BPS vs Watts vs arc length

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

Original poster: "S & J Young by way of Terry Fritz <twftesla-at-qwest-dot-net>" <youngs-at-konnections-dot-net>

Hi all,
 
I took some measurements of my filtered DC powered coil to determine the effect
of break rate (BPS) verses DC watts for a constant length spark discharge
between my twin TC toroids with breakout points.  I was hoping higher BPS would
be more efficient (same spark length at less power).  WRONG!  Once again, John
Freau is right - lower break rates appear to be more efficient.  
 
Here are measurements for a constant 30 inch discharge.  I set the BPS, then
cranked up the power until the two coronas just joined and became brighter in
the center of the arc.  For interest, I also show the AC VA into the two MOTs
of my power supply.  The MOTs start saturating around 100 volts and the current
draw goes up fast.   Use courier new or some fixed width font:
 
BPS       Watts     VA
 200      374.4     896 
 300      379.5     651  
 400      421.2     669
 500      444.4     680
 600      494.0     771
 700      527.8     800
 800      572.0     942 
 900      626.4     924 
1000      680.0     982
 
The AC input volts go from 112 (MOTS highly saturated- thus the high VA) at 200
BPS down to 78 volts at 1000 BPS.   (The 800 BPS VA is probably bad data -
should be about 865)
 
Some conclusions:
1) It appears spark length is nearly completely a function of power to the TC
primary.  The BPS just complements the Variac as a method for controlling
power.  Higher BPS is NOT more efficient.  But it sure is dramatic to run up
the RPM and watch the sparks get longer and hotter as the "siren scream" pitch
from the arc goes up! 
 
2) I did the same experiment with a 40 inch arc and got the same results -
linear BPS VS power relationship.  Power was 590 to 929 watts for 300-1000
BPS.  (At less than 300 BPS, there was not enough power input to produce 40
inch sparks - power supply maxed out at 15 KV.)
 
3) MOTS are free or cheap but inefficient when input volts goes above 95 or
so.  A potential transformer would be much better. 
 
4) MOTS with triplers are better than MOTS with doublers.  RSG performs much
better at the higher voltages from a pair of triplers.
 
5) The "Deanogap" (David Dean SPDT RSG configuration) continues to work great! 
Very efficient!  No power wasting series resistor!  Higher BPS per RPM!  Thanks
again Deano.
 
--Steve