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Re: Optimal Quenching Tests

Tesla List wrote:
> 
> Subscriber: FutureT-at-aol-dot-com Wed Jan  8 22:49:05 1997
> Date: Wed, 8 Jan 1997 15:30:28 -0500 (EST)
> From: FutureT-at-aol-dot-com
> To: tesla-at-pupman-dot-com
> Subject: Re: Optimal Quenching Tests
> 
> >> I wonder though, does the spectral splitting really go away, or are its
>  > effects just minimized?  It seems to me that for the notch to form in the
>  >> first place, there must be spectral splitting occuring (this causes the
>  > beating which causes the notch).
> >>snip
> 
>  >It actually goes away (at least per my PSPICE analysis)! And apparently,
>  >is backed up by results of high-power spark gap transmitters and recent
>  >experimentation (per earlier posts on this phenomonon from Ed and
> > Richard. I did a Fast Fourier Transform analysis where the ONLY thing I
> >changed was the gap "on" time. Once I hit the optimal value, or below,
>  >the twin peaks in primary current and secondary voltage went away, to be
>  >replaced by a single peak at the commen resonant frequency of primary
>  >and secondary. If I "detuned" the primary to be lower (as most of us
> >do), I STILL got one peak, centered at the secondary's resonanct
> > frequency as long as I optimally quenched. I don't fully understand
> > exactly WHY this should be, but it IS real...
> 
>  > >  snip
> 
>  >>  >> 6)  When I quenched at 8 us in the above example,  I saw no notches
> in
>  >> the
>  >>  >> secondary waveform;  I saw only a build-up, followed by a nice high
>  >> amplitude
>  >>  >> ring-down.  But yes, I agree, more work needs to be done to verify
> the
> >>  >>  optimal quenching conditions needed for optimal spark output.
>  >>  >>
>  >
>  >> > This makes sense - if we quench once the energy flow from
>  >> > primary-secondary has completed, but before it can reverse, then we'll
>  >> >never see a secondary notch! A real poser is why the spectral splitting
>  > > >also seems to go away...
>  >
>  >>Certainly once the gap quenches, spectral splitting is gone, but I would
>  >> speculate that there is some spectral splitting occuring before the gap
>  >> quenches, even on first notch quench, but this splitting may not have
> time to
>  >>beat and re-beat with all the frequency and out of phase components that
>  >>occur during beating.  Thus with a slow or bad quench (and insufficient
> spark
>  >> loading to lower the Q), the beating and re-beating may get "out of hand"
>  >> (and out of the sec coil--as racing sparks)?
> 
>  >Before doing the simulation, this is what I thought as well. Certainly
>  >the latter effect seems to occur... Now all I need's a GOOD gap system!
>  >
>   > >  >>    John Freau
>  >   >>snip
>  >> >    --Bert--
>  >> snip
>  >> John Freau
> > snip
>  >    -- Bert --
>   >>
> All,
> 
> Help theorists!   If the above is true, who can explain why splitting (pri
> and sec)  that occurs before the first notch goes away before the first
> notch, when quenched at the first notch?   Hard for me to accept without
> understanding.   It would seem to me that if the above is true, then
> splitting must never occur before the first notch whether we happen to quench
> at first notch or not, otherwise, the gap would have to "know" it was going
> to quench before it happened (not likely).  And if the split does not occur
> before the first notch, then what forms the notch in the first place?  (seems
> to me that splitting and beating is what forms the notch).   Ah, the
> mysteries of coiling.
> 
> John Freau

John,

Because the spectral splitting does _not_ occur during the time the gap
initially ignites and the first primary notch! Believe it or not, ever
since (October) I found out about this phenomenon, I've been thinking
about why... ya' know, one of those things that make you go hmmmm....? 

However, I think I understand at least part of it. Some speculation:

1. The secondary usually has a much higher Q than the primary. During
the first ring-up, the secondary will actually "pull" a mistuned
primary's frequency to the secondary circuits resonant frequency Fs.
(This is handy for when we run primary frequency a bit lower than Fs for
ion-cloud compensation).

2. During secondary ring-up (but before breakout), the secondary "looks"
like a series LC at resonance, i.e., the reactances cancel, and it
appears like a resistive load. Hence no splitting during the first
ring-up.

3. This resistive load gets coupled back into the primary as a resistive
load (other than the fact it can "pull" the primary frequency to Fs). In
effect, during ring-up, the energy transfer is one-way from primary to
secondary, into a resistive load, hence no split. The primary is dumoing
energy into the "black hole" of the secondary tank circuit, and not
getting any back (yet).

4. The first primary notch comes from the fact that, eventually, we run
out of primary energy (i.e., finite "bang" size). At this point, all the
remaining system energy now resides in the secondary LC, just itching to
couple back into the primary if we let it. 

I haven't taken the speculation past this point... However, "classical
theory", observation, and PSPICE all show that frequency splitting will
occur beyond this point (once energy flow reverses).

Flames, brickbats, etc. are welcomed!

-- Bert --