[time-nuts] Hydrogen Maser KIT! Update #1

Bob Camp kb8tq at n1k.org
Sun Nov 2 17:20:25 EST 2014


OK, it works better if it bounces off the wall. The line width is narrower. Does it work at all (is there a line you can find) without the coating?

Yes you would need to find a paper from the 1960’s to find anybody trying to run one that way.


> On Nov 2, 2014, at 5:04 PM, Magnus Danielson <magnus at rubidium.dyndns.org> wrote:
> Hi Attila,
> On 11/02/2014 10:43 PM, Attila Kinali wrote:
>> On Sun, 2 Nov 2014 16:28:47 -0500
>> Bob Camp <kb8tq at n1k.org> wrote:
>>> It’s been way too many years since my last Maser play session …
>>> Will it fire up *without* the Teflon coating on the bulb? Yes it works
>>> *better* with the Teflon (less wall interaction). Getting the bulb
>>> re-coated might be a major pain.
>> According to some of the papers i've read, parafin might be an alternative
>> to Teflon. The interaction of Hydrogen with Teflon is lower than with
>> Parafin, but it might be acceptable (Curiously, if it were a Rb maser,
>> you'd use a parafin coating instead of a Teflon coating).
> Parafin was used early, but in the strive to even further increase the interaction time with the hydrogen in the "bouncing box", telfon was preferred.
> In the early days they experimented with different coatings. The goal was to increase the time (and thus narrowing the bandwidth) of interaction before the hydrogen atoms loose state and cause a frequency shift. Rubidium gas cells have similar wall-shift, but advancements have stabilized the wall-shift by buffer-gas selection.
> A way to estimate the wall-shift is to run different sizes of glas-bulbs, and notice the maser frequency shift.
> The old hydrogen masers where really experimental platsforms to a much higher degree, but that also meant that validation was done.
> Then again the cavity shift is there, something that can be measured and compensated as a separate control loop, which has contributed to increase the stability and thus performance. Some hydrogen masers have proven themselves to be much more pressure sensitive than others.
> Finding the lack of hydrogen masers in my lab disturbing.
> Cheers,
> Magnus
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