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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