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

Jim Lux jimlux at earthlink.net
Sun May 5 13:42:06 EDT 2013

On 5/5/13 10:01 AM, Magnus Danielson wrote:
> Hi Jim,
> On 05/05/2013 03:59 PM, Jim Lux wrote:
>> On 5/5/13 1:48 AM, Magnus Danielson wrote:
>>> The above is a summary of things collected from a variety of sources,
>>> but I think this coarse walk-through of issues gives some insight as to
>>> what issues pops up where and the milage vary a lot within each group.
>>> Modern high-performance rubidium gas-cells outperform the early
>>> caesiums, high-performance crystals outperform several rubidiums.
>>> The HP5065A is an example of an old clock with really good performance,
>>> so modern is not everything, and the modern compact telecom rubidiums
>>> and for that mater CSAC is more space/power oriented than ultimate
>>> performance of the technology as such.
>> I wonder where mercury ion fits in the scheme of things, since that's
>> where we're spending some money for spacecraft applications right now.
>> It's supposed to be orders of magnitude better than Rb.

> It would be interesting to see if your effort on space qualified ion
> traps spills over to the commercial market. If you get spare samples, I
> can give you an address to send them. ;-)

Hah.. getting just one made is a chore.. I've not worked on the project, 
but it's in the same general program as the stuff I do, so we all see 
each others' presentations at the semi-annual reviews.  It took 
significantly more time than expected to get the physics package 
manufacturing worked out.

Then there's whole thing of making 40 GHz electronics that are small, 
low power, radiation tolerant, etc.; I seem to recall that there's a 
tiny PMT in the system too, so that means HV, which is no easy feat 

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