[time-nuts] Mercury Ion Clock

Magnus Danielson magnus at rubidium.dyndns.org
Sat Nov 1 14:08:09 EDT 2014


The lack of hydrogen masers here is disturbing. So is better cesiums 
tanked up and fresh.

Will see what I can do with what I got.

Fixing up rubidiums and cesiums is currently how far this lab goes.


On 11/01/2014 06:23 PM, paul swed wrote:
> Magnus I would say that yes I do have various backups and none as good as
> any of this discussion. Agreeing with Jim much of this appears to me to be
> semi-reasonable and in particular in a amateur lab environment. But I am
> afraid thats just about how far I am going to get on the project. Its right
> behind the H maser. Any day now. Recovering the Frankenstein CS was about
> my real limit. I haven't seen any tubes show up on ebay lately. :-) Such is
> life.
> Regards
> Paul
> On Sat, Nov 1, 2014 at 12:49 PM, Jim Lux <jimlux at earthlink.net> wrote:
>> On 11/1/14, 9:08 AM, Magnus Danielson wrote:
>>> Paul,
>>> You mean, as all time-nuts already have redundant sites with at least 4
>>> 5071As with high-performance tubes, redundant cesium and rubidium
>>> fointains, set of active hydrogen masers, with everything in tight
>>> temperature, humidity and pressure control, UPS and diesel-engines,
>>> GPS/GLONASS/GALILEO receiver on temperature-stabilized piller and
>>> antenna, do TWSTFT to major labs... since money is no issue, right?
>>> The main problem with cesium tubes as I recall it is really the ionizer
>>> in the mass-spectrometer being poluted with cesium, this then creates
>>> bad S/N before running out of cesium in the oven.
>>> Yes, I agree it would be a great clock to have, but practical limits in
>>> cost is a challenge for most, so it would be interesting to look at it
>>> and ask how cheap it could be done.
>> Having been to a few of the design reviews and such for the DSAC, and
>> before, when it was called the 1 liter atomic clock, etc.
>> I think one could build one *if* you have a fairly wide collection of
>> skills, and you weren't hung up on it being tiny and low power, and zero
>> maintenance.
>> For instance, building a perfectly sealed physics package that is space
>> flight compatible is non-trivial. Most of us don't have e-beam welding
>> equipment sitting around (nor does JPL.. we contract that kind of stuff
>> out).  As Prestage points out in the article below, they started looking at
>> how they build long life Traveling Wave Tubes for space (another precision
>> ion optics device), and having spent some time in various TWT factories
>> over the past 15 years: there is a lot of art in the manufacturing process.
>> http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/41329/1/07-2003.pdf
>> http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/41395/1/08-0610.pdf
>> However, if you were happy with "lab grade" construction, and you have the
>> Kurt Lesker and Duniway catalogs as bedside reading, I think you'd have a
>> chance.
>> The ion trap and such is a fairly straightforward thing, from what I
>> understand: you need the usual vacuum pumps and such to build one.  If you
>> don't want it to run for years without servicing, then issues of the
>> mercury content are less important.
>> (BTW, the space clock uses thermal dissociation of HgO to get the mercury)
>> The PMT is an off the shelf thing. Check out the amateur built fusion
>> reactor (fusor) websites on where to get PMTs and amplifiers (they're used
>> behind a scintillator)
>> The 40 GHz stuff these days is not nearly as exotic as it used to be. The
>> challenge might be test equipment when you're debugging your 40 GHz
>> synthesis chain.
>> I don't think it would be *easy*, but I think doable, and nothing in the
>> system is particularly expensive or that exotic.  It's sort of like
>> telescope building.. The raw materials to make a 18" reflector telescope
>> aren't all that expensive, nor is there some secret sauce: it's just time
>> to grind the mirror (and recover from mistakes) and build the system.
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