Ion Pump

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Peter Schmelcher
Posts: 228
Joined: Sat Nov 13, 2010 1:56 am
Real name: Peter Schmelcher

Ion Pump

Post by Peter Schmelcher »

Ion pumps are not needed for fusors, I just got tired of the continuous pumping noise so I added an old used 8L/s Varian on pump. The 8L/s specification is at the mounting flange with no flow restrictions, so my pumping speed around two bends is considerably slower. Basically this ion pump is a penning gauge optimized for pumping atoms. The operating voltage is 3300V and it consumes under 3.5W (100uA = 1E-6 Torr). Before bake out the operating current was high and the resulting pump lifetime would have been only a few days. I shut down the HV and did a good bake out for 24 hours. After the bake out the initial current was 8uA. The current gradually increased over many weeks but has finally stabilized. The pressure rise is probably a result of o ring hydrogen permeation finally reaching equilibrium and this process takes months.

The chamber pressure is 70E-7 +-10Torr and varies with changing room temperature.

The panel meter was an after thought that makes it easy to see how good the well used pump is working. Ion pumps consume themselves by the physics of pumping. At this pressure a new pump would last 5 years.

-Peter
IonPump1.jpg
IonPump2.jpg
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Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Ion Pump

Post by Dennis P Brown »

Very nice unit - getting it up and working to such a low value is impressive. Could do some very high-quality metal coatings (high purity) especially at the low-end range! Maybe a Pd or Ti target coatings for wall fusion testing?
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