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Re: theory(?) for long sparks
From: Greg Leyh[SMTP:lod-at-pacbell-dot-net]
Sent: Friday, November 28, 1997 3:56 AM
To: Tesla List
Subject: Re: theory(?) for long sparks
Malcolm Watts wrote:
> > So, then, if you want to produce a 100 meter spark, (i.e. 1E4 cm), the
> > voltage has to be there for at least 5000 microseconds, and probably
> > longer. Further, the voltage has to be high enough to overcome the drop in
> > a 100 meter long spark channel, i.e. several MV.
>
> That is the way lightning does it until the discharge channel is
> complete as far as I know.
>
> > A tesla coil running at 100 kHz (for example), has a half period of only 5
> > microseconds, well short of the desirable 5 milliseconds. It is possible
> > that the fine structure (i.e. the 100 kHz carrier) isn't the significant
> > thing, but rather the overall envelope (i.e. the time til the first
> > "notch"), which would be more consistent with the observed 1-3 meter length
> > sparks from a medium sized tesla coil.
>
> I've been leaning towards that view myself in the last few months. It
> might well explain why low frequency running at quite modest k's
> (e.g. 0.12) works very well. At that k and at low frequecies, transfer
> time is lengthened as is the time energy hangs around in the
> secondary. There ought to be a definitive experiment to test this.
> Compare a high frequency coil running at very low k's with a low
> frequency coil running at much higher k's. The awful catch is that
> the gap also has more time to lose it all at the lower k's. So, low
> frequency running at moderately high k has to be better (not to
> mention the benefits of a higher L/C ratio in the primary).
Hopefully, we'll soon see what happens at 37.9kHz, with k=0.25.
-GL