[time-nuts] Heating or Cooling an LPRO (was Re: chip scale atomic clock)
Magnus Danielson
magnus at rubidium.dyndns.org
Fri Jan 1 13:55:07 UTC 2010
Bob Camp wrote:
> Hi
>
> As I recall there are "good reasons" for the temperatures that the physics package gets stabilized to. Something about the C-field and the temperature combining to improve the state selection.
It rather relates to the properties of the gas cells. The gas-lamp needs
to be heated. The intensity of the ligth will perform a frequency
pulling, so that forces you to want the gas lamp to have a stable
intensity, which implies a stable temperature. The filtering gas cell
will modulate its transparancy with temperature. The Rb-85 does not
perfectly match the line of Rb-87 that we want to let through, so it
needs heating for a good match to occur and stable such as the intensity
for the line will be modulated by the temperature. The resonance gas
cell needs stable temperature to let the wall-shift and gas-shift in a
stable balance. The modulation due to intensity is a significant pulling
factor. The cavity pulling of the resonance cavity also depends on
temperature, as it deforms the cavity. The main problem with these
standards is keeping all of these shifts stable. This is why ovenization
is used. It is also very clearly the physical package that needs it and
the my-metal.
> Of course we have made it to the eiswein, so that may be a bit off...
Well, as long as we are having the eiswein, and not the Rubidiums, we
should be fine.
Cheers,
Magnus
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