[time-nuts] homebrew H maser
jimlux at earthlink.net
Thu Sep 2 04:48:07 UTC 2010
J. Forster wrote:
> If you try to cut corners with high vacuun technology, you will be
> disappointed. Even with all new parts and carefull assembly, you will
> almost certainly have to He Leak Detect the system to get it tight. I've
> done this stuff. It is doable but certainly not trivial. And you cannot be
not trivial is an understatement..
High vacuum seems straightforward until you sweat blood on it. Oh. that
fingerprint that serves as a virtual leak for weeks. That Kapton tape
that trapped a few molecules of whatever under it and outgassed.
The gas diffusing out through the drilled bolt.. sure it's drilled, but
the conductance is so patheticaly low, you're literally waiting until
the gas molecules happen to randomly bounce their wey up the hole.
It is the most horribly frustrating experience you will have. Unless
you're running HUGE fast pumps.. then you just don't care.. Back when I
sweated this kind of thing, I would have killed for the size pumps we
run at JPL on the big vacuum chambers.. Outgas, what outgas, it just
gets pumped away... But when you're running a 2 or 3 inch diff or turbo
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