Quench, Coherence etc.

To: "'Tesla List'" <tesla-at-pupman-dot-com>
Subject: Quench, Coherence etc.
From: Tesla List <tesla-at-stic-dot-net>
Date: Wed, 12 Aug 1998 20:30:37 -0500
Approved: tesla-at-stic-dot-net

----------
From:  Richard Hull [SMTP:rhull-at-richmond.infi-dot-net]
Sent:  Wednesday, August 12, 1998 12:05 AM
To:  Tesla List
Subject:  Re: Quench, Coherence etc.



Tesla List wrote:

> ----------
> From:  Gary Lau  11-Aug-1998 1508 [SMTP:lau-at-hdecad.ENET.dec-dot-com]
> Sent:  Tuesday, August 11, 1998 2:26 PM
> To:  tesla-at-pupman-dot-com
> Subject:  Re. Quench, Coherence etc.
>
> >From:  Malcolm Watts [SMTP:MALCOLM-at-directorate.wnp.ac.nz]
> >         Here are a few results obtained from some experiments. Power
> > supply was DC charger, BPS = 1.
> >
> > Two Coil System
> >
> > Lsec : 20.6mH,  Csec : 13.5pF,  H/D : 4.8,  Cterm : 6pF or so
> > Fs(w. term) : 250kHz
> > Lp : 17uH,  Cp : 25nF,  Vp : 13kV  (system breakout about 9kV)
> > Ep : 2.1J
> > Ttransfer : 12uS,  Ringup : 3 cycles of Fs,  k : 0.16
> > Gap = adjustable pipe gap.  Number of gaps varied from 2 to 8 during
> > tests. Adjusted to fire at 13kV for each number of gaps.
> >
> > Results: - 2 gaps : no effective quench except with attached streamer.
> >            Mostly 3, 4th notch quench. 11" hot blue spark to ground
> >            rod 20% of the time.
> >          - 4 gaps : quench mostly 2nd notch w. no breakout, always
> >            with breakout. Spark about the same as 2 gaps.
> >          - 6 gaps : quench always 2nd notch. Spark increased to 11.5"
> >            20% of the time.
> >          - 8 gaps : quench always 1st notch. Spark 10.5" for 20% of
> >            shots - yep, it decreased.
>
> >***** I looked in vain for any signs of a shift in V/I distribution
> >in all tests, breakout or not. Coherence if it exists remains
> >elusive. The resonator was carefully chosen to have a delay line type
> >H/D with only a 1/4 of the total capacitance in the top. I
> >superimposed the beat envelope captured in the scope on the first
> >notch quenched waveform.
> >
> >    If breakout did not occur under optimal quench, the secondary
> >oscillated to no good effect for a very long time but it was all
> >decay after quench. No sudden rise in amplitude; in fact no rise at
> >all.
> >
> >  A most interesting thing was noted that suggests that optimum
> >quench <> optimum sparks (also suggested in the spark lengths above).
> >For the same breakout conditions, the amplitude of the waveform was
> >significantly higher in the second ringup than if the system
> >optimally quenched and decayed. In effect, the coil had two hits at
> >the air some time apart and with still high amplitude on the second
> >hit. Arc dynamic theorists might have something to say about that one.
> >
> >     I made a note elsewhere about the streamers observed and how
> >their number related to breakout voltage and ROC.
> >
> >Sorry about the unintended snippage.
> >Malcolm
>
> What I read from this experiment was that as the number of gaps increased,
> the quenching improved, but that spark output diminished as gaps increased
> above a certain point.
>
> Terry Fritz's experiments comparing multi and single gaps at various coupling
> coefficients also showed that with single gaps, higher secondary currents
> resulted, but at the expense of inferior quenching.
>
> This appears to suggest higher gap losses in multi-gap designs.  That Terry's
> multi-gaps quenched better than his single gap is not surprising since
> neither of his gaps had any sort of forced air flow.  Could a "full
> blown" single gap with optimally adjusted airflow offer better performance
> (not necessarilly better quenching) than a multi-gap arrangement?  I'm nearing
> completion of such a gap and will report on it's comparative performance soon.
>
> Regards, Gary Lau
> Waltham, MA USA

  Lots of basically good generalizations here based on experiment.  Still systems
could be produced which would seem to refute some of them.  The important thing is
to realize that such refutation might not detract from the overall view but are
only exceptions based on skewed system dynamics.

More gaps in most all systems reduce output after a point and quench much better.
Gap losses may or may not go up as gap number increases.  A very high loss gap
system might well out perform a very, very low loss gap system.  Our training and
common sense would direct us to low loss gaps, always.  Thoughtful observation
might prove this blanket concept  to be wrong in certain instances.

Richard Hull, TCBOR