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Re: Sparklength inquiry



> Original Poster: FutureT-at-aol-dot-com
> 
> In a message dated 98-09-22 07:16:29 EDT, you write:
> 
> << Awhile back, someone (perhaps Mark Rzeszotarski?)
> > came up with a curve fit of power consumption vs
> > coil scale.  I remember that it seemed to fit the
> > real-world data fairly well, and that it's baseline
> > showed that coil power increases with the *square*
> > of the coil dimensions.
> 
> Greg, all,
> 
> I posted the square law suggestion some time ago, based on my
> results with the sync gap coils in which I obtained 42" sparks using
> 620 watts, and 64" sparks using 1570 watts.  I was relating input
> power to spark length.  I then scaled up the spark lengths using the
> square law, and your 25" spark TC fit well on the curve.  This
> posting was before I improved the efficiency of my coils, the old
> figures were:
> 
> Power input                spark length          toroid dia (inches)
> 680 W                    actual       42"                   20
> 2100 W                   actual       65"                   30
> 8400 W                               134"                   60
> 33.6kW                                22'                  120
> 67kW                                  31'                  240
> 134kW                                 44'                  480
> 538kW                                 88'                  960

Thanks John.  I agree that it's possible to do somewhat better
than the curve that you have defined above, but your basic curve
itself seems to give a realistic, conservative estimate of a
coil's performance vs power level.  I had calculated that ALF
would need 5.1MW to develop 300ft arcs.  This curve when inter-
polated gives 6.3MW -at- 300ft.  However, if you use your same
square law and interpolate from a good performer such as Ed
Wingate's coil (15ft at 10kW I believe),  you get:
(300/15)^2 * 10kW = 4MW.

Likewise, if you increase Ed's power to 26kW, then:
15ft * SQRT(26/10) = 24.1ft, which is very close to my present
coil specs (26kW, 25ft).

Given these results, it seems like 5.1MW is in the ballpark 
for a 300ft discharge.


-GL
www.lod-dot-org