To minimize the possibility of leaks in the tubing between the pump and chamber, I replaced the tubing with brass fittings, inspired by the Oakland University demo fusor viewtopic.php?f=18&t=10731&p=71044&hili ... sor#p71044, detailed in their report: download/file.php?id=10487
I integrated the ball valve into the line. (photo 3).
There was a definite improvement in plasma quality. At less than 1/4 maximum variac output and seconds of pumping, I got the same level of plasma as I was getting at max power and ten minutes of pumping before. It looked like this when first turned on:
Eventually, after a cleaning, tightening of some threads, and at a higher voltage input, I got some very nice pictures.
Still only marginal improvements. Based on other image of similar demo fusors (such as the images on this post: viewtopic.php?f=18&t=7838), I don't think the vacuum could possibly be better than 1000 mtorr, and is probably much worse. More work is necessary. On future runs, I will probably try not using vacuum grease and/or replacing the teflon tape with Loctite 290.
-John
New Brass Piping, plus updates
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- Posts: 52
- Joined: Fri Sep 02, 2016 2:35 pm
- Real name: John Beutz
- Location: Minnesota