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Re: Aluminum electrodes in TCBOR static gap




Hi all,

>> The gap unit WAS firing and making a huge glow, but no spark.
>
> This sounds very much like something that Malcolm mentioned about
> his single static gap running well at low voltages, but just "fizzing"
> at higher voltages.  This sounds like a total power input power
> arc....no quenching at all.  In other words, like just arcing a NST as
> in a Jacob's ladder more or less, possibly caused by overheating of the
> gap.
>
> cheers,
> John Freau

I think this behaviour may be due more to overheating of the static gap,
than lack of actual quenching.  I have seen this happen whilst monitoring
the static gap voltage waveform.  When the static gap overheats the
breakdown voltage drops considerably,  and the spark gap seems to
"re-ignite" preamaturely following each firing.  This results in the
static gap firing at a much faster rate,  but with the tank capacitor only
partially charged.  The higher firing rate causes a high pitched "frantic
fizzling" sound from the gap and even more heating.

Since bang energy is proportional to V^2,  the lower firing voltage causes
bang energy to drop like a rock !  Although the firing rate is higher, it
is outweighed by the massive drop in bang energy.  The total power
throughput falls and the secondary sparks cease.

I found that high voltages,  and small capacitors were worst for provoking
this effect.  I eliminated the problem with a large volume of air blown
through the TCBOR-gap,  before moving to a rotary design.

Well that is my theory anyhow,
Comments ?
                                                Cheers,

                                                - Richie,