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Quench, Coherence etc.
----------
From: Bert Hickman [SMTP:bert.hickman-at-aquila-dot-com]
Sent: Wednesday, August 12, 1998 7:10 AM
To: Tesla List
Subject: Re: Quench, Coherence etc.
Tesla List wrote:
>
> ----------
> From: Malcolm Watts [SMTP:MALCOLM-at-directorate.wnp.ac.nz]
> Sent: Monday, August 10, 1998 9:07 PM
> To: tesla-at-pupman-dot-com
> Subject: Re: Quench, Coherence etc.
>
> Earlier I wrote:
>
> <snip>
> > 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.
>
> In case that sounds like nonsense, the second ringup presented the
> air with a higher voltage further out in time but at the expense of
> presenting a null in between as energy ended up back in the primary.
> In effect what happened was (air streamers only):
>
> *
> *
> * *
> *
> *
> * * 1st notch quench
>
> *
> *
> * *
> * *
> *
> * * * 2nd notch quench
>
> 1st ringup time and amplitudes are identical. I have the two
> waveforms in the scope and am looking at them superimposed right now.
>
> Malcolm
Malcolm and all,
Verrryyy Interesting! Is there a reason you'd suspect the first ringup
might be different - wouldn't it only be a function of k? What is
surprising is that longer sparks appear to be correlated with 2nd notch
quenching... certainly counterintuitive, since there would seem to be
significantly less overall energy available to incinerate the air in the
2nd notch case. However, if looking ONLY at streamer length, the 2nd
notch case does provide two opportunities for spark propagation during
the rising ringup voltage envelope (ala Bazelyan & Raizer). This more
conducive environment happening twice instead of just once may account
for additional sparklength.
A thought: can you distinguish any difference in the ringdown rate
between the 1st and 2nd notch quench cases? I'm wondering if the 2nd
notch case may, in fact, result in better overall energy transfer to the
air, since during the 2nd notch we would be coupling energy through a
well ionized path during much of the ringup and ringdown periods. If so,
we might be able to observe a _lower_ secondary Q during the 2nd
ringdown reflecting more efficient(?) incineration of the air as
compared to the 1st notch quencing case. It might be possible that
initial streamer propagation, followed by reignition and streamer
extension during the successive ringup, might actually be more effective
in extending streamer length [assuming relatively high k and relatively
low primary/gap losses between successive ringups].
Certainly much food for thought here...
-- Bert --