Dear Attila You don't need a cryo-cooler, you can just use a cryostat if a break in operation (when you top up the helium) is not a problem. We operated one of the UWA CSOs like this as the flywheel for our Yb trapped ion frequency standard.
A few other national standards labs use the CSOs - one for an ultra low phase noise reference, another as the flywheel in their timescale comprising fountains etc. Cheers Michael On Thu., 10 Nov. 2016 at 11:48 am, Attila Kinali <att...@kinali.ch> wrote: > On Thu, 10 Nov 2016 11:20:37 +1100 > Jim Palfreyman <jim77...@gmail.com> wrote: > > > Anyone got any comments on this? > > > > > http://www.theleadsouthaustralia.com.au/industries/technology/worlds-most-precise-clock-set-for-commercial-countdown/ > > Cryogenic sapphire or whispering gallery mode oscillators have been around > for quite some time. You basically have a piece of sapphire (aluminium > oxide > in crystaline form)[1] in a cavity[2,3], cool everything down to liquid > helium temperatures and use this as an oscillator. There are two popular > configurations, one is to use the sapphire as resonant element like in > an LC or crystal oscillator, or more commonly, to use the sapphire as a > filter element in Pound locking scheme[4]. > > The short term stability of these oscillators is AFAIK unsurpassed > and flat up to 1000-10'000s, but exhibits drift at longer taus[5]. > > Their biggest problem is that they need a liquid helium cryo-cooler > which causes vibrations that need to be carefully filtered out. > This also makes them relatively large (fill between one and two 19" racks) > > > Attila Kinali > > [1] http://www.uliss-st.com/uploads/pics/tech2.jpg > [2] http://inspirehep.net/record/1244235/files/cavity.png > [3] http://www.uliss-st.com/uploads/media/imgmedias.jpg > [4] That's the (original) microwave variant of the Pound-Drever-Hall > locking scheme, see > https://en.wikipedia.org/wiki/Pound%E2%80%93Drever%E2%80%93Hall_technique > [5] http://inspirehep.net/record/1409150/plots > -- > 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. > _______________________________________________ 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.
