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RE: spark gap ?



At 06:59 4/09/98 -0600, Gary Lau wrote:

>I think you know the answer now.  If you have no airflow, it's like
>asking "Will a 4 or 8 cylinder engine deliver more HP, even though I
>don't put oil in it?"  If you are determined to not use airflow, Terry
>Fritz has shown that gaps with a large number of very small spaces work
>well.  Gaps with 10 or fewer segments run TERRIBLY with no airflow,

Don't know that I would entirely agree with this.  I have a lot of respect
for Terry's work & build one of his gaps (TFG) shortly after his original
post.  This certainly produced an improvement over the 4-gap large-diameter
copper tube arrangement I had at the time.

Unfortunately this self-ignited as I had the rows of copper tubing too
close together (was > 2x total series gap for the row, but you have to
remember field concentration at the ends and adjacent surface effects !!!).
 Just a design point subsequent builders might want to keep in mind !

The real problem I had was fouling between the gaps, and from subsequent
posts I was not alone in this area ;-)

My subsequent/current gap has only *3 stages*, and even without airflow
this worked significantly better than the TFG.  This used tungsten TIG
electrodes and LOTS of heat sink.  3 gaps were chosen by chance ..... I
bought their complete stock ;-)

Conclusion ........ it ain't *that* simple.  I have been playing this game
for only 4-5 months (ie. complete bloody novice) but have realized there is
a lot of science in spark gaps !

>you should remember that airflow should be channeled THROUGH the gap arcs
>as much as possible.

Recently finished the forced-air part of the gap & this certainly improves
performance, but to a lesser degree than going from a TFG multi-gap to the
current one *without airflow*.

Both gaps can be seen at

	http://www.cobweb-dot-com.au/~dkfinnis/photos.htm

I strongly suspect that using a material, or providing an environment (eg
argon), which limits metal-oxidation is highly desirable.

My 2c worth .......



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