[time-nuts] OCXO sensitive to gravity
Magnus Danielson
magnus at rubidium.dyndns.org
Fri Aug 14 07:52:14 UTC 2009
Rick Karlquist wrote:
> Tom Duckworth wrote:
>> The orientation change is due more to the earth's magnetic flux effect on
>> the oscillator, and less so from gravity.
>>
>> Tom
>> Tom Duckworth
>> tomduck at comcast.net
>
> Sorry, this is simply incorrect. Magnetic flux from the
> earth has no effect on quartz oscillators. There is no
> mechanism there. Acceleration definitely affects quartz.
>
> Magnetic flux could have an effect on atomic standards,
> but they normally have magnetic shielding to mitigate
> this effect. Orientation (or at least acceleration)
> can affect cesium beam standards because the atoms
> are flying. Len Cutler put in a fix to mitigate against
> this in the 5071A CBT. AFAIK, orientation doesn't affect
> Rb standards.
Magnetic flux do influence rubidium standards as well, infact they are
more sensitive than cesium. Again, magnetic sheilding is used, but to a
less excessive level than cesium and hydrogen. All atomic clocks do in
their physics depend on the magnetic field, and modern cesium clocks use
nearby sidebands (mf=-1 and mf=+1) which has much higher dependence on
magnetic flux as gears to steer the magnetic flux for the center (mf=0)
pidestal.
However, rubidiums optically pumped gas cells (which is a more accurate
description of what we call "normal" rubidium clocks) has a number of
severe limitations, which makes excess shielding pointless.
A rubidium fontain however... now that is a different matter altogether.
Cheers,
Magnus
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