[time-nuts] homebrew H maser
jimlux at earthlink.net
Thu Sep 2 05:43:18 UTC 2010
Hal Murray wrote:
> jimlux at earthlink.net said:
>> 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.
> I've never worked with vacuum gear.
> I assume "drilled bolt" refers to a bolt through a drilled hole so there is
> some slop between the bolt and the hole.
No... the bolt has a hole through it, to provide a gas path when you
install it into a blind tapped hole. Otherwise, the trapped gas in the
bottom of the hole slowly leaks out past the threads.
> Can I use vacuum grease as a seal around the bolt? Or does it outgas too
> much if you are going for seriously low pressures?
For the most part, grease is more trouble than it's worth. Knife edge
seals are where it's at.
> Can I use a soft(er) metal washer and mash it to a gas tight fit by
> tightening the bolt enough?
Not exactly.. what you see is a knife edge cutting into a softer
metal... "mashing" implies gas trapped between layers.. That kind of
thing crops up in TWT manufacturing, where they stack all the parts of
the gun or the collector...
> How low a pressure does a H maser need? Where is it relative to say
> fingerprints outgassing?
That's a good question.. I don't know.
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