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

[J. Forster]

Apples and oranges.

What Robert presumably means is tha the working fluid (He) in the closed
cycle refrigerator used in a cryopump has to be extrremely pure to avoid
freezing up in the expansion engine at the cold side.

As I said before, the H2 probably does not have to be Research Grade,
because the H2 is admitted to the MASER system via a "Palladium Valve".
Such a valve is, in fact, a solid Palladium plug that is heated. H2
diffuses through Palladium at high temperatures, but virtually not at all
at room temperature. The flow rate through the "valve" is adjusted by
adjusting the temperature.

Palladium is also used to purify H2, as other gasses do not diffuse
through it significantly.

-John

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


> 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.
>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> time-nuts mailing list -- time-nuts at febo.com
>>>>>> To unsubscribe, go to
>>>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>>>> and follow the instructions there.
>>>>>>
>>>>> _______________________________________________
>>>>> time-nuts mailing list -- time-nuts at febo.com
>>>>> To unsubscribe, go to
>>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>>> and follow the instructions there.
>>>>>
>>>>
>>>> _______________________________________________
>>>> time-nuts mailing list -- time-nuts at febo.com
>>>> To unsubscribe, go to
>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>> and follow the instructions there.
>>>>
>>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>