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Re: [TCML] Scoping Quench




Greg,

When you say you want to see if your gap is quenching... do you mean you want to
see if it's quenching at all, or if it's quenching well?  If your spark output streamers
seem normal, then surely the gap is quenching.  

I think there are various views about what quenching means.  Some folks think
that if a gap doesn't quench at the first notch, then it's not quenching.  I don't agree
with this definition.  Even if a gap quenches at the 4th notch, it's still quenching.  If a gap
is not quenching at all, then it's power arcing.  Power arcing will tend to severely
kill the spark output length.  From what I've seen, the notch where the gap quenches
depends a lot on the type of spark gap, and also on the spark loading.  When a coil
is well tuned, and putting out nice strong sparks, this tends to make the gap quench
faster (at an earlier notch).  If there are multiple gaps, or lots of air flow, this helps
the gap to quench earlier too.  In the case of multiple gaps, the losses will also be 
higher however.  

In general, I don't think the exact notch of quenching makes a lot of difference in
the spark streamer length.  Many small or medium sized coils quench at the 3rd notch.
Large coils may quench on the 1st notch at times.  Most of the obtained spark length
seems to depend on the energy transfered to the secondary during the first
energy transfer from the primary.  First notch quenching might increase the
spark length slightly by maybe 5% or so.  I'm just guessing here.  A somewhat late
quench (for example 3rd notch), gives the capacitors a little less charging time,
and may perhaps affect the spark length by that mechanism also.  Not all that much
research has been done in this area.  

To observe the quench-time, you can observe either the primary or secondary
ringdown of the coil.  When the notches end in the RF envelope, then the gap
has quenched.  You'll see a smooth ringdown from that point.  I used to observe
the quench point using a scope with an antenna pick up, set up some distance 
from the Tesla coil.   

Cheers,
John



 
 
G Hunter wrote: 
 
>What's the best way to observe primary circuit performance of a SGTC using an oscilloscope? I'm not interested in secondary ring down. I want to see if my spark gap is quenching. Should I use a regular 10X probe? If so, what should I probe? (I'm keenly aware of the high voltage hazard). 
> 
>Cheers, 
> 
>Greg 
> 
> 
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