cyropumping materials

[John Geary]

Posted to CCD-world:
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The recent discussion of the (non)desireablility of putting porous anodized
surfaces in vacuum touched on another side of vacuum practise, the use of
cold porous materials for cleaning up the dewar vacuum and especially for
sucking up residual water vapor.  Many of us use cold activated charcoal,
which has the advantage over zeolite materials in outgassing thoroughly at
room temperature, without radical heating needed.  However, it is in
practise a rather dirty material from a dust standpoint, which will
invariably be deposited on your CCD surface as if it were a magnet (it seems).

So, is there something more "solid" we could use?  I was thinking about cold
sintered bronze, often used for air filters and the like.  Anyone know
anything about this, or other materials?

--JG


"When the chips are down, the buffalo is empty"  -Anon.

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