[time-nuts] Re: ammonia, cesium, masers, etc.

[Lux, Jim]

On 9/20/21 7:17 AM, Poul-Henning Kamp wrote:
> --------
> paul swed writes:
>
>> Though honestly bending 23 GHz waveguide might be tricky. Or simply leave it
>> straight after all it Amatuer grade.
> I seem to recall that there was about 10-ish meter coiled up in the
> one on the famous old picture.  That might be a bit unwieldy.  On the
> other hand, that was probably not waveguide as much as just plain
> copper-tubing ?

That would depend on whether you want to control moding. (the picture 
says rectangular) Bending WG is pretty easy if the radius is large 
compared to the size of the WG - it's very soft copper, so you just need 
an appropriate form around which to bend it. The trick of filling it 
with sand also helps.  At 23 GHz, you probably want to use WR34 or WR42 
(Hmm, probably the bigger, so you're farther from cutoff, 17 and 14 GHz 
respectively).

>
>> Lastly they discussed an Amonia maser. Never knew. Wonder if it actually
>> vented amonia slowly. Sort of sounds that way.
> I would suspect the main problem with an amonia maser is that the
> Amonia disassociates and the hydrogen leaks out though the metal ?
>
I wonder, though, if you were "building your own atomic clock" whether 
ammonia might not be easier than Cs or Rb, for instance. These days a 23 
GHz oscillator and other parts are fairly easy to come by, and ammonia 
is somewhat easier to handle than Cs or Rb. I would normally think you 
can get any of them by just ordering them, but since ammonia is used in 
synthesis of methamphetamine, it may not be so easy to get a small 
bottle of ammonia gas.