[time-nuts] homebrew H maser

jimlux 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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