Hi Michael,
yes, I will document everything on my website. In fact, most of it is
already done, but right now I am writing the vacuum system part and I
want to document all the steps that I did until now. And now it is far
from perfect. So I will show all different setups and number them. My
current setup is setup number III.
It won't be long ;-)
Jens
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-
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