Mike:
After trying Varian Starcell and Varian triode ion pumps on
our extraction line several years ago, we ended up giving up on them
and relying entirely on turbo pumps. Both the Starcell and triode
pumps had very low blanks as long as they pumped entirely clean gas.
However, as soon as they were exposed to any incompletely gettered
gas still containing reactive components, their argon blanks
increased to unacceptable levels and stayed there until they were
baked. Eventually we decided they were more trouble than they were
worth as extraction line pumps, and removed them from the line. We
have a Varian triode pump on our MAP 215-50 mass spectrometer that
has never had a high blank problem, presumably because it has only
pumped clean gas.
We have never tried non-Varian ion pumps, perhaps they
operate better on extraction lines. I expect that two stage
turbo-then-ion pumping, as suggested by Mack Kennedy, would prevent
the high blank problems that we experienced.
Bill McIntosh
>I was wondering if anyone has had experience with performance of Varian
>Starcell pumps vs Phi (Perkin Elmer, Physical Electronics) differential ion
>ion pumps. The pump is to go on the extraction line of an Ar system and thus
>will see the full range of gases and associated crap. Prices are essentially
>equivalent and the performance specs look broadly similar, but the details
>are difficult to unravel.
>
>Any input or recommendations from other members of the board would be
>appreciated.
>
>Mike Villeneuve
>Geological Survey of Canada
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William C. McIntosh
[log in to unmask]
Volcanologist/Geochronologist
New Mexico Geochronology Research Laboratory
N.M. Bureau of Geology
New Mexico Tech
801 Leroy Place
Socorro, New Mexico, 87801-4796, USA
505-835-5324 office; -5271 lab; -6333 Fax
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