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Re: theory(?) for long sparks
From: Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: Wednesday, November 26, 1997 1:50 AM
To: Tesla List
Subject: Re: theory(?) for long sparks
Hi Jim,
Interesting idea.....
> From: Jim Lux[SMTP:jimlux-at-earthlink-dot-net]
> Sent: Tuesday, November 25, 1997 8:27 AM
> To: Tesla List
> Subject: theory(?) for long sparks
>
<snip>
> 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).
Malcolm