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Results of new single static gap




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From:  Marcus Young [SMTP:MEYoung-at-uq-dot-net.au]
Sent:  Tuesday, August 18, 1998 1:05 AM
To:  Tesla List
Subject:  Re: Results of new single static gap

Hello Teslaphiles,

Hello everyone! Been without internet for ages, but ime back on at last :)
Ill try answer a few quuestions here ...i say ill try!

>I have constructed a new, single stage static gap.  Imagine two 1.0" OD
>brass cylinder electrodes with a hole through their axis, 0.5" ID.  A
>vacuum cleaner motor is attached to a common manifold, so air is drawn
>across the faces of the two cylinders into their central holes.  The
>vacuum motor is on it's own variac.  Gap setting was 0.42".  Spark output
>was directly proportional to gap length.

OK, the air quenching for this type of gap probably requires a bit more than
what the average vacum cleaner could give you. A two electrode gap at the 
power your using probably needs something more like compressed air to 
achive a good quench. 

>With this gap I have achieved a new personal best - 51".  Previously I
>had been using a 10 x .03" fan cooled RQ-style gap, achieving 42".  Power
>supply is 15kV/60 mA NST, 4.25" x 23" #22AWG secondary, two stacked
>toroids- 4.5" x 15.5" plus 6" x 24".

Ime not sure exactly what an RQ gap is looks like, but if its a series gap 
Ime sure you can get more arc for your buck that way. Maybe that gap needs 
needs better air quenching. Dont forget how damn finicky you have 
to be about tiny adjustments with series gaps. Take the finicky adjustment
of the single gap and multiply it by 10 and do it under a magnifying glass!! 
hehe....Well allmost. :)
Ive allways found the smallest adjustment to the total spacing of series
gaps  
meant the difference between little sparks and great big arcs. 
Once when adjusting a series gaps on a similar powered system to yours,
I found altering spacing 'barley visible to the human eye' made a truly
profound difference to performance. 
Personally Ide go for a few less gaps...mebbe 8-6 or so. That in itself will
make tuning the gaps easier. 

>Also unexpected was the effect of the vacuum motor variac.  My goal in
>designing this gap was to maximize the airflow through the gap arc,
>believing that there was a critical value, above and below which would
>diminish results.  It turned out that any airflow, from maybe 5% of
>variac on up, produced the same performance.

Well, like I say a vacum cleaner probably isnt gutsy enough. Go for
compressed air.
Very easy to set up with only one gap.. 
Theres certainly a diminishing point. But the more air blast, the longer
the arcs, at least 
in my humble experience. Ime not sure if an upper critical limit actually
exists.. 

>To be fair, the 10 gap assembly was always operated at it's maximum
>number of gaps, so it's unknown and probable that I'd get better than 42"
>if I increased the number or setting of it's gaps.  I guess the next step
>is to build and compare with a multi-gap with comparable total gap

Ten or less should work just fine given a little more tuning I think. 


Another thing to remember is that when you change the total gap spacing,
your also 
changing the whole system to a degree. Less voltage in with closer spaced
gap will
mess with the power input levels which may in turn mess with the coupling and 
capacitance requirements. Try small adjustments of the coupling and the
terminal
capacitance when you change the gap distance..

Marcus