Hi > On Nov 2, 2014, at 6:09 PM, Magnus Danielson <[email protected]> > wrote: > > Bob, > > Yes, but your Q will suffer.
Ok, so it might / might not work depending on how high a Q it needs to start functioning. I think I might try it before I went crazy coating he bulb. There will be a *lot* of weird things to debug and associated tear downs to find them. Having a fragile bulb coating to deal with on top of everything else might just be more than can be dealt with. Bob > > Yes, I've dug out *aged* papers. I was sad to see that JPLs server was taken > down before I got to download their wealth of papers. Naturally it happen > just after I found out it also had a hydrogen maser section, but also Chuck's > papers was lovely to have collected in that form. > > I have been lazy not to read up on all the hydrogen maser I have in book-form > at home... should definitely read up more on those. > > It is interesting to see how variation on themes got considerable narrower > somewhere in the 60/70s shift to the rubidium gas-cell, active and passive > hydrogen maser and finally cesium atomic beam. It seems like the knowledge of > why they narrowed down to that set is somewhat lost to most, but as one reads > up on the old stuff one learns of the variation of these themes that have > been tested. The CSAC thus belongs to the gas cell type for instance, with > that set of problems, but with a few twist and turns. The fountains (Cs or > Rb) is a variation of the beam apparatus, but with a few twist and turns. The > ion clocks is really an extension of the hydrogen maser's bouncing box in > it's attempt to create long observations times. > > I think I recall that someone attempted a cryogenic hydrogen maser, which > would have benefits as to the lower temperature and thus speed of the > hydrogen atoms, producing even longer observations times. Hydrogen being so > darn light get into high speed for the temperature. Oh, some doppler benefits > would also to be expected. > > Cheers, > Magnus > > > On 11/02/2014 11:20 PM, Bob Camp wrote: >> Hi >> >> OK, it works better if it bounces off the wall. The line width is narrower. >> Does it work at all (is there a line you can find) without the coating? >> >> Yes you would need to find a paper from the 1960’s to find anybody trying to >> run one that way. >> >> Bob >> >>> On Nov 2, 2014, at 5:04 PM, Magnus Danielson <[email protected]> >>> wrote: >>> >>> Hi Attila, >>> >>> On 11/02/2014 10:43 PM, Attila Kinali wrote: >>>> On Sun, 2 Nov 2014 16:28:47 -0500 >>>> Bob Camp <[email protected]> wrote: >>>> >>>>> It’s been way too many years since my last Maser play session … >>>>> >>>>> Will it fire up *without* the Teflon coating on the bulb? Yes it works >>>>> *better* with the Teflon (less wall interaction). Getting the bulb >>>>> re-coated might be a major pain. >>>> >>>> According to some of the papers i've read, parafin might be an alternative >>>> to Teflon. The interaction of Hydrogen with Teflon is lower than with >>>> Parafin, but it might be acceptable (Curiously, if it were a Rb maser, >>>> you'd use a parafin coating instead of a Teflon coating). >>> >>> Parafin was used early, but in the strive to even further increase the >>> interaction time with the hydrogen in the "bouncing box", telfon was >>> preferred. >>> >>> In the early days they experimented with different coatings. The goal was >>> to increase the time (and thus narrowing the bandwidth) of interaction >>> before the hydrogen atoms loose state and cause a frequency shift. Rubidium >>> gas cells have similar wall-shift, but advancements have stabilized the >>> wall-shift by buffer-gas selection. >>> >>> A way to estimate the wall-shift is to run different sizes of glas-bulbs, >>> and notice the maser frequency shift. >>> >>> The old hydrogen masers where really experimental platsforms to a much >>> higher degree, but that also meant that validation was done. >>> >>> Then again the cavity shift is there, something that can be measured and >>> compensated as a separate control loop, which has contributed to increase >>> the stability and thus performance. Some hydrogen masers have proven >>> themselves to be much more pressure sensitive than others. >>> >>> Finding the lack of hydrogen masers in my lab disturbing. >>> >>> Cheers, >>> Magnus >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
