5" for 0.2 joules input and the big one gives about
28" for 7 joules. This last measurement was a streamer to air because I
don't like arcing the big coil to ground while it's grounded to my house
wiring :-0

Believe it or not, these measurements are consistent with the estimated peak
topload voltages of my coils and the breakdown voltage of an air gap of the
size I measured. For Tesla coils at low bps, the RF voltage seems to spark
about the same distance as a DC voltage of the same amplitude would.

If I assume the breakdown voltage vs. gap length figures in the literature
are valid for my setups, I can calculate what the top voltage really is, and
so find the efficiency. It works out to be something like 60%. Although
given the uncertanties, I would rather say "between 50% and 80%" :)

I checked these calculations by measuring the secondary base current once
ringup was complete and doing 1/2CV^2=1/2LI^2, it gave about the same
answer.

Steve C.