Years ago I built such a gap based on 1" copper pipe and fittings:
http://hot-streamer.com/greg/vacgap.htm
http://hot-streamer.com/greg/junk.htm
I have not fired it up since 2005, when Katrina thoughtfully immersed it in dirty salt water. However, it worked fine before that, and still might.
I have no scope data for it, no idea how well it quenched, no performance data relative to other styles of spark gap. I used it with three different tesla coil power supplies, and it held up fine: 1) two 9kv/60ma NSTs, 2) two MOTs driving voltage doublers, 3) and an 11kv pole transformer at up to 7200VA.
Run times were as long as I wanted them to be--several minutes sometimes. I never had to shut down a coil due to overheating or power arcing. Clearly, the gap could remove heat faster than the arc could create it. The electrodes got only warm to the touch, even on runs over 1 minute. The gap faces got black and sooty-looking after a few minutes, but copper erosion was insignificant. I never had to replace the Cu reducers I was using.
The gap was maintenance-free. At first I cleaned the electrodes frequently. Eventually, I got lazy and quit cleaning it. This had no visible impact on performance.
On the plus side, the gap was easy to build, simple to adjust, maintenance-free, and capable of handling even pole-pig power levels without distress.
On the minus side, it was bulky, very loud, and required it's own 15A AC outlet & extension cord.
I never built a larger one, but I did build a smaller one based on 3/4" Cu pipe and fittings. It worked well on a 4"x18" coil driven by a pair of voltage-doubled MOTs. This little rig produced 42" streamers. Again, the noise level was obnoxious. Other than that, the little sucker gap was a winner.
If I ever get my workshop set up, I plan to experiment further with the sucker-style gap and take some o-scope readings.
Cheers,
Greg
P.S. Simple hyperbaric-type gap:
http://hot-streamer.com/greg/inside.htm
An even simpler variant:
http://hot-streamer.com/greg/blogap.htm
--- On Sun, 9/7/08, Sfxneon@xxxxxxx <Sfxneon@xxxxxxx> wrote:
From: Sfxneon@xxxxxxx <Sfxneon@xxxxxxx>
Subject: [TCML] High Power Static Gaps
To: tesla@xxxxxxxxxx
Date: Sunday, September 7, 2008, 12:05 AM
Hi All,
I'm curious about the spark lengths achieved by others
using a single static
vacuum aspirated gap, (I believe the one designed by Gary
Lau if memory
serves)? It uses a vacuum cleaner motor, PVC pipe and two
large copper tubing end
caps with holes in the middle for the electrodes.
What are the limiting factors with this type of gap? Can it
be scaled up for
higher power? It's a beautifully simple and elegant
design, without the need
for any close tolerance machine work like with rotaries,
and it's much safer
too.
Tony Greer
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