RE: TC Spark Energy

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

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


 >Another possiblity is that there is some impedance matching going on
between
 >the primary and the resonator.  What if the primary impedance is so low,
that
 >"reasonable" power transfer is limited?  It has been frequently
demonstrated
 >in the past that machines with smaller capacitors, higher input voltages
 >and larger
 >primaries for a given operational frequency (i.e. higher surge impedance)
 >have generally had higher efficiencies (i.e. longer spark length for given
 >input power)
 >then machines with lower surge impedances operating at lower voltages.
 >There also may be a significant amount of energy transfer capacitively
 >between primary and resonator; this clearly would be the case with higher
 >operational voltages.

I don't know about this. The math shows that the energy transfer in the OLTC
is no different to a conventional coil. The resonator shouldn't care if the
magnetic field coupling to it comes from one turn with a very high current,
or 10 turns with 1/10 of the current. My measurements with Rogowski coils
sensing the primary current, antenna probes, current shunts in the secondary
base, etc. seem to back this up.

I will <knock on wood> say that I think the primary part of my OLTCs is as
good as, or better than, the best spark-gap coils at getting power into the
resonator. I also don't think the secondary losses are that much more than a
spark-gap coil. I think the real reason is something to do with the coupling
between resonator and streamers- I think this is affected somehow by the low
frequency, high bps, or lower-than normal output voltage.

When I say "degraded"... The results I have been getting with the OLTC II
are as good as, if not better, than my conventional coil. But my
conventional coil barely cranks out 40" with 1kW of power input, whereas
according to John Freau's equation, it should do 53". Incidentally, it is
one of those "machines with smaller capacitors, higher voltages, and larger
primaries" that Dave mentioned. It has a 12nF cap bank charging to 20kV, a
13 turn primary, and a 400bps ASRG with rather small brass electrodes
(getting smaller every run)

I can almost see where this is leading. Maybe there is a "critical bps"
(depending on your coil size and construction) and increasing the bps above
this value just heats the streamers rather than growing them? I remember
Richie Burnett mentioning something similar. He found the output from his
coil grew massively between 100 and 200bps, but going to 300 and 400 didn't
make much difference. Then again, maybe if he had tried a bigger garage :)

This is difficult to quantify because so many factors are interacting. Power
supplies sag as you crank the bps up, etc. But now people like Marco
DeNicolai (and me :) ) have coils where the bps and charging voltage can be
set accurately, we're in a position to start looking at it.

Assuming anyone actually cares about squeezing the last foot of sparks out
of their setup ;)

Steve C.