[time-nuts] Fwd: Re: homebrew H maser

Bob Camp lists at rtty.us
Wed Sep 1 23:34:37 UTC 2010


Hi

My guess is that you either need a cryo pump or ion pumps and a very good seal.

Bob



On Sep 1, 2010, at 5:15 PM, Robert Darlington <rdarlington at gmail.com> wrote:

> You can pickup oil diffusion pumps pretty inexpensively.   They're not quite
> ion pumps but they get you way down there and they're fast.  With proper
> traps you don't really have to worry about coating your experimental physics
> package with oil.  They're cheap to run and easy to maintain.  Ion pumps are
> about as simple as things get and could probably be made very easily by some
> of us "vacuum-nuts" but I never had the need.  Turbo pumps probably won't do
> the job and they're expensive and unforgiving.  Not only did one of mine
> crash, it crashed when a sputtering gun melted through.  80,000 RPM spinning
> foil blades don't like hitting the gun cooling water very much!
> 
> Good luck!
> 
> -Bob
> 
> On Wed, Sep 1, 2010 at 2:30 PM, Chris Howard <chris at elfpen.com> wrote:
> 
>> 
>> 
>>  Given the quality of vacuum the manual seems to imply, I'm guessing this
>>> wont cut it.   I'll bet that even low impurity Teflon has a long bakeout
>>> period.
>>> 
>>> 
>> Too bad they don't have some kind of "getter" to allow lower vacuum specs.
>> I expect they thought of that.
>> 
>> The thing does sound like a giant hydrogenated vacuum tube.
>> 
>> 
>> 
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