[time-nuts] vs Hg ion? Re: GPS clock stabilitiy, Rb vs Cs

[Magnus Danielson]

On 05/05/2013 06:50 PM, Jim Lux wrote:
> On 5/5/13 8:42 AM, Richard (Rick) Karlquist wrote:
>> At HP in the 1990's, Len Cutler's group built some experimental
>> mercury ion standards for USNO (IIRC). They were of the
>> trapped ion type. BTW, it is important to understand that
>> the architecture is the key factor, not the flavor of atom.
>> When people say rubidium is inferior to cesium, they really
>> mean a gas call is inferior to an atomic beam, etc.
>>
>>
> OK, that's interesting..
>
> So the Hg ion they're building for Deep Space Atomic Clock (DSAC) is a
> trapped ion type. The whole thing is, as I recall, 1 liter, 1 kilo,
> including both the physics package and the electronics.
>
> It's targeting USO type applications.

They have been targeting this goal for a very long time. Several 
interesting papers is to be found at PTTI, NIST etc.

Getting good performance with small volume and power is definitely 
interesting, and it does not have to be on the rice-grain level.

Cheers,
Magnus