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Re: Very weak coupling and life of primary arc

Hi Boris,

	I assume you have seen my paper "A Comparison Study of Multi-Gap and
Simple Tesla Coil Spark Gaps with Various Primary to Secondary Coupling
Coefficients." at
http://www.peakpeak-dot-com/~terryf/tesla/experiments/sgap/sgap.html  on this
subject.

	The lower the coupling (<~0.06) the more likely it is for the gap to
quench on the first notch.  Multi-gaps are able to give first notch
quenching at higher coupling (~0.15) according to the tests reported in
that paper.

	One thing that paper also shows is how much loss is taking place
(actually, measured output voltage).  A given gap my give first notch
quenching but my be so lossy that it lowers the system power significantly.
 A very low resistance gap that quenches after many notches may actually
give better performance.  In other words, low loss my be better that early
quenching.  It depends somewhat on the system.  the low coupling cases give
far less output voltage than the high coupling cases.  the paper shows that
my coil's performance really peaked with a muti gap at a coupling of
0.1753.  However, at high coupling, the simple gap gave equally high peak
output voltage but never really had any significant quenching.

	After much study, a multi gap that gave first notch quenching at
reasonably high coupling
(http://www.peakpeak-dot-com/~terryf/tesla/misc/terrygap.jpg) gave the best
performance for a static gap.  However, a low series resistance rotary
(http://www.peakpeak-dot-com/~terryf/tesla/misc/RGAP.ZIP) seemed to give much
better overall performance despite the fact it has practically no
quenching.  Modeling of this particular system shows that quenching on the
first or fifth notch is far less important than keeping the primary tank
losses minimal.

	I think a multi gap carefully adjusted to optimal coupling will give the
best performance for a static gap.  However you will have to search around
to find the best coupling point.  Use the paper as a guide.  Note that too
much coupling reaches a point where the whole system suddenly looses
performance drastically and the wave forms show heavy distortion.  About
the same point where racing arcs will begin ;-)

Cheers,

	Terry


At 11:58 AM 09/23/1999 -0700, you wrote:
>
>Hi Terry,All,
>I'm interested in the correctness of one claim that
>concerns weak prim/sec coupling and lasting of prim.
>gap arc.
>If k is very low (read k< 0.1) it is claimed that
>after all the energy is completely transferred to
>secondary circuit for the first time,primary arc turns
>off and doesn't refire again.
>In other words this is a case where there's no return
>of energy from secondary way back to primary.
>Relatively small induced voltage across Lp by mag.
>influence of secondary is found to be a reason (which
>is understandable since small k).
>However ,I doubt.The gap should lost its conductive
>properties in 1 microsec. itself!
>It is emphasized: no need of any rotary
>,cooling,forced air flow in gap if input power isn't
>to considerable (1 KW aprox.limit)-just static gap
>employed.
>Maybe it would work if multiple series gap used?
>And yes, just for any case -the protection of power
>transformer is a must here.
>
>Every experience/info/thoughts on this subject is
>welcome.
>
>-Boris
> 
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