Re: [TCML] Re: Position of baffle inside secondary

["Dex Dexter" <dexterlabs@xxxxxxxxxxx>]

I was surprised to learn of the existance of the optimum coupling with respect to the best performance of SG coils.Dr.Resonance tells that the optimum for his coils is about k=0.13-014.Before that I just thought tighter the coupling better the performance and the only problems with tighter couplings were racing sparks and flashovers.But even if the conditions are such that secondary itself is free from undesired discharges ,beyond certain coupling point spark lenghts might start to diminish!Contrary to what I expected.Well,Dr. R makes all his coils with aspect ratio of the secondary H/D=4.5..and I suspect the systems with different H/D parameter have different optimum couplings.H/D ratio is not only thing to consider in respect to these matters but is a good candidate to put on test.

Dex        

--- tcml88@xxxxxxxxxxx wrote:

From: Paul Nicholson <tcml88@xxxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Cc:
Subject: Re: [TCML] Re: Position of baffle inside secondary
Date: Sun, 12 Jul 2009 22:23:07 +0100

Dex Dexter wrote:
 > Maybe sudden streamer loading is also responsible for racing
 > sparks ,flshovers and (according to Dr.R) shorter spark
 > performance from classical coils with couplings tighter than
 > k>0.2 ??

I think you're right.  Modeling of coils without breakout
doesn't produce much in the way of damaging looking voltage
gradients, even for some quite silly k values and extreme
tunings.   There are some HF transients when the coupling
is tightly concentrated onto a small part of the secondary,
but nothing that jumps out and says racing arcs.

Little is known about this subject.  Modest k and good sized
topload seem to be the practical recipe to avoid racing arcs,
but the actual mechanism(s) are not understood.

 > Something unusual is going on in my opinion.

Yes, something that doesn't emerge from the linear no-breakout
models.  Fluctuating breakout load sending HF transients back
down into the coil?  A topic with many guesses, no measurements
to go on.  A difficult thing to study.  I have a suspicion that
high frequencies are involved but there's no evidence for that.
--
Paul Nicholson





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