Hello Thanks for your PDF Bob
> Message: 5 > Date: Mon, 03 Nov 2008 01:46:37 +0100 > From: Adrian <[EMAIL PROTECTED]> > Subject: Re: [time-nuts] Rb lamp lifetime... > To: Yuri Ostry <[EMAIL PROTECTED]>, Discussion of precise time and > frequency measurement <time-nuts@febo.com> > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset="iso-8859-1" > > Hello, > > there are some interesting hints (including lamp rejuvenation) in the > attached papaer that was posted here a few months ago by Gerald > Molenkamp VK3FGJM. > > Regards, > Adrian > > > Yuri Ostry schrieb: > > Hello, > > > > Readed list archives and googled a lot, and seen two opposing points of > > view - one is that there is nothing to age in Rb lamp, another is that > > Rb lamp is degrading when in operation (without details, how and why). > > > > I'm planning to get some Efratom Rb oscillator to use it in a > > constantly running home lab frequency reference. Trying to understand > > for myself, is it worth to get spare unit (or even two) of the same > > model just to have replacement lamp on hand. > > > > One more question - does someone seen Rb standard that is > > malfunctioned due to degraded lamp, that, at same time, does have > > good vacuum. If so, which model, and how the failed lamp looks like? > > Was there any attempts to "rejuvenate" the lamp? (for example, heating > > to remove glass darkening, if any, or similar experiments). > > > > By the way, I'm very curious about physical process that may cause > > lamp degradation. > > > > Rubidium-87 that is included in the lamp (according to > > manuals) is a radionuclide, beta emitter. It decays very slowly (4.7 > > billion years half life) to stable Strontium-87, emitting 282.62keV > > electrons and (anti?)neutrino. I don't think that 87Rb decay may > > interfere with unit operation after tens of years, unless 87Sr is > > "poisonous" so much so it can interfere with lamp operation even in > > tiniest amounts. > > > > The only reference I located to date, is following article, that is > > not available to general public. It is hard to understand for me just > > from this abstract, does it specifically related to space environment > > factors, or it is something that may cause degradation of Rb clocks > > that is operated in average lab on Earth. ;) > > > > > >> A Mechanism of Rubidium Atomic Clock Degradation: Ring-Mode to > >> Red-Mode Transition in rf-Discharge Lamps > >> Camparo, J. Mackay, R. > >> Aerosp. Corp., El Segundo; > >> > >> > >> This paper appears in: Frequency Control Symposium, 2007 Joint with > >> the 21st European Frequency and Time Forum. IEEE International > >> Publication Date: May 29 2007-June 1 2007 > >> On page(s): 45-48 > >> Location: Geneva, > >> ISSN: 1075-6787 > >> ISBN: 978-1-4244-0647-0 > >> INSPEC Accession Number: 9805223 > >> Digital Object Identifier: 10.1109/FREQ.2007.4319027 > >> Current Version Published: 2007-10-01 > >> > >> > >> > >> > >> > >> Abstract > >> In the vapor-cell atomic clock, long-term stability can be > >> influenced by slow variations in the discharge lamp's output via the > >> light-shift effect. Additionally, over a multi-year mission lifetime > >> the lamp's aging can degrade its optical pumping efficiency. > >> Understanding the mechanism(s) that drives these changes is > >> particularly important for spacecraft devices, where the atomic > >> clocks are called upon to function continuously and reliably for > >> many years. Here, we consider the two well-known, but little > >> studied, modes associated with alkali rf-discharge lamp operation: > >> the ring mode and the red mode. Consistent with previous research, > >> we find that the ring mode is best for optical pumping, and that the > >> clock-signal amplitude degrades significantly when the lamp operates > >> in the red mode. Examining the emission spectrum as the lamp > >> transitions between these two modes, we show that the ring-mode to > >> red-mode transition is driven by radiation trapping within the lamp. > >> > > > > > > > > -------------- next part -------------- > A non-text attachment was scrubbed... > Name: EFRATOM Model FRS Lamp assembly repair.pdf > Type: application/pdf > Size: 59765 bytes > Desc: not available > Url : > http://www.febo.com/pipermail/time-nuts/attachments/20081103/c205b683/attachment.pdf > > ------------------------------ > > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > End of time-nuts Digest, Vol 52, Issue 8 > **************************************** > _______________________________________________ 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.