On 01/25/2013 03:52 PM, jb-electronics wrote: > Hi folks, > > I am still working on Nixie tubes, but I have to take it a little slow > at the moment because I switched my university and I am currently sort > of living in two cities ;-) > > However, today I had some time so I took a look at my vacuum system. > My problem was that even after I closed the valve to my pump at a > pressure of 1.5E-2 mbar, the pressure would rise up to 20mbar in 20 > minutes. So there was a leak. > > I then checked every part of my system (swagelok adapter, needle > valve) by replacing them with a blind flange and recording the > pressure after 10s, 20s, 30s, 40s, 50s, 60s, 120s, 300s, 600s, 1200s > and plotted them. I realised that there was insufficient greasing on > my needle valve, and the most interesting thing is that it is not > airtight if the scale is adjusted to just zero. You have to (gently) > adjust it below the scale zero point. Then I get a leakage rate of > just 1.2 琨ar/s which is very low. > > My system has a volume of at most (!) 65ml, so the leakage rate now is > Q = 5.4E-6 mbar l/s which is pretty good I think. See my results here: > > http://www.jb-electronics.de/tmp/leakage.png > http://www.jb-electronics.de/tmp/leakage_extensive.png > > Note that the Q value in these diagrams needs to be multiplied with 65ml. > > The next step will be to find a good connection to the pressure > reducer for my gas bottle. Right now I am using a PVC hose (terrible), > and I have huge leakage rates. > > But as always: One thing at a time ;-) > > Jens >
Very cool. So the leakage rate seems pretty low, but I'd be concerned about the total vacuum that your system can accomplish. Although I have never built nixie tubes myself, I did a good amount of research to go down that road. My research came up with some claims that you need to get down in the 10E-6 torr before the fill for good results with a nixie tube. Anyhow, please keep a image journal of your work. It looks like a great deal of fun. Michael- -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To post to this group, send an email to neonixie-l@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
