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

J. Forster jfor at quik.com
Wed Sep 1 23:37:36 UTC 2010


Yup. If you do use oil, you need an LN2 trap.

-John

===============

> 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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