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. -- Sincerely, Yuri UA3ATQ/KI7XJ mailto:[EMAIL PROTECTED] _______________________________________________ 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.