On Sat, 25 Jun 2016 18:33:28 -0700 "Tom Van Baak" <t...@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. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.