Re: Static Gap question.

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Antonio Carlos M. de Queiroz" <acmq-at-compuland-dot-com.br> 

Tesla list wrote:
 >
 > Original poster: Ed Phillips <evp-at-pacbell-dot-net>

 >         I'm not experienced in this area but did built one "parallel 
pipe" gap
 > which worked quite well.  Used 3/4" couplings for copper pipe and
 > rounded the ends a bit by chucking the pieces in the lathe and using a
 > fine file until things "looked right".  I was surprised that when the
 > pipe was reasonably parallel there didn't seem to be any particular
 > tendency to spark at the ends only.  My gap has 7 pipes, with spacing
 > which will just "note break down" with the 12 kV NST connected open
 > circuit.  I found that by mounting the gap so the axis of the pipes was
 > vertical I had enough convection cooling to permit 30 second runs at
 > around 600 watts input to the transformer.  When I originally ran the
 > thing I had problems with fairly hard black "stuff" building up on both
 > sides of each gap.  Once I cleaned the pipes the first time this effect
 > almost disappeared.

I found a (bad) picture of a parallel pipe gap that I use:

http://www.coe.ufrj.br/~acmq/tesla/567gap.jpg

My original intention was to be able to adjust the gap spacing by
rotating all the pipes to the same angle. But this would require
very precise positioning of the screws that hold the pipes at their
centers, what was not the obtained result. Anyway, I can adjust the
gap easily, but the angles betwen the pipes become irregular. It uses
3/4" brass tubes, and becomes too hot after about 30 seconds too,
without forced ventilation.

It can be observed that the gap sparks at the edges when the pipes
are not very parallel, but shows no big preference when they are
almost parallel.
Maybe because the sparks push the hot, or ionized, air to the sides,
and then the spark keeps running along the pipes randomly, or because
other elements close to the pipes distort the electric field.

Antonio Carlos M. de Queiroz