Jim,
On 11/01/2014 05:49 PM, Jim Lux wrote:
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.
Ah, yes, *most* time-nuts is not aiming to shoot their clocks into deep
space. We are satisfied to stay in geostationary orbit or lower ;-)
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.
Yes. I guess a bit of baking out the build is also to be recommended.
I guess most of us don't do vacuum in our labs, so there is a challenge
in itself, as there is many beginners mistakes to be done there.
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)
Have tou cared to get the right isotope or do you use the natural
abundance spreading? Hg-199 has an abundance of 16,87%.
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)
Ah yes. Got a NaI(Tl) scintilator with about 1 cm copper filter and a
matching PMT. No amp thought, but then again, I do not know what I
should measure with it. :)
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 was thinking the same, especially when consider optical clocks, then
40 GHz isn't as esoteric. Traditional cesiums and rubidiums use a pair
of synthesized frequencies being then sent into a step-recover diode
inside a tuned cavity which then does the mixing and selects the right
combination.
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.
Would be a fun project to do, things to be learned.
Cheers,
Magnus
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