Re: Resonant charging and quench time

Tesla List wrote:

> Playing with a MicroSim model of it I bumped into a sad thing: when the
> spark gap OPENS there is, of course, some power still left in the primary
> capacitor/coil circuit. The current left in the primary coil will make up a
> high voltage spike that, in turn, will charge back the primary capacitor to
> a certain potential.
> The polarity and magnitude of this voltage DEPENDS ON THE QUENCH TIME, i.e.
> on the exact moment in  time the spark gap opens!

> Has anybody noticed this effect? Any comments about this? Am I wrong ?

A normal spark gap will open only when the current through it is zero,
very close to zero. Voltage spikes can really happen, but if they are
strong they ignite the gap again. The modelling of a true spark gap is a
complex issue, that shall take into consideration the temperature of the
gap and the current through it. The gap opens when the current through
is low enough, and it is cold enough (I have some ideas on how to model
gap, but will first hear what others comment). A simple switch that
opens at
fixed times will not give correct results. 
The idea of "resonant charging" never works as ideally assumed, because
if the gap closes in the first cycle it drains all the energy that would
have to accumulate in the circuit, were it really resonate. The
can only be useful if the normal output voltage of the transformer is
enough to ignite the gap. The increased voltage due to resonance will
eventually ignite the gap, after a few cycles -without- ignition.
The input circuit is not working at sinusoidal steady state, and the
consideration that there is a capacitance value that cancells out the
output reactance of the power transformer does not work correctly. It
is an approximation at most.

Antonio Carlos M. de Queiroz