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RE: Gary Lau's gap
>Original Poster: "Payne, Will E" <will.e.payne-at-lmco-dot-com>
>
>I switched to a Lau Gap with good results. I have 40 in sparks using 0.017
>uF SW caps and about 1.3 kW input. However, with close spacing, I will
>suddenly lose breakout, followed by an audibly "faster" sounding SG
>discharge which continues to increase until its almost a continuous sounding
>arc. Obviously at this point quenching is virtially non existent. Input
>power rises and I have to shut down. Running of the airflow with no SG
>discharge for 10 s to 1 min seems to clear the problem for a while, but its
>getting worse. Reducing the power by opening 3/4 of my ballast switches (HW
>elements) will not restore quenching once its lost. Wider gap is less
>sensitive, but mine will not fire at the lowest power setting.
>
>I'm using 3/4 Cu pipe end to end with no fittings. I thought ionized air
>was being trapped in a boundary layer and killing the quench, but I have to
>shut off HV for much longer than I would expect for this failure mode. My
>Cu electrodes are becoming dark and eroded which may be a factor. RIght now
>I'm down because the washtub sprung a leak, when I'm up agin, I hope to be
>instrumented for measurements thanks to Terry and his excellent Mk I fiber
>optic VI probes. Y'all missed the bargain of the century.
>
>I still want to know if I'm in the ballpark with 40 in from my SW cap
>system, running from a 70:1 PT, about 1.3 kW thru the xformer, maybe 2-3 kW
>in ballast.
>
>Will
>
>ps Gary is it OK with you to post this type gap on my site ?
Hi Will:
No problem posting your gap, I doubt I'm the first person to use a
single gap.
I suspect that your use of 3/4" pipe with no fittings may be making your
quench worse, due to the sharp radius of curvature on the ends. This
will cause sparks to break out prematurely and to power-arc. See my
recent post about safety gap experiments! With my main single gap, I
made sure that the arcing surfaces were as flat and blunt as possible.
What was your gap spacing and what is your PT voltage?
Regards, Gary Lau
Waltham, MA USA