Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx> Hi Cameron,Using five 2.25" diameter stock, you want about 0.25" total gap spacing for 14.4kV. So about 0.06" gap per segment. It doesn't always work out to 1/4", but the diameter of your pipe predicted that value. As with all gaps, there can be a decent amount of error in calcs due to shape and surface. Make sure you polish them up including the ends.
I personally would not be comfortable with a static gap for a pig, especially with little thermal conductivity (so few pipes). It will work yes, but you may get real hot - real fast. The pipes will require a lot of air cooling to keep the gap arcing at a reasonable voltage. This however does make a great gap for 60mA to 120mA supply.
When it gets hot, the breakdown voltage will drop, and your spark lengths will start out great, but soon diminish in length. This can happen rather fast if the gap is processing a lot of power. Thus, the recommendation for RSG's when running pig power. Piping heats up and cools down quickly, but if the cooling is not adequate for the power, it will get hot fast and stay hot.
Take care, Bart Tesla list wrote:
Original poster: "Cameron B. Prince" <cplists@xxxxxxxxxx> Hey guys, I've been working on a large series gap for my pole pig driven coil and I have a few questions. My prototype can be seen here: http://www.teslauniverse.com/members/cprince/images/seriesgap/ It's using five 2.25 inch O.D. brass nipples for four gaps maximum. My main concern is the gap distance. As you will see in the photos, a standard sheet of paper will just barely slide between some of the gaps. The others are slightly wider. I tried my best to maintain tolerances, but it's very difficult to drill the 7.25 inch PVC couple properly even with a press. My other concerns are the number of gaps. Is four going to be enough? Any thoughts, suggestions or feedback would be greatly appreciated. Thanks, Cameron