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Re: [TCML] quench times again



Hi John, Chris, (hope you all had a great Thanksgiving!),

Something to keep in mind regarding the arc grounded case (and I shared with Chris already). True, the low impedance of the leader empties the stored energy in the secondary very quickly, but this will not change the transfer time. The energy transfer is function of the mutual inductance (which is not changed due to a ground strike). The gap will continue to conduct until all the energy is out and it will occur at the same time as it would with air streamers, except that it will quench at the next available primary notch depending when the strike to ground occurred.

At the strike to ground, the secondary amplitude will drop like a rock, but the remaining primary energy transfer will continue to keep the gap conducting until there is no more energy to do so. So, the transfer time is not affected, but the quench time is.

The ground strikes, primary strikes, etc.. occur (hopefully more ground strikes). If we are quenching in air say 2nd, 3rd, or 4th notch, we will likely be quenching at 1st notch on those events. So the system is quenching at different times. For those who have only air strikes, there will be more consistency. But for my little red coil, I'm hitting grounded objects all the time and a lot of ungrounded objects about as much as I'm throwing out air streamers. The arc impedance is changing all the time due to those external annoyances, so quench time is affected. This can be quite different from coiler to coiler just based on coil size, power, where, and how we run our coils.

I performed a 20 minute continuous run last weekend at 1000W. Considering everything that was hit and how often, I'm sure quench times were all over the place.

Take care,
Bart


FutureT@xxxxxxx wrote:
In a message dated 11/22/2007 11:47:26 A.M. US Eastern Standard Time, list@xxxxxxxxxxxxxxxxxxxxxxxxx writes:

I am also trying to work out, that other than coupling and frequency which effect the tank "transfer speed" to secondary... can the secondary itself become "easier to drive" to make the transfer quicker ? this is why I thought that a lower inductance would take less time to "charge" and the energy transfer would be quicker than a lower inductance.... though this could just be down to a higher frequency...


cheers,
Chris



Chris, I'll ignore the arc-to-ground case which is a special case. Most folks like to see mostly air streamers I think. The transfer speed to the secondary is not the problem preventing fast quenching. The real problem
is streamer (actually leader) impedance.  If the streamers were  somehow
of a lower impedance, this would drain the energy faster from the  secondary.
Low impedance results in a heavier loading effect by the streamers.
If the streamers were of low enough impedance, then there would be no energy left to go back into the primary and prevent quenching. The effect
of streamer loading reflects back through the system to affect the  quench
time.  In the case of the arc-to-ground, the streamer impedance  becomes
very low, and drains the energy quickly.  If the energy transfers  to the
secondary quickly, but can't
get out quickly via the streamers, then there's a bottle-neck, a  traffic
jam.  It's as if many cars are streaming onto a highway from  various
feeder roads, but up ahead a couple of lanes are shut down for  repair.
Now the traffic backs up.  If the cars speed quickly to that  bottle-neck,
it won't do them a lick of good.  They'll still have to slow down or  stop
until the traffic ahead makes its way through the constriction.   Souping
up the engines of the cars, or reducing the friction of the car's powertrain, etc. won't help. The only thing that will help is to
remove the constriction, to open the lanes of the highway which are
closed for repair.  This opening of the lanes, would be analogous  to
reducing the impedance of the streamers of the TC. John



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