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Re: Sparklength inquiry



In a message dated 98-09-23 03:03:30 EDT, you write:

<< > 
> > 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  (revised)         spark length      toroid dia (inches)
> > 680 W            620W          actual       42"                   20
> > 2100 W          1570W         actual       64"                   30
> > 8400 W           6280W                       128"                   60
> > 33.6kW           25kW                          21'                  120
> > 67kW                                                 31'
240
> > 134kW            100kW                        42'                  480
> > 538kW             400kW                       84'                  960
> >                        1.6MW                     168'                1920 
> >***new***           5.1MW                     300'                
 
> 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.  

Greg,

Agreed.
I noted in my posting above that this chart was created before I 
improved the efficiency of my coils. I added a new column in the
chart above, and plugged in the values for my present efficiency
of my coils (see chart).  Using these new values, I show a need
for only 5.1MW to develop the 300 foot spark, which by coincidence(?)
agrees exactly with your figure.

John Freau

 >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 >>