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Re: Overtones and velocity factors

Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Hi,

I have not been involved with this much since I have been "really busy" :o)))
I think D.C. and me are the only "low coupling" folks ;-)) If the primary system does not eat power like mad, low coupling losses in the primary circuit are less important and the coil naturally runs better. LTR systems tend to run at lower currents reducing losses and D.C.'s systems have big heavy primaries that have low loss too. The SISG will no doubt change all that an order of magnitude or two further...
Quench is also not too important if the streamers naturally use all the systems energy in the first cycle anyway... Coupling adjusts that...
Computer models tend to point to lower and lower coupling for best operation. However, the "energy rise time" of higher coupled systems is probably very important for long streamer formation. The Russians have specific numbers for this for there 400++ foot Marx generators!!!
I remember an out of tune coil once at a gathering... It had 1 foot long primary to secondary arcs!! We put a 3/16 sheet of G-10 fiberglass between them. The arcs "blew right through it"!! I though to myself at the time. "That is really screwed up and there is no explanation for it"!!! There still is not. But there are "many strange things" that go on down near the primary to secondary coupling area!!!
I always wrote it off to "transformer action" but Paul and Dmitry seem to have shot that idea out of the water... 


High voltages - who needs 'em :)  Measurements are more rewarding
in the long run.  Making sparks - Bah!   Hope you can measure
some resonant frequencies and the associated in-coil wavelengths
to demonstrate the above.
I too always wondered about people that did not watch sparks only on a "scope screen"... Your gonna go blind :O))))) 


A few.  A tie-up between racing arcs and gap behaviour is a
rich source of possibilities.  We'd better go read Terry's old
paper mentioned in

> http://www.pupman.com/listarchives/1998/July/msg00019.html


The modern link is here:

http://hot-streamer.com/TeslaCoils/MyPapers/sgap/sgap.html


Gerry wrote:
> What measurements do you have in mind and what type and quality
> equipment is needed for the measurement.

Capture of a secondary base current waveform on a digital scope,
transferred to a computer file for analysis.  Only rough amplitude
calibration needed.  Wide bandwidth, though, say up to 30 times the
TC operating frequency.


Gosh!!  Who has equipment like that!!!  :o)))
Would a single shot primary base current waveform capture of a spark with and without racing arcs help. The big old coil was good at that. I can fire at 5400V with the SISG (extremely repeatable).... I don't have enough section yet though for higher voltages. Maybe it would still race though since it had plenty or room for lowering. With all the new solid state stuff, "repeatability" is a giant new advantage we have ;-)) 


One sample of the genuine phenomena is
all that's needed, so no long damaging runs required.  We would
analyse the captured waveform to determine what signal components
are present - chances are the offending signal(s) will be quite
prominent.  We would work out their voltage and current
distributions and approximate gradients, and by modelling,
determine which parts of the structure are involved in generating
them.
I guess that is "yes"... My problem here is that the play rooms are about 1/4 their original size now... I might need to take a sawsall and start some serious "cleaning up"... :-))) The pool table is going out in 1/8th sections...
Single shot operation does very little damage in any case.... This would be on the big old secondary coil... It is still "just fine" ;-))) 


The cross check at that point would be detection of the
offending resonances during low power sweeps and showing by probing
and loading that the nodes and antinodes are in the predicted
places.  The tricky bit is getting a coil to display classic racing
arcs on demand.  Maybe John has pointed the way there.
Single shot operation makes racing arcs far more "safe". Would it matter if "miss tuning" was used to help at racing arcs along?? 



Variation on the above:  Just fire the primary under various gap
operating conditions, without the secondary (is that possible
or would that damage something?).  See what frequencies are excited
and at what levels.  Knowing that, we can calculate how the
secondary would cope with them.
Spark gaps are very unpredictable and have all kinds off odd quirks that might just add to the noise... Today, (literally - "TODAY" ;-))) we have new gaps that can remove those variations ;-)) 

Cheers,

        Terry



--
Paul Nicholson
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