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Vortex gap loss measurements

Today I found some time and performed a comparison between the gap losses of
my single vacuum gap, and my new single vortex gap.  To do so, I scoped the
primary ringdown with no secondary in place.  I used a Terry Fritz fiber
optic voltage probe across the primary coil and a digital storage scope to
record the results.  I have not yet accurately calibrated the voltage
readout, so for now, the results are just relative to each other.

With no secondary in place, the ringdown is a linearly decrementing
waveform, not logarithmic.  As such, the slope of the ringdown indicates the
losses in the circuit and is independent of the gap firing voltage.  I
performed ringdown slope measurements at a variety of gap widths to vary the
initial voltage, but the ringdown slope is a constant, independent of Vgap.

The power to the blower motor is varied through a lamp dimmer and I tried
varying the motor speed to see what effect that had.  At very low speed, the
linearly decrementing waveform became slightly logarithmic-looking, but
still predominantly linear.  The gap breakdown voltage appeared to change
slightly at low speed, but this was hard to measure as it was slight and the
bang-to-bang gap breakdown voltage is not as consistent as one might hope.

The slope decrement figures are assuming that my probe is accurately
calibrated for voltage, though I suspect it may not be, so the figures are
useful only for relative comparison purposes.  
The pressurized vortex gap decremented at 200V/usec.
The vacuum gap decremented at 235V/usec (17.5% faster).
The vortex gap breakdown voltage is about 20% higher than the vacuum gap at
the same gap distance.

Vortex gap web page: 


Vacuum gap web page: 



Regards, Gary Lau
Waltham, MA USA