Re: Spark length equation and pri. program

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

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

spark length between two electrodes IS in fact primarily determined by
voltage... roughly 71 kV/inch, 30 kV/cm.  However, if the field is
nonuniform (like very long gaps with reasonable sized electrodes), and the
voltage is over a few hundred kV, lots of other factors come into play,
like streamers, leader development, etc. For instance, lightning strikes
occur in a field of around 10 kV/meter, 100 V/cm... and nobody is going to
claim that lightning isn't a spark.

For long sparks in nonuniform fields (like tesla coils), the energy stored
in the topload is probably a bigger factor. This, in turn, is related to
how much energy you put into the system,and how often it discharges (i.e.
once per half cycle of the AC, once per gap presentation on a rotary, etc.)
John Freau has proposed an equation for run of the mill coils that comes
out to length(inches) = 1.7 * sqrt( input power in watts).  So, for your
12/60 NST (=720W), a spark length of 45 inches isn't out of the question.


Tesla list wrote:
> 
> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Kidd6488-at-aol-dot-com>
> 
> Hi, all...
> 
> I have been thinking lately about the relationship between spark length and
> voltage. current isn't a factor is it? for example, 12kV can jump about
> half and inch, and 1MV can jump, (guessing here) two yards? I was trying to
> figure out an equation to find max. spark distance by voltage, but haven't
> been able to do so. Someone had to already find it, and I'm probably just
> re-inventing something, but hey, its worth a shot...
> 
> Also, I need some guidance on making a primary. It will be a flat spiral,
> using Greg's design with the 7 pipes... I just don't know how many turns
> I'll need. I have a 12/60 NST, MMC will be 11x2 .1uf GG (ggek group), and
> static gap... Is there a simple program to determine turns, and tapped
> turns? Also, I don't know if anyone replied to my post about the
> double-tapped primary, or if i accidently deleted it :-( ... but I'll
> re-post...
> 
> -------------------------------
> Jonathon Reinhart
> hometown.aol-dot-com/kidd6488/tesla