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

[Bob Camp]

Hi

My guess is that you're already stuck with ultra pure gas to get it working as a maser.

Bob



On Sep 1, 2010, at 8:40 PM, Robert Darlington <rdarlington at gmail.com> wrote:

> And cryo means ultra high purity helium.  I learned about that the hard
> way.  They don't like pumping gravel (solidified trace amounts of oxygen,
> argon, etc.)
> 
> -Bob
> 
> On Wed, Sep 1, 2010 at 5:37 PM, J. Forster <jfor at quik.com> wrote:
> 
>> 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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>> 
>> 
>> 
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