[time-nuts] Quartz Crystal Motional Movement

Attila Kinali attila at kinali.ch
Sun Jun 26 09:56:31 UTC 2016


On Sat, 25 Jun 2016 18:33:28 -0700
"Tom Van Baak" <tvb at LeapSecond.com> wrote:

> Don't forget about University of Western Australia's multi-decade gift
> to the world -- whispering gallery Cryogenic Sapphire Oscillator (CSO
>) -- which have Q near 1e9.


Yes, but these are entirely a different kind of resonator sturcture.
While quartz crystals are mechanical oscillators, ie a piece of material
stretching, contracting, twisting defining the resonant frequency,
the CSO are electromagnetic resonators, that trap a wave inside a
structure, much like cavity or stripline resonators.

The big Q in CSO comes from a much lower damping in the material
at cryogenic temperature and the ease at which a signal can be
coupled in without disturbing the resonator. Their biggest disadvantage
is that they need quite an infrastrucutre for cooling and constant
maintenance. The CSO's i've seen are all usualy just a couple cm
in size (around the size of a fist), but the cooling system fills
the better part of an 19" rack.

Fun fact: quartz crystals also get an increase in Q with cryogenic
temperatures, but not as high as CSO's.


			Attila Kinali

-- 
Malek's Law:
        Any simple idea will be worded in the most complicated way.



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