[time-nuts] So what’s inside that Cs Beam Tube anyway?

Attila Kinali attila at kinali.ch
Tue Nov 1 06:51:21 EDT 2016

On Mon, 31 Oct 2016 14:50:51 -0700
ed breya <eb at telight.com> wrote:

> It's a shame that they're not built in such a way that just the wear-out 
> parts could be replaced, and not wasting all the rest of the design and 
> craftsmanship that's probably just fine.

Because it's not that easy. We are talking about a high vacuum system
here. While you can get a vacuum tube working with a simple rotary
pump. You can even have something like an ion pump to make the vacuum
a bit cleaner and make it perform better. But this will not work with
the level of vacuum you need for a Cs standard. A small finger print
left somewhere on something, will outgas for many months and make
the whole system perform an order of magnitude or two worse than speced.

Yes, Cs beam standards are not as finicky as the modern Cs fountains
or even worse the optical clocks, but they are still very sensitive.

It would be possible to make the tube such that you could change the
"consumables". But it would still take a skilled technician in a clean
lab with special equipment to do the maintenance. But I am not sure
whether it would be that much cheaper than a new tube. And you always
have the risk that something goes wrong and you have the scrap the
tube for good. 

			Attila Kinali
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
                 -- Miss Matheson, The Diamond Age, Neil Stephenson

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