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Re: Re: Racing Spark Prediction

Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Very informative explaination of the two modes. Are the two frequencies just present (sinA + sinB) or do they modulate (sinA*sinB) and produce side bands. I my thinking on this is admittedly loose and centered around the presence of two frequencies not modulating but still beating with each other and a poorly quenched SG allowing enough time for the two frequencies to beat with each other in a way maximize a voltage gradient.

Gerry R.

Original poster: <a1accounting@xxxxxxxxxxxxx>

> and forth between the secondary and primary and does not decay fast
> enough for the beat to occur.  If this thinking is correct, maybe
> this explains how quenching (or lack of) can be one cause (but not
> the only cause) of racing arcs.  Even with perfect first notch
> quenching, I think, racing arcs can be caused by excessive coupling.
> Gerry R.
You should not think about the energy of one of the modes moving from primary to secondary because that is not what occurs.
Try this quick explanation below. I hope it helps

There are two ways to think or describing how the energy sloshes back and for.
One way is to think about a sin wave that starts of large in the primary and is gradual transferred to the secondary and then back to the primary. The energy flowing from primary to secondary and back. i.e. an amplitude modulated sinwave

Mathematically its described as two modes (the split frequencies) that simultaneously oscillate in the primary and secondary. The secondary phase relative to the primary is +90deg for one of the modes and -90deg for the other. Initially both modes have equal (approximately) amplitude and phase in the primary. But in the secondary they are out phase by 180deg and hence cancel. So zero voltage initially in the secondary.

As time progresses because the frequencies are different for the two modes the primary oscillations shift out of phase (beats) and cancel so. So no voltage in the primary. At that time the oscillations are in phase in the secondary and sum. So the voltage in the secondary is at a max.

In short in the two mode description of the system the mode frequencies do not move from primary to secondary.

The two ways are equivalent. As you probably know they are linked via the trig identity sinA* sinB = sin(A-B) +sin(A+B)